<?php

namespace App\Services;

use RuntimeException;

/** Offline structural validation. This never approves a source or writes territories. */
final class TerritorialCsvAudit
{
    public const HEADERS = ['province_code', 'province_name', 'district_code', 'district_name', 'admin_post_code', 'admin_post_name', 'locality_code', 'locality_name', 'locality_type', 'latitude', 'longitude'];

    /** @param list<string> $provinceCodes
     * @return array<string,mixed>
     */
    public function inspect(string $path, array $provinceCodes): array
    {
        if (! is_file($path) || ! is_readable($path) || filesize($path) > 20 * 1024 * 1024) {
            throw new RuntimeException('CSV inacessível ou superior a 20 MiB.');
        }
        $bytes = file_get_contents($path);
        if ($bytes === false || ! mb_check_encoding($bytes, 'UTF-8') || str_contains($bytes, "\0")) {
            throw new RuntimeException('O CSV deve ser UTF-8 sem bytes nulos.');
        }
        // Parse the exact bytes hashed, avoiding a second read of a changing input.
        $stream = fopen('php://temp', 'w+');
        if ($stream === false) {
            throw new RuntimeException('Não foi possível preparar a leitura.');
        }
        fwrite($stream, preg_replace('/^\xEF\xBB\xBF/', '', $bytes) ?? $bytes);
        rewind($stream);
        try {
            if (fgetcsv($stream, null, ';', '"', '') !== self::HEADERS) {
                throw new RuntimeException('Cabeçalho inválido: usar o contrato INE com separador ponto e vírgula.');
            }
            $errors = $seen = $names = $totals = [];
            $duplicates = $count = 0;
            while (($values = fgetcsv($stream, null, ';', '"', '')) !== false) {
                $count++;
                if ($count > 50000) {
                    throw new RuntimeException('O CSV excede 50.000 registos.');
                }
                $issues = [];
                if (count($values) !== count(self::HEADERS)) {
                    $errors[] = ['record' => $count + 1, 'issues' => ['column_count']];

                    continue;
                }
                $row = array_combine(self::HEADERS, array_map(fn ($v) => trim((string) $v), $values));
                foreach ($row as $field => $value) {
                    if (mb_strlen($value) > 255 || preg_match('/[\x00-\x1F\x7F]/', $value)) {
                        $issues[] = 'invalid_field:'.$field;
                    }
                }
                if (! preg_match('/^[0-9]{2}$/D', $row['province_code']) || ! in_array($row['province_code'], $provinceCodes, true)) {
                    $issues[] = 'unknown_province';
                }
                foreach (['province', 'district', 'admin_post', 'locality'] as $kind) {
                    $code = $row[$kind.'_code'];
                    $name = $row[$kind.'_name'];
                    if (($kind === 'province' || $kind === 'district' || $code !== '') && $name === '') {
                        $issues[] = 'missing_name:'.$kind;
                    }
                    if (($kind === 'province' || $kind === 'district' || $name !== '') && $code === '') {
                        $issues[] = 'missing_code:'.$kind;
                    }
                    if ($code === '') {
                        continue;
                    }
                    if (! preg_match('/^[0-9]+$/D', $code)) {
                        $issues[] = 'invalid_code:'.$kind;
                    }
                    $parent = match ($kind) {
                        'province' => 'MZ', 'district' => $row['province_code'],
                        'admin_post' => $row['district_code'], default => $row['admin_post_code'],
                    };
                    $identity = $kind.':'.$code;
                    $definition = [$parent, $name];
                    if ($kind === 'locality') {
                        $definition = [...$definition, $row['locality_type'], $row['latitude'], $row['longitude']];
                    }
                    if (isset($seen[$identity]) && $seen[$identity] !== $definition) {
                        $issues[] = 'conflicting_code:'.$kind;
                    }
                    $seen[$identity] ??= $definition;
                    $nameKey = $kind.':'.$parent.':'.mb_strtolower($name);
                    if (isset($names[$nameKey]) && $names[$nameKey] !== $code) {
                        $issues[] = 'ambiguous_name:'.$kind;
                    }
                    $names[$nameKey] ??= $code;
                    $totals[$row['province_code']][$kind][$code] = true;
                }
                if ($row['locality_code'] !== '' && $row['admin_post_code'] === '') {
                    $issues[] = 'locality_requires_reviewed_parent_exception';
                }
                if (($row['latitude'] === '') !== ($row['longitude'] === '')) {
                    $issues[] = 'incomplete_coordinates';
                }
                foreach (['latitude' => 90, 'longitude' => 180] as $field => $bound) {
                    if ($row[$field] !== '' && (! preg_match('/^-?[0-9]+(?:\.[0-9]+)?$/D', $row[$field]) || abs((float) $row[$field]) > $bound)) {
                        $issues[] = 'invalid_coordinate:'.$field;
                    }
                }
                if ($row['locality_code'] === '' && ($row['latitude'] !== '' || $row['longitude'] !== '' || $row['locality_type'] !== '')) {
                    $issues[] = 'locality_metadata_without_locality';
                }
                $fingerprint = hash('sha256', json_encode($row, JSON_THROW_ON_ERROR));
                if (isset($seen['row:'.$fingerprint])) {
                    $duplicates++;
                }
                $seen['row:'.$fingerprint] = [];
                if ($issues !== []) {
                    $errors[] = ['record' => $count + 1, 'issues' => array_values(array_unique($issues))];
                }
            }
            if ($count === 0) {
                $errors[] = ['record' => 1, 'issues' => ['empty_dataset']];
            }
            ksort($totals);
            $counts = [];
            foreach ($totals as $province => $kinds) {
                $counts[$province] = array_map('count', $kinds);
            }

            return ['schema_version' => 1, 'sha256' => hash('sha256', $bytes), 'encoding' => 'UTF-8',
                'delimiter' => ';', 'coordinate_crs' => 'EPSG:4326', 'records' => $count,
                'duplicate_records' => $duplicates, 'rejected_records' => count($errors),
                'status' => $errors === [] ? 'structurally_valid_requires_review' : 'rejected',
                'candidate_counts_by_province' => $counts, 'errors' => $errors];
        } finally {
            fclose($stream);
        }
    }
}