perf: win check now tracks safe cells revealed instead of scanning the whole grid

lib/mnswpr.js

@@ -86,6 +86,8 @@ const Minesweeper = function(appId, version, hooks = undefined) {
   let mines = new Set()
   // Cells currently highlighted, so removeHighlights only resets these (<=9) instead of the whole grid
   let highlightedCells = []
+  // Count of safe (non-mine) cells revealed, so the win check is O(1) instead of scanning the whole grid
+  let revealedSafeCount = 0
 
   this.initialize = function() {
     const headingElement = document.createElement('h1')
@@ -194,6 +196,7 @@ const Minesweeper = function(appId, version, hooks = undefined) {
     flagsCount = setting.mines
     mines.clear()
     highlightedCells = []
+    revealedSafeCount = 0
 
     for (let i = 0; i < setting.rows; i++) {
       let row = grid.insertRow(i)
@@ -560,14 +563,8 @@ const Minesweeper = function(appId, version, hooks = undefined) {
   }
 
   function checkLevelCompletion() {
-    let levelComplete = true
+    const safeCells = setting.rows * setting.cols - setting.mines
-    for (let i=0; i<setting.rows; i++) {
+    if (revealedSafeCount >= safeCells && grid.getAttribute('game-status') == 'active') {
-      for(let j=0; j<setting.cols; j++) {
-        const cell = grid.rows[i].cells[j] 
-        if (!isMine(cell) && cell.innerHTML=='') levelComplete=false
-      }
-    }
-    if (levelComplete && grid.getAttribute('game-status') == 'active') {
       grid.setAttribute('game-status', 'win')
       revealMines()
     }
@@ -817,6 +814,9 @@ const Minesweeper = function(appId, version, hooks = undefined) {
   function openCell(cell) {
     if (grid.getAttribute('game-status') != 'active') return
 
+    // A cell can be re-opened via chording, so only count the first reveal
+    const wasOpen = getStatus(cell) == 'clicked' || getStatus(cell) == 'empty'
+
     cell.className='clicked'
     setStatus(cell, 'clicked')
     firstClick = false
@@ -826,6 +826,7 @@ const Minesweeper = function(appId, version, hooks = undefined) {
       flagsDisplay.innerHTML = '&#128561;'
       grid.setAttribute('game-status', 'over')
     } else {
+      if (!wasOpen) revealedSafeCount++
       const mineCount = countMinesAround(cell)
       if (mineCount==0) { 
         handleEmpty(cell)

test/minesweeper.test.js

@@ -29,14 +29,24 @@ function everyCell(grid, fn) {
 describe('Minesweeper board', () => {
   beforeEach(() => {
     localStorage.clear()
-    // Fake timers stop the 1ms game clock interval from running during tests.
+    // Fake timers stop the requestAnimationFrame game clock from running during tests.
     vi.useFakeTimers()
   })
 
   afterEach(() => {
     vi.useRealTimers()
+    vi.restoreAllMocks()
   })
 
+  // Mount a game on a custom board injected via the cached 'setting' localStorage key.
+  function mountCustomGame(setting, hooks) {
+    localStorage.setItem('setting', JSON.stringify(setting))
+    document.body.innerHTML = '<div id="app"></div>'
+    const game = new Minesweeper('app', 'dev', hooks)
+    game.initialize()
+    return document.getElementById('grid')
+  }
+
   it('renders the beginner grid (9x9) by default', () => {
     const grid = mountGame()
     expect(grid.rows.length).toBe(9)
@@ -116,4 +126,33 @@ describe('Minesweeper board', () => {
     })
     expect(highlighted).toBe(1)
   })
+
+  it('declares a win once every safe cell is revealed', () => {
+    // A mine-free 3x3 board: one click cascades to reveal all 9 safe cells.
+    let finished = null
+    const grid = mountCustomGame(
+      { rows: 3, cols: 3, mines: 0, id: 'test', name: 'test' },
+      { levelChanged: () => {}, gameDone: (g) => { finished = g.status } }
+    )
+
+    leftClick(grid.rows[1].cells[1])
+
+    expect(finished).toBe('win')
+    expect(grid.getAttribute('game-status')).toBe('done')
+    everyCell(grid, cell => expect(cell.getAttribute('data-status')).not.toBe('default'))
+  })
+
+  it('does not declare a win until the last safe cell is revealed', () => {
+    // 1x3 board with the single mine pinned to the middle column.
+    vi.spyOn(Math, 'random').mockReturnValue(0.5)
+    const grid = mountCustomGame({ rows: 1, cols: 3, mines: 1, id: 'test', name: 'test' })
+
+    // First safe cell: adjacent to the mine, shows "1", no cascade -> not yet won.
+    leftClick(grid.rows[0].cells[0])
+    expect(grid.getAttribute('game-status')).toBe('active')
+
+    // Revealing the remaining safe cell completes the board.
+    leftClick(grid.rows[0].cells[2])
+    expect(grid.getAttribute('game-status')).toBe('done')
+  })
 })