<?php
require_once(__DIR__ . '/../auth_check.php');
require_once(__DIR__ . '/../../class/db-functions.php');
require_once(__DIR__ . '/../../include/training_coverage.php');

header('Content-Type: application/json');

if ($_SERVER['REQUEST_METHOD'] !== 'POST') {
    http_response_code(405);
    echo json_encode(['success' => false, 'message' => 'Metodo non consentito.']);
    exit;
}

$pdo = DBHandlerSelect::getInstance()->getConnection();

$id          = (int)($_POST['id'] ?? 0);
$name        = trim($_POST['name'] ?? '');
$description = trim($_POST['description'] ?? '');
$freqRaw     = $_POST['default_frequency_months'] ?? '';
$remRaw      = $_POST['default_reminder_days'] ?? '';
$sort_order   = isset($_POST['sort_order']) && $_POST['sort_order'] !== '' ? (int)$_POST['sort_order'] : 999;
$is_active    = isset($_POST['is_active']) ? ((int)$_POST['is_active'] === 1 ? 1 : 0) : 1;
$is_mandatory = isset($_POST['is_mandatory']) && (int)$_POST['is_mandatory'] === 1 ? 1 : 0;

$freq = ($freqRaw === '' || $freqRaw === null) ? null : max(0, (int)$freqRaw);
$rem  = ($remRaw  === '' || $remRaw  === null) ? 30   : max(0, (int)$remRaw);

/* Coperture: corsi assorbiti da questo */
$coveredIds = isset($_POST['covered_ids']) ? (array)$_POST['covered_ids'] : [];
$coveredIds = array_values(array_unique(array_filter(array_map('intval', $coveredIds), function ($v) {
    return $v > 0;
})));

if ($name === '') {
    echo json_encode(['success' => false, 'message' => 'Il nome del corso è obbligatorio.']);
    exit;
}

/**
 * Riscrive le coperture del corso: cancella le vecchie e inserisce le nuove,
 * scartando auto-copertura e relazioni che creerebbero un ciclo.
 */
function saveCoverage(PDO $pdo, int $topicId, array $coveredIds): array
{
    $skipped = [];

    $pdo->prepare("DELETE FROM training_topic_coverage WHERE topic_id = :tid")
        ->execute(['tid' => $topicId]);

    if (!$coveredIds) return $skipped;

    $ins = $pdo->prepare("
        INSERT IGNORE INTO training_topic_coverage
            (topic_id, covered_topic_id, inherit_expiry, created_at)
        VALUES (:tid, :cid, 'own', NOW())
    ");

    foreach ($coveredIds as $cid) {
        if ($cid === $topicId) {
            continue;
        }
        if (tc_wouldCreateCycle($pdo, $topicId, $cid)) {
            $skipped[] = $cid;
            continue;
        }
        $ins->execute(['tid' => $topicId, 'cid' => $cid]);
    }

    return $skipped;
}

try {
    $pdo->beginTransaction();

    if ($id > 0) {
        $check = $pdo->prepare("SELECT COUNT(*) FROM training_topics WHERE name = :name AND id <> :id");
        $check->execute(['name' => $name, 'id' => $id]);
        if ((int)$check->fetchColumn() > 0) {
            $pdo->rollBack();
            echo json_encode(['success' => false, 'message' => 'Esiste già un altro corso con questo nome.']);
            exit;
        }

        $stmt = $pdo->prepare("
            UPDATE training_topics
            SET name = :name,
                description = :description,
                default_frequency_months = :freq,
                default_reminder_days = :rem,
                sort_order = :sort_order,
                is_active = :is_active,
                is_mandatory = :is_mandatory,
                updated_at = NOW()
            WHERE id = :id
        ");
        $stmt->execute([
            'name'         => $name,
            'description'  => $description !== '' ? $description : null,
            'freq'         => $freq,
            'rem'          => $rem,
            'sort_order'   => $sort_order,
            'is_active'    => $is_active,
            'is_mandatory' => $is_mandatory,
            'id'           => $id,
        ]);

        $skipped = saveCoverage($pdo, $id, $coveredIds);
        $pdo->commit();

        $msg = $skipped
            ? 'Corso aggiornato. Alcune coperture sono state ignorate perché avrebbero creato un riferimento circolare.'
            : null;

        echo json_encode(array_filter([
            'success' => true,
            'id'      => $id,
            'message' => $msg,
        ], function ($v) {
            return $v !== null;
        }));
        exit;
    }

    $check = $pdo->prepare("SELECT COUNT(*) FROM training_topics WHERE name = :name");
    $check->execute(['name' => $name]);
    if ((int)$check->fetchColumn() > 0) {
        $pdo->rollBack();
        echo json_encode(['success' => false, 'message' => 'Esiste già un corso con questo nome.']);
        exit;
    }

    $stmt = $pdo->prepare("
        INSERT INTO training_topics
            (name, description, default_frequency_months, default_reminder_days, sort_order, is_active, is_mandatory, created_at, updated_at)
        VALUES
            (:name, :description, :freq, :rem, :sort_order, :is_active, :is_mandatory, NOW(), NOW())
    ");
    $stmt->execute([
        'name'         => $name,
        'description'  => $description !== '' ? $description : null,
        'freq'         => $freq,
        'rem'          => $rem,
        'sort_order'   => $sort_order,
        'is_active'    => $is_active,
        'is_mandatory' => $is_mandatory,
    ]);

    $newId = (int)$pdo->lastInsertId();
    saveCoverage($pdo, $newId, $coveredIds);

    $pdo->commit();
    echo json_encode(['success' => true, 'id' => $newId]);
} catch (Exception $e) {
    if ($pdo->inTransaction()) {
        $pdo->rollBack();
    }
    echo json_encode(['success' => false, 'message' => $e->getMessage()]);
}