<?php

namespace App\Services;

use Illuminate\Http\UploadedFile;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Facades\Log;

class GoogleVisionOcrService
{
    /**
     * Call Google Cloud Vision API to detect text in the uploaded image.
     */
    public static function extractPassportData(UploadedFile $file): array
    {
        $apiKey = config('services.google.vision_api_key');
        if (empty($apiKey)) {
            Log::warning('Google Vision API key is not configured.');
            return [
                'success' => false,
                'message' => 'Google Vision API key is not configured.',
                'data' => self::emptyData(),
            ];
        }

        try {
            $base64Image = base64_encode($file->get());
            
            $url = "https://vision.googleapis.com/v1/images:annotate?key={$apiKey}";
            
            $payload = [
                'requests' => [
                    [
                        'image' => [
                            'content' => $base64Image,
                        ],
                        'features' => [
                            [
                                'type' => 'TEXT_DETECTION',
                            ],
                        ],
                    ],
                ],
            ];

            $response = Http::withoutVerifying()->timeout(30)->post($url, $payload);

            if (!$response->successful()) {
                Log::error('Google Vision API error response: ' . $response->body());
                return [
                    'success' => false,
                    'message' => 'Google Vision API request failed.',
                    'data' => self::emptyData(),
                ];
            }

            $json = $response->json();
            $fullText = $json['responses'][0]['fullTextAnnotation']['text'] ?? '';
            
            if (empty($fullText)) {
                Log::warning('Google Vision API did not detect any text.');
                return [
                    'success' => true,
                    'data' => self::emptyData(),
                ];
            }

            $parsedData = self::parsePassportText($fullText);
            return [
                'success' => true,
                'data' => $parsedData,
            ];

        } catch (\Exception $e) {
            Log::error('Google Vision OCR exception: ' . $e->getMessage());
            return [
                'success' => false,
                'message' => 'An error occurred during OCR processing.',
                'data' => self::emptyData(),
            ];
        }
    }

    private static function emptyData(): array
    {
        return [
            'date_of_birth'   => null,
            'date_of_expiry'  => null,
            'date_of_issue'   => null,
            'given_names'     => null,
            'issuing_country' => null,
            'nationality'     => null,
            'passport_number' => null,
            'place_of_birth'  => null,
        ];
    }

    /**
     * Parse raw OCR text to extract passport fields.
     */
    public static function parsePassportText(string $text): array
    {
        $data = self::emptyData();
        
        // Split text into lines
        $lines = explode("\n", $text);
        $cleanLines = [];
        foreach ($lines as $line) {
            $line = trim($line);
            if ($line !== '') {
                $cleanLines[] = $line;
            }
        }

        // Try to parse MRZ first
        $mrzLines = self::findMrzLines($cleanLines);
        if ($mrzLines) {
            $mrzData = self::parseMrz($mrzLines[0], $mrzLines[1]);
            foreach ($mrzData as $key => $val) {
                if ($val !== null) {
                    $data[$key] = $val;
                }
            }
        }

        // ── Passport Number fallback ─────────────────────────────────────────
        if (empty($data['passport_number'])) {
            foreach ($cleanLines as $line) {
                if (preg_match('/(?:passport|pass\s*no|doc\s*no|document|number|no\.?)\s*[:\-\s]\s*([A-Z0-9]{7,9})/i', $line, $matches)) {
                    $data['passport_number'] = strtoupper($matches[1]);
                    break;
                }
            }
            if (empty($data['passport_number'])) {
                foreach ($cleanLines as $line) {
                    if (preg_match('/\b([A-Z][0-9]{7,8}|[A-Z0-9]{8,9})\b/', $line, $matches)) {
                        $data['passport_number'] = strtoupper($matches[1]);
                        break;
                    }
                }
            }
        }

        // ── Given Names fallback ─────────────────────────────────────────────
        if (empty($data['given_names'])) {
            foreach ($cleanLines as $line) {
                if (preg_match('/(?:given\s*names?|first\s*names?|name|nom)\s*[:\-\s]\s*([A-Z\s]{2,})/i', $line, $matches)) {
                    $data['given_names'] = trim(strtoupper($matches[1]));
                    break;
                }
            }
        }

        // ── Place of Birth fallback ──────────────────────────────────────────
        if (empty($data['place_of_birth'])) {
            foreach ($cleanLines as $line) {
                if (preg_match('/(?:place\s*of\s*birth|lieu\s*de\s*naissance|birthplace)\s*[:\-\s]\s*([A-Z\s]{2,})/i', $line, $matches)) {
                    $data['place_of_birth'] = trim(strtoupper($matches[1]));
                    break;
                }
            }
        }

        // ── Dates fallback ───────────────────────────────────────────────────
        if (empty($data['date_of_birth'])) {
            $data['date_of_birth'] = self::findDateByKeyword($cleanLines, ['birth', 'dob', 'naissance']);
        }
        if (empty($data['date_of_expiry'])) {
            $data['date_of_expiry'] = self::findDateByKeyword($cleanLines, ['expiry', 'expiration', 'exp', 'valable']);
        }
        if (empty($data['date_of_issue'])) {
            $data['date_of_issue'] = self::findDateByKeyword($cleanLines, ['issue', 'delivrance', 'issued']);
        }

        // ── Nationality fallback ─────────────────────────────────────────────
        if (empty($data['nationality'])) {
            foreach ($cleanLines as $line) {
                if (preg_match('/(?:nationality|nationalite)\s*[:\-\s]\s*([A-Z\s]{3,})/i', $line, $matches)) {
                    $data['nationality'] = trim(strtoupper($matches[1]));
                    break;
                }
            }
        }

        // ── Issuing Country fallback ─────────────────────────────────────────
        if (empty($data['issuing_country'])) {
            foreach ($cleanLines as $line) {
                if (preg_match('/(?:issuing\s*state|issuing\s*country|country)\s*[:\-\s]\s*([A-Z\s]{3,})/i', $line, $matches)) {
                    $data['issuing_country'] = trim(strtoupper($matches[1]));
                    break;
                }
            }
        }

        return $data;
    }

    /**
     * Look for MRZ lines in clean lines.
     */
    private static function findMrzLines(array $lines): ?array
    {
        $candidateLines = [];
        foreach ($lines as $line) {
            $cleaned = str_replace(' ', '', $line);
            $cleaned = str_replace('«', '<', $cleaned);
            if (strlen($cleaned) >= 35 && strlen($cleaned) <= 50) {
                $candidateLines[] = [
                    'original' => $line,
                    'cleaned' => $cleaned
                ];
            }
        }

        for ($i = 0; $i < count($candidateLines); $i++) {
            $c1 = $candidateLines[$i]['cleaned'];
            if (strpos($c1, 'P') === 0) {
                for ($j = 0; $j < count($candidateLines); $j++) {
                    if ($i === $j) continue;
                    $c2 = $candidateLines[$j]['cleaned'];
                    if (preg_match('/^[A-Z0-9<]{35,50}$/', $c2)) {
                        if (preg_match('/\d{6}/', $c2)) {
                            return [$candidateLines[$i]['cleaned'], $candidateLines[$j]['cleaned']];
                        }
                    }
                }
            }
        }

        return null;
    }

    /**
     * Parse standard 44-character passport MRZ lines.
     */
    private static function parseMrz(string $line1, string $line2): array
    {
        $data = self::emptyData();

        $line1 = str_pad(substr($line1, 0, 44), 44, '<');
        $line2 = str_pad(substr($line2, 0, 44), 44, '<');

        $data['issuing_country'] = str_replace('<', '', substr($line1, 2, 3));

        $namePart = substr($line1, 5);
        $parts = explode('<<', $namePart);
        $surname = isset($parts[0]) ? str_replace('<', ' ', $parts[0]) : '';
        $givenNames = isset($parts[1]) ? str_replace('<', ' ', $parts[1]) : '';
        
        $data['given_names'] = trim(strtoupper($givenNames));
        if (empty($data['given_names'])) {
            $data['given_names'] = trim(strtoupper($surname));
        }

        $data['passport_number'] = str_replace('<', '', substr($line2, 0, 9));
        $data['nationality'] = str_replace('<', '', substr($line2, 10, 3));

        $rawDob = substr($line2, 13, 6);
        if (ctype_digit($rawDob)) {
            $data['date_of_birth'] = self::formatMrzDate($rawDob, true);
        }

        $rawExpiry = substr($line2, 21, 6);
        if (ctype_digit($rawExpiry)) {
            $data['date_of_expiry'] = self::formatMrzDate($rawExpiry, false);
        }

        return $data;
    }

    private static function formatMrzDate(string $yymmdd, bool $isBirth): string
    {
        $yy = intval(substr($yymmdd, 0, 2));
        $mm = substr($yymmdd, 2, 2);
        $dd = substr($yymmdd, 4, 2);

        $currentYear = intval(date('Y'));
        $currentYearShort = $currentYear % 100;

        if ($isBirth) {
            $year = ($yy > $currentYearShort) ? (1900 + $yy) : (2000 + $yy);
        } else {
            $year = ($yy > ($currentYearShort + 20)) ? (1900 + $yy) : (2000 + $yy);
        }

        return "{$dd}/{$mm}/{$year}";
    }

    private static function findDateByKeyword(array $lines, array $keywords): ?string
    {
        foreach ($lines as $i => $line) {
            $matched = false;
            foreach ($keywords as $kw) {
                if (stripos($line, $kw) !== false) {
                    $matched = true;
                    break;
                }
            }

            if ($matched) {
                $textToSearch = $line;
                if (isset($lines[$i + 1])) {
                    $textToSearch .= ' ' . $lines[$i + 1];
                }

                if (preg_match('/(\d{1,2})[\/\-\.](\d{1,2})[\/\-\.](\d{4})/', $textToSearch, $matches)) {
                    $day = str_pad($matches[1], 2, '0', STR_PAD_LEFT);
                    $month = str_pad($matches[2], 2, '0', STR_PAD_LEFT);
                    $year = $matches[3];
                    return "{$day}/{$month}/{$year}";
                }
                if (preg_match('/(\d{4})[\/\-\.](\d{1,2})[\/\-\.](\d{1,2})/', $textToSearch, $matches)) {
                    $year = $matches[1];
                    $month = str_pad($matches[2], 2, '0', STR_PAD_LEFT);
                    $day = str_pad($matches[3], 2, '0', STR_PAD_LEFT);
                    return "{$day}/{$month}/{$year}";
                }
            }
        }

        return null;
    }
}