chore: initial commit

.editorconfig

@@ -0,0 +1,389 @@
+root = true
+
+# All files
+[*]
+indent_style = space
+
+# Xml files
+[*.xml]
+indent_size = 2
+
+# Xml project files
+[*.{csproj,fsproj,vbproj,proj,slnx}]
+indent_size = 2
+
+# Xml config files
+[*.{props,targets,config,nuspec}]
+indent_size = 2
+
+[*.json]
+indent_size = 2
+
+# C# files
+[*.cs]
+
+#### Core EditorConfig Options ####
+
+# Indentation and spacing
+indent_size = 2
+tab_width = 2
+
+# New line preferences
+insert_final_newline = false
+
+#### .NET Coding Conventions ####
+[*.{cs,vb}]
+
+# Organize usings
+dotnet_separate_import_directive_groups = true
+dotnet_sort_system_directives_first = true
+file_header_template = unset
+
+# this. and Me. preferences
+dotnet_style_qualification_for_event = false:silent
+dotnet_style_qualification_for_field = false:silent
+dotnet_style_qualification_for_method = false:silent
+dotnet_style_qualification_for_property = false:silent
+
+# Language keywords vs BCL types preferences
+dotnet_style_predefined_type_for_locals_parameters_members = true:silent
+dotnet_style_predefined_type_for_member_access = true:silent
+
+# Parentheses preferences
+dotnet_style_parentheses_in_arithmetic_binary_operators = always_for_clarity:silent
+dotnet_style_parentheses_in_other_binary_operators = always_for_clarity:silent
+dotnet_style_parentheses_in_other_operators = never_if_unnecessary:silent
+dotnet_style_parentheses_in_relational_binary_operators = always_for_clarity:silent
+
+# Modifier preferences
+dotnet_style_require_accessibility_modifiers = for_non_interface_members:silent
+
+# Expression-level preferences
+dotnet_style_coalesce_expression = true:suggestion
+dotnet_style_collection_initializer = true:suggestion
+dotnet_style_explicit_tuple_names = true:suggestion
+dotnet_style_namespace_match_folder = true:suggestion
+dotnet_style_null_propagation = true:suggestion
+dotnet_style_object_initializer = true:suggestion
+dotnet_style_operator_placement_when_wrapping = beginning_of_line
+dotnet_style_prefer_auto_properties = true:suggestion
+dotnet_style_prefer_collection_expression = when_types_loosely_match:suggestion
+dotnet_style_prefer_compound_assignment = true:suggestion
+dotnet_style_prefer_conditional_expression_over_assignment = true:suggestion
+dotnet_style_prefer_conditional_expression_over_return = true:suggestion
+dotnet_style_prefer_foreach_explicit_cast_in_source = when_strongly_typed:suggestion
+dotnet_style_prefer_inferred_anonymous_type_member_names = true:suggestion
+dotnet_style_prefer_inferred_tuple_names = true:suggestion
+dotnet_style_prefer_is_null_check_over_reference_equality_method = true:suggestion
+dotnet_style_prefer_simplified_boolean_expressions = true:suggestion
+dotnet_style_prefer_simplified_interpolation = true:suggestion
+
+# Field preferences
+dotnet_style_readonly_field = true:warning
+
+# Parameter preferences
+dotnet_code_quality_unused_parameters = all:suggestion
+
+# Suppression preferences
+dotnet_remove_unnecessary_suppression_exclusions = none
+
+#### C# Coding Conventions ####
+[*.cs]
+
+# var preferences
+csharp_style_var_elsewhere = false:silent
+csharp_style_var_for_built_in_types = false:silent
+csharp_style_var_when_type_is_apparent = false:silent
+
+# Expression-bodied members
+csharp_style_expression_bodied_accessors = true:silent
+csharp_style_expression_bodied_constructors = false:silent
+csharp_style_expression_bodied_indexers = true:silent
+csharp_style_expression_bodied_lambdas = true:suggestion
+csharp_style_expression_bodied_local_functions = false:silent
+csharp_style_expression_bodied_methods = false:silent
+csharp_style_expression_bodied_operators = false:silent
+csharp_style_expression_bodied_properties = true:silent
+
+# Pattern matching preferences
+csharp_style_pattern_matching_over_as_with_null_check = true:suggestion
+csharp_style_pattern_matching_over_is_with_cast_check = true:suggestion
+csharp_style_prefer_extended_property_pattern = true:suggestion
+csharp_style_prefer_not_pattern = true:suggestion
+csharp_style_prefer_pattern_matching = true:silent
+csharp_style_prefer_switch_expression = true:suggestion
+
+# Null-checking preferences
+csharp_style_conditional_delegate_call = true:suggestion
+
+# Modifier preferences
+csharp_prefer_static_anonymous_function = true:suggestion
+csharp_prefer_static_local_function = true:warning
+csharp_preferred_modifier_order = public,private,protected,internal,file,const,static,extern,new,virtual,abstract,sealed,override,readonly,unsafe,required,volatile,async:suggestion
+csharp_style_prefer_readonly_struct = true:suggestion
+csharp_style_prefer_readonly_struct_member = true:suggestion
+
+# Code-block preferences
+csharp_prefer_braces = true:silent
+csharp_prefer_simple_using_statement = true:suggestion
+csharp_style_namespace_declarations = file_scoped:suggestion
+csharp_style_prefer_method_group_conversion = true:silent
+csharp_style_prefer_primary_constructors = true:suggestion
+csharp_style_prefer_top_level_statements = true:silent
+
+# Expression-level preferences
+csharp_prefer_simple_default_expression = true:suggestion
+csharp_style_deconstructed_variable_declaration = true:suggestion
+csharp_style_implicit_object_creation_when_type_is_apparent = true:suggestion
+csharp_style_inlined_variable_declaration = true:suggestion
+csharp_style_prefer_index_operator = true:suggestion
+csharp_style_prefer_local_over_anonymous_function = true:suggestion
+csharp_style_prefer_null_check_over_type_check = true:suggestion
+csharp_style_prefer_range_operator = true:suggestion
+csharp_style_prefer_tuple_swap = true:suggestion
+csharp_style_prefer_utf8_string_literals = true:suggestion
+csharp_style_throw_expression = true:suggestion
+csharp_style_unused_value_assignment_preference = discard_variable:suggestion
+csharp_style_unused_value_expression_statement_preference = discard_variable:silent
+
+# 'using' directive preferences
+csharp_using_directive_placement = outside_namespace:silent
+
+#### C# Formatting Rules ####
+
+# New line preferences
+csharp_new_line_before_catch = true
+csharp_new_line_before_else = true
+csharp_new_line_before_finally = true
+csharp_new_line_before_members_in_anonymous_types = true
+csharp_new_line_before_members_in_object_initializers = true
+csharp_new_line_before_open_brace = all
+csharp_new_line_between_query_expression_clauses = true
+
+# Indentation preferences
+csharp_indent_block_contents = true
+csharp_indent_braces = false
+csharp_indent_case_contents = true
+csharp_indent_case_contents_when_block = true
+csharp_indent_labels = one_less_than_current
+csharp_indent_switch_labels = true
+
+# Space preferences
+csharp_space_after_cast = false
+csharp_space_after_colon_in_inheritance_clause = true
+csharp_space_after_comma = true
+csharp_space_after_dot = false
+csharp_space_after_keywords_in_control_flow_statements = true
+csharp_space_after_semicolon_in_for_statement = true
+csharp_space_around_binary_operators = before_and_after
+csharp_space_around_declaration_statements = false
+csharp_space_before_colon_in_inheritance_clause = true
+csharp_space_before_comma = false
+csharp_space_before_dot = false
+csharp_space_before_open_square_brackets = false
+csharp_space_before_semicolon_in_for_statement = false
+csharp_space_between_empty_square_brackets = false
+csharp_space_between_method_call_empty_parameter_list_parentheses = false
+csharp_space_between_method_call_name_and_opening_parenthesis = false
+csharp_space_between_method_call_parameter_list_parentheses = false
+csharp_space_between_method_declaration_empty_parameter_list_parentheses = false
+csharp_space_between_method_declaration_name_and_open_parenthesis = false
+csharp_space_between_method_declaration_parameter_list_parentheses = false
+csharp_space_between_parentheses = false
+csharp_space_between_square_brackets = false
+
+# Wrapping preferences
+csharp_preserve_single_line_blocks = true
+csharp_preserve_single_line_statements = true
+
+#### Naming styles ####
+[*.{cs,vb}]
+
+# Naming rules
+
+dotnet_naming_rule.types_and_namespaces_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.types_and_namespaces_should_be_pascalcase.symbols = types_and_namespaces
+dotnet_naming_rule.types_and_namespaces_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.interfaces_should_be_ipascalcase.severity = suggestion
+dotnet_naming_rule.interfaces_should_be_ipascalcase.symbols = interfaces
+dotnet_naming_rule.interfaces_should_be_ipascalcase.style = ipascalcase
+
+dotnet_naming_rule.type_parameters_should_be_tpascalcase.severity = suggestion
+dotnet_naming_rule.type_parameters_should_be_tpascalcase.symbols = type_parameters
+dotnet_naming_rule.type_parameters_should_be_tpascalcase.style = tpascalcase
+
+dotnet_naming_rule.methods_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.methods_should_be_pascalcase.symbols = methods
+dotnet_naming_rule.methods_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.properties_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.properties_should_be_pascalcase.symbols = properties
+dotnet_naming_rule.properties_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.events_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.events_should_be_pascalcase.symbols = events
+dotnet_naming_rule.events_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.local_variables_should_be_camelcase.severity = suggestion
+dotnet_naming_rule.local_variables_should_be_camelcase.symbols = local_variables
+dotnet_naming_rule.local_variables_should_be_camelcase.style = camelcase
+
+dotnet_naming_rule.local_constants_should_be_camelcase.severity = suggestion
+dotnet_naming_rule.local_constants_should_be_camelcase.symbols = local_constants
+dotnet_naming_rule.local_constants_should_be_camelcase.style = camelcase
+
+dotnet_naming_rule.parameters_should_be_camelcase.severity = suggestion
+dotnet_naming_rule.parameters_should_be_camelcase.symbols = parameters
+dotnet_naming_rule.parameters_should_be_camelcase.style = camelcase
+
+dotnet_naming_rule.public_fields_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.public_fields_should_be_pascalcase.symbols = public_fields
+dotnet_naming_rule.public_fields_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.private_fields_should_be__camelcase.severity = suggestion
+dotnet_naming_rule.private_fields_should_be__camelcase.symbols = private_fields
+dotnet_naming_rule.private_fields_should_be__camelcase.style = _camelcase
+
+dotnet_naming_rule.private_static_fields_should_be_s_camelcase.severity = suggestion
+dotnet_naming_rule.private_static_fields_should_be_s_camelcase.symbols = private_static_fields
+dotnet_naming_rule.private_static_fields_should_be_s_camelcase.style = s_camelcase
+
+dotnet_naming_rule.public_constant_fields_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.public_constant_fields_should_be_pascalcase.symbols = public_constant_fields
+dotnet_naming_rule.public_constant_fields_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.private_constant_fields_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.private_constant_fields_should_be_pascalcase.symbols = private_constant_fields
+dotnet_naming_rule.private_constant_fields_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.public_static_readonly_fields_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.public_static_readonly_fields_should_be_pascalcase.symbols = public_static_readonly_fields
+dotnet_naming_rule.public_static_readonly_fields_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.private_static_readonly_fields_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.private_static_readonly_fields_should_be_pascalcase.symbols = private_static_readonly_fields
+dotnet_naming_rule.private_static_readonly_fields_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.enums_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.enums_should_be_pascalcase.symbols = enums
+dotnet_naming_rule.enums_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.local_functions_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.local_functions_should_be_pascalcase.symbols = local_functions
+dotnet_naming_rule.local_functions_should_be_pascalcase.style = pascalcase
+
+dotnet_naming_rule.non_field_members_should_be_pascalcase.severity = suggestion
+dotnet_naming_rule.non_field_members_should_be_pascalcase.symbols = non_field_members
+dotnet_naming_rule.non_field_members_should_be_pascalcase.style = pascalcase
+
+# Symbol specifications
+
+dotnet_naming_symbols.interfaces.applicable_kinds = interface
+dotnet_naming_symbols.interfaces.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.interfaces.required_modifiers = 
+
+dotnet_naming_symbols.enums.applicable_kinds = enum
+dotnet_naming_symbols.enums.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.enums.required_modifiers = 
+
+dotnet_naming_symbols.events.applicable_kinds = event
+dotnet_naming_symbols.events.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.events.required_modifiers = 
+
+dotnet_naming_symbols.methods.applicable_kinds = method
+dotnet_naming_symbols.methods.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.methods.required_modifiers = 
+
+dotnet_naming_symbols.properties.applicable_kinds = property
+dotnet_naming_symbols.properties.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.properties.required_modifiers = 
+
+dotnet_naming_symbols.public_fields.applicable_kinds = field
+dotnet_naming_symbols.public_fields.applicable_accessibilities = public, internal
+dotnet_naming_symbols.public_fields.required_modifiers = 
+
+dotnet_naming_symbols.private_fields.applicable_kinds = field
+dotnet_naming_symbols.private_fields.applicable_accessibilities = private, protected, protected_internal, private_protected
+dotnet_naming_symbols.private_fields.required_modifiers = 
+
+dotnet_naming_symbols.private_static_fields.applicable_kinds = field
+dotnet_naming_symbols.private_static_fields.applicable_accessibilities = private, protected, protected_internal, private_protected
+dotnet_naming_symbols.private_static_fields.required_modifiers = static
+
+dotnet_naming_symbols.types_and_namespaces.applicable_kinds = namespace, class, struct, interface, enum
+dotnet_naming_symbols.types_and_namespaces.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.types_and_namespaces.required_modifiers = 
+
+dotnet_naming_symbols.non_field_members.applicable_kinds = property, event, method
+dotnet_naming_symbols.non_field_members.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.non_field_members.required_modifiers = 
+
+dotnet_naming_symbols.type_parameters.applicable_kinds = namespace
+dotnet_naming_symbols.type_parameters.applicable_accessibilities = *
+dotnet_naming_symbols.type_parameters.required_modifiers = 
+
+dotnet_naming_symbols.private_constant_fields.applicable_kinds = field
+dotnet_naming_symbols.private_constant_fields.applicable_accessibilities = private, protected, protected_internal, private_protected
+dotnet_naming_symbols.private_constant_fields.required_modifiers = const
+
+dotnet_naming_symbols.local_variables.applicable_kinds = local
+dotnet_naming_symbols.local_variables.applicable_accessibilities = local
+dotnet_naming_symbols.local_variables.required_modifiers = 
+
+dotnet_naming_symbols.local_constants.applicable_kinds = local
+dotnet_naming_symbols.local_constants.applicable_accessibilities = local
+dotnet_naming_symbols.local_constants.required_modifiers = const
+
+dotnet_naming_symbols.parameters.applicable_kinds = parameter
+dotnet_naming_symbols.parameters.applicable_accessibilities = *
+dotnet_naming_symbols.parameters.required_modifiers = 
+
+dotnet_naming_symbols.public_constant_fields.applicable_kinds = field
+dotnet_naming_symbols.public_constant_fields.applicable_accessibilities = public, internal
+dotnet_naming_symbols.public_constant_fields.required_modifiers = const
+
+dotnet_naming_symbols.public_static_readonly_fields.applicable_kinds = field
+dotnet_naming_symbols.public_static_readonly_fields.applicable_accessibilities = public, internal
+dotnet_naming_symbols.public_static_readonly_fields.required_modifiers = readonly, static
+
+dotnet_naming_symbols.private_static_readonly_fields.applicable_kinds = field
+dotnet_naming_symbols.private_static_readonly_fields.applicable_accessibilities = private, protected, protected_internal, private_protected
+dotnet_naming_symbols.private_static_readonly_fields.required_modifiers = readonly, static
+
+dotnet_naming_symbols.local_functions.applicable_kinds = local_function
+dotnet_naming_symbols.local_functions.applicable_accessibilities = *
+dotnet_naming_symbols.local_functions.required_modifiers = 
+
+# Naming styles
+
+dotnet_naming_style.pascalcase.required_prefix = 
+dotnet_naming_style.pascalcase.required_suffix = 
+dotnet_naming_style.pascalcase.word_separator = 
+dotnet_naming_style.pascalcase.capitalization = pascal_case
+
+dotnet_naming_style.ipascalcase.required_prefix = I
+dotnet_naming_style.ipascalcase.required_suffix = 
+dotnet_naming_style.ipascalcase.word_separator = 
+dotnet_naming_style.ipascalcase.capitalization = pascal_case
+
+dotnet_naming_style.tpascalcase.required_prefix = T
+dotnet_naming_style.tpascalcase.required_suffix = 
+dotnet_naming_style.tpascalcase.word_separator = 
+dotnet_naming_style.tpascalcase.capitalization = pascal_case
+
+dotnet_naming_style._camelcase.required_prefix = _
+dotnet_naming_style._camelcase.required_suffix = 
+dotnet_naming_style._camelcase.word_separator = 
+dotnet_naming_style._camelcase.capitalization = camel_case
+
+dotnet_naming_style.camelcase.required_prefix = 
+dotnet_naming_style.camelcase.required_suffix = 
+dotnet_naming_style.camelcase.word_separator = 
+dotnet_naming_style.camelcase.capitalization = camel_case
+
+dotnet_naming_style.s_camelcase.required_prefix = s_
+dotnet_naming_style.s_camelcase.required_suffix = 
+dotnet_naming_style.s_camelcase.word_separator = 
+dotnet_naming_style.s_camelcase.capitalization = camel_case
+

.gitignore

@@ -0,0 +1,490 @@
+## Ignore Visual Studio temporary files, build results, and
+## files generated by popular Visual Studio add-ons.
+##
+## Get latest from `dotnet new gitignore`
+
+# appsettings
+appsettings*.json
+
+# dotenv files
+.env
+
+# User-specific files
+*.rsuser
+*.suo
+*.user
+*.userosscache
+*.sln.docstates
+
+# User-specific files (MonoDevelop/Xamarin Studio)
+*.userprefs
+
+# Mono auto generated files
+mono_crash.*
+
+# Build results
+[Dd]ebug/
+[Dd]ebugPublic/
+[Rr]elease/
+[Rr]eleases/
+x64/
+x86/
+[Ww][Ii][Nn]32/
+[Aa][Rr][Mm]/
+[Aa][Rr][Mm]64/
+bld/
+[Bb]in/
+[Oo]bj/
+[Ll]og/
+[Ll]ogs/
+
+# Visual Studio 2015/2017 cache/options directory
+.vs/
+# Uncomment if you have tasks that create the project's static files in wwwroot
+#wwwroot/
+
+# Visual Studio 2017 auto generated files
+Generated\ Files/
+
+# MSTest test Results
+[Tt]est[Rr]esult*/
+[Bb]uild[Ll]og.*
+
+# NUnit
+*.VisualState.xml
+TestResult.xml
+nunit-*.xml
+
+# Build Results of an ATL Project
+[Dd]ebugPS/
+[Rr]eleasePS/
+dlldata.c
+
+# Benchmark Results
+BenchmarkDotNet.Artifacts/
+
+# .NET
+project.lock.json
+project.fragment.lock.json
+artifacts/
+
+# Tye
+.tye/
+
+# ASP.NET Scaffolding
+ScaffoldingReadMe.txt
+
+# StyleCop
+StyleCopReport.xml
+
+# Files built by Visual Studio
+*_i.c
+*_p.c
+*_h.h
+*.ilk
+*.meta
+*.obj
+*.iobj
+*.pch
+*.pdb
+*.ipdb
+*.pgc
+*.pgd
+*.rsp
+# but not Directory.Build.rsp, as it configures directory-level build defaults
+!Directory.Build.rsp
+*.sbr
+*.tlb
+*.tli
+*.tlh
+*.tmp
+*.tmp_proj
+*_wpftmp.csproj
+*.log
+*.tlog
+*.vspscc
+*.vssscc
+.builds
+*.pidb
+*.svclog
+*.scc
+
+# Chutzpah Test files
+_Chutzpah*
+
+# Visual C++ cache files
+ipch/
+*.aps
+*.ncb
+*.opendb
+*.opensdf
+*.sdf
+*.cachefile
+*.VC.db
+*.VC.VC.opendb
+
+# Visual Studio profiler
+*.psess
+*.vsp
+*.vspx
+*.sap
+
+# Visual Studio Trace Files
+*.e2e
+# but not directories ending in .e2e
+!*.e2e/
+
+# TFS 2012 Local Workspace
+$tf/
+
+# Guidance Automation Toolkit
+*.gpState
+
+# ReSharper is a .NET coding add-in
+_ReSharper*/
+*.[Rr]e[Ss]harper
+*.DotSettings.user
+
+# TeamCity is a build add-in
+_TeamCity*
+
+# DotCover is a Code Coverage Tool
+*.dotCover
+
+# AxoCover is a Code Coverage Tool
+.axoCover/*
+!.axoCover/settings.json
+
+# Coverlet is a free, cross platform Code Coverage Tool
+coverage*.json
+coverage*.xml
+coverage*.info
+
+# Visual Studio code coverage results
+*.coverage
+*.coveragexml
+
+# NCrunch
+_NCrunch_*
+.*crunch*.local.xml
+nCrunchTemp_*
+
+# MightyMoose
+*.mm.*
+AutoTest.Net/
+
+# Web workbench (sass)
+.sass-cache/
+
+# Installshield output folder
+[Ee]xpress/
+
+# DocProject is a documentation generator add-in
+DocProject/buildhelp/
+DocProject/Help/*.HxT
+DocProject/Help/*.HxC
+DocProject/Help/*.hhc
+DocProject/Help/*.hhk
+DocProject/Help/*.hhp
+DocProject/Help/Html2
+DocProject/Help/html
+
+# Click-Once directory
+publish/
+
+# Publish Web Output
+*.[Pp]ublish.xml
+*.azurePubxml
+# Note: Comment the next line if you want to checkin your web deploy settings,
+# but database connection strings (with potential passwords) will be unencrypted
+*.pubxml
+*.publishproj
+
+# Microsoft Azure Web App publish settings. Comment the next line if you want to
+# checkin your Azure Web App publish settings, but sensitive information contained
+# in these scripts will be unencrypted
+PublishScripts/
+
+# NuGet Packages
+*.nupkg
+# NuGet Symbol Packages
+*.snupkg
+# The packages folder can be ignored because of Package Restore
+**/[Pp]ackages/*
+# except build/, which is used as an MSBuild target.
+!**/[Pp]ackages/build/
+# Uncomment if necessary however generally it will be regenerated when needed
+#!**/[Pp]ackages/repositories.config
+# NuGet v3's project.json files produces more ignorable files
+*.nuget.props
+*.nuget.targets
+
+# Microsoft Azure Build Output
+csx/
+*.build.csdef
+
+# Microsoft Azure Emulator
+ecf/
+rcf/
+
+# Windows Store app package directories and files
+AppPackages/
+BundleArtifacts/
+Package.StoreAssociation.xml
+_pkginfo.txt
+*.appx
+*.appxbundle
+*.appxupload
+
+# Visual Studio cache files
+# files ending in .cache can be ignored
+*.[Cc]ache
+# but keep track of directories ending in .cache
+!?*.[Cc]ache/
+
+# Others
+ClientBin/
+~$*
+*~
+*.dbmdl
+*.dbproj.schemaview
+*.jfm
+*.pfx
+*.publishsettings
+orleans.codegen.cs
+
+# Including strong name files can present a security risk
+# (https://github.com/github/gitignore/pull/2483#issue-259490424)
+#*.snk
+
+# Since there are multiple workflows, uncomment next line to ignore bower_components
+# (https://github.com/github/gitignore/pull/1529#issuecomment-104372622)
+#bower_components/
+
+# RIA/Silverlight projects
+Generated_Code/
+
+# Backup & report files from converting an old project file
+# to a newer Visual Studio version. Backup files are not needed,
+# because we have git ;-)
+_UpgradeReport_Files/
+Backup*/
+UpgradeLog*.XML
+UpgradeLog*.htm
+ServiceFabricBackup/
+*.rptproj.bak
+
+# SQL Server files
+*.mdf
+*.ldf
+*.ndf
+
+# Business Intelligence projects
+*.rdl.data
+*.bim.layout
+*.bim_*.settings
+*.rptproj.rsuser
+*- [Bb]ackup.rdl
+*- [Bb]ackup ([0-9]).rdl
+*- [Bb]ackup ([0-9][0-9]).rdl
+
+# Microsoft Fakes
+FakesAssemblies/
+
+# GhostDoc plugin setting file
+*.GhostDoc.xml
+
+# Node.js Tools for Visual Studio
+.ntvs_analysis.dat
+node_modules/
+
+# Visual Studio 6 build log
+*.plg
+
+# Visual Studio 6 workspace options file
+*.opt
+
+# Visual Studio 6 auto-generated workspace file (contains which files were open etc.)
+*.vbw
+
+# Visual Studio 6 auto-generated project file (contains which files were open etc.)
+*.vbp
+
+# Visual Studio 6 workspace and project file (working project files containing files to include in project)
+*.dsw
+*.dsp
+
+# Visual Studio 6 technical files
+*.ncb
+*.aps
+
+# Visual Studio LightSwitch build output
+**/*.HTMLClient/GeneratedArtifacts
+**/*.DesktopClient/GeneratedArtifacts
+**/*.DesktopClient/ModelManifest.xml
+**/*.Server/GeneratedArtifacts
+**/*.Server/ModelManifest.xml
+_Pvt_Extensions
+
+# Paket dependency manager
+.paket/paket.exe
+paket-files/
+
+# FAKE - F# Make
+.fake/
+
+# CodeRush personal settings
+.cr/personal
+
+# Python Tools for Visual Studio (PTVS)
+__pycache__/
+*.pyc
+
+# Cake - Uncomment if you are using it
+# tools/**
+# !tools/packages.config
+
+# Tabs Studio
+*.tss
+
+# Telerik's JustMock configuration file
+*.jmconfig
+
+# BizTalk build output
+*.btp.cs
+*.btm.cs
+*.odx.cs
+*.xsd.cs
+
+# OpenCover UI analysis results
+OpenCover/
+
+# Azure Stream Analytics local run output
+ASALocalRun/
+
+# MSBuild Binary and Structured Log
+*.binlog
+
+# NVidia Nsight GPU debugger configuration file
+*.nvuser
+
+# MFractors (Xamarin productivity tool) working folder
+.mfractor/
+
+# Local History for Visual Studio
+.localhistory/
+
+# Visual Studio History (VSHistory) files
+.vshistory/
+
+# BeatPulse healthcheck temp database
+healthchecksdb
+
+# Backup folder for Package Reference Convert tool in Visual Studio 2017
+MigrationBackup/
+
+# Ionide (cross platform F# VS Code tools) working folder
+.ionide/
+
+# Fody - auto-generated XML schema
+FodyWeavers.xsd
+
+# VS Code files for those working on multiple tools
+.vscode/*
+!.vscode/settings.json
+!.vscode/tasks.json
+!.vscode/launch.json
+!.vscode/extensions.json
+*.code-workspace
+
+# Official VS Code C# Dev Kit Extension exclusion
+*.lscache
+
+# Local History for Visual Studio Code
+.history/
+
+# Windows Installer files from build outputs
+*.cab
+*.msi
+*.msix
+*.msm
+*.msp
+
+# JetBrains Rider
+*.sln.iml
+.idea/
+
+##
+## Visual studio for Mac
+##
+
+
+# globs
+Makefile.in
+*.userprefs
+*.usertasks
+config.make
+config.status
+aclocal.m4
+install-sh
+autom4te.cache/
+*.tar.gz
+tarballs/
+test-results/
+
+# content below from: https://github.com/github/gitignore/blob/main/Global/macOS.gitignore
+# General
+.DS_Store
+.AppleDouble
+.LSOverride
+
+# Icon must end with two \r
+Icon
+
+
+# Thumbnails
+._*
+
+# Files that might appear in the root of a volume
+.DocumentRevisions-V100
+.fseventsd
+.Spotlight-V100
+.TemporaryItems
+.Trashes
+.VolumeIcon.icns
+.com.apple.timemachine.donotpresent
+
+# Directories potentially created on remote AFP share
+.AppleDB
+.AppleDesktop
+Network Trash Folder
+Temporary Items
+.apdisk
+
+# content below from: https://github.com/github/gitignore/blob/main/Global/Windows.gitignore
+# Windows thumbnail cache files
+Thumbs.db
+ehthumbs.db
+ehthumbs_vista.db
+
+# Dump file
+*.stackdump
+
+# Folder config file
+[Dd]esktop.ini
+
+# Recycle Bin used on file shares
+$RECYCLE.BIN/
+
+# Windows Installer files
+*.cab
+*.msi
+*.msix
+*.msm
+*.msp
+
+# Windows shortcuts
+*.lnk
+
+# Vim temporary swap files
+*.swp

LICENSE.md

@@ -0,0 +1,19 @@
+Copyright (c) 2026 Stevan Freeborn
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,64 @@
+# Chunked & Resumable File Upload Example
+
+This is a reference implementation for chunked, parallel, and resumable file uploads using a minimal API and vanilla JavaScript.
+
+The implementation was developed within the constraints of using on-premise local disk storage hosted behind a reverse proxy with payload size limits that would otherwise prevent handling large file uploads.
+
+## Architecture
+
+The storage is designed around direct random-access offset writing. As data chunks arrive, they are written directly into a single `upload.part` file using `FileShare.ReadWrite`. The exact byte position of each chunk is calculated using `offset = index * chunkSize`. This removes double-storage overhead by avoiding temporary file duplication and reassembly on disk.
+
+This approach makes file assembly basically instant. Finalizing a file takes less than 1 ms and operates with O(1) time complexity because the server only needs to atomically rename `upload.part` to its destination name using `File.Move`. This eliminates the need for background worker services, disk-copying loops, or complex progress-tracking channels between the server and client.
+
+To guarantee end-to-end data integrity across parallel chunk transmissions, the program uses a two-tiered SHA-256 verification model alongside deterministic session hashing:
+
+- **Per-Chunk Verification**: On the client, SHA-256 hashes are calculated lazily for each chunk right before transmission using `crypto.subtle.digest`. Upon receipt, the server streams the chunk payload, independently computes its SHA-256 digest, and validates it against the client's hash using constant-time byte comparison (`CryptographicOperations.FixedTimeEquals`). Once validated, the chunk is written to disk alongside a `{index}-{hash}.done` marker file.
+- **Composite End-to-End File Verification**: When all chunks finish uploading, the client orders the individual chunk hashes, joins them into a comma-separated string (`hash_0,hash_1,..., hash_n-1`), and computes a final composite SHA-256 hash. When `/Files/{fileId}/complete` is invoked, the server independently recalculates the composite hash from its stored `.done` marker files. The atomic `File.Move` rename executes only if the composite hashes match, guaranteeing that no chunks were corrupted, omitted, or reassembled out of sequence.
+- **Deterministic Session Identification**: The session `fileId` is created by hashing the file's primary metadata (`name-size-lastModified`) into a standard GUID string. This ensures that re-selecting an interrupted file produces the exact same session key, allowing the program to query existing `.done` markers and resume uploading without starting over.
+
+On the client, concurrency is controlled through a worker pool to prevent browser socket exhaustion. The client performs lazy hashing by calculating SHA-256 hashes on-the-fly right before each chunk is transmitted, keeping main thread memory usage low and the UI responsive.
+
+Once files are successfully uploaded, the program supports immediate media range streaming. The `GET /Files/{fileId}/download` endpoint enables HTTP Range processing, allowing users to stream audio/video or view files directly within browser tabs without downloading the entire file first.
+
+> [!NOTE]
+> The program is packaged as a standalone, single-file native executable using **.NET Native AOT compilation**. All static web assets (HTML, JavaScript, CSS) are embedded directly into the executable via `ManifestEmbeddedFileProvider`. To maintain compatibility with AOT compilation, the program relies on reflection-free `System.Text.Json` source generation.
+
+## How It Works
+
+- **Session Initialization (`POST /Files/{fileId}`)**: Client computes a GUID from the file's metadata and requests a session. Returns `200 OK` for new uploads or `409 Conflict` if a session already exists.
+- **Resumability Check (`GET /Files/{fileId}/status`)**: Server scans for existing `{index}-{hash}.done` marker files and returns an array of completed chunk indices.
+- **Parallel Chunk Uploads (`POST /Files/{fileId}/upload`)**: Worker pool sends chunks concurrently. Chunks are verified against their SHA-256 hash and written asynchronously into `upload.part` at `index * chunkSize`.
+- **Completion (`POST /Files/{fileId}/complete`)**: Server validates the composite hash of all completed chunks and renames `upload.part` to the final filename.
+- **Retrieval (`GET /Files/{fileId}/download`)**: Serves the finalized file with full HTTP Range request support for playback or viewing.
+
+## Building and Running
+
+### Development Mode
+
+Run the project directly using the .NET SDK:
+
+```powershell
+dotnet run --project .\src\
+```
+
+### Publish as a Single-File Native AOT Executable
+
+Compile the program into a single, self-contained native binary:
+
+```powershell
+# Windows
+dotnet publish .\src\ -c Release -r win-x64
+dotnet publish .\src\ -c Release -r win-arm64
+
+# Linux
+dotnet publish ./src/ -c Release -r linux-x64
+dotnet publish ./src/ -c Release -r linux-arm64
+
+# macOS
+dotnet publish ./src/ -c Release -r osx-arm64
+dotnet publish ./src/ -c Release -r osx-x64
+```
+
+The output binary will be located in:
+
+`.\src\bin\Release\net11.0\<runtime>\publish\`

src/ChunkedUploadExample.csproj

@@ -0,0 +1,20 @@
+<Project Sdk="Microsoft.NET.Sdk.Web">
+
+  <PropertyGroup>
+    <TargetFramework>net11.0</TargetFramework>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <PublishAot>true</PublishAot>
+    <GenerateEmbeddedFilesManifest>true</GenerateEmbeddedFilesManifest>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.FileProviders.Embedded" Version="10.0.11" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Content Remove="wwwroot\**\*" />
+    <EmbeddedResource Include="wwwroot\**\*" />
+  </ItemGroup>
+
+</Project>

src/Program.cs

@@ -0,0 +1,286 @@
+using System.Security.Cryptography;
+using System.Text;
+using System.Text.Json.Serialization;
+
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.StaticFiles;
+using Microsoft.Extensions.FileProviders;
+
+var builder = WebApplication.CreateBuilder(args);
+
+builder.Services.ConfigureHttpJsonOptions(
+  options => options.SerializerOptions.TypeInfoResolverChain.Insert(0, AppJsonContext.Default)
+);
+
+builder.Services.AddSingleton<FileService>();
+
+builder.Services.AddProblemDetails();
+
+var app = builder.Build();
+var fileProvider = new ManifestEmbeddedFileProvider(typeof(Program).Assembly, "wwwroot");
+
+app.UseHttpsRedirection();
+
+app.UseDefaultFiles(new DefaultFilesOptions
+{
+  FileProvider = fileProvider,
+});
+
+app.UseStaticFiles(new StaticFileOptions
+{
+  FileProvider = fileProvider,
+});
+
+app.UseStatusCodePages();
+
+app.MapPost("/Files/{fileId}", (string fileId, FileService fileService) =>
+{
+  if (fileService.IsValidFileId(fileId) is false)
+  {
+    return Results.BadRequest("Invalid fileId.");
+  }
+
+  var fileDirectory = fileService.GetFileDirectory(fileId);
+
+  if (Directory.Exists(fileDirectory))
+  {
+    return Results.Conflict(new SessionResponse(fileId, "Session already exists, resuming upload."));
+  }
+
+  Directory.CreateDirectory(fileDirectory);
+
+  return Results.Ok(new SessionResponse(fileId, "New upload session created."));
+});
+
+app.MapGet("/Files/{fileId}/status", (string fileId, FileService fileService) =>
+{
+  if (fileService.IsValidFileId(fileId) is false)
+  {
+    return Results.BadRequest("Invalid fileId.");
+  }
+
+  var fileDirectory = fileService.GetFileDirectory(fileId);
+
+  if (Directory.Exists(fileDirectory) is false)
+  {
+    return Results.NotFound("Session not found.");
+  }
+
+  var uploadedChunks = Directory.GetFiles(fileDirectory, "*.done")
+    .Select(n =>
+    {
+      var parts = Path.GetFileNameWithoutExtension(n).Split('-');
+      return new ChunkStatusInfo(int.Parse(parts[0]), parts[1]);
+    })
+    .OrderBy(c => c.Index)
+    .ToList();
+
+  return Results.Ok(new SessionStatusResponse(fileId, uploadedChunks));
+});
+
+app.MapPost("/Files/{fileId}/upload", async (
+  string fileId,
+  IFormFile chunk,
+  [FromForm] int index,
+  [FromForm] long chunkSize,
+  [FromForm] string hash,
+  FileService fileService
+) =>
+{
+  if (fileService.IsValidFileId(fileId) is false)
+  {
+    return Results.BadRequest("Invalid fileId.");
+  }
+
+  var fileDirectory = fileService.GetFileDirectory(fileId);
+
+  if (Directory.Exists(fileDirectory) is false)
+  {
+    return Results.NotFound("Session not found.");
+  }
+
+  if (chunk.Length is 0 || chunk.Length > 10_000_000)
+  {
+    return Results.BadRequest("Invalid chunk length.");
+  }
+
+  if (index < 0 || chunkSize <= 0)
+  {
+    return Results.BadRequest("Invalid index or chunkSize.");
+  }
+
+  var markerFilePath = Path.Combine(fileDirectory, $"{index}-{hash}.done");
+
+  if (File.Exists(markerFilePath))
+  {
+    return Results.Ok(new ChunkUploadResponse(fileId, index, "already_exists"));
+  }
+
+  using var formStream = chunk.OpenReadStream();
+  var hashBytes = await SHA256.HashDataAsync(formStream);
+  var calculatedHash = Convert.ToHexString(hashBytes).ToLowerInvariant();
+
+  if (CryptographicOperations.FixedTimeEquals(Encoding.UTF8.GetBytes(calculatedHash), Encoding.UTF8.GetBytes(hash.ToLowerInvariant())) is false)
+  {
+    return Results.BadRequest("Chunk hash mismatch.");
+  }
+
+  var partFilePath = Path.Combine(fileDirectory, "upload.part");
+  long byteOffset = index * chunkSize;
+
+  var fileStreamOptions = new FileStreamOptions
+  {
+    Mode = FileMode.OpenOrCreate,
+    Access = FileAccess.Write,
+    Share = FileShare.ReadWrite,
+    BufferSize = 81920,
+    Options = FileOptions.Asynchronous
+  };
+
+  formStream.Position = 0;
+
+  using var targetStream = new FileStream(partFilePath, fileStreamOptions);
+  targetStream.Seek(byteOffset, SeekOrigin.Begin);
+  await formStream.CopyToAsync(targetStream);
+
+  await File.WriteAllTextAsync(markerFilePath, string.Empty);
+
+  return Results.Ok(new ChunkUploadResponse(fileId, index, "ok"));
+});
+
+app.MapPost("/Files/{fileId}/complete", (
+  string fileId,
+  FileCompleteRequest request,
+  FileService fileService
+) =>
+{
+  if (fileService.IsValidFileId(fileId) is false)
+  {
+    return Results.BadRequest("Invalid fileId.");
+  }
+
+  var fileDirectory = fileService.GetFileDirectory(fileId);
+
+  if (Directory.Exists(fileDirectory) is false)
+  {
+    return Results.NotFound();
+  }
+
+  var safeFilename = Path.GetFileName(request.Filename);
+  var partFilePath = Path.Combine(fileDirectory, "upload.part");
+  var finalFilePath = Path.Combine(fileDirectory, safeFilename);
+
+  if (File.Exists(partFilePath) is false)
+  {
+    return Results.BadRequest("No upload data found.");
+  }
+
+  var completedChunkHashes = Directory.GetFiles(fileDirectory, "*.done")
+    .Select(n =>
+    {
+      var parts = Path.GetFileNameWithoutExtension(n).Split('-');
+      return (Index: int.Parse(parts[0]), Hash: parts[1]);
+    })
+    .OrderBy(t => t.Index)
+    .Select(t => t.Hash);
+
+  var compositeHashBytes = SHA256.HashData(Encoding.UTF8.GetBytes(string.Join(',', completedChunkHashes)));
+  var compositeHash = Convert.ToHexString(compositeHashBytes).ToLowerInvariant();
+
+  if (CryptographicOperations.FixedTimeEquals(Encoding.UTF8.GetBytes(compositeHash), Encoding.UTF8.GetBytes(request.CompositeHash.ToLowerInvariant())) is false)
+  {
+    return Results.BadRequest("Composite hash mismatch.");
+  }
+
+  File.Move(partFilePath, finalFilePath, overwrite: true);
+
+  foreach (var marker in Directory.GetFiles(fileDirectory, "*.done"))
+  {
+    File.Delete(marker);
+  }
+
+  return Results.Ok(new CompleteResponse("complete", finalFilePath));
+});
+
+app.MapGet("/Files/{fileId}/download", (string fileId, FileService fileService) =>
+{
+  if (fileService.IsValidFileId(fileId) is false)
+  {
+    return Results.BadRequest("Invalid fileId.");
+  }
+
+  var fileDirectory = fileService.GetFileDirectory(fileId);
+
+  if (Directory.Exists(fileDirectory) is false)
+  {
+    return Results.NotFound("Session not found.");
+  }
+
+  var filePath = Directory.GetFiles(fileDirectory)
+    .FirstOrDefault(f => f.EndsWith(".done") is false && f.EndsWith(".part") is false);
+
+  if (filePath == null || File.Exists(filePath) is false)
+  {
+    return Results.NotFound("Assembled file not found.");
+  }
+
+  var fileName = Path.GetFileName(filePath);
+  var provider = new FileExtensionContentTypeProvider();
+
+  if (provider.TryGetContentType(fileName, out var contentType) is false)
+  {
+    contentType = "application/octet-stream";
+  }
+
+  return Results.File(filePath, contentType, enableRangeProcessing: true);
+});
+
+app.MapDelete("/Files/{fileId}", (string fileId, FileService fileService) =>
+{
+  if (fileService.IsValidFileId(fileId) is false)
+  {
+    return Results.BadRequest("Invalid fileId.");
+  }
+
+  var fileDirectory = fileService.GetFileDirectory(fileId);
+
+  if (Directory.Exists(fileDirectory) is false)
+  {
+    return Results.NotFound();
+  }
+
+  Directory.Delete(fileDirectory, true);
+
+  return Results.NoContent();
+});
+
+app.Run();
+
+record FileCompleteRequest(string Filename, string CompositeHash);
+record SessionResponse(string FileId, string Message);
+record ChunkStatusInfo(int Index, string Hash);
+record SessionStatusResponse(string FileId, List<ChunkStatusInfo> UploadedChunks);
+record ChunkUploadResponse(string FileId, int Index, string Status);
+record CompleteResponse(string Status, string Path);
+
+[JsonSerializable(typeof(FileCompleteRequest))]
+[JsonSerializable(typeof(SessionResponse))]
+[JsonSerializable(typeof(ChunkStatusInfo))]
+[JsonSerializable(typeof(SessionStatusResponse))]
+[JsonSerializable(typeof(ChunkUploadResponse))]
+[JsonSerializable(typeof(CompleteResponse))]
+internal partial class AppJsonContext : JsonSerializerContext
+{
+}
+
+internal class FileService
+{
+  public bool IsValidFileId(string fileId) => Guid.TryParse(fileId, out _);
+
+  public string GetFileDirectory(string fileId)
+  {
+    return IsValidFileId(fileId) is false
+      ? throw new ArgumentException("Invalid file ID", nameof(fileId))
+      : Path.Combine(AppContext.BaseDirectory, "Files", fileId);
+  }
+}

src/Properties/launchSettings.json

@@ -0,0 +1,23 @@
+{
+  "$schema": "https://json.schemastore.org/launchsettings.json",
+  "profiles": {
+    "https": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": false,
+      "applicationUrl": "https://localhost:7181;http://localhost:5009",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    },
+    "http": {
+      "commandName": "Project",
+      "dotnetRunMessages": true,
+      "launchBrowser": false,
+      "applicationUrl": "http://localhost:5009",
+      "environmentVariables": {
+        "ASPNETCORE_ENVIRONMENT": "Development"
+      }
+    }
+  }
+}

src/wwwroot/index.html

@@ -0,0 +1,41 @@
+<!doctype html>
+<html lang="en">
+
+<head>
+  <meta charset="UTF-8" />
+  <meta name="viewport" content="width=device-width, initial-scale=1" />
+  <title>Chunked Upload Example</title>
+  <link href="style.css" rel="stylesheet" />
+  <script src="index.js" type="module" defer></script>
+</head>
+
+<body>
+  <main>
+    <div>
+      <form>
+        <fieldset>
+          <label for="file">Upload File</label>
+          <input type="file" id="file" name="file" />
+        </fieldset>
+      </form>
+      <div id="fileDownload" class="hidden" style="margin-top: 1rem; margin-bottom: 1rem;">
+        <a id="downloadLink" href="#" target="_blank" rel="noopener noreferrer">
+          View / Download Assembled File
+        </a>
+      </div>
+    </div>
+    <div class="chunks">
+      <h3>File: <span id="fileId"><span></h3>
+      <div id="chunks-display">
+      </div>
+      <div id="fileStatus">
+        <div class="red-x hidden">❌</div>
+        <div class="checkmark hidden">✅</div>
+        <div class="spinner hidden"></div>
+        <div class="status"></div>
+      </div>
+    </div>
+  </main>
+</body>
+
+</html>

src/wwwroot/index.js

@@ -0,0 +1,240 @@
+document.addEventListener("DOMContentLoaded", () => {
+  const fileInputElement = document.getElementById("file");
+  const chunksDisplayElement = document.getElementById("chunks-display");
+  const fileIdElement = document.getElementById("fileId");
+  const fileStatusElement = document
+    .getElementById("fileStatus")
+    ?.querySelector(".status");
+  const fileRedXElement = document
+    .getElementById("fileStatus")
+    ?.querySelector(".red-x");
+  const fileCheckmarkElement = document
+    .getElementById("fileStatus")
+    ?.querySelector(".checkmark");
+  const fileSpinnerElement = document
+    .getElementById("fileStatus")
+    ?.querySelector(".spinner");
+
+  const fileDownloadElement = document.getElementById("fileDownload");
+  const downloadLinkElement = document.getElementById("downloadLink");
+
+  if (
+    !fileInputElement ||
+    !chunksDisplayElement ||
+    !fileIdElement ||
+    !fileStatusElement
+  ) {
+    throw new Error("Required DOM elements missing.");
+  }
+
+  fileInputElement.addEventListener("change", async function(e) {
+    const file = e?.target?.files?.item(0);
+
+    if (!file) {
+      return;
+    }
+
+    fileIdElement.innerText = "";
+    chunksDisplayElement.innerHTML = "";
+
+    if (fileDownloadElement) {
+      fileDownloadElement.classList.add("hidden");
+    }
+
+    if (downloadLinkElement) {
+      downloadLinkElement.href = "#";
+    }
+
+    const fileId = await generateDeterministicFileId(file);
+    fileIdElement.innerText = fileId;
+    fileSpinnerElement?.classList.remove("hidden");
+    fileRedXElement?.classList.add("hidden");
+    fileCheckmarkElement?.classList.add("hidden");
+    fileStatusElement.innerText = "Checking upload session...";
+
+    const createFileResponse = await fetch(`/files/${fileId}`, {
+      method: "POST",
+    });
+    let existingChunksMap = new Map();
+
+    if (createFileResponse.status === 409 || createFileResponse.ok) {
+      const statusRes = await fetch(`/Files/${fileId}/status`);
+
+      if (statusRes.ok) {
+        const statusData = await statusRes.json();
+
+        for (const item of statusData.uploadedChunks || []) {
+          existingChunksMap.set(item.index, item.hash);
+        }
+      }
+    } else {
+      fileSpinnerElement?.classList.add("hidden");
+      fileRedXElement?.classList.remove("hidden");
+      fileStatusElement.innerText = "Unable to create upload session";
+      return;
+    }
+
+    const CHUNK_SIZE = 8 * 1024 * 1024;
+    const totalChunks = Math.ceil(file.size / CHUNK_SIZE);
+    const chunkHashes = new Array(totalChunks);
+    const pendingIndices = [];
+
+    for (let index = 0; index < totalChunks; index++) {
+      const chunkElement = document.createElement("div");
+      const chunkId = `${fileId}-${index}`;
+      const isAlreadyUploaded = existingChunksMap.has(index);
+
+      if (isAlreadyUploaded) {
+        chunkHashes[index] = existingChunksMap.get(index);
+      } else {
+        pendingIndices.push(index);
+      }
+
+      chunkElement.innerHTML = `
+        <div id="${chunkId}" class="chunk">
+          <div>Chunk ${index}</div>
+          <div class="chunk-status">
+            <div class="red-x hidden">❌</div>
+            <div class="checkmark ${isAlreadyUploaded ? "" : "hidden"}">✅</div>
+            <div class="spinner ${isAlreadyUploaded ? "hidden" : ""}"></div>
+            <div class="status">${isAlreadyUploaded ? "Resumed (On Disk)" : "In Progress"}</div>
+          </div>
+        </div>`;
+
+      chunksDisplayElement.appendChild(chunkElement);
+    }
+
+    fileStatusElement.innerText =
+      pendingIndices.length < totalChunks
+        ? "Resuming upload..."
+        : "Uploading...";
+
+    const MAX_CONCURRENCY = 4;
+    let uploadFailed = false;
+
+    async function worker() {
+      while (pendingIndices.length > 0 && !uploadFailed) {
+        const index = pendingIndices.shift();
+        const start = index * CHUNK_SIZE;
+        const end = Math.min(start + CHUNK_SIZE, file.size);
+        const blob = file.slice(start, end);
+
+        const chunkId = `${fileId}-${index}`;
+        const chunkElement = document.getElementById(chunkId);
+        const chunkRedX = chunkElement?.querySelector(".red-x");
+        const chunkCheckmark = chunkElement?.querySelector(".checkmark");
+        const chunkSpinner = chunkElement?.querySelector(".spinner");
+        const chunkStatus = chunkElement?.querySelector(".status");
+
+        try {
+          const hash = await calculateHash(blob);
+          chunkHashes[index] = hash;
+
+          const formData = new FormData();
+          formData.append("chunk", blob);
+          formData.append("index", index);
+          formData.append("chunkSize", CHUNK_SIZE);
+          formData.append("hash", hash);
+
+          const response = await fetch(`/Files/${fileId}/upload`, {
+            method: "POST",
+            body: formData,
+          });
+
+          if (!response.ok) {
+            throw new Error(`Chunk ${index} failed`);
+          }
+
+          chunkCheckmark?.classList.remove("hidden");
+          chunkSpinner?.classList.add("hidden");
+
+          if (chunkStatus) {
+            chunkStatus.innerText = "Succeeded";
+          }
+        } catch (err) {
+          console.err(err);
+          uploadFailed = true;
+
+          chunkRedX?.classList.remove("hidden");
+          chunkSpinner?.classList.add("hidden");
+
+          if (chunkStatus) {
+            chunkStatus.innerText = "Failed";
+          }
+        }
+      }
+    }
+
+    const workers = Array.from(
+      {
+        length: Math.min(MAX_CONCURRENCY, Math.max(1, pendingIndices.length)),
+      },
+      () => worker(),
+    );
+
+    await Promise.all(workers);
+
+    if (uploadFailed) {
+      fileSpinnerElement?.classList.add("hidden");
+      fileRedXElement?.classList.remove("hidden");
+      fileStatusElement.innerText =
+        "Upload paused/failed. Select file again to resume.";
+      return;
+    }
+
+    const sortedHashes = chunkHashes.join(",");
+    const encoder = new TextEncoder();
+    const uint8Array = encoder.encode(sortedHashes);
+    const compositeHashBuffer = await crypto.subtle.digest(
+      "SHA-256",
+      uint8Array,
+    );
+    const compositeHashHex = convertToHexString(compositeHashBuffer);
+
+    const completeResponse = await fetch(`/Files/${fileId}/complete`, {
+      method: "POST",
+      headers: { "content-type": "application/json" },
+      body: JSON.stringify({
+        filename: file.name,
+        compositeHash: compositeHashHex,
+      }),
+    });
+
+    if (completeResponse.ok) {
+      fileSpinnerElement?.classList.add("hidden");
+      fileCheckmarkElement?.classList.remove("hidden");
+      fileStatusElement.innerText = "File uploaded and assembled successfully";
+
+      if (downloadLinkElement && fileDownloadElement) {
+        downloadLinkElement.href = `/Files/${fileId}/download`;
+        fileDownloadElement.classList.remove("hidden");
+      }
+    } else {
+      fileSpinnerElement?.classList.add("hidden");
+      fileRedXElement?.classList.remove("hidden");
+      fileStatusElement.innerText = "File assembly failed";
+    }
+  });
+});
+
+async function generateDeterministicFileId(file) {
+  const signature = `${file.name}-${file.size}-${file.lastModified}`;
+  const encoder = new TextEncoder();
+  const data = encoder.encode(signature);
+  const hashBuffer = await crypto.subtle.digest("SHA-256", data);
+  const hex = convertToHexString(hashBuffer);
+  return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20, 32)}`;
+}
+
+async function calculateHash(blob) {
+  const buffer = await blob.arrayBuffer();
+  const hashBuffer = await crypto.subtle.digest("SHA-256", buffer);
+  return convertToHexString(hashBuffer);
+}
+
+function convertToHexString(buffer) {
+  return Array.from(new Uint8Array(buffer))
+    .map((b) => b.toString(16).padStart(2, "0"))
+    .join("")
+    .toLowerCase();
+}

src/wwwroot/style.css

@@ -0,0 +1,112 @@
+* {
+  padding: 0;
+  margin: 0;
+  box-sizing: border-box;
+}
+
+.hidden {
+  display: none;
+}
+
+:root {
+  font-size: 16px;
+  font-family: Arial, Helvetica, sans-serif;
+}
+
+html,
+body {
+  height: 100%;
+}
+
+body {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  padding: 1rem;
+  overflow: hidden;
+}
+
+main {
+  display: flex;
+  justify-content: start;
+  gap: 1rem;
+  flex: 1;
+  width: 100%;
+  overflow: hidden;
+}
+
+main > * {
+  flex: 1;
+  border: 0.25rem solid black;
+  padding: 0.5rem;
+}
+
+fieldset {
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+  border: none;
+}
+
+fieldset label {
+  font-weight: bold;
+}
+
+.chunks {
+  display: flex;
+  flex-direction: column;
+  gap: 1rem;
+}
+
+#chunks-display {
+  display: flex;
+  flex-direction: column;
+  gap: 0.25rem;
+  overflow-y: scroll;
+}
+
+.chunk {
+  display: flex;
+  justify-content: space-between;
+  gap: 0.25rem;
+}
+
+.chunk-status {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  gap: 0.5rem;
+}
+
+.spinner {
+  height: 1rem;
+  width: 1rem;
+  border: 2px solid grey;
+  border-left: 2px solid red;
+  border-radius: 50%;
+}
+
+.spinner:not(.hidden) {
+  animation: spin 1s ease-in-out infinite;
+}
+
+@keyframes spin {
+  0% {
+    rotate: 0;
+  }
+  50% {
+    rotate: 180deg;
+  }
+  100% {
+    rotate: 360deg;
+  };
+}
+
+#fileStatus {
+  display: flex;
+  width: 100%;
+  align-items: center;
+  justify-content: center;
+  gap: 0.5rem;
+}