import { Field, Mino } from 'tetris-fumen'
import { SplitMix64 } from './prng.js'

export class Simul {
    constructor(seed, config) {
        let rng1 = new SplitMix64(seed);
        let rng2 = rng1.clone();
        this.queue = new Queue(rng1, config.rules.previews);
        this.cheese = new Cheese(rng2, config.goal, config.rules.min, config.rules.max);
        this.matrix = this.cheese.generate(0, false);
        this._nextField = Field.create(this.matrix);
    }

    play(mino) {
        let page = {
            field: this._nextField,
            comment: this.queue.quiz(),
            operation: mino,
        };
        this._nextField = undefined;

        this.queue.remove(mino.type);

        let field = Field.create(this.matrix);
        field.fill(mino);
        let matrix1 = field.str(FLATTEN);

        field.clearLine();
        let matrix2 = field.str(FLATTEN);

        let comboing = matrix1 !== matrix2;
        let level = getGarbageLevel(matrix2);
        let garbage = this.cheese.generate(level, comboing);
        this.matrix = matrix2 + garbage;

        if (garbage !== '') {
            this._nextField = Field.create(this.matrix);
        }

        return page;
    }
}

const FLATTEN = { reduced: true, separator: '', garbage: false };

export class Queue {
    constructor(rng, previews) {
        // see `static tidepool::sim::PIECES`
        this._bag = 'IJLOSTZ'.split('');
        this._pos = 0;
        this._rng = rng;
        this.hold = null;
        this.next = [];
        while (this.next.length < previews) {
            this.next.push(this._pop());
        }
    }

    _pop() {
        // see `static tidepool::sim::Bag::pop()`
        let i = this._pos;
        this._pos += 1;
        this._pos %= this._bag.length;
        let j = this._rng.genRange(i, this._bag.length);
        let tmp = this._bag[j];
        this._bag[j] = this._bag[i];
        this._bag[i] = tmp;
        return tmp;
    }

    quiz() {
        return `#Q=[${this.hold||''}](${this.next[0]})${this.next.slice(1).join('')}`;
    }

    remove(ty) {
        let top = this.next.shift();
        this.next.push(this._pop());
        if (this.hold === ty || top !== ty) {
            if (!this.hold) {
                this.next.shift();
                this.next.push(this._pop());
            }
            this.hold = top;
        }
    }
}

export class Cheese {
    constructor(rng, total, min, max) {
        this._col = rng.genRange(0, 10);
        this._rng = rng;
        this.linesLeft = total;
        this._level = 0;
        this._remaining = total;
        this._min = min;
        this._max = max;
    }

    _nextColumn() {
        // see `static tidepool::sim::Cheese::next()`
        this._col += this._rng.genRange(1, 10);
        this._col %= 10;
        return this._col;
    }

    generate(level, comboing = false) {
        let target = comboing ? this._min : this._max;
        let count = Math.min(this._remaining, Math.max(0, target - level));
        this._remaining -= count;

        let result = [];
        for (let i = 0; i < count; i++) {
            let col = this._nextColumn();
            for (let x = 0; x < 10; x++) {
                result.push((x === col) ? '_' : 'X');
            }
        }
        return result.join('');
    }
}

function getGarbageLevel(matrix) {
    let level = 0;
    for (let i = 0; i < matrix.length; i++) {
        let y = Math.floor(i / 10);
        let cell = matrix[matrix.length - i - 1];
        if (cell === 'X') {
            level = y + 1;
        }
    }
    return level;
}

if (false) {
    // see `tidepool::sim::test::test_deterministic()`
    let sim = new Simul("0x1234567800ABCDEF", {
        goal: 100,
        rules: { min: 0, max: 9, previews: 7 },
    });
    console.log(sim.queue.next.join(',')); // J,L,T,Z,S,O,I
    console.log(sim.matrix);
    // XXX_XXXXXXXXXXX_XXXX_XXXXXXXXXXXX_XXXXXXX_XXXXXXXX_XXXXXXXXXXXXXXXXXX_XXXX_XXXXX_XXXXXXXXX
}