import { PongGame, PongState, TICK_MS, COUNTDOWN_SECONDS, FIELD_HEIGHT, PADDLE_MARGIN, PADDLE_WIDTH, PADDLE_HEIGHT, WIN_SCORE, SERVE_PAUSE_MS, botLogin, BotLevel } from '../pongGame';
import { GameError } from '../minigames';
import { fakeClock } from './helpers/fakeClock';

/** Deterministická pseudonáhoda, ať se boti nechovají pokaždé stejně jako s konstantou. */
function lcg(seed = 1) {
    let x = seed;
    return () => (x = (x * 1103515245 + 12345) % 2147483648) / 2147483648;
}

function setup(random?: () => number) {
    const clock = fakeClock(random);
    const states: PongState[] = [];
    const game = new PongGame(s => states.push(s), s => states.push(s), clock);
    const last = () => states[states.length - 1];
    const player = (login: string) => last().players.find(p => p.login === login)!;
    const startGame = () => {
        game.join('alice');
        game.join('bob');
        game.start('alice');
        clock.advance(COUNTDOWN_SECONDS * 1000);
    };
    const ticks = (n: number) => clock.advance(n * TICK_MS);
    return { game, clock, last, player, startGame, ticks };
}

describe('pong', () => {
    test('je jen pro dva hráče a hru spouští zakladatel', () => {
        const ctx = setup();
        ctx.game.join('alice');
        expect(() => ctx.game.start('alice')).toThrow(GameError);
        ctx.game.join('bob');
        expect(() => ctx.game.join('carol')).toThrow(GameError);
        expect(() => ctx.game.start('bob')).toThrow(GameError);
        ctx.game.start('alice');
        expect(ctx.last().phase).toBe('countdown');
    });

    test('pálka se hýbe podle vstupu a nevyjede z hřiště', () => {
        const ctx = setup();
        ctx.startGame();
        ctx.game.input('alice', 'up');
        ctx.ticks(10);
        expect(ctx.player('alice').y).toBeLessThan(FIELD_HEIGHT / 2);
        ctx.ticks(100);
        expect(ctx.player('alice').y).toBe(45);
        ctx.game.input('alice', 'stop');
        const y = ctx.player('alice').y;
        ctx.ticks(5);
        expect(ctx.player('alice').y).toBe(y);
    });

    test('míček se od pálky odrazí', () => {
        const ctx = setup();
        ctx.startGame();
        const face = PADDLE_MARGIN + PADDLE_WIDTH;
        ctx.game.setBallForTest(face + 20, FIELD_HEIGHT / 2, -400, 0);
        ctx.ticks(3);
        expect(ctx.last().ball.x).toBeGreaterThan(face);
        expect(ctx.player('bob').score).toBe(0);
    });

    test('minutý míček je bod pro soupeře a hra končí na vítězné skóre', () => {
        const ctx = setup();
        ctx.startGame();
        for (let i = 0; i < WIN_SCORE; i++) {
            // Míček u horního okraje, kam pálka uprostřed nedosáhne
            ctx.game.setBallForTest(60, 10, -600, 0);
            ctx.ticks(10);
            if (i < WIN_SCORE - 1) {
                expect(ctx.player('bob').score).toBe(i + 1);
                ctx.clock.advance(SERVE_PAUSE_MS);
            }
        }
        expect(ctx.last()).toMatchObject({ phase: 'finished', winner: 'bob' });
    });

    test('myš: pálka rychle dojede k cílové výšce a šipka myš přebije', () => {
        const ctx = setup();
        ctx.startGame();
        ctx.game.aim('alice', 0);
        ctx.ticks(5);
        expect(ctx.player('alice').y).toBe(PADDLE_HEIGHT / 2);
        ctx.game.input('alice', 'down');
        ctx.ticks(5);
        expect(ctx.player('alice').y).toBeGreaterThan(PADDLE_HEIGHT / 2);
    });

    test('bota přidá jen zakladatel a lze ho odebrat', () => {
        const ctx = setup();
        ctx.game.join('alice');
        expect(() => ctx.game.addBot('bob', 'easy')).toThrow(GameError);
        expect(() => ctx.game.addBot('alice', 'superhard')).toThrow(GameError);
        ctx.game.addBot('alice', 'hard');
        expect(ctx.last().players.map(p => p.login)).toEqual(['alice', botLogin('hard')]);
        ctx.game.removeBot('alice');
        expect(ctx.last().players).toHaveLength(1);
    });

    /** Odehraje zápas člověka, který myší dokonale sleduje míček, proti botovi. */
    function playAgainstBot(level: BotLevel, maxSeconds: number) {
        const ctx = setup(lcg(7));
        ctx.game.join('alice');
        ctx.game.addBot('alice', level);
        ctx.game.start('alice');
        ctx.clock.advance(COUNTDOWN_SECONDS * 1000);
        for (let t = 0; t < maxSeconds * 1000 && ctx.last().phase === 'playing'; t += TICK_MS) {
            ctx.game.aim('alice', ctx.last().ball.y);
            ctx.ticks(1);
        }
        return ctx;
    }

    test('lehký bot proti dokonalému hráči prohraje', () => {
        const ctx = playAgainstBot('easy', 300);
        expect(ctx.last()).toMatchObject({ phase: 'finished', winner: 'alice' });
    });

    test('nemožný bot neztratí ani bod', () => {
        const ctx = playAgainstBot('impossible', 120);
        expect(ctx.player('alice').score).toBe(0);
        expect(ctx.player(botLogin('impossible')).score).toBe(0);
    });
});