import {
    _decorator, Button, Component, EventTouch, Label, Node, Prefab,
    instantiate, tween, UIOpacity, v3, Vec3,
} from 'cc';
import { Card } from '../../core/cards/Card';
import { BasicBot } from '../../core/bot/BasicBot';
import { Match } from '../../core/match/Match';
import { Action, ActionType, Actions, IllegalActionError } from '../../core/rules/Action';
import { Phase, PlayerId } from '../../core/rules/GameState';
import { legalActions } from '../../core/rules/DurakRules';
import { intentFor } from '../../core/rules/intent';
import { Layout, Palette, Timing } from '../common/Theme';
import { Strings } from '../common/Strings';
import { CardLibrary } from './CardLibrary';
import { CardView } from './CardView';

const { ccclass, property } = _decorator;

export type MatchOutcome = 'win' | 'loss' | 'draw';

/** Seat ids. The human is always seated first; the rules core does not care. */
const HUMAN: PlayerId = 'player';
const OPPONENT: PlayerId = 'opponent';

/**
 * The match screen.
 *
 * It renders whatever the current `GameState` says, rather than replaying the
 * event stream: after every action the whole table is laid out again and the
 * card nodes tween to their new places. Because a card node stays bound to its
 * card for as long as it is visible, "the six of clubs moved from my hand to the
 * table" needs no special case — it is the same node arriving at a new position.
 *
 * The screen never reads anything the player should not see. The opponent's hand
 * is drawn from its *size*, and the only cards ever turned face up are the ones
 * the rules have made public.
 */
@ccclass('GameScreen')
export class GameScreen extends Component {
    @property(Prefab)
    cardPrefab: Prefab | null = null;

    @property(CardLibrary)
    library: CardLibrary | null = null;

    @property({ type: Node, tooltip: 'Parent for every card node.' })
    cardLayer: Node | null = null;

    @property(Node)
    deckAnchor: Node | null = null;

    @property(Label)
    deckCountLabel: Label | null = null;

    @property(Label)
    opponentLabel: Label | null = null;

    @property(Label)
    messageLabel: Label | null = null;

    @property(Button)
    takeButton: Button | null = null;

    @property(Button)
    doneButton: Button | null = null;

    @property({ type: Node, tooltip: 'Shown when the match is over.' })
    resultOverlay: Node | null = null;

    @property(Label)
    resultTitle: Label | null = null;

    @property(Label)
    resultBody: Label | null = null;

    @property(Button)
    quitButton: Button | null = null;

    @property({ type: Button, tooltip: 'Dismisses the result overlay.' })
    continueButton: Button | null = null;

    /** Set by `MainFlow`. */
    onFinished: ((outcome: MatchOutcome) => void) | null = null;
    onQuitRequested: (() => void) | null = null;

    private _match: Match | null = null;
    private _bot = new BasicBot(OPPONENT);
    /** Card nodes in use, keyed by the card they show. */
    private _views = new Map<Card, CardView>();
    /** Face-down nodes standing in for the opponent's hand and the deck. */
    private _anonymous: CardView[] = [];
    private _pool: CardView[] = [];
    private _busy = false;
    private _selected: Card | null = null;
    private _pendingOutcome: MatchOutcome | null = null;

    // -----------------------------------------------------------------------
    // Lifecycle
    // -----------------------------------------------------------------------

    onLoad(): void {
        // Subscribed in code rather than through the scene's clickEvents list, so
        // the wiring is visible in the source and a renamed handler is a compile
        // error instead of a button that silently stops working.
        this.takeButton?.node.on(Button.EventType.CLICK, this.take, this);
        this.doneButton?.node.on(Button.EventType.CLICK, this.done, this);
        this.quitButton?.node.on(Button.EventType.CLICK, this.quit, this);
        this.continueButton?.node.on(Button.EventType.CLICK, this.dismissResult, this);
    }

    onDestroy(): void {
        this.takeButton?.node.off(Button.EventType.CLICK, this.take, this);
        this.doneButton?.node.off(Button.EventType.CLICK, this.done, this);
        this.quitButton?.node.off(Button.EventType.CLICK, this.quit, this);
        this.continueButton?.node.off(Button.EventType.CLICK, this.dismissResult, this);
    }

    startNewMatch(): void {
        this.teardown();
        setActive(this.resultOverlay, false);

        // Bootstrap preloads the card art, so this is all but instant; going
        // through whenReady means a cold start cannot deal onto blank cards.
        const library = this.library;
        if (!library) {
            console.error('[game] no card library assigned');
            return;
        }
        library.whenReady(() => {
            if (!this.isValid || !this.node.activeInHierarchy) {
                return;
            }
            this._match = new Match({
                players: [HUMAN, OPPONENT],
                seed: (Math.random() * 0x7fffffff) | 0,
            });
            this._busy = false;
            this._selected = null;

            this.render(Timing.deal);
            this.scheduleOnce(() => this._advance(), Timing.deal + 0.2);
        });
    }

    /** Releases every card node and forgets the match. Safe to call twice. */
    teardown(): void {
        this.unscheduleAllCallbacks();
        for (const view of [...this._views.values(), ...this._anonymous]) {
            view.cancelAnimations();
            this._recycle(view);
        }
        this._views.clear();
        this._anonymous.length = 0;
        this._match?.clearListeners();
        this._match = null;
        this._selected = null;
        this._busy = false;
    }

    onDisable(): void {
        this.unscheduleAllCallbacks();
    }

    /** Wired to the Leave button. */
    quit(): void {
        this.onQuitRequested?.();
    }

    // -----------------------------------------------------------------------
    // Input
    // -----------------------------------------------------------------------

    /** Wired to the Take button. */
    take(): void {
        this._submit(Actions.take(HUMAN));
    }

    /** Wired to the Done button. */
    done(): void {
        this._submit(Actions.pass(HUMAN));
    }

    private _onCardTapped(card: Card): void {
        const match = this._match;
        if (!match || this._busy || match.currentActor !== HUMAN) {
            return;
        }

        const action = this._match ? intentFor(this._match.state, HUMAN, card) : null;
        if (!action) {
            this._flashMessage(Strings.cannotPlayThat);
            this._nudge(card);
            return;
        }
        this._submit(action);
    }

    private _submit(action: Action): void {
        const match = this._match;
        if (!match || this._busy) {
            return;
        }
        try {
            match.perform(action);
        } catch (error) {
            if (error instanceof IllegalActionError) {
                this._flashMessage(Strings.cannotPlayThat);
                return;
            }
            throw error;
        }

        this._selected = null;
        this._busy = true;
        this.render(Timing.play);
        this.scheduleOnce(() => this._advance(), Timing.play + 0.05);
    }

    // -----------------------------------------------------------------------
    // Turn loop
    // -----------------------------------------------------------------------

    /** Hands the move on: finish, wait for the player, or let the bot think. */
    private _advance(): void {
        const match = this._match;
        if (!match) {
            return;
        }

        if (match.finished) {
            this._busy = true;
            this.scheduleOnce(() => this._showResult(), Timing.turnBreak);
            return;
        }

        if (match.currentActor === HUMAN) {
            this._busy = false;
            this.render(Timing.play);
            return;
        }

        this._busy = true;
        this.render(Timing.play);
        this.scheduleOnce(() => {
            const current = this._match;
            if (!current || current.currentActor !== OPPONENT) {
                return;
            }
            current.perform(this._bot.decide(current.viewFor(OPPONENT)));
            this.render(Timing.play);
            this.scheduleOnce(() => this._advance(), Timing.play + 0.05);
        }, Timing.botThinking);
    }

    private _showResult(): void {
        const match = this._match;
        if (!match) return;

        const outcome: MatchOutcome = match.loser === null
            ? 'draw'
            : (match.loser === HUMAN ? 'loss' : 'win');

        setText(this.resultTitle, {
            win: Strings.wonTitle, loss: Strings.lostTitle, draw: Strings.drawTitle,
        }[outcome]);
        setText(this.resultBody, {
            win: Strings.wonBody, loss: Strings.lostBody, draw: Strings.drawBody,
        }[outcome]);

        if (this.resultOverlay) {
            this.resultOverlay.active = true;
            const opacity = this.resultOverlay.getComponent(UIOpacity)
                ?? this.resultOverlay.addComponent(UIOpacity);
            opacity.opacity = 0;
            tween(opacity).to(0.25, { opacity: 255 }).start();
        }

        this._pendingOutcome = outcome;
    }

    /** Wired to the result overlay's button. */
    dismissResult(): void {
        const outcome = this._pendingOutcome ?? 'draw';
        this._pendingOutcome = null;
        this.onFinished?.(outcome);
    }

    // -----------------------------------------------------------------------
    // Rendering
    // -----------------------------------------------------------------------

    /** Lays the whole table out from the current state, tweening over `duration`. */
    render(duration: number): void {
        const match = this._match;
        if (!match || !this.library || !this.cardLayer) {
            return;
        }
        const state = match.state;
        const view = match.viewFor(HUMAN);
        const live = new Set<Card>();

        // Trump card, lying under the deck.
        if (state.deck.length > 0) {
            live.add(state.trumpCard);
            this._place(state.trumpCard, true,
                v3(Layout.region.trump.x, Layout.region.trump.y, 0), 0.62, 90, duration);
        }

        // The player's hand: a straight row, tightened as it grows.
        const hand = [...view.hand].sort(byTrumpThenRank(state.trumpSuit));
        const step = Math.min(
            Layout.handStep,
            hand.length > 1 ? (Layout.handMaxWidth - Layout.cardWidth) / (hand.length - 1) : Layout.handStep,
        );
        const handLeft = -step * (hand.length - 1) / 2;
        hand.forEach((card, i) => {
            live.add(card);
            const lifted = card === this._selected ? Layout.handLift : 0;
            this._place(card, true,
                v3(handLeft + i * step, Layout.region.playerHandY + lifted, 0), 1, 0, duration);
        });

        // The table: attacking cards with whatever beat them, three to a row.
        state.table.forEach((slot, i) => {
            const column = i % 3;
            const row = Math.floor(i / 3);
            const x = (column - 1) * Layout.region.tableColumnStep;
            const y = Layout.region.tableTopY - row * Layout.region.tableRowStep;

            live.add(slot.attack);
            this._place(slot.attack, true, v3(x, y, 0), Layout.tableCardScale, 0, duration);

            if (slot.defence) {
                live.add(slot.defence);
                this._place(slot.defence, true,
                    v3(x + Layout.beatOffset.x, y + Layout.beatOffset.y, 0),
                    Layout.tableCardScale, 8, duration);
            }
        });

        this._retireCardsNotIn(live, duration);
        this._renderAnonymous(state.deck.length, view.opponents[0]?.handSize ?? 0, duration);
        this._renderChrome(view.opponents[0]?.handSize ?? 0);
    }

    /** Face-down nodes: a short stack for the deck, and the opponent's hand. */
    private _renderAnonymous(deckSize: number, opponentHand: number, duration: number): void {
        // Three backs are enough to read as a pile; drawing twenty-four is waste.
        const deckBacks = Math.min(deckSize, 3);
        const needed = deckBacks + opponentHand;

        while (this._anonymous.length < needed) {
            this._anonymous.push(this._take(null, false));
        }
        while (this._anonymous.length > needed) {
            this._recycle(this._anonymous.pop() as CardView);
        }

        for (let i = 0; i < deckBacks; i++) {
            this._anonymous[i].moveTo(
                v3(Layout.region.deck.x + i * 3, Layout.region.deck.y + i * 3, 0),
                0.62, 0, duration,
            );
        }

        const step = Math.min(70, opponentHand > 1 ? 760 / (opponentHand - 1) : 70);
        const left = -step * (opponentHand - 1) / 2;
        for (let i = 0; i < opponentHand; i++) {
            this._anonymous[deckBacks + i].moveTo(
                v3(left + i * step, Layout.region.opponentHandY, 0),
                Layout.opponentCardScale, 0, duration,
            );
        }
    }

    private _renderChrome(opponentHand: number): void {
        const match = this._match;
        if (!match) return;
        const state = match.state;

        setText(this.deckCountLabel, `${Strings.deckLeft} ${state.deck.length}`);
        setText(this.opponentLabel, `${Strings.opponentHand}: ${opponentHand}`);
        setActive(this.deckAnchor, state.deck.length > 0);

        const mine = match.currentActor === HUMAN;
        const options = mine ? legalActions(state, HUMAN) : [];
        setButton(this.takeButton, mine && options.some((a) => a.type === ActionType.Take));
        setButton(this.doneButton, mine && options.some((a) => a.type === ActionType.Pass));

        if (match.finished) {
            setText(this.messageLabel, '');
        } else if (!mine) {
            setText(this.messageLabel, Strings.opponentThinking);
        } else if (state.phase === Phase.Defence) {
            setText(this.messageLabel, Strings.yourDefence);
        } else if (state.phase === Phase.Reinforce) {
            setText(this.messageLabel, Strings.addMore);
        } else {
            setText(this.messageLabel, Strings.yourMove);
        }
    }

    // -----------------------------------------------------------------------
    // Card node pool
    // -----------------------------------------------------------------------

    private _place(card: Card, faceUp: boolean, position: Vec3, scale: number, angle: number, duration: number): void {
        let view = this._views.get(card);
        if (!view) {
            view = this._take(card, faceUp);
            // A card appearing for the first time slides out of the deck.
            view.moveTo(v3(Layout.region.deck.x, Layout.region.deck.y, 0), 0.62, 0, 0);
            this._views.set(card, view);
        }
        view.flipTo(faceUp);
        view.moveTo(position, scale, angle, duration);
        view.node.setSiblingIndex(this.cardLayer?.children.length ?? 0);
    }

    /** Cards that have left the visible table — they went to the discard or a hand. */
    private _retireCardsNotIn(live: Set<Card>, duration: number): void {
        for (const [card, view] of [...this._views]) {
            if (live.has(card)) continue;
            this._views.delete(card);

            const goingToOpponent = !this._match?.state.discard.includes(card);
            const target = goingToOpponent
                ? v3(0, Layout.region.opponentHandY, 0)
                : v3(Layout.region.discard.x, Layout.region.discard.y, 0);

            view.moveTo(target, 0.4, 0, duration);
            view.flipTo(false);
            view.fadeOut(duration, () => this._recycle(view));
        }
    }

    private _take(card: Card | null, faceUp: boolean): CardView {
        let view = this._pool.pop();
        if (!view) {
            const node = instantiate(this.cardPrefab as Prefab);
            view = node.getComponent(CardView) as CardView;
            node.on(Node.EventType.TOUCH_END, (event: EventTouch) => {
                event.propagationStopped = true;
                const tapped = view?.card;
                if (tapped) this._onCardTapped(tapped);
            });
        }
        view.node.parent = this.cardLayer;
        view.node.active = true;
        view.bind(this.library as CardLibrary, card, faceUp);
        return view;
    }

    private _recycle(view: CardView): void {
        view.cancelAnimations();
        view.node.active = false;
        view.node.parent = null;
        if (!this._pool.includes(view)) {
            this._pool.push(view);
        }
    }

    // -----------------------------------------------------------------------
    // Feedback
    // -----------------------------------------------------------------------

    private _flashMessage(text: string): void {
        if (!this.messageLabel) return;
        this.messageLabel.string = text;
        this.messageLabel.color = Palette.bad;
        this.scheduleOnce(() => {
            if (this.messageLabel) this.messageLabel.color = Palette.cream;
            this._renderChrome(this._match?.viewFor(HUMAN).opponents[0]?.handSize ?? 0);
        }, 1.1);
    }

    /** A small shake, so a rejected tap is felt rather than only read. */
    private _nudge(card: Card): void {
        const view = this._views.get(card);
        if (!view) return;
        const home = view.node.position.clone();
        tween(view.node)
            .to(0.05, { position: home.clone().add3f(-10, 0, 0) })
            .to(0.05, { position: home.clone().add3f(10, 0, 0) })
            .to(0.05, { position: home })
            .start();
    }
}

/** Trumps to the right, ascending — the order a player would hold them in. */
function byTrumpThenRank(trumpSuit: number) {
    return (a: Card, b: Card): number => {
        const aTrump = a.suit === trumpSuit ? 1 : 0;
        const bTrump = b.suit === trumpSuit ? 1 : 0;
        if (aTrump !== bTrump) return aTrump - bTrump;
        if (a.suit !== b.suit) return a.suit - b.suit;
        return a.rank - b.rank;
    };
}

function sameAction(wanted: Action) {
    return (other: Action): boolean =>
        other.type === wanted.type
        && (other as { card?: Card }).card === (wanted as { card?: Card }).card;
}

function setText(label: Label | null, text: string): void {
    if (label) label.string = text;
}

function setActive(node: Node | null, active: boolean): void {
    if (node) node.active = active;
}

function setButton(button: Button | null, enabled: boolean): void {
    if (!button) return;
    button.node.active = enabled;
    button.interactable = enabled;
}