finish implementing /api/check route

routes/api.js

@@ -1,6 +1,8 @@
 'use strict';
 
 const SudokuSolver = require('../controllers/sudoku-solver');
+import { columns } from '../models/columns';
+import { rows } from '../models/rows';
 
 module.exports = function (app) {
 
@@ -9,23 +11,87 @@ module.exports = function (app) {
     app.route('/api/check')
         .post((req, res) => {
 
+            // get puzzle string, coordinate, and value
+            // from request
+            const puzzleString = req.body.puzzle;
+            const coordinate = req.body.coordinate;
+            const value = req.body.value;
+
+            // if any of the three are not in request return error
+            if (puzzleString == undefined || coordinate == undefined || value == undefined) return res.status(200).json({error: 'Required field(s) missing'});
+
+            // attempt to validate puzzle
+            const validate = solver.validate(puzzleString);
+
+            // if puzzle invalid return error
+            if (validate != true) return res.status(200).json({error: validate});
+            
+            // get row and col from coordinate value
+            const row = coordinate.slice(0,1)
+            const col = coordinate.slice(1, coordinate.length);
+
+            // get the valid rows and cols
+            const validRows = Object.keys(rows);
+            const validColumns = Object.keys(columns);
+
+            // if the passed row or col value are not valid return error.
+            if (!validRows.includes(row) || !validColumns.includes(col)) return res.status(200).json({error: 'Invalid coordinate'});
+
+            // if the value passed is NaN or less than 1 or greater than 9 return error.
+            if (parseInt(value) < 1 || parseInt(value) > 9 || isNaN(parseInt(value))) return res.status(200).json({error: 'Invalid value'});
+
+            // default response
+            const resObj = {
+                valid: true
+            };
+
+            // check if value can be placed in row, col, and grid according to pass coordinate
+            const validRow = solver.checkRowPlacement(puzzleString, row, col, value);
+            const validCol = solver.checkColPlacement(puzzleString, row, col, value);
+            const validGrid = solver.checkRegionPlacement(puzzleString, row, col, value);
+
+            // if any conflicts build response
+            // build response indicating invalid placement
+            // and conflicts causing invalid placement
+            if (!validRow || !validCol || !validGrid) {
+
+                resObj.valid = false;
+                resObj.conflict = [];
+
+                if (!validRow) resObj.conflict.push('row');
+                if (!validCol) resObj.conflict.push('column');
+                if (!validGrid) resObj.conflict.push('grid');
+
+                return res.status(200).json(resObj);
+            }
+
+            // if all previous checks pass return default valid response.
+            return res.status(200).json(resObj);
         });
 
     app.route('/api/solve')
         .post((req, res) => {
 
+            // get puzzle string from request
             const puzzleString = req.body.puzzle;
 
+            // if no puzzle string in request
+            // return error
             if (puzzleString == undefined) return res.status(200).json({error: 'Required field missing' });
 
+            // attempt to validate puzzle
             const validate = solver.validate(puzzleString);
 
+            // if puzzle string invalid return error
             if (validate != true) return res.status(200).json({error: validate});
 
+            // attempt to solve puzzle
             const solution = solver.solve(puzzleString);
             
+            // if puzzle can't be solved return error
             if (solution == false) return res.status(200).json({error: 'Puzzle cannot be solved'});
 
+            // otherwise return solution
             return res.status(200).json({solution: solution});
 
         });