// TODO optimization: use '' for empty blocks, undefined as a sentinel

export const create = (width, height) =>
    Array(height).fill([]).map(() => Array(width).fill(undefined))

export const clone = grid => [...grid.map(row => [...row])]

export const draw = (grid, x: number, y: number, block, rotation: number, color) => {
    // TODO doesn't need to be pure, clone in caller
    const bucket1 = clone(grid)
    block.coords[rotation].forEach(([xx, yy]) =>
        bucket1[y + yy][x + xx] = color)
    return bucket1
}

// check for free, return true if so
export const check = (grid, x, y, block, rotation) => {
    const [width, height] = [grid[0].length, grid.length]

    const predicate = ([xx, yy]) =>
        x + xx >= 0 &&
        x + xx < width &&
        y + yy >= 0 &&
        y + yy < height &&
        grid[y + yy][x + xx] === undefined

    return block.coords[rotation].every(predicate)
}

// clear full lines (non pure)
export const sweep = grid => {
    let linesCleared = 0

    const width = grid[0].length
    for (const [rowIndex, row] of grid.entries()) {
        const full = row.every(cell => cell !== undefined)
        if (full) {
            grid.splice(rowIndex, 1)
            grid.unshift(new Array(width).fill(undefined))
            linesCleared++
        }
    }

    return linesCleared
}