/**
 * @node imap-extract-attachments
 * @name IMAP Extract Attachments
 * @category email
 * @version 1.4.0
 * @description Extract attachments from email as binary files. Compatible with OCR Upload and other binary-accepting nodes.
 * @icon paperclip
 */

const configSchema = {
    type: 'object',
    properties: {
        emailSource: {
            type: 'string',
            title: 'Email Source',
            description: 'Path to email data containing the raw body (e.g., {{item.body}} for loop iterations, or {{data.body}} for direct input)'
        },
        deduplicateByHash: {
            type: 'boolean',
            title: 'Deduplicate by Content',
            description: 'Skip storing attachments that already exist (based on content hash). Prevents duplicates when processing the same email multiple times.',
            default: true
        },
        filterMimeTypes: {
            type: 'string',
            title: 'Filter by MIME Types',
            description: 'Comma-separated list of MIME types to include (e.g. application/pdf, image/*). Leave empty for all attachments.'
        },
        filterExtensions: {
            type: 'string',
            title: 'Filter by Extensions',
            description: 'Comma-separated list of file extensions to include (e.g. pdf, jpg, png). Leave empty for all.'
        },
        maxSize: {
            type: 'integer',
            title: 'Max Size (bytes)',
            description: 'Maximum attachment size in bytes (0 = no limit)',
            default: 0
        },
        storeInDatabase: {
            type: 'boolean',
            title: 'Store in Database',
            description: 'Store extracted attachments in database for later retrieval',
            default: false
        },
        storageCollection: {
            type: 'string',
            title: 'Storage Collection',
            description: 'Select collection to store attachments',
            dynamicOptions: {
                source: 'storage.collections',
                labelField: 'name',
                valueField: 'name',
                filter: { access: 'read-write' }
            }
        },
        storageTtlHours: {
            type: 'number',
            title: 'TTL (hours)',
            default: 24,
            description: 'Auto-delete stored files after hours (0 = never)'
        },
        binaryStoragePath: {
            type: 'string',
            title: 'Binary Storage Path',
            default: './data/attachments',
            description: 'Base directory for storing binary files on disk'
        }
    }
};

const inputSchema = {
    type: 'object',
    properties: {
        raw: {
            type: 'string',
            description: 'Raw email content (from IMAP Fetch or IMAP Trigger with fetchContent enabled)'
        },
        email: {
            type: 'object',
            description: 'Email object containing raw property'
        }
    }
};

const outputSchema = {
    type: 'object',
    properties: {
        attachments: {
            type: 'array',
            description: 'Array of extracted attachments as binary file objects',
            items: {
                type: 'object',
                properties: {
                    type: { type: 'string', const: 'binary' },
                    data: { type: 'string', description: 'Base64-encoded content' },
                    mimeType: { type: 'string' },
                    filename: { type: 'string' },
                    size: { type: 'number' },
                    contentId: { type: 'string', description: 'Content-ID for inline attachments' },
                    storage: {
                        type: 'object',
                        description: 'Storage reference (if storeInDatabase enabled)',
                        properties: {
                            collection: { type: 'string' },
                            id: { type: 'string' }
                        }
                    }
                }
            }
        },
        count: { type: 'integer', description: 'Number of attachments extracted' },
        totalSize: { type: 'integer', description: 'Total size of all attachments in bytes' }
    }
};

const outputs = [
    { name: 'main', displayName: 'Attachments', type: 'object', color: '#f59e0b' }
];

/**
 * Parse MIME multipart content and extract attachments
 */
function parseMimeContent(rawEmail) {
    const attachments = [];

    // Find boundary from Content-Type header
    const boundaryMatch = rawEmail.match(/boundary=["']?([^"'\s;]+)["']?/i);
    if (!boundaryMatch) {
        // Not a multipart email, no attachments
        return attachments;
    }

    const boundary = boundaryMatch[1];
    const parts = rawEmail.split('--' + boundary);

    for (let i = 1; i < parts.length; i++) {
        const part = parts[i];

        // Skip the closing boundary marker
        if (part.trim() === '--' || part.trim().startsWith('--')) {
            continue;
        }

        // Parse headers and body from this part
        const headerEndIndex = part.indexOf('\r\n\r\n');
        const headerEndIndex2 = part.indexOf('\n\n');
        const actualHeaderEnd = headerEndIndex !== -1 ? headerEndIndex : headerEndIndex2;

        if (actualHeaderEnd === -1) continue;

        const headers = part.substring(0, actualHeaderEnd);
        const body = part.substring(actualHeaderEnd + (headerEndIndex !== -1 ? 4 : 2));

        // Check if this is an attachment
        const contentDisposition = headers.match(/Content-Disposition:\s*([^\r\n]+)/i);
        const contentType = headers.match(/Content-Type:\s*([^\r\n;]+)/i);
        const contentTransferEncoding = headers.match(/Content-Transfer-Encoding:\s*([^\r\n]+)/i);
        const contentId = headers.match(/Content-ID:\s*<?([^>\r\n]+)>?/i);

        // Extract filename from Content-Disposition or Content-Type
        let filename = null;
        const filenameMatch = headers.match(/filename=["']?([^"'\r\n;]+)["']?/i);
        const filenameStarMatch = headers.match(/filename\*=(?:UTF-8''|utf-8'')([^\r\n;]+)/i);
        const nameMatch = headers.match(/name=["']?([^"'\r\n;]+)["']?/i);

        if (filenameStarMatch) {
            try {
                filename = decodeURIComponent(filenameStarMatch[1]);
            } catch (e) {
                filename = filenameStarMatch[1];
            }
        } else if (filenameMatch) {
            filename = filenameMatch[1];
        } else if (nameMatch) {
            filename = nameMatch[1];
        }

        // Determine if this is an attachment (has filename or Content-Disposition: attachment)
        const isAttachment = filename ||
            (contentDisposition && contentDisposition[1].toLowerCase().includes('attachment'));

        // Skip if not an attachment and no filename
        if (!isAttachment) continue;

        // Get MIME type
        const mimeType = contentType ? contentType[1].trim() : 'application/octet-stream';

        // Skip text/plain and text/html parts (these are usually the email body)
        if (mimeType.startsWith('text/plain') || mimeType.startsWith('text/html')) {
            if (!filename) continue;  // Only skip if no filename (body part)
        }

        // Decode content based on transfer encoding
        let data = body.trim();
        const encoding = contentTransferEncoding ? contentTransferEncoding[1].trim().toLowerCase() : '';

        if (encoding === 'base64') {
            // Already base64 encoded, just clean it up
            data = data.replace(/[\r\n\s]/g, '');
        } else if (encoding === 'quoted-printable') {
            // Decode quoted-printable and then base64 encode
            const decoded = decodeQuotedPrintable(data);
            data = smartbotic.utils.base64Encode(decoded);
        } else {
            // Raw or 7bit/8bit - base64 encode it
            data = smartbotic.utils.base64Encode(data);
        }

        // Generate filename if not present
        if (!filename) {
            const ext = getExtensionForMimeType(mimeType);
            filename = 'attachment_' + (attachments.length + 1) + ext;
        }

        // Calculate size (approximate from base64)
        const size = Math.floor(data.length * 3 / 4);

        attachments.push({
            type: 'binary',
            data: data,
            mimeType: mimeType,
            filename: filename,
            size: size,
            contentId: contentId ? contentId[1] : null
        });
    }

    return attachments;
}

/**
 * Decode quoted-printable encoding
 */
function decodeQuotedPrintable(str) {
    return str
        .replace(/=\r?\n/g, '')  // Remove soft line breaks
        .replace(/=([0-9A-Fa-f]{2})/g, (match, hex) => {
            return String.fromCharCode(parseInt(hex, 16));
        });
}

/**
 * Get file extension for common MIME types
 */
function getExtensionForMimeType(mimeType) {
    const mimeMap = {
        'application/pdf': '.pdf',
        'application/msword': '.doc',
        'application/vnd.openxmlformats-officedocument.wordprocessingml.document': '.docx',
        'application/vnd.ms-excel': '.xls',
        'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet': '.xlsx',
        'application/vnd.ms-powerpoint': '.ppt',
        'application/vnd.openxmlformats-officedocument.presentationml.presentation': '.pptx',
        'application/zip': '.zip',
        'application/x-rar-compressed': '.rar',
        'application/x-7z-compressed': '.7z',
        'application/gzip': '.gz',
        'image/jpeg': '.jpg',
        'image/png': '.png',
        'image/gif': '.gif',
        'image/bmp': '.bmp',
        'image/webp': '.webp',
        'image/tiff': '.tiff',
        'text/plain': '.txt',
        'text/csv': '.csv',
        'text/html': '.html',
        'application/json': '.json',
        'application/xml': '.xml'
    };

    return mimeMap[mimeType.toLowerCase()] || '.bin';
}

/**
 * Check if MIME type matches filter pattern (supports wildcards like "image/*")
 */
function matchesMimeType(mimeType, patterns) {
    if (!patterns || patterns.length === 0) return true;

    const lowerMime = mimeType.toLowerCase();

    for (const pattern of patterns) {
        const lowerPattern = pattern.trim().toLowerCase();
        if (lowerPattern.endsWith('/*')) {
            const prefix = lowerPattern.slice(0, -1);
            if (lowerMime.startsWith(prefix)) return true;
        } else if (lowerMime === lowerPattern) {
            return true;
        }
    }

    return false;
}

/**
 * Check if filename matches extension filter
 */
function matchesExtension(filename, extensions) {
    if (!extensions || extensions.length === 0) return true;

    const lowerFilename = filename.toLowerCase();

    for (const ext of extensions) {
        const lowerExt = ext.trim().toLowerCase();
        const dotExt = lowerExt.startsWith('.') ? lowerExt : '.' + lowerExt;
        if (lowerFilename.endsWith(dotExt)) return true;
    }

    return false;
}

module.exports = {
    configSchema,
    inputSchema,
    outputSchema,
    outputs,

    async execute(config, input, context) {
        // Get raw email content from input
        let rawEmail = null;

        // First priority: use configured emailSource if provided
        // The expression (e.g., {{item.body}}) is evaluated by the workflow engine,
        // so config.emailSource contains the actual email body string
        if (config.emailSource && typeof config.emailSource === 'string' && config.emailSource.length > 0) {
            rawEmail = config.emailSource;
            smartbotic.log.info('IMAP Extract Attachments: Using configured email source');
        }

        // Fallback: try to auto-detect from various input structures
        if (!rawEmail) {
            rawEmail = input.raw || input.body;

            if (!rawEmail && input.email) {
                rawEmail = input.email.raw || input.email.body;
            }

            if (!rawEmail && input.data) {
                rawEmail = input.data.raw || input.data.body;
            }

            // Support loop iteration input (item/currentItem from Loop node)
            if (!rawEmail && input.item) {
                rawEmail = input.item.raw || input.item.body;
            }

            if (!rawEmail && input.currentItem) {
                rawEmail = input.currentItem.raw || input.currentItem.body;
            }
        }

        if (!rawEmail) {
            // Log available keys for debugging
            const availableKeys = Object.keys(input || {}).join(', ');
            smartbotic.log.warn('IMAP Extract Attachments: No raw email found. Input keys: ' + availableKeys);
            throw new Error('No raw email content provided. Configure the "Email Source" field with an expression like {{item.body}} for loop iterations, or ensure the email data is properly connected.');
        }

        // Parse MIME content
        let attachments = parseMimeContent(rawEmail);

        // Apply filters
        const mimeFilters = config.filterMimeTypes
            ? config.filterMimeTypes.split(',').map(s => s.trim()).filter(s => s)
            : [];
        const extFilters = config.filterExtensions
            ? config.filterExtensions.split(',').map(s => s.trim()).filter(s => s)
            : [];
        const maxSize = config.maxSize || 0;

        attachments = attachments.filter(att => {
            // Filter by MIME type
            if (!matchesMimeType(att.mimeType, mimeFilters)) return false;

            // Filter by extension
            if (!matchesExtension(att.filename, extFilters)) return false;

            // Filter by size
            if (maxSize > 0 && att.size > maxSize) return false;

            return true;
        });

        // Store attachments - always write to disk, optionally store metadata in database
        const storagePath = config.binaryStoragePath || './data/attachments';
        const timestamp = Date.now();
        const deduplicateByHash = config.deduplicateByHash !== false;  // Default to true

        for (const att of attachments) {
            // Generate file path - use content hash for deduplication if enabled
            const date = new Date(timestamp);
            const yearMonth = `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, '0')}`;
            const safeFilename = att.filename.replace(/[^a-zA-Z0-9._-]/g, '_');

            let filePath;
            let skipWrite = false;

            if (deduplicateByHash) {
                // Calculate content hash for deduplication
                const contentHash = smartbotic.utils.hash(att.data);
                att.contentHash = contentHash;

                // Use hash-based path: basePath/YYYY-MM/hash_filename
                // Using first 16 chars of SHA-256 hash (64 bits) for reasonable uniqueness
                const shortHash = contentHash.substring(0, 16);
                filePath = `${storagePath}/${yearMonth}/${shortHash}_${safeFilename}`;

                // Check if file already exists
                if (smartbotic.fs.exists(filePath)) {
                    smartbotic.log.info(`Attachment ${att.filename} already exists (hash: ${shortHash}), reusing: ${filePath}`);
                    att.filePath = filePath;
                    att.deduplicated = true;
                    delete att.data;  // Remove base64 data from memory
                    skipWrite = true;
                }
            } else {
                // Use UUID-based path for unique storage
                const uuid = smartbotic.utils.uuid();
                filePath = `${storagePath}/${yearMonth}/${uuid}_${safeFilename}`;
            }

            if (!skipWrite) {
                // Write binary data to disk
                const writeResult = smartbotic.fs.writeFile(filePath, att.data, 'base64');
                if (writeResult.success) {
                    // Replace base64 data with file path
                    att.filePath = filePath;
                    att.deduplicated = false;
                    delete att.data;  // Remove base64 data from memory
                    smartbotic.log.info(`Stored attachment ${att.filename} to disk: ${filePath}`);
                } else {
                    smartbotic.log.warn(`Failed to write attachment to disk: ${writeResult.error}`);
                    // Keep base64 data as fallback
                }
            }
        }

        // Store metadata in database if configured (without binary data)
        if (config.storeInDatabase && attachments.length > 0) {
            const collection = config.storageCollection || 'email_attachments';
            const ttlHours = config.storageTtlHours || 0;
            const ttlMs = ttlHours > 0 ? ttlHours * 60 * 60 * 1000 : 0;

            for (const att of attachments) {
                // Store only metadata, not the binary data
                const storageDoc = {
                    filename: att.filename,
                    mimeType: att.mimeType,
                    size: att.size,
                    contentId: att.contentId,
                    contentHash: att.contentHash,  // For deduplication lookup
                    deduplicated: att.deduplicated,
                    extractedAt: timestamp,
                    filePath: att.filePath  // Reference to disk location
                };

                const insertResult = smartbotic.storage.insert(collection, storageDoc, null, ttlMs);
                if (insertResult.success) {
                    att.storage = {
                        collection: collection,
                        id: insertResult.id
                    };
                    smartbotic.log.info(`Stored attachment metadata ${att.filename} in ${collection}/${insertResult.id}`);
                }
            }
        }

        // Calculate total size
        const totalSize = attachments.reduce((sum, att) => sum + att.size, 0);

        smartbotic.log.info(`Extracted ${attachments.length} attachment(s), total size: ${totalSize} bytes`);

        return {
            attachments,
            count: attachments.length,
            totalSize
        };
    }
};