// src/utils/VideoManager.js

export class VideoManager {
    constructor(callbacks) {
        // callbacks 用于通知 React 组件更新界面
        // 例如: onStatusUpdate, onSessionStart, onSessionEnd
        this.callbacks = callbacks || {};

        this.videoElement = null; // 显示后端处理后的视频
        this.stream = null; // 本地摄像头流
        this.pc = null;
        this.dataChannel = null;

        this.isStreaming = false;
        this.sessionId = null;
        this.frameRate = 30;

        // 状态平滑处理
        this.currentStatus = false;
        this.statusBuffer = [];
        this.bufferSize = 5;

        // 检测数据
        this.latestDetectionData = null;
        this.lastConfidence = 0;
        this.detectionHoldMs = 30;

        // 通知系统
        this.notificationEnabled = true;
        this.notificationThreshold = 30; // 默认30秒
        this.unfocusedStartTime = null;
        this.lastNotificationTime = null;
        this.notificationCooldown = 60000; // 通知冷却时间60秒
    }

    // 初始化：获取摄像头流，并记录展示视频的元素
    async initCamera(videoRef) {
        try {
            this.stream = await navigator.mediaDevices.getUserMedia({
                video: {
                    width: { ideal: 640 },
                    height: { ideal: 480 },
                    facingMode: 'user'
                },
                audio: false
            });

            this.videoElement = videoRef;
            return true;
        } catch (error) {
            console.error('Camera init error:', error);
            throw error;
        }
    }

    async startStreaming() {
        if (!this.stream) {
            console.error('❌ No stream available');
            throw new Error('Camera stream not initialized');
        }
        this.isStreaming = true;

        console.log('📹 Starting streaming...');

        // 请求通知权限
        await this.requestNotificationPermission();
        // 加载通知设置
        await this.loadNotificationSettings();

        this.pc = new RTCPeerConnection({
            iceServers: [
                { urls: 'stun:stun.l.google.com:19302' },
                { urls: 'stun:stun1.l.google.com:19302' },
                { urls: 'stun:stun2.l.google.com:19302' },
                { urls: 'stun:stun3.l.google.com:19302' },
                { urls: 'stun:stun4.l.google.com:19302' }
            ],
            iceCandidatePoolSize: 10
        });

        // 添加连接状态监控
        this.pc.onconnectionstatechange = () => {
            console.log('🔗 Connection state:', this.pc.connectionState);
        };

        this.pc.oniceconnectionstatechange = () => {
            console.log('🧊 ICE connection state:', this.pc.iceConnectionState);
        };

        this.pc.onicegatheringstatechange = () => {
            console.log('📡 ICE gathering state:', this.pc.iceGatheringState);
        };

        // DataChannel for status updates
        this.dataChannel = this.pc.createDataChannel('status');
        this.dataChannel.onmessage = (event) => {
            try {
                const data = JSON.parse(event.data);
                this.handleServerMessage(data);
            } catch (e) {
                console.error('Failed to parse data channel message:', e);
            }
        };

        this.pc.ontrack = (event) => {
            const stream = event.streams[0];
            if (this.videoElement) {
                this.videoElement.srcObject = stream;
                this.videoElement.autoplay = true;
                this.videoElement.playsInline = true;
                this.videoElement.play().catch(() => {});
            }
        };

        // Add local camera tracks
        this.stream.getTracks().forEach((track) => {
            this.pc.addTrack(track, this.stream);
        });

        const offer = await this.pc.createOffer();
        await this.pc.setLocalDescription(offer);

        // Wait for ICE gathering to complete so SDP includes candidates
        await new Promise((resolve) => {
            if (this.pc.iceGatheringState === 'complete') {
                resolve();
                return;
            }
            const onIce = () => {
                if (this.pc.iceGatheringState === 'complete') {
                    this.pc.removeEventListener('icegatheringstatechange', onIce);
                    resolve();
                }
            };
            this.pc.addEventListener('icegatheringstatechange', onIce);
        });

        console.log('📤 Sending offer to server...');
        const response = await fetch('/api/webrtc/offer', {
            method: 'POST',
            headers: { 'Content-Type': 'application/json' },
            body: JSON.stringify({
                sdp: this.pc.localDescription.sdp,
                type: this.pc.localDescription.type
            })
        });

        if (!response.ok) {
            const errorText = await response.text();
            console.error('❌ Server error:', errorText);
            throw new Error(`Server returned ${response.status}: ${errorText}`);
        }

        const answer = await response.json();
        console.log('✅ Received answer from server, session_id:', answer.session_id);

        await this.pc.setRemoteDescription(answer);
        console.log('✅ Remote description set successfully');

        this.sessionId = answer.session_id;
        if (this.callbacks.onSessionStart) {
            this.callbacks.onSessionStart(this.sessionId);
        }

    }

    async requestNotificationPermission() {
        if ('Notification' in window && Notification.permission === 'default') {
            try {
                await Notification.requestPermission();
            } catch (error) {
                console.error('Failed to request notification permission:', error);
            }
        }
    }

    async loadNotificationSettings() {
        try {
            const response = await fetch('/api/settings');
            const settings = await response.json();
            if (settings) {
                this.notificationEnabled = settings.notification_enabled ?? true;
                this.notificationThreshold = settings.notification_threshold ?? 30;
            }
        } catch (error) {
            console.error('Failed to load notification settings:', error);
        }
    }

    sendNotification(title, message) {
        if (!this.notificationEnabled) return;
        if ('Notification' in window && Notification.permission === 'granted') {
            try {
                const notification = new Notification(title, {
                    body: message,
                    icon: '/vite.svg',
                    badge: '/vite.svg',
                    tag: 'focus-guard-distraction',
                    requireInteraction: false
                });

                // 3秒后自动关闭
                setTimeout(() => notification.close(), 3000);
            } catch (error) {
                console.error('Failed to send notification:', error);
            }
        }
    }

    handleServerMessage(data) {
        switch (data.type) {
            case 'detection':
                this.updateStatus(data.focused);
                this.latestDetectionData = {
                    detections: data.detections || [],
                    confidence: data.confidence || 0,
                    focused: data.focused,
                    timestamp: performance.now()
                };
                this.lastConfidence = data.confidence || 0;

                if (this.callbacks.onStatusUpdate) {
                    this.callbacks.onStatusUpdate(this.currentStatus);
                }
                break;
            default:
                break;
        }
    }

    updateStatus(newFocused) {
        this.statusBuffer.push(newFocused);
        if (this.statusBuffer.length > this.bufferSize) {
            this.statusBuffer.shift();
        }

        if (this.statusBuffer.length < this.bufferSize) return false;

        const focusedCount = this.statusBuffer.filter(f => f).length;
        const focusedRatio = focusedCount / this.statusBuffer.length;

        const previousStatus = this.currentStatus;

        if (focusedRatio >= 0.75) {
            this.currentStatus = true;
        } else if (focusedRatio <= 0.25) {
            this.currentStatus = false;
        }

        // 通知逻辑
        this.handleNotificationLogic(previousStatus, this.currentStatus);
    }

    handleNotificationLogic(previousStatus, currentStatus) {
        const now = Date.now();

        // 如果从专注变为不专注，记录开始时间
        if (previousStatus && !currentStatus) {
            this.unfocusedStartTime = now;
        }

        // 如果从不专注变为专注，清除计时
        if (!previousStatus && currentStatus) {
            this.unfocusedStartTime = null;
        }

        // 如果持续不专注
        if (!currentStatus && this.unfocusedStartTime) {
            const unfocusedDuration = (now - this.unfocusedStartTime) / 1000; // 秒

            // 检查是否超过阈值且不在冷却期
            if (unfocusedDuration >= this.notificationThreshold) {
                const canSendNotification = !this.lastNotificationTime ||
                                           (now - this.lastNotificationTime) >= this.notificationCooldown;

                if (canSendNotification) {
                    this.sendNotification(
                        '⚠️ Focus Alert',
                        `You've been distracted for ${Math.floor(unfocusedDuration)} seconds. Get back to work!`
                    );
                    this.lastNotificationTime = now;
                }
            }
        }
    }

    async stopStreaming() {
        this.isStreaming = false;

        try {
            if (document.pictureInPictureElement) {
                await document.exitPictureInPicture();
            }
            if (this.videoElement && typeof this.videoElement.webkitSetPresentationMode === 'function') {
                if (this.videoElement.webkitPresentationMode === 'picture-in-picture') {
                    this.videoElement.webkitSetPresentationMode('inline');
                }
            }
        } catch (e) {
            // ignore PiP exit errors
        }

        if (this.pc) {
            try {
                this.pc.getSenders().forEach(sender => sender.track && sender.track.stop());
                this.pc.close();
            } catch (e) {
                console.error('Failed to close RTCPeerConnection:', e);
            }
            this.pc = null;
        }

        if (this.stream) {
            this.stream.getTracks().forEach(track => track.stop());
            this.stream = null;
        }

        if (this.videoElement) {
            this.videoElement.srcObject = null;
        }

        if (this.sessionId) {
            try {
                const response = await fetch('/api/sessions/end', {
                    method: 'POST',
                    headers: { 'Content-Type': 'application/json' },
                    body: JSON.stringify({ session_id: this.sessionId })
                });
                const summary = await response.json();
                if (this.callbacks.onSessionEnd) {
                    this.callbacks.onSessionEnd(summary);
                }
            } catch (e) {
                console.error('Failed to end session:', e);
            }
        }

        // 清理通知状态
        this.unfocusedStartTime = null;
        this.lastNotificationTime = null;
        this.sessionId = null;
    }

    setFrameRate(rate) {
        this.frameRate = Math.max(1, Math.min(60, rate));
        if (this.stream) {
            const videoTrack = this.stream.getVideoTracks()[0];
            if (videoTrack && videoTrack.applyConstraints) {
                videoTrack.applyConstraints({ frameRate: { ideal: this.frameRate, max: this.frameRate } }).catch(() => {});
            }
        }
    }
}