<?php
/**
 * CSV Transformer
 * Transforms global campaign CSV into regional CSVs per the Make.com blueprint logic
 */

use League\Csv\Reader;
use League\Csv\Writer;
use Carbon\Carbon;

class CSVTransformer {
    private $config;
    private $isoCodes;
    private $errors = [];
    private $warnings = [];

    public function __construct() {
        $appConfig = require __DIR__ . '/config.php';
        $this->config = $appConfig['global_to_local'];
        $this->isoCodes = $this->config['iso_codes'];
    }

    /**
     * Validate uploaded CSV file
     */
    public function validateUpload($file) {
        $errors = [];

        // Check if file was uploaded
        if (!isset($file['tmp_name']) || empty($file['tmp_name'])) {
            $errors[] = 'No file was uploaded';
            return ['valid' => false, 'errors' => $errors];
        }

        // Check for upload errors
        if ($file['error'] !== UPLOAD_ERR_OK) {
            $errors[] = 'File upload error: ' . $this->getUploadErrorMessage($file['error']);
            return ['valid' => false, 'errors' => $errors];
        }

        // Check file extension
        $ext = strtolower(pathinfo($file['name'], PATHINFO_EXTENSION));
        if ($ext !== 'csv') {
            $errors[] = 'Invalid file type. Expected .csv, got .' . $ext;
            return ['valid' => false, 'errors' => $errors];
        }

        // Check file size
        if ($file['size'] > $this->config['max_file_size']) {
            $maxMB = round($this->config['max_file_size'] / 1048576, 2);
            $sizeMB = round($file['size'] / 1048576, 2);
            $errors[] = "File too large. Maximum size: {$maxMB}MB, uploaded: {$sizeMB}MB";
            return ['valid' => false, 'errors' => $errors];
        }

        // Check if file is empty
        if ($file['size'] === 0) {
            $errors[] = 'File is empty';
            return ['valid' => false, 'errors' => $errors];
        }

        return ['valid' => true, 'filename' => $file['name']];
    }

    /**
     * Get upload error message
     */
    private function getUploadErrorMessage($code) {
        switch ($code) {
            case UPLOAD_ERR_INI_SIZE:
            case UPLOAD_ERR_FORM_SIZE:
                return 'File exceeds maximum allowed size';
            case UPLOAD_ERR_PARTIAL:
                return 'File was only partially uploaded';
            case UPLOAD_ERR_NO_FILE:
                return 'No file was uploaded';
            case UPLOAD_ERR_NO_TMP_DIR:
                return 'Missing temporary folder';
            case UPLOAD_ERR_CANT_WRITE:
                return 'Failed to write file to disk';
            default:
                return 'Unknown upload error';
        }
    }

    /**
     * Parse CSV and validate structure
     */
    public function parseCSV($filePath) {
        try {
            $csv = Reader::createFromPath($filePath, 'r');
            $csv->setHeaderOffset(0);  // First row is headers

            $headers = $csv->getHeader();
            $records = iterator_to_array($csv->getRecords());

            // Validate column count (should have at least 12 columns based on blueprint)
            if (count($headers) < 12) {
                return [
                    'success' => false,
                    'error' => 'Invalid CSV structure',
                    'details' => 'Expected at least 12 columns, found ' . count($headers),
                    'action' => 'Verify you uploaded the correct CSV file'
                ];
            }

            // Check if CSV has data rows
            if (count($records) === 0) {
                return [
                    'success' => false,
                    'error' => 'CSV has no data rows',
                    'details' => 'CSV contains only headers, no data to process',
                    'action' => 'Upload a CSV file with data rows'
                ];
            }

            return [
                'success' => true,
                'headers' => $headers,
                'rows' => $records,
                'rowCount' => count($records)
            ];

        } catch (Exception $e) {
            return [
                'success' => false,
                'error' => 'CSV parsing failed',
                'details' => $e->getMessage(),
                'action' => 'Check if the file is a valid CSV with comma delimiters'
            ];
        }
    }

    /**
     * Extract campaign number from filename
     * Expected pattern: *_CAMPAIGNNUM_*.csv
     */
    public function extractCampaignNumber($filename) {
        // Remove .csv extension
        $nameWithoutExt = preg_replace('/\.csv$/i', '', $filename);

        // Split by underscore
        $parts = explode('_', $nameWithoutExt);

        // Try to find campaign number (should be in part 2 based on blueprint)
        if (isset($parts[2]) && is_numeric($parts[2])) {
            return [
                'success' => true,
                'campaignNumber' => $parts[2]
            ];
        }

        // Try to find any numeric part
        foreach ($parts as $part) {
            if (is_numeric($part) && strlen($part) >= 4) {
                return [
                    'success' => true,
                    'campaignNumber' => $part,
                    'warning' => 'Campaign number found but not in expected position'
                ];
            }
        }

        return [
            'success' => false,
            'error' => 'Campaign number not found in filename',
            'details' => "Expected pattern: *_CAMPAIGN#_*.csv, got: $filename",
            'action' => 'Rename file to include campaign number (e.g., Global_123456_Assets.csv)'
        ];
    }

    /**
     * Transform CSV data per Make.com blueprint logic
     */
    public function transformData($rows, $campaignNumber, $businessUnit) {
        $transformedRows = [];
        $this->errors = [];
        $this->warnings = [];

        $rowNumber = 1;  // Start from 1 (after header)

        foreach ($rows as $inputRow) {
            $rowNumber++;

            // Get columns by position (0-indexed)
            $cols = array_values($inputRow);

            // Validate required columns exist
            if (count($cols) < 12) {
                $this->errors[] = [
                    'row' => $rowNumber,
                    'error' => 'Insufficient columns',
                    'details' => 'Row has ' . count($cols) . ' columns, expected at least 12'
                ];
                continue;
            }

            // Extract data from columns
            $productId = $cols[1] ?? '';  // col2
            $category = $cols[3] ?? '';   // col4
            $media = $cols[4] ?? '';      // col5
            $subMedia = $cols[5] ?? '';   // col6
            $destination = $cols[6] ?? '';  // col7
            $format = $cols[7] ?? '';     // col8
            $supplyDate = $cols[8] ?? '';  // col9
            $liveDate = $cols[9] ?? '';    // col10
            $endDate = $cols[10] ?? '';    // col11
            $specialInstructions = $cols[11] ?? '';  // col12

            // Validate required fields
            if (empty($productId)) {
                $this->warnings[] = [
                    'row' => $rowNumber,
                    'warning' => 'Missing Product ID',
                    'severity' => 'high'
                ];
            }

            // Transform dates (parse and add 1 month per blueprint)
            $transformedSupplyDate = $this->transformDate($supplyDate, $rowNumber, 'Supply date');
            $transformedLiveDate = $this->transformDate($liveDate, $rowNumber, 'Live date');
            $transformedEndDate = $this->transformDate($endDate, $rowNumber, 'End date');

            // Create one output row for each ISO code (16 markets)
            foreach ($this->isoCodes as $isoCode) {
                $isoCode = trim($isoCode);

                // Extract country code (2nd part after dash)
                $parts = explode('-', $isoCode);
                $country = isset($parts[1]) ? $parts[1] : '';

                // Build output row per blueprint mapping
                $transformedRow = [
                    'Title' => $productId . '_' . $isoCode,
                    'Status' => 'Booked',
                    'Category' => $category,
                    'Media' => $media,
                    'Sub media' => $subMedia,
                    'Destination' => $destination,
                    'Format' => $format,
                    'Supply date' => $transformedSupplyDate,
                    'Live date' => $transformedLiveDate,
                    'End date' => $transformedEndDate,
                    'Special instructions' => $specialInstructions,
                    'Language' => $isoCode,
                    'Country' => $country,
                    'Quantity' => '1',
                    'Pos Code' => '',
                    'Duplicate' => '',
                    'Product ID' => $productId,
                    'Creative Execution' => $productId
                ];

                $transformedRows[] = $transformedRow;
            }
        }

        return [
            'success' => count($this->errors) === 0,
            'rows' => $transformedRows,
            'inputRowCount' => count($rows),
            'outputRowCount' => count($transformedRows),
            'errors' => $this->errors,
            'warnings' => $this->warnings
        ];
    }

    /**
     * Transform date: parse, add 1 month, format DD/MM/YYYY
     */
    private function transformDate($dateString, $rowNumber, $fieldName) {
        if (empty($dateString)) {
            $this->warnings[] = [
                'row' => $rowNumber,
                'warning' => "Empty $fieldName",
                'severity' => 'medium'
            ];
            return '';
        }

        try {
            // Try parsing with different formats per blueprint logic
            // Format 1: "DD MMM YYYY" (length check in blueprint: length = 17)
            if (strlen($dateString) >= 11 && preg_match('/\d{1,2}\s+[A-Za-z]{3}\s+\d{4}/', $dateString)) {
                $date = Carbon::createFromFormat('d M Y', $dateString);
            }
            // Format 2: "DD/MM/YYYY"
            else if (preg_match('/\d{1,2}\/\d{1,2}\/\d{4}/', $dateString)) {
                $date = Carbon::createFromFormat('d/m/Y', $dateString);
            }
            // Try ISO format
            else {
                $date = Carbon::parse($dateString);
            }

            // Add 1 month per blueprint
            $date->addMonth();

            // Format as DD/MM/YYYY
            return $date->format('d/m/Y');

        } catch (Exception $e) {
            $this->errors[] = [
                'row' => $rowNumber,
                'error' => "Invalid $fieldName format",
                'details' => "Unable to parse '$dateString' - " . $e->getMessage(),
                'action' => 'Use format DD/MM/YYYY or DD MMM YYYY'
            ];

            return $dateString;  // Return original if can't parse
        }
    }

    /**
     * Generate output filename per blueprint
     */
    public function generateFilename($campaignNumber, $businessUnit, $isoCode) {
        $timestamp = time();

        // Extract country from ISO code
        $parts = explode('-', $isoCode);
        $country = isset($parts[1]) ? $parts[1] : '';

        // Format: OMG{campaign}_GlobalACIngest_{BU}-{Country}_{timestamp}.csv
        return "OMG{$campaignNumber}_GlobalACIngest_{$businessUnit}-{country}_{$timestamp}.csv";
    }

    /**
     * Get errors
     */
    public function getErrors() {
        return $this->errors;
    }

    /**
     * Get warnings
     */
    public function getWarnings() {
        return $this->warnings;
    }

    /**
     * Has errors
     */
    public function hasErrors() {
        return count($this->errors) > 0;
    }

    /**
     * Has warnings
     */
    public function hasWarnings() {
        return count($this->warnings) > 0;
    }
}