<?php
/**
 * HomeController
 *
 * Handles all data-fetching and view-variable assembly for the public home page
 * (public/index.php).
 *
 * Responsibilities:
 *  - Parse and validate GET parameters (`page`, `year`)
 *  - Determine the display mode (default random-latest / year-filtered / paginated all)
 *  - Run the appropriate Database queries
 *  - Batch-load cover images for theses without a banner_path
 *  - Assemble OG / meta tag array
 *  - Return a flat array of view variables ready for template extraction
 *
 * The class has NO output side-effects; all template rendering stays in
 * public/index.php so the view layer remains easy to inspect and modify.
 */
class HomeController
{
    private const ITEMS_PER_PAGE = 24;

    private Database $db;

    public function __construct(Database $db)
    {
        $this->db = $db;
    }

    // ── Factory ───────────────────────────────────────────────────────────────

    /**
     * Convenience factory: loads the Database singleton and returns a ready
     * controller instance.
     */
    public static function create(): self
    {
        require_once APP_ROOT . '/src/Database.php';

        return new self(Database::getInstance());
    }

    // ── Main entry point ─────────────────────────────────────────────────────

    /**
     * Process the current request and return all variables needed by the view.
     *
     * @return array<string, mixed>
     */
    public function handle(): array
    {
        $page = isset($_GET['page']) ? max(1, (int) $_GET['page']) : 1;
        $year = isset($_GET['year']) ? (int) $_GET['year'] : null;
        // Normalise zero (e.g. ?year=0) to null so it is treated as "no filter"
        if ($year === 0) {
            $year = null;
        }

        // Default home view: random theses from latest year (no year filter, no explicit page)
        $isDefaultView = ($year === null && $page === 1);

        $itemsToLoad    = [];
        $totalItems     = 0;
        $availableYears = [];
        $latestYear     = null;
        $coverMap       = [];

        try {
            $offset         = ($page - 1) * self::ITEMS_PER_PAGE;
            $availableYears = $this->db->getAvailableYears();

            if ($year !== null) {
                $itemsToLoad = $this->db->searchTheses(['year' => $year], self::ITEMS_PER_PAGE, $offset);
                $totalItems  = $this->db->countSearchResults(['year' => $year]);
            } elseif ($isDefaultView) {
                $latestYear  = $this->db->getLatestPublishedYear();
                $itemsToLoad = $this->db->getLatestYearTheses(self::ITEMS_PER_PAGE);
                $totalItems  = count($itemsToLoad); // no multi-page on default view
            } else {
                $itemsToLoad = $this->db->getPublishedTheses(self::ITEMS_PER_PAGE, $offset);
                $totalItems  = $this->db->countPublishedTheses();
            }

            // Batch-load cover images for theses that have no banner_path
            if (!empty($itemsToLoad)) {
                $needCover = array_column(
                    array_filter($itemsToLoad, static fn($t) => empty($t['banner_path'])),
                    'id'
                );
                if (!empty($needCover)) {
                    $coverMap = $this->db->getCoverPathsForTheses($needCover);
                }
            }
        } catch (Exception $e) {
            error_log('HomeController: ' . $e->getMessage());
            // Return safe empty state; view will show "Aucun mémoire trouvé"
            $isDefaultView = false;
        }

        $totalPages = $isDefaultView ? 1 : (int) ceil($totalItems / self::ITEMS_PER_PAGE);
        // Avoid division by zero on empty DB
        if ($totalPages < 1) {
            $totalPages = 0;
        }

        $baseParams = array_filter(['year' => $year]);

        return [
            // Pagination / filter state
            'page'          => $page,
            'year'          => $year,
            'isDefaultView' => $isDefaultView,
            'totalItems'    => $totalItems,
            'totalPages'    => $totalPages,
            'baseParams'    => $baseParams,

            // Thesis data
            'itemsToLoad'    => $itemsToLoad,
            'latestYear'     => $latestYear,
            'availableYears' => $availableYears,
            'coverMap'       => $coverMap,

            // Page meta
            'pageTitle'       => 'Posterg – Mémoires de l\'ERG',
            'metaDescription' => 'Posterg répertorie et valorise les mémoires de fin d\'études (TFE) de l\'erg – École de Recherches Graphiques de Bruxelles.',
            'ogTags'          => [
                'type'        => 'website',
                'title'       => 'Posterg – Mémoires de l\'ERG',
                'description' => 'Posterg répertorie et valorise les mémoires de fin d\'études (TFE) de l\'erg – École de Recherches Graphiques de Bruxelles.',
                'url'         => 'https://posterg.erg.be/',
                'site_name'   => 'Posterg – ERG',
            ],

            // Layout
            'currentNav' => '',
            'extraCss'   => ['/assets/css/main.css'],
            'bodyClass'  => 'home-body',
        ];
    }
}