/**
 * Photo Queue - Image compression and upload queue
 *
 * Handles image capture, compression, storage, and upload queueing for offline mode.
 * Converts HEIC (iOS) to JPEG, compresses images, and stores them for later upload.
 */

import { db, OperationType } from './db.js';
import { isOfflineModeEnabled, getDeviceId } from './offlineSettings.js';

// Import image compression from CDN
const imageCompression = await import('https://cdn.jsdelivr.net/npm/browser-image-compression@2/dist/browser-image-compression.mjs').then(m => m.default);

// Compression settings
const COMPRESSION_OPTIONS = {
    maxSizeMB: 1,           // Max 1MB after compression
    maxWidthOrHeight: 1920, // Max dimension
    useWebWorker: true,
    fileType: 'image/jpeg',
    initialQuality: 0.8
};

// Upload status
export const UploadStatus = {
    PENDING: 'pending',
    COMPRESSING: 'compressing',
    UPLOADING: 'uploading',
    COMPLETED: 'completed',
    FAILED: 'failed'
};

const API_BASE = '/MobileApp/Workorder/Workorder';

/**
 * Generate unique local ID
 */
function generateLocalId() {
    if (crypto.randomUUID) {
        return crypto.randomUUID();
    }
    return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {
        const r = Math.random() * 16 | 0;
        const v = c === 'x' ? r : (r & 0x3 | 0x8);
        return v.toString(16);
    });
}

/**
 * Check if file is HEIC format (iOS)
 */
function isHeicFile(file) {
    const type = file.type?.toLowerCase() || '';
    const name = file.name?.toLowerCase() || '';
    return type === 'image/heic' ||
           type === 'image/heif' ||
           name.endsWith('.heic') ||
           name.endsWith('.heif');
}

/**
 * Convert HEIC to JPEG
 */
async function convertHeicToJpeg(file) {
    try {
        // Dynamically import heic2any
        const heic2any = await import('https://cdn.jsdelivr.net/npm/heic2any@0.0.4/dist/heic2any.min.js').then(m => m.default || window.heic2any);

        const result = await heic2any({
            blob: file,
            toType: 'image/jpeg',
            quality: 0.9
        });

        // heic2any can return array or single blob
        const jpegBlob = Array.isArray(result) ? result[0] : result;

        // Create new file with .jpg extension
        const newName = file.name.replace(/\.(heic|heif)$/i, '.jpg');
        return new File([jpegBlob], newName, { type: 'image/jpeg' });
    } catch (error) {
        console.error('[PhotoQueue] HEIC conversion failed:', error);
        throw new Error('HEIC-Konvertierung fehlgeschlagen');
    }
}

/**
 * Compress image file
 */
async function compressImage(file, onProgress) {
    try {
        // Handle HEIC files first
        let processedFile = file;
        if (isHeicFile(file)) {
            onProgress?.({ phase: 'converting', message: 'Konvertiere HEIC...' });
            processedFile = await convertHeicToJpeg(file);
        }

        // Check if compression needed
        const fileSizeMB = processedFile.size / (1024 * 1024);
        if (fileSizeMB <= COMPRESSION_OPTIONS.maxSizeMB && processedFile.type === 'image/jpeg') {
            // Already small enough and correct format
            return processedFile;
        }

        onProgress?.({ phase: 'compressing', message: 'Komprimiere Bild...' });

        const compressedFile = await imageCompression(processedFile, {
            ...COMPRESSION_OPTIONS,
            onProgress: (progress) => {
                onProgress?.({ phase: 'compressing', progress });
            }
        });

        console.log(`[PhotoQueue] Compressed ${file.name}: ${fileSizeMB.toFixed(2)}MB -> ${(compressedFile.size / (1024 * 1024)).toFixed(2)}MB`);

        return compressedFile;
    } catch (error) {
        console.error('[PhotoQueue] Compression failed:', error);
        throw new Error('Bildkomprimierung fehlgeschlagen');
    }
}

/**
 * Queue photo for upload
 */
export async function queuePhoto(workorderId, file, documentType, description = '') {
    const localId = generateLocalId();

    // Create initial entry
    const entry = {
        localId,
        workorderId,
        documentType,
        description,
        originalFileName: file.name,
        originalSize: file.size,
        mimeType: file.type,
        status: UploadStatus.COMPRESSING,
        progress: 0,
        createdAt: Date.now(),
        deviceId: getDeviceId(),
        error: null
    };

    // Store entry
    await db.pendingFiles.add(entry);

    try {
        // Compress image
        const compressedFile = await compressImage(file, (progressInfo) => {
            // Update status
            db.pendingFiles.update(localId, { progress: progressInfo.progress || 0 });
        });

        // Convert to blob and store
        const blob = new Blob([compressedFile], { type: 'image/jpeg' });

        await db.pendingFiles.update(localId, {
            status: UploadStatus.PENDING,
            blob,
            compressedSize: blob.size,
            fileName: compressedFile.name || `photo_${localId}.jpg`,
            progress: 100
        });

        console.log(`[PhotoQueue] Queued photo ${localId} for workorder ${workorderId}`);

        return {
            success: true,
            localId,
            message: 'Foto wird bei nächster Verbindung hochgeladen'
        };
    } catch (error) {
        await db.pendingFiles.update(localId, {
            status: UploadStatus.FAILED,
            error: error.message
        });

        return {
            success: false,
            localId,
            error: error.message
        };
    }
}

/**
 * Get pending photos
 */
export async function getPendingPhotos() {
    return db.pendingFiles
        .where('status')
        .equals(UploadStatus.PENDING)
        .toArray();
}

/**
 * Get pending photos for workorder
 */
export async function getWorkorderPendingPhotos(workorderId) {
    return db.pendingFiles
        .where('workorderId')
        .equals(workorderId)
        .toArray();
}

/**
 * Get pending photos count
 */
export async function getPendingCount() {
    return db.pendingFiles
        .where('status')
        .anyOf([UploadStatus.PENDING, UploadStatus.UPLOADING])
        .count();
}

/**
 * Upload single photo
 */
export async function uploadPhoto(localId, onProgress) {
    const entry = await db.pendingFiles.get(localId);
    if (!entry || entry.status !== UploadStatus.PENDING) {
        return { success: false, error: 'Foto nicht gefunden oder bereits verarbeitet' };
    }

    await db.pendingFiles.update(localId, { status: UploadStatus.UPLOADING });

    try {
        const formData = new FormData();
        formData.append('workorderId', entry.workorderId);
        formData.append('documentType', entry.documentType);
        formData.append('description', entry.description || '');
        formData.append('files[]', entry.blob, entry.fileName);

        const response = await fetch(`${API_BASE}/uploadDocumentation`, {
            method: 'POST',
            credentials: 'include',
            body: formData
        });

        const result = await response.json();

        if (result.success) {
            // Mark as completed but keep for a while (cleanup later)
            await db.pendingFiles.update(localId, {
                status: UploadStatus.COMPLETED,
                completedAt: Date.now(),
                serverResponse: result
            });

            console.log(`[PhotoQueue] Uploaded photo ${localId}`);
            return { success: true, localId, serverResponse: result };
        } else {
            await db.pendingFiles.update(localId, {
                status: UploadStatus.FAILED,
                error: result.error || 'Upload fehlgeschlagen'
            });

            return { success: false, localId, error: result.error };
        }
    } catch (error) {
        console.error(`[PhotoQueue] Upload failed for ${localId}:`, error);

        await db.pendingFiles.update(localId, {
            status: UploadStatus.PENDING, // Back to pending for retry
            error: error.message
        });

        return { success: false, localId, error: error.message, retriable: true };
    }
}

/**
 * Upload all pending photos
 */
export async function uploadAllPending(onProgress) {
    const pending = await getPendingPhotos();
    const total = pending.length;
    let uploaded = 0;
    let failed = 0;

    for (const photo of pending) {
        onProgress?.({
            current: uploaded + 1,
            total,
            fileName: photo.fileName
        });

        const result = await uploadPhoto(photo.localId);
        if (result.success) {
            uploaded++;
        } else {
            failed++;
        }
    }

    return { uploaded, failed, total };
}

/**
 * Delete pending photo
 */
export async function deletePendingPhoto(localId) {
    await db.pendingFiles.delete(localId);
    console.log(`[PhotoQueue] Deleted pending photo ${localId}`);
}

/**
 * Delete all pending photos for workorder
 */
export async function deleteWorkorderPhotos(workorderId) {
    const count = await db.pendingFiles
        .where('workorderId')
        .equals(workorderId)
        .delete();
    console.log(`[PhotoQueue] Deleted ${count} pending photos for workorder ${workorderId}`);
    return count;
}

/**
 * Retry failed photo
 */
export async function retryPhoto(localId) {
    await db.pendingFiles.update(localId, {
        status: UploadStatus.PENDING,
        error: null
    });
}

/**
 * Cleanup completed photos older than specified time
 */
export async function cleanupCompleted(maxAgeMs = 24 * 60 * 60 * 1000) {
    const cutoff = Date.now() - maxAgeMs;
    const count = await db.pendingFiles
        .where('status')
        .equals(UploadStatus.COMPLETED)
        .filter(p => p.completedAt && p.completedAt < cutoff)
        .delete();
    console.log(`[PhotoQueue] Cleaned up ${count} completed photos`);
    return count;
}

/**
 * Get thumbnail blob for pending photo (for preview)
 */
export async function getPhotoThumbnail(localId) {
    const entry = await db.pendingFiles.get(localId);
    if (!entry || !entry.blob) return null;

    // Create small thumbnail using canvas
    return new Promise((resolve) => {
        const img = new Image();
        img.onload = () => {
            const canvas = document.createElement('canvas');
            const maxSize = 200;
            let width = img.width;
            let height = img.height;

            if (width > height) {
                if (width > maxSize) {
                    height = Math.round((height * maxSize) / width);
                    width = maxSize;
                }
            } else {
                if (height > maxSize) {
                    width = Math.round((width * maxSize) / height);
                    height = maxSize;
                }
            }

            canvas.width = width;
            canvas.height = height;

            const ctx = canvas.getContext('2d');
            ctx.drawImage(img, 0, 0, width, height);

            canvas.toBlob(resolve, 'image/jpeg', 0.7);
        };
        img.onerror = () => resolve(null);
        img.src = URL.createObjectURL(entry.blob);
    });
}

/**
 * Get photo URL for display (creates object URL)
 */
export async function getPhotoUrl(localId) {
    const entry = await db.pendingFiles.get(localId);
    if (!entry || !entry.blob) return null;
    return URL.createObjectURL(entry.blob);
}

/**
 * Get storage size used by pending photos
 */
export async function getStorageUsed() {
    const photos = await db.pendingFiles.toArray();
    let totalSize = 0;
    for (const photo of photos) {
        if (photo.blob) {
            totalSize += photo.blob.size;
        }
    }
    return totalSize;
}

/**
 * Check if there's enough storage for new photo
 */
export async function hasStorageSpace(estimatedSize = 2 * 1024 * 1024) {
    if (navigator.storage && navigator.storage.estimate) {
        const estimate = await navigator.storage.estimate();
        const available = (estimate.quota || 0) - (estimate.usage || 0);
        const buffer = 10 * 1024 * 1024; // 10MB buffer
        return available > (estimatedSize + buffer);
    }
    return true; // Assume we have space if we can't check
}

export default {
    UploadStatus,
    queue: queuePhoto,
    getPending: getPendingPhotos,
    getWorkorderPhotos: getWorkorderPendingPhotos,
    getPendingCount,
    upload: uploadPhoto,
    uploadAll: uploadAllPending,
    delete: deletePendingPhoto,
    deleteForWorkorder: deleteWorkorderPhotos,
    retry: retryPhoto,
    cleanup: cleanupCompleted,
    getThumbnail: getPhotoThumbnail,
    getUrl: getPhotoUrl,
    getStorageUsed,
    hasSpace: hasStorageSpace
};