const csv = require('csv-parse');
const { Readable } = require('stream');
const nocodbService = require('../services/nocodb');
const { forwardGeocode } = require('../services/geocoding');
const logger = require('../utils/logger');
const config = require('../config');

// In-memory storage for processing results (in production, use Redis or database)
const processingResults = new Map();

class DataConvertController {
    constructor() {
        // Bind methods to preserve 'this' context
        this.processCSV = this.processCSV.bind(this);
        this.parseCSV = this.parseCSV.bind(this);
        this.saveGeocodedData = this.saveGeocodedData.bind(this);
        this.downloadReport = this.downloadReport.bind(this);
    }

    // Process CSV upload and geocode addresses with SSE progress updates
    async processCSV(req, res) {
        try {
            if (!req.file) {
                return res.status(400).json({
                    success: false,
                    error: 'No file uploaded'
                });
            }

            // Store the filename for later use in notes
            const originalFilename = req.file.originalname;
            const sessionId = Date.now().toString(); // Simple session ID for storing results

            // Set up SSE headers
            res.writeHead(200, {
                'Content-Type': 'text/event-stream',
                'Cache-Control': 'no-cache',
                'Connection': 'keep-alive',
                'X-Accel-Buffering': 'no' // Disable Nginx buffering
            });

            // Parse CSV
            const results = await this.parseCSV(req.file.buffer);
            
            if (!results || results.length === 0) {
                res.write(`data: ${JSON.stringify({ type: 'error', message: 'CSV file is empty or invalid' })}\n\n`);
                res.end();
                return;
            }

            // Validate required address field
            const hasAddressField = results[0].hasOwnProperty('address') || 
                                   results[0].hasOwnProperty('Address') ||
                                   results[0].hasOwnProperty('ADDRESS');
            
            if (!hasAddressField) {
                res.write(`data: ${JSON.stringify({ type: 'error', message: 'CSV must contain an "address" column' })}\n\n`);
                res.end();
                return;
            }

            // Send initial progress
            res.write(`data: ${JSON.stringify({ 
                type: 'start', 
                total: results.length 
            })}\n\n`);
            res.flush && res.flush();

            // Process all addresses
            const processedData = [];
            const allResults = []; // Store ALL results for report generation
            const errors = [];
            const total = results.length;

            // Process each address with progress updates
            for (let i = 0; i < results.length; i++) {
                const row = results[i];
                
                // Extract address - with better validation
                const addressField = row.address || row.Address || row.ADDRESS || 
                                    row.street_address || row['Street Address'] || 
                                    row.full_address || row['Full Address'];
                
                // Extract unit number if available
                const unitField = row.unit || row.Unit || row.UNIT || 
                                row.unit_number || row['Unit Number'] || row.unit_no;
                
                if (!addressField || addressField.trim() === '') {
                    logger.warn(`Row ${i + 1}: Empty or missing address field`);
                    
                    const errorRow = {
                        ...row,
                        latitude: '',
                        longitude: '',
                        'Geo-Location': '',
                        geocoded_address: '',
                        geocode_success: false,
                        geocode_status: 'FAILED',
                        geocode_error: 'Missing address field',
                        csv_filename: originalFilename,
                        row_number: i + 1
                    };
                    
                    allResults.push(errorRow);
                    errors.push({
                        index: i,
                        address: 'No address provided',
                        error: 'Missing address field'
                    });
                    
                    // Send progress update
                    res.write(`data: ${JSON.stringify({
                        type: 'progress',
                        current: i + 1,
                        total: total,
                        currentAddress: 'No address - skipping',
                        status: 'failed'
                    })}\n\n`);
                    res.flush && res.flush();
                    
                    continue; // Skip to next row
                }

                // Construct full address with unit if available
                let address = addressField.trim();
                if (unitField && unitField.toString().trim()) {
                    const unit = unitField.toString().trim();
                    // Add unit prefix if it doesn't already exist
                    if (!unit.toLowerCase().startsWith('unit') && 
                        !unit.toLowerCase().startsWith('apt') && 
                        !unit.toLowerCase().startsWith('#')) {
                        address = `Unit ${unit}, ${address}`;
                    } else {
                        address = `${unit}, ${address}`;
                    }
                }                // Send progress update
                res.write(`data: ${JSON.stringify({ 
                    type: 'progress', 
                    current: i + 1, 
                    total: total,
                    currentAddress: address,
                    status: 'processing'
                })}\n\n`);
                res.flush && res.flush();

                try {
                    logger.info(`Geocoding ${i + 1}/${total}: ${address}`);

                    // Geocode the address
                    const geocodeResult = await forwardGeocode(address);
                    
                    if (geocodeResult && geocodeResult.coordinates) {
                        // Check if result is malformed
                        const isMalformed = geocodeResult.validation && geocodeResult.validation.isMalformed;
                        const confidence = geocodeResult.validation ? geocodeResult.validation.confidence : 100;
                        const warnings = geocodeResult.validation ? geocodeResult.validation.warnings : [];
                        
                        const processedRow = {
                            ...row,
                            latitude: geocodeResult.coordinates.lat,
                            longitude: geocodeResult.coordinates.lng,
                            'Geo-Location': `${geocodeResult.coordinates.lat};${geocodeResult.coordinates.lng}`,
                            geocoded_address: geocodeResult.formattedAddress || address,
                            geocode_success: true,
                            geocode_status: isMalformed ? 'WARNING' : 'SUCCESS',
                            geocode_error: '',
                            confidence_score: confidence,
                            warnings: warnings.join('; '),
                            is_malformed: isMalformed,
                            provider: geocodeResult.provider || 'Unknown',
                            csv_filename: originalFilename,
                            row_number: i + 1
                        };
                        
                        processedData.push(processedRow);
                        allResults.push(processedRow);

                        // Send success update with status
                        const successMessage = { 
                            type: 'geocoded', 
                            data: processedRow,
                            index: i,
                            status: isMalformed ? 'warning' : 'success',
                            confidence: confidence,
                            warnings: warnings
                        };
                        const successJson = JSON.stringify(successMessage);
                        logger.info(`Successfully geocoded: ${address} (Confidence: ${confidence}%)`);
                        res.write(`data: ${successJson}\n\n`);
                        res.flush && res.flush();
                    } else {
                        throw new Error('Geocoding failed - no coordinates returned');
                    }
                    
                } catch (error) {
                    logger.error(`Failed to geocode address: ${address}`, error.message);
                    
                    // Create error row with original data plus error info
                    const errorRow = {
                        ...row,
                        latitude: '',
                        longitude: '',
                        'Geo-Location': '',
                        geocoded_address: '',
                        geocode_success: false,
                        geocode_status: 'FAILED',
                        geocode_error: error.message,
                        confidence_score: 0,
                        warnings: '',
                        is_malformed: false,
                        csv_filename: originalFilename,
                        row_number: i + 1
                    };
                    
                    allResults.push(errorRow);
                    
                    const errorData = {
                        index: i,
                        address: address,
                        error: error.message
                    };
                    errors.push(errorData);

                    // Send error update
                    const errorMessage = { 
                        type: 'error', 
                        data: errorData 
                    };
                    const errorJson = JSON.stringify(errorMessage);
                    logger.debug(`Sending error update: ${errorJson.length} chars`);
                    res.write(`data: ${errorJson}\n\n`);
                    res.flush && res.flush(); // Ensure data is sent immediately
                }

                // Add delay to avoid rate limiting
                await new Promise(resolve => setTimeout(resolve, 2000));
            }

            // Store processing results for report generation
            const successful = processedData.filter(r => r.geocode_status === 'SUCCESS').length;
            const warnings = processedData.filter(r => r.geocode_status === 'WARNING').length;
            const failed = errors.length;
            const malformed = processedData.filter(r => r.is_malformed).length;
            
            processingResults.set(sessionId, {
                filename: originalFilename,
                timestamp: new Date().toISOString(),
                allResults: allResults,
                summary: {
                    total: total,
                    successful: successful,
                    warnings: warnings,
                    failed: failed,
                    malformed: malformed
                }
            });

            // Send completion
            const completeMessage = { 
                type: 'complete',
                processed: processedData.length,
                successful: successful,
                warnings: warnings,
                errors: errors.length,
                malformed: malformed,
                total: total,
                sessionId: sessionId // Include session ID for report download
            };
            const completeJson = JSON.stringify(completeMessage);
            logger.info(`Sending completion message: ${completeJson.length} chars`);
            res.write(`data: ${completeJson}\n\n`);
            res.flush && res.flush(); // Ensure data is sent immediately

            res.end();

        } catch (error) {
            logger.error('CSV processing error:', error);
            res.write(`data: ${JSON.stringify({ 
                type: 'fatal_error', 
                message: 'Failed to process CSV file',
                error: error.message 
            })}\n\n`);
            res.end();
        }
    }

    // Parse CSV buffer into array of objects
    async parseCSV(buffer) {
        return new Promise((resolve, reject) => {
            const results = [];
            const stream = Readable.from(buffer);
            
            stream
                .pipe(csv.parse({
                    columns: true,
                    skip_empty_lines: true,
                    trim: true
                }))
                .on('data', (data) => results.push(data))
                .on('error', reject)
                .on('end', () => resolve(results));
        });
    }

    // Enhanced save method that transforms data to match locations table structure
    async saveGeocodedData(req, res) {
        try {
            const { data } = req.body;
            
            if (!data || !Array.isArray(data)) {
                return res.status(400).json({
                    success: false,
                    error: 'Invalid data format'
                });
            }

            const results = {
                success: 0,
                failed: 0,
                errors: []
            };

            // Process each location
            for (const location of data) {
                try {
                    // Transform to match locations table structure
                    // Preserve original address, don't overwrite with geocoded address
                    const originalAddress = location.address || location.Address || location.ADDRESS;
                    const geocodedAddress = location.geocoded_address;

                    const locationData = {
                        'Geo-Location': location['Geo-Location'],
                        latitude: parseFloat(location.latitude),
                        longitude: parseFloat(location.longitude),
                        Address: originalAddress, // Always use the original address from CSV
                        created_by_user: req.session.userEmail || 'csv_import',
                        last_updated_by_user: req.session.userEmail || 'csv_import'
                    };

                    // Track if geocoded address differs from original
                    const addressDiffers = geocodedAddress && 
                                           geocodedAddress.toLowerCase() !== originalAddress.toLowerCase();

                    // Map CSV fields to NocoDB fields
                    const fieldMapping = {
                        'first name': 'First Name',
                        'firstname': 'First Name',
                        'first_name': 'First Name',
                        'last name': 'Last Name',
                        'lastname': 'Last Name',
                        'last_name': 'Last Name',
                        'email': 'Email',
                        'phone': 'Phone',
                        'unit': 'Unit Number',
                        'unit number': 'Unit Number',
                        'unit_number': 'Unit Number',
                        'support level': 'Support Level',
                        'support_level': 'Support Level',
                        'sign': 'Sign',
                        'sign size': 'Sign Size',
                        'sign_size': 'Sign Size',
                        'notes': 'Notes'
                    };

                    // Process all fields from CSV
                    Object.keys(location).forEach(key => {
                        const lowerKey = key.toLowerCase();
                        
                        // Skip already processed fields
                        if (['latitude', 'longitude', 'geo-location', 'geocoded_address', 'geocode_success', 'address', 'csv_filename'].includes(lowerKey)) {
                            return;
                        }

                        // Check if we have a mapping for this field
                        if (fieldMapping[lowerKey]) {
                            const targetField = fieldMapping[lowerKey];
                            
                            // Special handling for certain fields
                            if (targetField === 'Sign') {
                                // Convert to boolean
                                locationData[targetField] = ['true', 'yes', '1', 'y'].includes(String(location[key]).toLowerCase());
                            } else if (targetField === 'Support Level') {
                                // Ensure it's a string number 1-4
                                const level = parseInt(location[key]);
                                if (level >= 1 && level <= 4) {
                                    locationData[targetField] = String(level);
                                }
                            } else if (targetField === 'Notes') {
                                // Build notes with existing content, CSV info, and geocoding info
                                const noteParts = [];
                                
                                // Add existing notes if present
                                if (location[key]) {
                                    noteParts.push(location[key]);
                                }
                                
                                // Add CSV import info
                                noteParts.push(`Imported from CSV: ${location.csv_filename || 'unknown'}`);
                                
                                // Add geocoded address if it differs from original
                                if (addressDiffers) {
                                    noteParts.push(`Geocoded as: ${geocodedAddress}`);
                                }
                                
                                locationData[targetField] = noteParts.join(' | ');
                            } else {
                                locationData[targetField] = location[key];
                            }
                        }
                    });

                    // If no notes field was found in CSV, add the CSV import info and geocoding info
                    if (!locationData['Notes']) {
                        const noteParts = [`Imported from CSV: ${location.csv_filename || 'unknown'}`];
                        
                        // Add geocoded address if it differs from original
                        if (addressDiffers) {
                            noteParts.push(`Geocoded as: ${geocodedAddress}`);
                        }
                        
                        locationData['Notes'] = noteParts.join(' | ');
                    }

                    // Create location in NocoDB
                    const result = await nocodbService.create(config.nocodb.tableId, locationData);
                    results.success++;
                    logger.debug(`Successfully saved location: ${locationData.Address}`);
                    
                } catch (error) {
                    logger.error('Failed to save location:', error);
                    logger.error('Location data:', locationData);
                    results.failed++;
                    results.errors.push({
                        address: location.address || location.Address || location.ADDRESS,
                        error: error.message
                    });
                }
            }

            res.json({
                success: true,
                results: results
            });

        } catch (error) {
            logger.error('Save geocoded data error:', error);
            res.status(500).json({
                success: false,
                error: 'Failed to save locations'
            });
        }
    }

    // Generate and download processing report
    async downloadReport(req, res) {
        try {
            const { sessionId } = req.params;
            
            if (!sessionId || !processingResults.has(sessionId)) {
                return res.status(404).json({
                    success: false,
                    error: 'Processing results not found or expired'
                });
            }

            const results = processingResults.get(sessionId);
            const { filename, timestamp, allResults, summary } = results;

            // Generate comprehensive report content
            const reportContent = this.generateComprehensiveReport(allResults, filename, timestamp, summary);
            
            // Set headers for text download
            const reportFilename = `geocoding-report-${sessionId}.txt`;
            res.setHeader('Content-Type', 'text/plain');
            res.setHeader('Content-Disposition', `attachment; filename="${reportFilename}"`);
            res.setHeader('Cache-Control', 'no-cache');

            logger.info(`Generating comprehensive report for session ${sessionId}: ${allResults.length} records`);

            res.send(reportContent);

            // Clean up stored results after download (optional)
            setTimeout(() => {
                processingResults.delete(sessionId);
                logger.info(`Cleaned up processing results for session ${sessionId}`);
            }, 60000); // Delete after 1 minute

        } catch (error) {
            logger.error('Download report error:', error);
            res.status(500).json({
                success: false,
                error: 'Failed to generate report'
            });
        }
    }

    // Generate comprehensive text report
    generateComprehensiveReport(results, originalFilename, timestamp, summary) {
        let report = `Geocoding Processing Report\n`;
        report += `Generated: ${timestamp}\n`;
        report += `Original File: ${originalFilename}\n`;
        report += `================================\n\n`;
        
        report += `Summary:\n`;
        report += `- Total Addresses: ${summary.total}\n`;
        report += `- Successfully Geocoded: ${summary.successful}\n`;
        report += `- Warnings (Low Confidence): ${summary.warnings}\n`;
        report += `- Failed: ${summary.failed}\n`;
        report += `- Potentially Malformed: ${summary.malformed}\n\n`;
        
        // Section for malformed addresses requiring review
        const malformedResults = results.filter(r => r.is_malformed);
        if (malformedResults.length > 0) {
            report += `ADDRESSES REQUIRING REVIEW (Potentially Malformed):\n`;
            report += `================================================\n`;
            malformedResults.forEach((result, index) => {
                const originalAddress = result.address || result.Address || result.ADDRESS || 'N/A';
                report += `\n${index + 1}. Original: ${originalAddress}\n`;
                report += `   Result: ${result.geocoded_address || 'N/A'}\n`;
                report += `   Confidence: ${result.confidence_score || 0}%\n`;
                if (result.warnings) {
                    report += `   Warnings: ${result.warnings}\n`;
                }
                report += `   Coordinates: ${result.latitude || 'N/A'}, ${result.longitude || 'N/A'}\n`;
                report += `   Row: ${result.row_number}\n`;
            });
            report += `\n`;
        }
        
        // Failed addresses section
        const failedResults = results.filter(r => r.geocode_status === 'FAILED');
        if (failedResults.length > 0) {
            report += `FAILED GEOCODING ATTEMPTS:\n`;
            report += `========================\n`;
            failedResults.forEach((result, index) => {
                const originalAddress = result.address || result.Address || result.ADDRESS || 'N/A';
                report += `\n${index + 1}. Address: ${originalAddress}\n`;
                report += `   Error: ${result.geocode_error}\n`;
                report += `   Row: ${result.row_number}\n`;
            });
            report += `\n`;
        }
        
        // Successful geocoding with low confidence
        const lowConfidenceResults = results.filter(r => 
            r.geocode_status === 'SUCCESS' && 
            r.confidence_score && 
            r.confidence_score < 75
        );
        if (lowConfidenceResults.length > 0) {
            report += `LOW CONFIDENCE SUCCESSFUL GEOCODING:\n`;
            report += `==================================\n`;
            lowConfidenceResults.forEach((result, index) => {
                const originalAddress = result.address || result.Address || result.ADDRESS || 'N/A';
                report += `\n${index + 1}. Original: ${originalAddress}\n`;
                report += `   Result: ${result.geocoded_address}\n`;
                report += `   Confidence: ${result.confidence_score}%\n`;
                if (result.warnings) {
                    report += `   Warnings: ${result.warnings}\n`;
                }
                report += `   Row: ${result.row_number}\n`;
            });
            report += `\n`;
        }
        
        // Summary statistics
        report += `DETAILED STATISTICS:\n`;
        report += `==================\n`;
        report += `Success Rate: ${((summary.successful / summary.total) * 100).toFixed(1)}%\n`;
        report += `Warning Rate: ${((summary.warnings / summary.total) * 100).toFixed(1)}%\n`;
        report += `Failure Rate: ${((summary.failed / summary.total) * 100).toFixed(1)}%\n`;
        report += `Malformed Rate: ${((summary.malformed / summary.total) * 100).toFixed(1)}%\n\n`;
        
        // Recommendations
        report += `RECOMMENDATIONS:\n`;
        report += `===============\n`;
        if (summary.malformed > 0) {
            report += `- Review ${summary.malformed} addresses marked as potentially malformed\n`;
        }
        if (summary.failed > 0) {
            report += `- Check ${summary.failed} failed addresses for formatting issues\n`;
        }
        if (summary.warnings > 0) {
            report += `- Verify ${summary.warnings} low confidence results manually\n`;
        }
        report += `- Consider using more specific address formats for better results\n`;
        report += `- Ensure addresses include proper directional indicators (NW, SW, etc.)\n`;
        
        return report;
    }

    // Generate CSV content for the report
    generateReportCSV(allResults, originalFilename, timestamp, summary) {
        if (!allResults || allResults.length === 0) {
            return 'No data available for report generation';
        }

        // Get all unique field names from the results
        const allFields = new Set();
        allResults.forEach(row => {
            Object.keys(row).forEach(field => allFields.add(field));
        });

        // Define the header order - put important fields first
        const priorityHeaders = [
            'geocode_status', 'geocode_error', 'address', 'Address', 
            'geocoded_address', 'latitude', 'longitude', 'Geo-Location'
        ];
        
        const otherHeaders = Array.from(allFields).filter(field => 
            !priorityHeaders.includes(field) && 
            !['geocode_success', 'csv_filename'].includes(field)
        ).sort();

        const headers = [...priorityHeaders.filter(h => allFields.has(h)), ...otherHeaders];

        // Generate CSV header with metadata
        let csvContent = `# Geocoding Processing Report\n`;
        csvContent += `# Original File: ${originalFilename}\n`;
        csvContent += `# Processed: ${timestamp}\n`;
        csvContent += `# Total Records: ${summary.total}\n`;
        csvContent += `# Successful: ${summary.successful}\n`;
        csvContent += `# Failed: ${summary.failed}\n`;
        csvContent += `# \n`;
        
        // Add CSV headers
        csvContent += headers.map(header => this.escapeCSVField(header)).join(',') + '\n';

        // Add data rows
        allResults.forEach(row => {
            const values = headers.map(header => {
                const value = row[header];
                return this.escapeCSVField(value !== undefined && value !== null ? String(value) : '');
            });
            csvContent += values.join(',') + '\n';
        });

        return csvContent;
    }

    // Escape CSV fields properly
    escapeCSVField(field) {
        if (field === null || field === undefined) return '';
        
        const stringField = String(field);
        
        // If field contains comma, quote, or newline, wrap in quotes and escape quotes
        if (stringField.includes(',') || stringField.includes('"') || stringField.includes('\n') || stringField.includes('\r')) {
            return '"' + stringField.replace(/"/g, '""') + '"';
        }
        
        return stringField;
    }
}

module.exports = new DataConvertController();