<?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/public.css"],
            "bodyClass" => "home-body",
        ];
    }
}