<?php
/**
 * Process CSV Upload
 * Handles CSV transformation with detailed progress tracking and error reporting
 */

error_reporting(E_ALL);
ini_set('display_errors', 1);

header('Content-Type: application/json');

try {
    // Load dependencies
    require_once __DIR__ . '/vendor/autoload.php';
    require_once __DIR__ . '/AuthMiddleware.php';
    require_once __DIR__ . '/CSVTransformer.php';
    require_once __DIR__ . '/OMGService.php';
    require_once __DIR__ . '/EmailService.php';

    // Authenticate
    $auth = new AuthMiddleware();
    $user = $auth->requireAuth();

    // Check if file was uploaded
    if (!isset($_FILES['csvFile'])) {
        echo json_encode([
            'success' => false,
            'stage' => 'upload',
            'error' => 'No file uploaded',
            'details' => 'Please select a CSV file to upload'
        ]);
        exit;
    }

    $file = $_FILES['csvFile'];
    $transformer = new CSVTransformer();
    $omgService = new OMGService();
    $emailService = new EmailService();

    $progress = [];

    // STAGE 1: Validate Upload
    $progress[] = ['stage' => 'upload', 'status' => 'processing', 'message' => 'Validating file upload...'];

    $validation = $transformer->validateUpload($file);

    if (!$validation['valid']) {
        echo json_encode([
            'success' => false,
            'stage' => 'upload',
            'error' => 'File validation failed',
            'details' => implode('; ', $validation['errors']),
            'action' => 'Please upload a valid CSV file (max 5MB)',
            'progress' => $progress
        ]);
        exit;
    }

    $filename = $validation['filename'];
    $progress[] = ['stage' => 'upload', 'status' => 'success', 'message' => 'File uploaded: ' . $filename];

    // STAGE 2: Parse CSV
    $progress[] = ['stage' => 'parse', 'status' => 'processing', 'message' => 'Parsing CSV file...'];

    $parseResult = $transformer->parseCSV($file['tmp_name']);

    if (!$parseResult['success']) {
        echo json_encode([
            'success' => false,
            'stage' => 'parse',
            'error' => $parseResult['error'],
            'details' => $parseResult['details'] ?? '',
            'action' => $parseResult['action'] ?? 'Check CSV format',
            'progress' => $progress
        ]);
        exit;
    }

    $rowCount = $parseResult['rowCount'];
    $progress[] = ['stage' => 'parse', 'status' => 'success', 'message' => "Parsed $rowCount data rows"];

    // STAGE 3: Extract Campaign Number
    $progress[] = ['stage' => 'campaign', 'status' => 'processing', 'message' => 'Extracting campaign number...'];

    $campaignResult = $transformer->extractCampaignNumber($filename);

    if (!$campaignResult['success']) {
        echo json_encode([
            'success' => false,
            'stage' => 'campaign',
            'error' => $campaignResult['error'],
            'details' => $campaignResult['details'] ?? '',
            'action' => $campaignResult['action'] ?? 'Fix filename format',
            'progress' => $progress
        ]);
        exit;
    }

    $campaignNumber = $campaignResult['campaignNumber'];
    $message = 'Campaign number: ' . $campaignNumber;
    if (isset($campaignResult['warning'])) {
        $message .= ' (warning: ' . $campaignResult['warning'] . ')';
    }
    $progress[] = ['stage' => 'campaign', 'status' => 'success', 'message' => $message];

    // STAGE 4: Call OMG API
    $progress[] = ['stage' => 'omg_api', 'status' => 'processing', 'message' => 'Looking up campaign in OMG...'];

    $projectResult = $omgService->getProject($campaignNumber);

    if (!$projectResult['success']) {
        echo json_encode([
            'success' => false,
            'stage' => 'omg_api',
            'error' => $projectResult['error'],
            'details' => $projectResult['details'] ?? '',
            'action' => $projectResult['action'] ?? 'Check OMG API configuration',
            'httpCode' => $projectResult['httpCode'] ?? 0,
            'endpoint' => $omgService->config['base_url'] . '/getProject?project_number=' . $campaignNumber,
            'progress' => $progress
        ]);
        exit;
    }

    $projectData = $projectResult['data'];
    $progress[] = ['stage' => 'omg_api', 'status' => 'success', 'message' => 'Retrieved campaign data from OMG'];

    // STAGE 5: Map Business Unit
    $progress[] = ['stage' => 'business_unit', 'status' => 'processing', 'message' => 'Mapping business unit...'];

    $businessArea = $omgService->getBusinessArea($projectData);

    if (empty($businessArea)) {
        echo json_encode([
            'success' => false,
            'stage' => 'business_unit',
            'error' => 'Business area not found in OMG response',
            'details' => 'The OMG API response did not contain a business_area field',
            'action' => 'Check if campaign data is complete in OMG system',
            'omgResponse' => $projectData,
            'progress' => $progress
        ]);
        exit;
    }

    $mappingResult = $omgService->mapBusinessUnit($businessArea);

    if (!$mappingResult['success']) {
        // Non-fatal warning - continue with "ERROR" value
        $progress[] = [
            'stage' => 'business_unit',
            'status' => 'warning',
            'message' => 'Business unit "' . $businessArea . '" not recognized - using "ERROR"',
            'warning' => $mappingResult['error']
        ];
        $businessUnit = 'ERROR';
    } else {
        $businessUnit = $mappingResult['businessUnit'];
        $progress[] = [
            'stage' => 'business_unit',
            'status' => 'success',
            'message' => 'Business unit: ' . $businessUnit
        ];
    }

    // STAGE 6: Transform Data
    $progress[] = ['stage' => 'transform', 'status' => 'processing', 'message' => 'Transforming data for 16 markets...'];

    $transformResult = $transformer->transformData($parseResult['rows'], $campaignNumber, $businessUnit);

    if (!$transformResult['success']) {
        echo json_encode([
            'success' => false,
            'stage' => 'transform',
            'error' => 'Data transformation failed',
            'details' => count($transformResult['errors']) . ' error(s) found',
            'errors' => $transformResult['errors'],
            'warnings' => $transformResult['warnings'],
            'action' => 'Review errors and fix CSV data',
            'progress' => $progress
        ]);
        exit;
    }

    $outputRowCount = $transformResult['outputRowCount'];
    $progress[] = [
        'stage' => 'transform',
        'status' => 'success',
        'message' => "Transformed {$rowCount} rows into {$outputRowCount} regional rows"
    ];

    // Generate CSV output
    use League\Csv\Writer;

    $csv = Writer::createFromString();
    $csv->insertOne(array_keys($transformResult['rows'][0]));  // Headers
    $csv->insertAll($transformResult['rows']);  // Data

    $csvContent = $csv->toString();

    // Generate filename (use first ISO code for single file preview)
    $outputFilename = $transformer->generateFilename($campaignNumber, $businessUnit, $transformer->config['iso_codes'][0]);

    // Store in session for later upload
    session_start();
    $_SESSION['processed_csv'] = [
        'content' => $csvContent,
        'filename' => $outputFilename,
        'campaignNumber' => $campaignNumber,
        'businessUnit' => $businessUnit,
        'rowCount' => $outputRowCount
    ];

    // Return success with preview data
    echo json_encode([
        'success' => true,
        'stage' => 'complete',
        'data' => [
            'inputRows' => $rowCount,
            'outputRows' => $outputRowCount,
            'campaignNumber' => $campaignNumber,
            'businessUnit' => $businessUnit,
            'filename' => $outputFilename,
            'preview' => array_slice($transformResult['rows'], 0, 50),  // First 50 rows for preview
            'csvContent' => $csvContent,
            'warnings' => $transformResult['warnings']
        ],
        'progress' => $progress
    ]);

} catch (Exception $e) {
    error_log('Process CSV exception: ' . $e->getMessage());
    error_log('Stack trace: ' . $e->getTraceAsString());

    echo json_encode([
        'success' => false,
        'stage' => 'exception',
        'error' => 'Unexpected error occurred',
        'details' => $e->getMessage(),
        'file' => $e->getFile(),
        'line' => $e->getLine()
    ]);
}