// SYNC.JS VERSION 8 - LOADING
console.log("[SYNC] Loading sync.js v8...");
// NextSnap - Sync Engine with Upload Queue and Retry Logic
'use strict';

const Sync = {
    currentUsername: null,
    isOnline: navigator.onLine,
    isSyncing: false,
    currentUpload: null,
    retryTimeouts: {},
    
    // Exponential backoff delays (in milliseconds)
    retryDelays: [5000, 15000, 45000, 120000, 300000], // 5s, 15s, 45s, 2m, 5m
    maxRetryDelay: 300000, // Cap at 5 minutes
    
    init(username) {
        this.currentUsername = username;
        this.setupEventListeners();
        
        // Check for pending uploads on init
        if (this.isOnline) {
            this.triggerSync();
        }
    },
    
    setupEventListeners() {
        // Listen for online/offline events
        window.addEventListener('online', () => {
            console.log('Network online - triggering sync');
            this.isOnline = true;
            this.updateConnectivityUI();
            this.triggerSync();
        });
        
        window.addEventListener('offline', () => {
            console.log('Network offline');
            this.isOnline = false;
            this.isSyncing = false;
            this.updateConnectivityUI();
        });
    },
    
    async triggerSync() {
        if (!this.isOnline || this.isSyncing) {
            return;
        }
        
        console.log('Starting sync...');
        this.isSyncing = true;
        this.updateConnectivityUI();
        
        try {
            await this.processQueue();
        } catch (error) {
            console.error('Sync error:', error);
        } finally {
            this.isSyncing = false;
            this.updateConnectivityUI();
        }
    },
    
    async processQueue() {
        // Get pending and uploading photos (retry stalled uploads)
        const pendingPhotos = await Storage.db.photos
            .where('username').equals(this.currentUsername)
            .and(photo => photo.status === 'pending' || photo.status === 'uploading')
            .sortBy('timestamp');
        
        if (pendingPhotos.length === 0) {
            console.log('No pending photos to upload');
            return;
        }
        
        console.log(`Found ${pendingPhotos.length} photos to upload`);
        
        // Process uploads sequentially (one at a time)
        for (const photo of pendingPhotos) {
            if (!this.isOnline) {
                console.log('Lost connection - stopping sync');
                break;
            }
            
            await this.uploadPhoto(photo);
        }
        
        // Update UI
        this.updatePendingCount();
        this.updateRecentPhotos();
    },
    
    async uploadPhoto(photo) {
        this.currentUpload = photo;
        
        try {
            console.log(`Uploading ${photo.filename}...`);
            
            // Update status to uploading
            await Storage.updatePhoto(photo.id, { status: 'uploading' });
            this.updatePendingCount();
            
            // Upload file
            const formData = new FormData();
            formData.append('file', photo.blob, photo.filename);
            
            const uploadUrl = `/api/files/upload?path=${encodeURIComponent(photo.targetPath)}`;
            
            const uploadResponse = await fetch(uploadUrl, {
                method: 'POST',
                body: formData
            });
            
            if (!uploadResponse.ok) {
                const error = await uploadResponse.json();
                throw new Error(error.error || 'Upload failed');
            }
            
            const uploadResult = await uploadResponse.json();
            console.log(`Upload successful: ${uploadResult.path}`);
            
            // Update status to uploaded
            await Storage.updatePhoto(photo.id, { status: 'uploaded' });
            
            // Verify file exists on server
            const verifyUrl = `/api/files/verify?path=${encodeURIComponent(uploadResult.path)}`;
            
            const verifyResponse = await fetch(verifyUrl);
            
            if (!verifyResponse.ok) {
                throw new Error('Verification failed - file not found on server');
            }
            
            const verifyResult = await verifyResponse.json();
            
            if (!verifyResult.exists) {
                throw new Error('Verification failed - file does not exist');
            }
            
            console.log(`Verification successful: ${uploadResult.path}`);
            
            // Update status to verified
            await Storage.updatePhoto(photo.id, { status: 'verified' });
            
            // Delete from IndexedDB (only after verification!)
            await Storage.deletePhoto(photo.id);
            console.log(`Deleted photo ${photo.id} from IndexedDB`);
            
            // Clear any pending retry
            if (this.retryTimeouts[photo.id]) {
                clearTimeout(this.retryTimeouts[photo.id]);
                delete this.retryTimeouts[photo.id];
            }
            
        } catch (error) {
            console.error(`Error uploading ${photo.filename}:`, error);
            
            // Handle upload failure
            await this.handleUploadFailure(photo, error.message);
        } finally {
            this.currentUpload = null;
        }
    },
    
    async handleUploadFailure(photo, errorMessage) {
        const retryCount = (photo.retryCount || 0) + 1;
        
        // Update photo with error info
        await Storage.updatePhoto(photo.id, {
            status: 'pending',
            retryCount: retryCount,
            lastError: errorMessage
        });
        
        // Calculate retry delay using exponential backoff
        const delayIndex = Math.min(retryCount - 1, this.retryDelays.length - 1);
        const delay = this.retryDelays[delayIndex];
        
        console.log(`Scheduling retry #${retryCount} in ${delay / 1000}s for ${photo.filename}`);
        
        // Schedule retry
        if (this.retryTimeouts[photo.id]) {
            clearTimeout(this.retryTimeouts[photo.id]);
        }
        
        this.retryTimeouts[photo.id] = setTimeout(() => {
            delete this.retryTimeouts[photo.id];
            
            if (this.isOnline) {
                console.log(`Retrying upload for ${photo.filename}`);
                this.uploadPhoto(photo);
            }
        }, delay);
    },
    
    
    
    async updateRecentPhotos() {
        if (typeof Camera !== 'undefined' && Camera.updateRecentPhotos) {
            await Camera.updateRecentPhotos();
        }
    },
    updateConnectivityUI() {
        const indicator = document.querySelector(".connectivity-indicator");
        if (!indicator) return;
        indicator.classList.remove("online", "offline", "syncing");
        if (!this.isOnline) {
            indicator.classList.add("offline");
            indicator.title = "Offline";
        } else if (this.isSyncing) {
            indicator.classList.add("syncing");
            indicator.title = "Syncing...";
        } else {
            indicator.classList.add("online");
            indicator.title = "Online";
        }
    },

    async updatePendingCount() {
        if (!this.currentUsername) return;
        const countElement = document.getElementById("pendingCount");
        const countValueElement = document.getElementById("pendingCountValue");
        if (!countElement || !countValueElement) return;
        const count = await Storage.getPhotoCount(this.currentUsername, "pending");
        if (count > 0) {
            countValueElement.textContent = count;
            countElement.style.display = "block";
        } else {
            countElement.style.display = "none";
        }
    },

    },
    getState() {
        return {
            isOnline: this.isOnline,
            isSyncing: this.isSyncing,
        };
    }

// Make Sync globally available as SyncEngine
window.SyncEngine = Sync;
console.log("[SYNC] SyncEngine exported:", typeof window.SyncEngine);