<?php

declare(strict_types=1);

namespace App\Services;

use DateTimeImmutable;
use RuntimeException;
use Throwable;

final class SchoolHolidayApiService
{
    private const DATASET = 'fr-en-calendrier-scolaire';

    /**
     * data.gouv.fr publie actuellement v2.0 comme URL de base officielle.
     * v2.1 et l'ancienne API 1.0 restent des solutions de repli afin que
     * la page continue à fonctionner lors d'une évolution du portail.
     */
    private const EXPLORE_ENDPOINTS = [
        'https://data.education.gouv.fr/api/explore/v2.0/catalog/datasets/' . self::DATASET . '/records',
        'https://data.education.gouv.fr/api/explore/v2.1/catalog/datasets/' . self::DATASET . '/records',
    ];

    private const LEGACY_ENDPOINT = 'https://data.education.gouv.fr/api/records/1.0/search/';

    private const ACADEMY_ZONES = [
        'aix-marseille' => 'Zone B',
        'amiens' => 'Zone B',
        'besancon' => 'Zone A',
        'bordeaux' => 'Zone A',
        'clermont-ferrand' => 'Zone A',
        'creteil' => 'Zone C',
        'dijon' => 'Zone A',
        'grenoble' => 'Zone A',
        'lille' => 'Zone B',
        'limoges' => 'Zone A',
        'lyon' => 'Zone A',
        'montpellier' => 'Zone C',
        'nancy-metz' => 'Zone B',
        'nantes' => 'Zone B',
        'nice' => 'Zone B',
        'normandie' => 'Zone B',
        'orleans-tours' => 'Zone B',
        'paris' => 'Zone C',
        'poitiers' => 'Zone A',
        'reims' => 'Zone B',
        'rennes' => 'Zone B',
        'strasbourg' => 'Zone B',
        'toulouse' => 'Zone C',
        'versailles' => 'Zone C',
    ];

    /**
     * Compatibilité avec le code existant : retourne uniquement les périodes.
     */
    public function previewCalendarYear(string $academy, int $calendarYear): array
    {
        return $this->previewCalendarYearDetailed($academy, $calendarYear)['periods'];
    }

    /**
     * Retourne toutes les périodes recouvrant une année civile, accompagnées
     * d'avertissements non bloquants. Une année civile chevauche deux années
     * scolaires. L'absence de publication de l'une d'elles ne doit donc plus
     * empêcher l'affichage des dates déjà disponibles.
     *
     * @return array{periods: array, warnings: array, school_years: array}
     */
    public function previewCalendarYearDetailed(string $academy, int $calendarYear): array
    {
        if ($calendarYear < 2000 || $calendarYear > 2100) {
            throw new RuntimeException('Année civile invalide.');
        }

        $academy = trim($academy);
        if ($academy === '') {
            throw new RuntimeException('Académie manquante.');
        }

        $schoolYears = [
            ($calendarYear - 1) . '-' . $calendarYear,
            $calendarYear . '-' . ($calendarYear + 1),
        ];

        $all = [];
        $warnings = [];
        $successfulQueries = 0;

        foreach ($schoolYears as $schoolYear) {
            try {
                $periods = $this->previewSchoolYear($academy, $schoolYear);
                $successfulQueries++;

                if ($periods === []) {
                    $warnings[] = sprintf(
                        'Aucune date publiée pour l’académie %s et l’année scolaire %s.',
                        $academy,
                        $schoolYear
                    );
                }

                foreach ($periods as $period) {
                    $key = $period['libelle'] . '|' . $period['date_debut'] . '|' . $period['date_fin'];
                    $all[$key] = $period;
                }
            } catch (Throwable $e) {
                $warnings[] = sprintf(
                    'Les dates de l’année scolaire %s n’ont pas pu être chargées : %s',
                    $schoolYear,
                    $e->getMessage()
                );
            }
        }

        if ($successfulQueries === 0) {
            throw new RuntimeException(implode(' ', $warnings));
        }

        $yearStart = sprintf('%04d-01-01', $calendarYear);
        $yearEnd = sprintf('%04d-12-31', $calendarYear);

        $periods = array_values(array_filter(
            $all,
            static fn(array $period): bool => $period['date_debut'] <= $yearEnd && $period['date_fin'] >= $yearStart
        ));

        usort($periods, static fn(array $a, array $b): int => strcmp($a['date_debut'], $b['date_debut']));

        return [
            'periods' => $periods,
            'warnings' => array_values(array_unique($warnings)),
            'school_years' => $schoolYears,
        ];
    }

    /**
     * Compatibilité avec l'ancienne API interne V5.17.
     */
    public function preview(string $academy, string $schoolYear): array
    {
        return $this->previewSchoolYear($academy, $schoolYear);
    }

    private function previewSchoolYear(string $academy, string $schoolYear): array
    {
        $errors = [];

        // 1. Recherche par académie. On essaie plusieurs graphies afin de ne
        // pas rendre la recherche dépendante des accents ou du type de tiret.
        foreach ($this->academyVariants($academy) as $academyVariant) {
            try {
                $records = $this->fetchExploreRecords([
                    'limit' => 100,
                    'lang' => 'fr',
                    'timezone' => 'Europe/Paris',
                    'order_by' => 'start_date',
                    'where' => 'annee_scolaire=' . $this->quoteWhereValue($schoolYear),
                    'refine' => 'location:' . $this->quoteWhereValue($academyVariant),
                ]);

                $periods = $this->normalize($records, $academy, $schoolYear, false);
                if ($periods !== []) {
                    return $periods;
                }
            } catch (Throwable $e) {
                $errors[] = $e->getMessage();
            }
        }

        // 2. Repli par zone. Il est utile lorsque le portail fournit une
        // période commune à toute la zone, sans ligne spécifique à l'académie.
        $zone = $this->zoneForAcademy($academy);
        if ($zone !== null) {
            try {
                $records = $this->fetchExploreRecords([
                    'limit' => 100,
                    'lang' => 'fr',
                    'timezone' => 'Europe/Paris',
                    'order_by' => 'start_date',
                    'where' => 'annee_scolaire=' . $this->quoteWhereValue($schoolYear),
                    'refine' => 'zones:' . $this->quoteWhereValue($zone),
                ]);

                $periods = $this->normalize($records, $academy, $schoolYear, true);
                if ($periods !== []) {
                    return $periods;
                }
            } catch (Throwable $e) {
                $errors[] = $e->getMessage();
            }
        }

        // 3. Dernier repli sur l'ancienne API Opendatasoft. Elle utilise un
        // format JSON différent, normalisé dans fetchLegacyRecords().
        foreach ($this->academyVariants($academy) as $academyVariant) {
            try {
                $records = $this->fetchLegacyRecords($academyVariant, $schoolYear);
                $periods = $this->normalize($records, $academy, $schoolYear, false);
                if ($periods !== []) {
                    return $periods;
                }
            } catch (Throwable $e) {
                $errors[] = $e->getMessage();
            }
        }

        if ($errors !== []) {
            throw new RuntimeException(end($errors) ?: 'Erreur inconnue de l’API du calendrier scolaire.');
        }

        return [];
    }

    private function fetchExploreRecords(array $parameters): array
    {
        $query = http_build_query($parameters, '', '&', PHP_QUERY_RFC3986);
        $lastError = null;

        foreach (self::EXPLORE_ENDPOINTS as $endpoint) {
            try {
                $payload = $this->fetchJson($endpoint . '?' . $query);
                $records = $payload['results'] ?? null;
                if (!is_array($records)) {
                    throw new RuntimeException('Réponse inattendue de l’API Explore.');
                }
                return $records;
            } catch (RuntimeException $e) {
                $lastError = $e;
            }
        }

        throw new RuntimeException($lastError?->getMessage() ?? 'API Explore indisponible.');
    }

    private function fetchLegacyRecords(string $academy, string $schoolYear): array
    {
        $query = http_build_query([
            'dataset' => self::DATASET,
            'rows' => 100,
            'sort' => 'start_date',
            'refine.location' => $academy,
            'refine.annee_scolaire' => $schoolYear,
        ], '', '&', PHP_QUERY_RFC3986);

        $payload = $this->fetchJson(self::LEGACY_ENDPOINT . '?' . $query);
        $records = $payload['records'] ?? null;
        if (!is_array($records)) {
            throw new RuntimeException('Réponse inattendue de l’ancienne API du calendrier scolaire.');
        }

        return array_values(array_filter(array_map(
            static fn(mixed $record): ?array => is_array($record) && is_array($record['fields'] ?? null)
                ? $record['fields']
                : null,
            $records
        )));
    }

    private function normalize(array $records, string $academy, string $schoolYear, bool $zoneFallback): array
    {
        $periods = [];
        $requestedAcademy = $this->normalizeAcademy($academy);

        foreach ($records as $record) {
            if (!is_array($record)) {
                continue;
            }

            // Certaines vacances communes sont publiées avec population "-".
            // En filtrant uniquement "Élèves", elles disparaissaient du résultat.
            if (!$this->isStudentPopulation($record['population'] ?? '')) {
                continue;
            }

            $recordAcademy = trim($this->stringValue($record['location'] ?? ''));
            if (!$zoneFallback && $recordAcademy !== '' && $this->normalizeAcademy($recordAcademy) !== $requestedAcademy) {
                continue;
            }

            $description = trim($this->stringValue($record['description'] ?? ''));
            if (!$this->isVacationDescription($description)) {
                continue;
            }

            $startRaw = $this->stringValue($record['start_date'] ?? '');
            $endRaw = $this->stringValue($record['end_date'] ?? '');
            $start = $this->dateOnly($startRaw);
            $returnDate = $this->dateOnly($endRaw);
            if ($start === null || $returnDate === null) {
                continue;
            }

            // L'API donne la date de reprise. PTA utilise des bornes inclusives,
            // donc le dernier jour de vacances est la veille de la reprise.
            $end = (new DateTimeImmutable($returnDate))->modify('-1 day')->format('Y-m-d');
            if ($end < $start) {
                $end = $start;
            }

            $zone = trim($this->stringValue($record['zones'] ?? ($record['zone'] ?? '')));
            $recordSchoolYear = trim($this->stringValue($record['annee_scolaire'] ?? $schoolYear));

            $key = $description . '|' . $start . '|' . $end;
            $periods[$key] = [
                'libelle' => $description,
                'date_debut' => $start,
                'date_fin' => $end,
                'date_reprise_api' => $returnDate,
                'annee_scolaire' => $recordSchoolYear !== '' ? $recordSchoolYear : $schoolYear,
                'academie' => $recordAcademy !== '' && !$zoneFallback ? $recordAcademy : $academy,
                'zone' => $zone !== '' ? $zone : ($this->zoneForAcademy($academy) ?? ''),
                'source' => 'DATA_GOUV',
            ];
        }

        $periods = array_values($periods);
        usort($periods, static fn(array $a, array $b): int => strcmp($a['date_debut'], $b['date_debut']));
        return $periods;
    }

    private function isVacationDescription(string $description): bool
    {
        $normalized = $this->normalizeText($description);
        if ($normalized === '') {
            return false;
        }
        if (str_contains($normalized, 'rentree') || str_contains($normalized, 'prerentree')) {
            return false;
        }

        foreach (['vacance', 'conge', 'pont', 'ete austral', 'hiver austral'] as $keyword) {
            if (str_contains($normalized, $keyword)) {
                return true;
            }
        }
        return false;
    }

    private function academyVariants(string $academy): array
    {
        $academy = trim(preg_replace('/\s+/u', ' ', $academy) ?? $academy);
        $variants = [$academy];
        $variants[] = str_replace(['–', '—', '‑'], '-', $academy);
        $variants[] = $this->stripAccents($academy);
        $variants[] = str_replace('-', ' ', $academy);
        $variants[] = str_replace('-', ' ', $this->stripAccents($academy));

        return array_values(array_unique(array_filter(array_map('trim', $variants))));
    }

    private function zoneForAcademy(string $academy): ?string
    {
        $key = $this->normalizeAcademy($academy);
        return self::ACADEMY_ZONES[str_replace(' ', '-', $key)] ?? null;
    }

    private function fetchJson(string $url): array
    {
        $body = false;
        $status = 0;

        if (function_exists('curl_init')) {
            $curl = curl_init($url);
            if ($curl === false) {
                throw new RuntimeException('Impossible d’initialiser cURL.');
            }
            curl_setopt_array($curl, [
                CURLOPT_RETURNTRANSFER => true,
                CURLOPT_FOLLOWLOCATION => true,
                CURLOPT_CONNECTTIMEOUT => 8,
                CURLOPT_TIMEOUT => 20,
                CURLOPT_ENCODING => '',
                CURLOPT_HTTPHEADER => ['Accept: application/json', 'User-Agent: PTA/7.3'],
            ]);
            $body = curl_exec($curl);
            $status = (int) curl_getinfo($curl, CURLINFO_RESPONSE_CODE);
            $error = curl_error($curl);
            curl_close($curl);
            if ($body === false) {
                throw new RuntimeException($error ?: 'Erreur réseau cURL.');
            }
        } else {
            $context = stream_context_create([
                'http' => [
                    'method' => 'GET',
                    'timeout' => 20,
                    'ignore_errors' => true,
                    'header' => "Accept: application/json\r\nUser-Agent: PTA/7.3\r\n",
                ],
            ]);
            $body = @file_get_contents($url, false, $context);
            if ($body === false) {
                throw new RuntimeException('La lecture d’URL distante est désactivée sur le serveur PHP. Activez cURL ou allow_url_fopen.');
            }
            foreach ($http_response_header ?? [] as $header) {
                if (preg_match('/^HTTP\/\S+\s+(\d{3})/', $header, $matches)) {
                    $status = (int) $matches[1];
                    break;
                }
            }
        }

        if ($status >= 400) {
            throw new RuntimeException('L’API a répondu avec le code HTTP ' . $status . '.');
        }

        $data = json_decode((string) $body, true);
        if (!is_array($data)) {
            throw new RuntimeException('Le contenu reçu depuis l’API n’est pas un JSON valide.');
        }
        return $data;
    }

    private function quoteWhereValue(string $value): string
    {
        return '"' . str_replace(['\\', '"'], ['\\\\', '\\"'], $value) . '"';
    }

    private function dateOnly(string $value): ?string
    {
        if (!preg_match('/^(\d{4}-\d{2}-\d{2})/', $value, $matches)) {
            return null;
        }
        return $matches[1];
    }

    private function stringValue(mixed $value): string
    {
        if (is_array($value)) {
            return implode(', ', array_map(static fn(mixed $item): string => (string) $item, $value));
        }
        return (string) $value;
    }


    private function isStudentPopulation(mixed $value): bool
    {
        $values = is_array($value) ? $value : [$value];
        foreach ($values as $item) {
            $population = $this->normalizeText((string) $item);
            if ($population === '' || in_array($population, ['-', 'eleves', 'tous', 'tout public'], true)) {
                return true;
            }
        }
        return false;
    }

    private function normalizeAcademy(string $value): string
    {
        $value = str_replace(['–', '—', '‑', '_', '-'], ' ', $value);
        return $this->normalizeText($value);
    }

    private function normalizeText(string $value): string
    {
        $value = $this->stripAccents($value);
        $value = str_replace(['–', '—', '‑', '_'], '-', $value);
        $value = strtolower($value);
        $value = preg_replace('/[^a-z0-9-]+/', ' ', $value) ?? $value;
        $value = preg_replace('/\s+/', ' ', $value) ?? $value;
        return trim($value);
    }

    private function stripAccents(string $value): string
    {
        return strtr($value, [
            'À' => 'A', 'Á' => 'A', 'Â' => 'A', 'Ã' => 'A', 'Ä' => 'A', 'Å' => 'A',
            'à' => 'a', 'á' => 'a', 'â' => 'a', 'ã' => 'a', 'ä' => 'a', 'å' => 'a',
            'Ç' => 'C', 'ç' => 'c',
            'È' => 'E', 'É' => 'E', 'Ê' => 'E', 'Ë' => 'E',
            'è' => 'e', 'é' => 'e', 'ê' => 'e', 'ë' => 'e',
            'Ì' => 'I', 'Í' => 'I', 'Î' => 'I', 'Ï' => 'I',
            'ì' => 'i', 'í' => 'i', 'î' => 'i', 'ï' => 'i',
            'Ñ' => 'N', 'ñ' => 'n',
            'Ò' => 'O', 'Ó' => 'O', 'Ô' => 'O', 'Õ' => 'O', 'Ö' => 'O',
            'ò' => 'o', 'ó' => 'o', 'ô' => 'o', 'õ' => 'o', 'ö' => 'o',
            'Ù' => 'U', 'Ú' => 'U', 'Û' => 'U', 'Ü' => 'U',
            'ù' => 'u', 'ú' => 'u', 'û' => 'u', 'ü' => 'u',
            'Ý' => 'Y', 'Ÿ' => 'Y', 'ý' => 'y', 'ÿ' => 'y',
            'Œ' => 'OE', 'œ' => 'oe', 'Æ' => 'AE', 'æ' => 'ae',
        ]);
    }
}