<?php
/**
 * HAL API Class - Handles communication with HAL API
 */

if (!defined('ABSPATH')) {
    exit;
}

class Thalim_HAL_API {

    // Fields to retrieve from HAL (expanded for import preview)
    private const FIELDS = 'halId_s,title_s,docType_s,authFullName_s,authIdHal_s,publicationDate_s,producedDate_s,submittedDate_s,journalTitle_s,bookTitle_s,uri_s,fileMain_s,abstract_s,keyword_s,publisher_s,modifiedDate_s,doiId_s,citationFull_s,conferenceTitle_s,city_s,country_s,defenseDate_s';

    /**
     * Fetch publications from THALIM structure
     *
     * @param int    $rows      Number of results to fetch
     * @param int    $start     Offset
     * @param string $sort      Solr sort expression
     * @param string $date_from Filter start date (YYYY-MM-DD), empty = no lower bound
     * @param string $date_to   Filter end date (YYYY-MM-DD), empty = no upper bound
     */
    public function fetch_publications($rows = 100, $start = 0, $sort = 'producedDate_tdate desc', $date_from = '', $date_to = '', $author_hal_id = '') {
        $url = $this->build_url($rows, $start, $sort, $date_from, $date_to, $author_hal_id);
        return $this->request($url);
    }

    /**
     * Fetch full HAL docs by a list of hal_ids (batched).
     * Uses Solr fq=halId_s:(id1 OR id2 OR ...) syntax. No structId filter —
     * fetch by halId exact, regardless of structure.
     *
     * @param string[] $hal_ids  HAL IDs to fetch.
     * @param int      $batch    Batch size (default 100).
     * @return array|WP_Error    Array keyed by halId_s, or WP_Error on failure.
     */
    public function fetch_by_hal_ids(array $hal_ids, int $batch = 100) {
        $docs = [];
        $chunks = array_chunk(array_values(array_unique($hal_ids)), $batch);
        foreach ($chunks as $chunk) {
            $filter = 'halId_s:(' . implode(' OR ', $chunk) . ')';
            $params = [
                'q='    . urlencode('*:*'),
                'fq='   . urlencode($filter),
                'rows=' . count($chunk),
                'fl='   . urlencode(self::FIELDS),
                'wt=json',
            ];
            $url  = THALIM_HAL_API_BASE . '?' . implode('&', $params);
            $data = $this->request($url);
            if (is_wp_error($data)) return $data;
            foreach ($data['response']['docs'] ?? [] as $doc) {
                if (!empty($doc['halId_s'])) {
                    $docs[$doc['halId_s']] = $doc;
                }
            }
            // Be polite with HAL if we have multiple chunks
            if (count($chunks) > 1) usleep(250000);
        }
        return $docs;
    }

    /**
     * Test API connection
     */
    public function test_connection() {
        $result = $this->fetch_publications(5);
        if (is_wp_error($result)) return $result;
        return [
            'success' => true,
            'total'   => $result['response']['numFound'] ?? 0,
            'sample'  => $result['response']['docs'] ?? []
        ];
    }

    /**
     * Build API URL with proper fq parameter handling
     *
     * @param int    $rows
     * @param int    $start
     * @param string $sort
     * @param string $date_from YYYY-MM-DD or empty
     * @param string $date_to   YYYY-MM-DD or empty
     */
    private function build_url($rows = 5, $start = 0, $sort = 'modifiedDate_tdate desc', $date_from = '', $date_to = '', $author_hal_id = '') {
        $doc_types = implode(' OR ', THALIM_HAL_DOC_TYPES);

        $from = $date_from ? $date_from . 'T00:00:00Z' : '*';
        $to   = $date_to   ? $date_to   . 'T23:59:59Z' : '*';

        $params = [
            'q=' . urlencode('*:*'),
            'fq=' . urlencode('structId_i:' . THALIM_HAL_STRUCT_ID),
            'fq=' . urlencode('docType_s:(' . $doc_types . ')'),
        ];

        if ($from !== '*' || $to !== '*') {
            $params[] = 'fq=' . urlencode('producedDate_tdate:[' . $from . ' TO ' . $to . ']');
        }

        if ($author_hal_id !== '') {
            $params[] = 'fq=' . urlencode('authIdHal_s:' . $author_hal_id);
        }

        $params = array_merge($params, [
            'rows=' . intval($rows),
            'start=' . intval($start),
            'sort=' . urlencode($sort),
            'fl=' . urlencode(self::FIELDS),
            'wt=json'
        ]);

        return THALIM_HAL_API_BASE . '?' . implode('&', $params);
    }

    /**
     * Get API URL for debugging display
     */
    public function get_api_url($rows = 5) {
        return $this->build_url($rows, 0);
    }

    /**
     * Make HTTP request
     */
    private function request($url) {
        $response = wp_remote_get($url, ['timeout' => 30, 'headers' => ['Accept' => 'application/json']]);
        if (is_wp_error($response)) return $response;

        $code = wp_remote_retrieve_response_code($response);
        if ($code !== 200) return new WP_Error('api_error', "HTTP $code");

        $data = json_decode(wp_remote_retrieve_body($response), true);
        return json_last_error() === JSON_ERROR_NONE ? $data : new WP_Error('json_error', 'Invalid JSON');
    }
}