<?php

/**
 * Notifications API
 *
 * GET  → returns recent notifications for the current user (last 7 days, max 30)
 * POST { action: 'mark_read', log_id?: N } → updates last_seen timestamp in user_preferences
 *
 * Notifications are derived from audit_log:
 *   - Tickets assigned to me    (action_type='assign', details.assigned_to = userId)
 *   - Comments on my tickets    (action_type='comment', ticket assigned_to/created_by = userId)
 *   - Status changes on watched (via ticket_watchers)
 *   - @mentions in comments     (action_type='comment', details.mentions[] contains username)
 */

require_once __DIR__ . '/bootstrap.php';
require_once dirname(__DIR__) . '/models/UserPreferencesModel.php';

$prefsModel = new UserPreferencesModel($conn);

// ── POST: mark all read (update last_seen timestamp) ──────────────
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $data = json_decode(file_get_contents('php://input'), true) ?? [];
    if (($data['action'] ?? '') === 'mark_read') {
        $prefsModel->setPreference($userId, 'notif_last_seen', date('Y-m-d H:i:s'));
        apiRespond(['success' => true]);
    } else {
        http_response_code(400);
        apiRespond(['success' => false, 'error' => 'Unknown action']);
    }
    exit;
}

// ── GET: fetch notifications ──────────────────────────────────────
if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
    http_response_code(405);
    apiRespond(['success' => false, 'error' => 'Method not allowed']);
    exit;
}

// Get last_seen timestamp (when user last marked all read)
$prefs = $prefsModel->getUserPreferences($userId);
$lastSeen = $prefs['notif_last_seen'] ?? null;

// Username for @mention detection
$myUsername = $currentUser['username'] ?? '';

// Query 1: Tickets assigned to me (events from other users)
$assignSql = "SELECT
    al.audit_id AS log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
    COALESCE(u.display_name, u.username, 'System') AS actor_name
  FROM audit_log al
  LEFT JOIN users u ON al.user_id = u.user_id
  WHERE al.action_type = 'assign'
    AND al.entity_type = 'ticket'
    AND al.user_id != ?
    AND al.created_at >= DATE_SUB(NOW(), INTERVAL 7 DAY)
    AND al.details LIKE ?
  ORDER BY al.created_at DESC
  LIMIT 15";

$assignLike = '%"assigned_to":' . $userId . '%';
$stmt = $conn->prepare($assignSql);
$stmt->bind_param('is', $userId, $assignLike);
$stmt->execute();
$assignRows = $stmt->get_result()->fetch_all(MYSQLI_ASSOC);
$stmt->close();

// Query 2: Comments on tickets I own or watch (events from other users)
// Comments are logged as action_type='create', entity_type='comment', ticket_id stored in details JSON.
// Avoid JSON_EXTRACT (not universally supported) — fetch recent entries then filter in PHP.

// Step A: ticket IDs the current user owns or watches
$myTicketIds = [];
$myTicketsSql = "SELECT DISTINCT ticket_id FROM tickets WHERE assigned_to = ? OR created_by = ?";
$stmt = $conn->prepare($myTicketsSql);
$stmt->bind_param('ii', $userId, $userId);
$stmt->execute();
$mtResult = $stmt->get_result();
while ($mtRow = $mtResult->fetch_assoc()) {
    $myTicketIds[(int)$mtRow['ticket_id']] = true;
    $myTicketIds[$mtRow['ticket_id']] = true;
}
$stmt->close();

$watchedSql = "SELECT ticket_id FROM ticket_watchers WHERE user_id = ?";
$stmt = $conn->prepare($watchedSql);
$stmt->bind_param('i', $userId);
$stmt->execute();
$wResult = $stmt->get_result();
while ($wRow = $wResult->fetch_assoc()) {
    $myTicketIds[(int)$wRow['ticket_id']] = true;
    $myTicketIds[$wRow['ticket_id']] = true;
}
$stmt->close();

// Step B: fetch recent comment audit events not by the current user
$commentSql = "SELECT
    al.audit_id AS log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
    COALESCE(u.display_name, u.username, 'System') AS actor_name
  FROM audit_log al
  LEFT JOIN users u ON al.user_id = u.user_id
  WHERE al.action_type IN ('comment', 'create')
    AND al.entity_type = 'comment'
    AND al.user_id != ?
    AND al.created_at >= DATE_SUB(NOW(), INTERVAL 7 DAY)
  ORDER BY al.created_at DESC
  LIMIT 50";

$stmt = $conn->prepare($commentSql);
$stmt->bind_param('i', $userId);
$stmt->execute();
$rawCommentRows = $stmt->get_result()->fetch_all(MYSQLI_ASSOC);
$stmt->close();

// Step C: filter to only comments on tickets the current user owns/watches
$commentRows = [];
foreach ($rawCommentRows as $rawRow) {
    $d   = json_decode($rawRow['details'] ?? '{}', true) ?? [];
    $tidRaw = $d['ticket_id'] ?? 0;
    $tid = (int)$tidRaw;
    if ($tid > 0 && (isset($myTicketIds[$tid]) || isset($myTicketIds[$tidRaw]))) {
        $commentRows[] = $rawRow;
        if (count($commentRows) >= 15) {
            break;
        }
    }
}

// Query 3: Status changes on watched tickets (from other users)
$statusSql = "SELECT DISTINCT
    al.audit_id AS log_id, al.action_type, al.entity_type, al.entity_id, al.details, al.created_at,
    COALESCE(u.display_name, u.username, 'System') AS actor_name
  FROM audit_log al
  LEFT JOIN users u ON al.user_id = u.user_id
  INNER JOIN ticket_watchers tw ON tw.ticket_id = CAST(al.entity_id AS UNSIGNED) AND tw.user_id = ?
  WHERE al.action_type = 'update'
    AND al.entity_type = 'ticket'
    AND al.user_id != ?
    AND al.created_at >= DATE_SUB(NOW(), INTERVAL 7 DAY)
    AND al.details LIKE '%\"status\":%'
  ORDER BY al.created_at DESC
  LIMIT 10";

$stmt = $conn->prepare($statusSql);
$stmt->bind_param('ii', $userId, $userId);
$stmt->execute();
$statusRows = $stmt->get_result()->fetch_all(MYSQLI_ASSOC);
$stmt->close();

// Merge, deduplicate by log_id, sort by created_at desc
$all = [];
$seen = [];
foreach (array_merge($assignRows, $commentRows, $statusRows) as $row) {
    $id = (int)$row['log_id'];
    if (isset($seen[$id])) {
        continue;
    }
    $seen[$id] = true;
    $all[] = $row;
}
usort($all, fn($a, $b) => strcmp($b['created_at'], $a['created_at']));
$all = array_slice($all, 0, 30);

// Format for response
$notifications = [];
foreach ($all as $row) {
    $details = json_decode($row['details'] ?? '{}', true) ?? [];
    // Comment rows: entity_id is the comment_id; real ticket_id is in details
    $actionType = ($row['action_type'] === 'create' && $row['entity_type'] === 'comment')
        ? 'comment'
        : $row['action_type'];
    $ticketId = ($actionType === 'comment')
        ? ($details['ticket_id'] ?? 0)
        : $row['entity_id'];
    $isRead = $lastSeen && $row['created_at'] <= $lastSeen;

    // Build human-readable title
    $title = match ($actionType) {
        'assign'  => "{$row['actor_name']} assigned ticket #{$ticketId} to you",
        'comment' => "{$row['actor_name']} commented on ticket #{$ticketId}",
        'update'  => (function () use ($row, $details, $ticketId) {
            // logTicketUpdate stores delta as {"status": {"from": "Open", "to": "In Progress"}}
            $from = $details['status']['from'] ?? ($details['old_value'] ?? '?');
            $to   = $details['status']['to']   ?? ($details['new_value'] ?? '?');
            return "{$row['actor_name']} changed status on #{$ticketId}: {$from} → {$to}";
        })(),
        default   => "{$row['actor_name']} updated ticket #{$ticketId}",
    };

    $ticketTitle = $details['title'] ?? null;
    if ($ticketTitle) {
        $title .= ' — ' . mb_substr($ticketTitle, 0, 40) . (mb_strlen($ticketTitle) > 40 ? '…' : '');
    }

    $notifications[] = [
        'log_id'     => (int)$row['log_id'],
        'ticket_id'  => $ticketId,
        'title'      => $title,
        'created_at' => $row['created_at'],
        'is_read'    => $isRead,
        'action'     => $actionType,
        'url'        => "/ticket/{$ticketId}",
    ];
}

$unreadCount = count(array_filter($notifications, fn($n) => !$n['is_read']));

apiRespond([
    'success'       => true,
    'notifications' => $notifications,
    'unread_count'  => $unreadCount,
    'last_seen'     => $lastSeen,
]);