class MultiplayerSystem {
    constructor(scene) {
        this.scene = scene;
        this.socket = null;
        this.otherPlayers = {}; // Map socketId -> Sprite
        this.isConnected = false;

        // Try to connect
        this.connect();
    }

    connect() {
        if (typeof io === 'undefined') {
            console.warn('⚠️ Socket.IO not found. Multiplayer disabled.');
            console.warn('Please run: npm install socket.io-client OR include CDN.');
            return;
        }

        console.log('🌐 Connecting to Multiplayer Server...');
        // Connect to localhost:3000
        this.socket = io('http://localhost:3000');

        this.socket.on('connect', () => {
            console.log('✅ Connected to Server! ID:', this.socket.id);
            this.isConnected = true;

            // Send initial pos
            if (this.scene.player) {
                const pos = this.scene.player.getPosition();
                this.socket.emit('playerMovement', {
                    x: pos.x,
                    y: pos.y,
                    anim: 'idle',
                    flipX: false
                });
            }
        });

        this.socket.on('currentPlayers', (players) => {
            Object.keys(players).forEach((id) => {
                if (id === this.socket.id) return;
                this.addOtherPlayer(players[id]);
            });
        });

        this.socket.on('newPlayer', (playerInfo) => {
            this.addOtherPlayer(playerInfo);
        });

        this.socket.on('playerDisconnected', (playerId) => {
            this.removeOtherPlayer(playerId);
        });

        this.socket.on('playerMoved', (playerInfo) => {
            if (this.otherPlayers[playerInfo.id]) {
                const sprite = this.otherPlayers[playerInfo.id];
                // Update target pos for interpolation (TODO: logic)
                // For now direct teleport

                // Convert grid to screen
                const iso = new IsometricUtils(48, 24);
                const screen = iso.toScreen(playerInfo.x, playerInfo.y);

                sprite.setPosition(screen.x + this.scene.terrainOffsetX, screen.y + this.scene.terrainOffsetY);
                sprite.setDepth(sprite.y);

                // Anim/Flip logic could go here
                if (playerInfo.flipX !== undefined) sprite.setFlipX(playerInfo.flipX);
            }
        });

        this.socket.on('worldAction', (action) => {
            // Handle world syncing
            if (action.type === 'build' && this.scene.buildingSystem) {
                // Hacky: place building remotely
                // this.scene.terrainSystem.placeStructure(...)
            }
        });
    }

    addOtherPlayer(playerInfo) {
        if (this.otherPlayers[playerInfo.id]) return;

        console.log('👤 New Player Joined:', playerInfo.id);

        // Use player sprite
        const iso = new IsometricUtils(48, 24);
        const screen = iso.toScreen(playerInfo.x, playerInfo.y);

        const sprite = this.scene.add.sprite(
            screen.x + this.scene.terrainOffsetX,
            screen.y + this.scene.terrainOffsetY,
            'player' // or player_idle
        );
        sprite.setOrigin(0.5, 1);
        sprite.setScale(0.3); // Same as local player

        // Add name tag
        const text = this.scene.add.text(0, -50, 'Player', { fontSize: '12px', fill: '#ffffff' });
        text.setOrigin(0.5);
        // Container? For now just sprite, text handling is complex

        this.otherPlayers[playerInfo.id] = sprite;
    }

    removeOtherPlayer(playerId) {
        if (this.otherPlayers[playerId]) {
            console.log('👋 Player Left:', playerId);
            this.otherPlayers[playerId].destroy();
            delete this.otherPlayers[playerId];
        }
    }

    update(delta) {
        if (!this.isConnected || !this.socket || !this.scene.player) return;

        // Rate limit: send 10 times second? Or every frame?
        // Let's send only if moved
        const player = this.scene.player;
        if (player.isMoving) {
            this.socket.emit('playerMovement', {
                x: player.gridX,
                y: player.gridY,
                anim: 'walk',
                flipX: player.sprite.flipX // Accessing internal sprite
            });
        }
    }
}