feat: add help and exit commands

commands.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"sort"
+)
+
+type context struct {
+	commands map[string]cliCommand
+}
+
+func (r *context) register(c cliCommand) {
+	if c.name != "" {
+		r.commands[c.name] = c
+	}
+}
+
+func NewContext() *context {
+	var exitCommand = cliCommand{
+		name:        "exit",
+		description: "Exit the Pokedex",
+		callback:    commandExit,
+	}
+
+	var helpCommand = cliCommand{
+		name:        "help",
+		description: "Displays a help message",
+		callback:    commandHelp,
+	}
+
+	c := &context{
+		commands: map[string]cliCommand{},
+	}
+
+	c.register(exitCommand)
+	c.register(helpCommand)
+
+	return c
+}
+
+type commandFunc func(c *context) error
+
+type cliCommand struct {
+	name        string
+	description string
+	callback    commandFunc
+}
+
+func commandExit(c *context) error {
+	fmt.Println("Closing the Pokedex... Goodbye!")
+	os.Exit(0)
+	return nil
+}
+
+func commandHelp(c *context) error {
+	fmt.Println("Welcome to the Pokedex!")
+	fmt.Println("Usage:")
+	fmt.Println("")
+
+	sortedKeys := []string{}
+
+	for k := range c.commands {
+		sortedKeys = append(sortedKeys, k)
+	}
+
+	sort.Strings(sortedKeys)
+
+	for _, key := range sortedKeys {
+		command := c.commands[key]
+		fmt.Printf("%s: %s\n", command.name, command.description)
+	}
+
+	return nil
+}