<?php
namespace App\Services\Documenti;

use App\Models\Documento;
use Illuminate\Support\Facades\Schema;
use Illuminate\Support\Facades\Storage;

class ImageTextExtractionService
{
    /**
     * @return array{status: 'ok'|'skipped'|'error', message?: string, chars?: int, engine?: string}
     */
    public function extractAndStore(Documento $documento, bool $force = false): array
    {
        $relativePath = $this->resolveImagePath($documento);
        if ($relativePath === null) {
            return ['status' => 'skipped', 'message' => 'Immagine non disponibile'];
        }

        if (! Storage::disk('local')->exists($relativePath)) {
            return ['status' => 'error', 'message' => 'File immagine non trovato su storage'];
        }

        if (! $force) {
            $existing = null;
            if (Schema::hasColumn('documenti', 'contenuto_ocr')) {
                $existing = $documento->contenuto_ocr;
            } elseif (Schema::hasColumn('documenti', 'testo_estratto_ocr')) {
                $existing = $documento->testo_estratto_ocr;
            }

            if (is_string($existing) && trim($existing) !== '') {
                return ['status' => 'skipped', 'message' => 'Testo già presente'];
            }
        }

        $tesseract = $this->findBinary('tesseract');
        if ($tesseract === null) {
            $this->updateOcrMetadata($documento, ['status' => 'pending_image_ocr', 'engine' => null, 'message' => 'tesseract non disponibile']);
            return ['status' => 'skipped', 'message' => 'Tesseract non disponibile'];
        }

        $absolutePath = Storage::disk('local')->path($relativePath);
        $language     = (string) config('services.tesseract.lang', 'ita+eng');
        $command      = escapeshellcmd($tesseract)
        . ' ' . escapeshellarg($absolutePath)
        . ' stdout -l ' . escapeshellarg($language)
            . ' 2>/dev/null';

        $output = shell_exec($command);
        $text   = $this->normalizeText(is_string($output) ? $output : '');

        if ($text === '') {
            $this->updateOcrMetadata($documento, ['status' => 'empty', 'engine' => 'tesseract', 'language' => $language]);
            return ['status' => 'error', 'message' => 'OCR immagine vuota'];
        }

        $update = [];
        if (Schema::hasColumn('documenti', 'contenuto_ocr')) {
            $update['contenuto_ocr'] = $text;
        }
        if (Schema::hasColumn('documenti', 'testo_estratto_ocr')) {
            $update['testo_estratto_ocr'] = mb_substr($text, 0, 20000);
        }
        if (Schema::hasColumn('documenti', 'metadati_ocr')) {
            $update['metadati_ocr'] = array_merge((array) ($documento->metadati_ocr ?? []), [
                'status'       => 'ok',
                'engine'       => 'tesseract',
                'language'     => $language,
                'extracted_at' => now()->toIso8601String(),
            ]);
        }

        if ($update === []) {
            return ['status' => 'error', 'message' => 'Schema documenti senza colonne OCR/testo'];
        }

        $documento->forceFill($update)->save();

        return ['status' => 'ok', 'chars' => mb_strlen($text), 'engine' => 'tesseract'];
    }

    private function resolveImagePath(Documento $documento): ?string
    {
        $candidate = null;

        if (isset($documento->percorso_file) && is_string($documento->percorso_file) && $documento->percorso_file !== '') {
            $candidate = $documento->percorso_file;
        } elseif (isset($documento->path_file) && is_string($documento->path_file) && $documento->path_file !== '') {
            $candidate = $documento->path_file;
        }

        if (! is_string($candidate) || trim($candidate) === '') {
            return null;
        }

        $candidate = trim($candidate);
        $lower     = strtolower($candidate);
        foreach (['.png', '.jpg', '.jpeg', '.webp', '.tif', '.tiff', '.bmp'] as $extension) {
            if (str_ends_with($lower, $extension)) {
                return $candidate;
            }
        }

        return null;
    }

    private function findBinary(string $name): ?string
    {
        $path = shell_exec('command -v ' . escapeshellarg($name) . ' 2>/dev/null');
        $path = is_string($path) ? trim($path) : '';
        return $path !== '' ? $path : null;
    }

    private function normalizeText(string $text): string
    {
        $text = str_replace("\r\n", "\n", $text);
        $text = str_replace("\r", "\n", $text);
        $text = str_replace("\0", '', $text);

        if (! mb_check_encoding($text, 'UTF-8')) {
            $text = mb_convert_encoding($text, 'UTF-8');
        }

        return trim($text);
    }

    private function updateOcrMetadata(Documento $documento, array $metadata): void
    {
        if (! Schema::hasColumn('documenti', 'metadati_ocr')) {
            return;
        }

        $documento->forceFill([
            'metadati_ocr' => array_merge((array) ($documento->metadati_ocr ?? []), $metadata),
        ])->save();
    }
}