let height       = 10
let width        = 10
let mine_rate    = 0.10
let current_time = undefined
let interval     = undefined

let mines = []
let visited = []

let running = false

function isValidPos(y, x) {
    return y >= 0 && y < height && x >= 0 && x < width
}

function* neighboursGenerator(y, x) {
    for (let i = -1; i <= 1; i++) {
        for (let j = -1; j <= 1; j++) {
            if (i === 0 && j === 0)
                continue
            let ret = [y + i, x + j]
            if (!isValidPos(...ret))
                continue
            yield ret
        }
    }
}

let cells = []

function floodFill(y, x) {
    visited[y][x] = true
    let cell = cells[y][x]
    cell.classList.add("visited")
    if (mines[y][x] !== 0)
        cell.textContent = mines[y][x]
    switch (mines[y][x]) {
        case 1: cell.style.color = "blue";     break
        case 2: cell.style.color = "green";    break
        case 3: cell.style.color = "red";      break
        case 4: cell.style.color = "darkblue"; break
        case 5: cell.style.color = "brown";    break
        case 6: cell.style.color = "cyan";     break
        case 7: cell.style.color = "black";    break
        case 8: cell.style.color = "grey";     break
    }
    if (mines[y][x] !== 0)
        return
    for (let [ny, nx] of neighboursGenerator(y, x))
        if (!visited[ny][nx])
            floodFill(ny, nx)
}

const timer_node = document.getElementById("minesweeper-timer")

const flash_message_node = document.getElementById("flash-message")
flash_message_node.addEventListener("click", () => { flash_message_node.hidden = true })

function endFlashMessage(won) {
    flash_message_node.textContent =
        `You ${won ? "won" : "lost"} in ${timer_node.textContent} seconds`
    flash_message_node.classList.remove("flash-won")
    flash_message_node.classList.remove("flash-lost")
    flash_message_node.classList.add(won ? "flash-won" : "flash-lost")
    flash_message_node.hidden = false;
    setTimeout(() => { flash_message_node.hidden = true }, 5000)
}

function initGrid() {
    let table = document.getElementById("minesweeper-table")
    table.innerHTML = ""

    width     = document.getElementById("minesweeper-width").value
    height    = document.getElementById("minesweeper-height").value
    mine_rate = document.getElementById("minesweeper-mine-rate").value / 100

    mines   = []
    visited = []
    cells   = []

    for (let i = 0; i < height; i++) {
        mines.push(new Array(width))
        visited.push(new Array(width))
        for (let j = 0; j < width; j++) {
            mines[i][j] = Math.random() < mine_rate ? -1 : 0;
            visited[i][j] = false;
        }
    }

    // count neighbour mines
    for (let i = 0; i < height; i++) {
        for (let j = 0; j < width; j++) {
            if (mines[i][j] === -1)
                continue
            mines[i][j] =
                [...neighboursGenerator(i, j)]
                .filter(([y, x]) => mines[y][x] === -1)
                .length
        }
    }

    for (let i = 0; i < height; i++) {
        cells.push([])
        let table_row = document.createElement("tr")
        for (let j = 0; j < width; j++) {
            let table_cell = document.createElement("td")
            let cell = document.createElement("button")
            cell.textContent = ""
            cell.addEventListener("click", () => {
                if (!running)
                    toggleRunning()
                if (cell.classList.contains("flagged")) {
                    cell.classList.remove("flagged")
                    return
                }
                if (mines[i][j] === -1) {
                    toggleRunning()
                    endFlashMessage(false)
                }
                else {
                    floodFill(i, j)
                    won = true;
                    for (let y = 0; y < width; y++) {
                        for (let x = 0; x < width; x++) {
                            if (mines[y][x] !== -1 && !cells[y][x].classList.contains("visited"))
                                won = false
                        }
                    }
                    if (won) {
                        toggleRunning()
                        endFlashMessage(true)
                    }
                }
            })
            cell.addEventListener("contextmenu", event => {
                event.preventDefault()
                if (!running)
                    toggleRunning()
                if (cell.classList.contains("visited"))
                    return
                if (cell.classList.contains("flagged"))
                    cell.classList.remove("flagged")
                else
                    cell.classList.add("flagged")
            })
            cells[i].push(cell)
            table_cell.appendChild(cell)
            table_row.appendChild(table_cell)
        }
        table.appendChild(table_row)
    }
}

for (input of document.querySelectorAll("#minesweeper-settings input")) {
    input.addEventListener("input", () => initGrid())
}

function toggleRunning() {
    flash_message_node.hidden = true;
    if (running) {
        clearInterval(interval)
        initGrid()
    }
    else {
        current_time = 0
        timer_node.textContent = current_time
        interval = setInterval(() => {
            timer_node.textContent = current_time
            current_time++
        }, 1000)
    }
    running         = !running
    let settings    = document.getElementById("minesweeper-settings")
    let info        = document.getElementById("minesweeper-game-info")
    settings.hidden = !settings.hidden
    info.hidden     = !info.hidden
}

document.getElementById("minesweeper-stop").addEventListener("click", toggleRunning)

initGrid()