<?php

/**
 * SchoolContext v3
 * - Scuola corrente dell'utente loggato e ruolo nella scuola
 * - Scuole tra cui può passare (owner multi-scuola, superadmin)
 * - Vista attiva (superadmin | school | teacher | student): permette a chi ha
 *   permessi alti di vedere l'app come un livello inferiore. Mai superiore.
 *
 * Uso (headscript):
 *   $schoolData = SchoolContext::resolve((int)$iduserlogin);
 *   $idschool   = SchoolContext::id();
 *
 * I controlli isSuperadmin()/isSchoolAdmin()/isStaff() tengono conto della
 * vista attiva. viewModes() e available() usano i permessi REALI.
 */

if (!class_exists('DBHandlerSelect')) {
    require_once __DIR__ . '/db-functions.php';
}

class SchoolContext
{
    /** Scuola di fallback durante la fase monoscuola (Seregno) */
    const DEFAULT_SCHOOL = 1;

    /** @var array|null scuola corrente (riga schools + school_role) */
    private static $school = null;

    /** @var int */
    private static $userId = 0;

    /** @var bool permesso REALE di superadmin */
    private static $superadmin = false;

    /** @var array scuole di cui l'utente è membro */
    private static $memberships = [];

    /* ================================================================== */
    /*  RISOLUZIONE SCUOLA                                                */
    /* ================================================================== */

    public static function resolve(int $userId): array
    {
        if (self::$school !== null) {
            return self::$school;
        }

        $pdo = self::pdo();
        self::$userId = $userId;

        $st = $pdo->prepare("SELECT is_superadmin FROM auth_users WHERE id = ?");
        $st->execute([$userId]);
        self::$superadmin = ($st->fetchColumn() === 'Y');

        self::$memberships = self::loadMemberships($userId);

        // TEMPORANEO (fase monoscuola): utente senza scuola -> agganciato a Seregno
        if (empty(self::$memberships) && !self::$superadmin) {
            $ins = $pdo->prepare(
                "INSERT IGNORE INTO school_user (user_id, idschool, school_role)
                 VALUES (?, ?, 'student')"
            );
            $ins->execute([$userId, self::DEFAULT_SCHOOL]);
            self::$memberships = self::loadMemberships($userId);
        }

        $requested = isset($_SESSION['idschool']) ? (int) $_SESSION['idschool'] : 0;
        $selected  = self::pick($requested);

        if ($selected === null) {
            http_response_code(403);
            die('Nessuna scuola attiva associata a questo account.');
        }

        $selected['idschool'] = (int) $selected['idschool'];
        $_SESSION['idschool'] = $selected['idschool'];

        self::$school = $selected;
        return self::$school;
    }

    /** Cambia scuola corrente. False se l'utente non può accedervi. */
    public static function switchTo(int $idschool): bool
    {
        if ($idschool <= 0) {
            return false;
        }
        foreach (self::available() as $s) {
            if ((int) $s['idschool'] === $idschool) {
                $_SESSION['idschool'] = $idschool;
                self::$school = null;
                self::resolve(self::$userId);
                return true;
            }
        }
        return false;
    }

    /** Scuole selezionabili (permessi reali). Superadmin: tutte. */
    public static function available(): array
    {
        if (!self::$superadmin) {
            return self::$memberships;
        }

        $roles = [];
        foreach (self::$memberships as $m) {
            $roles[(int) $m['idschool']] = $m['school_role'];
        }

        $all = self::pdo()->query("SELECT * FROM schools ORDER BY name")->fetchAll();
        foreach ($all as &$s) {
            $s['school_role'] = $roles[(int) $s['idschool']] ?? 'superadmin';
        }
        unset($s);
        return $all;
    }

    /* ================================================================== */
    /*  VISTA ATTIVA                                                      */
    /* ================================================================== */

    /**
     * Viste consentite in base ai permessi REALI, dalla più alta alla più bassa.
     * @return array chiave => etichetta
     */
    public static function viewModes(): array
    {
        $real  = self::realRole();
        $modes = [];

        if (self::$superadmin) {
            $modes['superadmin'] = 'Superadmin';
        }
        if (self::$superadmin || in_array($real, ['owner', 'admin'], true)) {
            $modes['school'] = 'Scuola';
        }
        if ($real === 'teacher') {
            $modes['teacher'] = 'Insegnante';
        }
        $modes['student'] = 'Allievo';

        return $modes;
    }

    /** Vista attiva (se quella in sessione non è consentita: la più alta) */
    public static function viewMode(): string
    {
        $modes = self::viewModes();
        $req = $_SESSION['view_mode'] ?? '';
        if (isset($modes[$req])) {
            return $req;
        }
        return (string) array_key_first($modes);
    }

    public static function setViewMode(string $mode): bool
    {
        if (!isset(self::viewModes()[$mode])) {
            return false;
        }
        $_SESSION['view_mode'] = $mode;
        return true;
    }

    /** Pagina iniziale per la vista attiva */
    public static function landingPage(): string
    {
        switch (self::viewMode()) {
            case 'superadmin':
                return 'sa-schools.php';
            case 'school':
            case 'teacher':
                return 'adminpanel.php';
            default:
                return 'userpanel.php';
        }
    }

    /* ================================================================== */
    /*  GETTER E CONTROLLI (tengono conto della vista)                    */
    /* ================================================================== */

    public static function id(): int
    {
        return self::get()['idschool'];
    }

    public static function get(): array
    {
        if (self::$school === null) {
            throw new RuntimeException('SchoolContext::resolve() non ancora chiamato');
        }
        return self::$school;
    }

    /** Ruolo REALE nella scuola: owner|admin|teacher|student|superadmin */
    public static function realRole(): string
    {
        return self::get()['school_role'];
    }

    /** Alias storico di realRole() */
    public static function role(): string
    {
        return self::realRole();
    }

    public static function isRealSuperadmin(): bool
    {
        return self::$superadmin;
    }

    public static function isSuperadmin(): bool
    {
        return self::viewMode() === 'superadmin';
    }

    public static function isOwner(): bool
    {
        return self::realRole() === 'owner' && self::isSchoolAdmin();
    }

    /** Gestisce la scuola (vista superadmin o scuola) */
    public static function isSchoolAdmin(): bool
    {
        return in_array(self::viewMode(), ['superadmin', 'school'], true);
    }

    /** Staff: amministratori + insegnanti */
    public static function isStaff(): bool
    {
        return self::isSchoolAdmin() || self::viewMode() === 'teacher';
    }

    public static function requireSchoolAdmin(): void
    {
        if (!self::isSchoolAdmin()) {
            self::deny();
        }
    }

    public static function requireStaff(): void
    {
        if (!self::isStaff()) {
            self::deny();
        }
    }

    public static function requireSuperadmin(): void
    {
        if (!self::isSuperadmin()) {
            self::deny();
        }
    }

    /* ================================================================== */
    /*  INTERNI                                                           */
    /* ================================================================== */

    private static function deny(): void
    {
        http_response_code(403);
        $home = self::$school ? self::landingPage() : 'userpanel.php';
        die('Accesso non autorizzato con la vista attuale. <a href="' . $home . '">Torna alla pagina iniziale</a>');
    }

    private static function pick(int $requested): ?array
    {
        foreach (self::$memberships as $m) {
            if ((int) $m['idschool'] === $requested) {
                return $m;
            }
        }

        if (self::$superadmin) {
            $pdo = self::pdo();
            if ($requested > 0) {
                $st = $pdo->prepare("SELECT * FROM schools WHERE idschool = ?");
                $st->execute([$requested]);
                $row = $st->fetch();
                if ($row) {
                    $row['school_role'] = 'superadmin';
                    return $row;
                }
            }
            if (!empty(self::$memberships)) {
                return self::$memberships[0];
            }
            $row = $pdo->query("SELECT * FROM schools ORDER BY idschool LIMIT 1")->fetch();
            if ($row) {
                $row['school_role'] = 'superadmin';
                return $row;
            }
            return null;
        }

        return self::$memberships[0] ?? null;
    }

    private static function loadMemberships(int $userId): array
    {
        $st = self::pdo()->prepare(
            "SELECT s.*, su.school_role
               FROM school_user su
               JOIN schools s ON s.idschool = su.idschool
              WHERE su.user_id = ?
                AND su.active = 'Y'
                AND s.status <> 'suspended'
           ORDER BY s.name"
        );
        $st->execute([$userId]);
        return $st->fetchAll();
    }

    private static function pdo(): PDO
    {
        return DBHandlerSelect::getInstance()->getConnection();
    }
}