import { Controller } from '@hotwired/stimulus';

/*
 * The shared, no-login puzzle board. Connects to the WebSocket relay
 * (src/Command/PuzzleRelayCommand.php) so every open tab on this room sees
 * the same piece positions and each other's cursors, live.
 *
 *   <div data-controller="puzzle-room"
 *        data-puzzle-room-room-value="chamber-of-motion"
 *        data-puzzle-room-relay-url-value="ws://127.0.0.1:8091">
 *     <form data-puzzle-room-target="joinForm" data-action="submit->puzzle-room#join">...</form>
 *     <div data-puzzle-room-target="board" hidden>
 *       <div data-puzzle-room-target="piece" data-piece-id="a"
 *            data-action="pointerdown->puzzle-room#startDrag">...</div>
 *     </div>
 *   </div>
 *
 * Room state (piece positions, who's online) lives only in the relay
 * process's memory - there is no database or cache behind this.
 */
const CLIENT_KEY = 'dmtools.puzzleClient';
const CURSOR_THROTTLE_MS = 40;
const PIECE_THROTTLE_MS = 40;
const RECONNECT_DELAY_MS = 2000;
const HEARTBEAT_INTERVAL_MS = 15000;

export default class extends Controller {
    static targets = ['board', 'piece', 'joinForm', 'nameInput', 'status'];
    static values = { room: String, relayUrl: String, resetToken: String };

    connect() {
        this.cursorEls = new Map();
        this.pieceEls = new Map();
        this.defaultPositions = new Map();
        this.pieceTargets.forEach((el) => {
            this.pieceEls.set(el.dataset.pieceId, el);
            this.defaultPositions.set(el.dataset.pieceId, { left: el.style.left, top: el.style.top });
        });
        this.dragging = null;

        this.onPointerMove = this.onPointerMove.bind(this);
        this.onPointerUp = this.onPointerUp.bind(this);
        this.onBoardPointerMove = this.onBoardPointerMove.bind(this);
        this.sendCursor = throttle((x, y) => this.send({ type: 'cursor', room: this.roomValue, x, y }), CURSOR_THROTTLE_MS);
        this.sendPieceMove = throttle((id, x, y) => this.send({ type: 'piece', room: this.roomValue, id, x, y, phase: 'move' }), PIECE_THROTTLE_MS);

        this.client = this.loadClient();
        if (this.client) {
            this.startSession();
        }
    }

    disconnect() {
        clearInterval(this.heartbeatTimer);
        this.socket?.close();
        clearTimeout(this.reconnectTimer);
        window.removeEventListener('pointermove', this.onPointerMove);
        window.removeEventListener('pointerup', this.onPointerUp);
    }

    join(event) {
        event.preventDefault();
        const name = this.nameInputTarget.value.trim();
        if (!name) return;

        this.client = { clientId: crypto.randomUUID(), name: name.slice(0, 40), color: randomColor() };
        try {
            sessionStorage.setItem(CLIENT_KEY, JSON.stringify(this.client));
        } catch {
            /* private mode: identity just won't survive a reload */
        }
        this.startSession();
    }

    loadClient() {
        try {
            const raw = sessionStorage.getItem(CLIENT_KEY);
            return raw ? JSON.parse(raw) : null;
        } catch {
            return null;
        }
    }

    startSession() {
        this.joinFormTarget.hidden = true;
        this.boardTarget.hidden = false;
        this.boardTarget.addEventListener('pointermove', this.onBoardPointerMove);
        this.connectSocket();
    }

    connectSocket() {
        this.setStatus('Connecting…');
        const socket = new WebSocket(this.relayUrlValue);
        this.socket = socket;

        socket.addEventListener('open', () => {
            this.send({
                type: 'join',
                room: this.roomValue,
                clientId: this.client.clientId,
                name: this.client.name,
                color: this.client.color,
            });
            this.heartbeatTimer = setInterval(() => this.send({ type: 'ping' }), HEARTBEAT_INTERVAL_MS);
        });
        socket.addEventListener('message', (event) => this.onMessage(event));
        socket.addEventListener('close', () => {
            clearInterval(this.heartbeatTimer);
            this.setStatus('Disconnected — retrying…');
            this.reconnectTimer = setTimeout(() => this.connectSocket(), RECONNECT_DELAY_MS);
        });
        socket.addEventListener('error', () => socket.close());
    }

    setStatus(text) {
        if (this.hasStatusTarget) this.statusTarget.textContent = text;
    }

    send(payload) {
        if (this.socket?.readyState === WebSocket.OPEN) {
            this.socket.send(JSON.stringify(payload));
        }
    }

    onMessage(event) {
        let message;
        try {
            message = JSON.parse(event.data);
        } catch {
            return;
        }

        switch (message.type) {
            case 'state':
                Object.entries(message.pieces || {}).forEach(([id, pos]) => this.placePiece(id, pos.x, pos.y));
                this.renderPresence(message.clients || []);
                break;
            case 'cursor':
                if (message.clientId !== this.client.clientId) this.renderCursor(message);
                break;
            case 'piece':
                if (message.clientId !== this.client.clientId) this.placePiece(message.id, message.x, message.y);
                break;
            case 'presence':
                this.renderPresence(message.clients || []);
                break;
            case 'reset':
                this.resetPieces();
                break;
        }
    }

    reset() {
        if (!this.resetTokenValue) return;
        if (!window.confirm('Reset the puzzle? This puts every gear back in the tray for everyone in this room.')) return;
        this.send({ type: 'reset', room: this.roomValue, resetToken: this.resetTokenValue });
    }

    resetPieces() {
        this.dragging = null;
        for (const [id, el] of this.pieceEls) {
            const pos = this.defaultPositions.get(id);
            if (!pos) continue;
            el.style.left = pos.left;
            el.style.top = pos.top;
        }
    }

    renderPresence(clients) {
        const seen = new Set(clients.map((c) => c.clientId));
        for (const [clientId, el] of this.cursorEls) {
            if (!seen.has(clientId)) {
                el.remove();
                this.cursorEls.delete(clientId);
            }
        }
        const others = clients.filter((c) => c.clientId !== this.client.clientId).length;
        this.setStatus(others > 0 ? `Connected — ${others} other${others === 1 ? '' : 's'} here` : "Connected — you're the only one here");
    }

    renderCursor(message) {
        let el = this.cursorEls.get(message.clientId);
        if (!el) {
            el = document.createElement('div');
            el.className = 'puzzle-cursor';
            el.innerHTML = '<span class="puzzle-cursor-dot"></span><span class="puzzle-cursor-label"></span>';
            el.querySelector('.puzzle-cursor-dot').style.background = message.color;
            el.querySelector('.puzzle-cursor-label').style.background = message.color;
            el.querySelector('.puzzle-cursor-label').textContent = message.name;
            this.boardTarget.appendChild(el);
            this.cursorEls.set(message.clientId, el);
        }
        el.style.left = `${message.x * 100}%`;
        el.style.top = `${message.y * 100}%`;
    }

    placePiece(id, x, y) {
        const el = this.pieceEls.get(id);
        if (!el || this.dragging?.id === id) return;
        el.style.left = `${x * 100}%`;
        el.style.top = `${y * 100}%`;
    }

    onBoardPointerMove(event) {
        const { x, y } = this.relativePosition(event);
        this.sendCursor(x, y);
    }

    relativePosition(event) {
        const rect = this.boardTarget.getBoundingClientRect();
        return {
            x: clamp((event.clientX - rect.left) / rect.width, 0, 1),
            y: clamp((event.clientY - rect.top) / rect.height, 0, 1),
        };
    }

    startDrag(event) {
        const el = event.currentTarget;
        el.setPointerCapture(event.pointerId);
        this.dragging = { id: el.dataset.pieceId, el };
        el.classList.add('is-dragging');
        window.addEventListener('pointermove', this.onPointerMove);
        window.addEventListener('pointerup', this.onPointerUp);
    }

    onPointerMove(event) {
        if (!this.dragging) return;
        const { x, y } = this.relativePosition(event);
        this.dragging.el.style.left = `${x * 100}%`;
        this.dragging.el.style.top = `${y * 100}%`;
        this.sendPieceMove(this.dragging.id, x, y);
    }

    onPointerUp(event) {
        if (!this.dragging) return;
        const { x, y } = this.relativePosition(event);
        this.send({ type: 'piece', room: this.roomValue, id: this.dragging.id, x, y, phase: 'drop' });
        this.dragging.el.classList.remove('is-dragging');
        this.dragging = null;
        window.removeEventListener('pointermove', this.onPointerMove);
        window.removeEventListener('pointerup', this.onPointerUp);
    }
}

function throttle(fn, ms) {
    let last = 0;
    let timer = null;
    return (...args) => {
        const now = Date.now();
        const remaining = ms - (now - last);
        clearTimeout(timer);
        if (remaining <= 0) {
            last = now;
            fn(...args);
        } else {
            timer = setTimeout(() => {
                last = Date.now();
                fn(...args);
            }, remaining);
        }
    };
}

function clamp(value, min, max) {
    return Math.min(max, Math.max(min, value));
}

function randomColor() {
    return `hsl(${Math.floor(Math.random() * 360)}, 70%, 55%)`;
}