<?php
// Message + attachment routes:
//   POST   /api/messages              (UI session: server encrypts)
//   POST   /api/messages              (client API: decrypt-reencrypt hop)
//   GET    /api/messages              (client API: re-encrypt for recipient)
//   DELETE /api/messages/{id}         (own only)
//   POST   /api/attachments           (client API)
//   GET    /api/attachments           (client API)

if (!defined('RELAY_BOOTSTRAPPED')) { http_response_code(404); exit; }

// $sessionTenant comes from routes/public.php earlier in the chain

// ── UI compose path: server encrypts plaintext with inter-tenant key ──

if ($route === '/api/messages' && $method === 'POST' && $sessionTenant && empty($_SERVER['HTTP_X_RELAY_KEY'])) {
    $input = json_decode(file_get_contents('php://input'), true) ?: [];
    $title = (string)($input['title'] ?? '');
    $body = (string)($input['body'] ?? '');
    $recipientName = trim((string)($input['recipient'] ?? $sessionTenant['username']));
    if ($body === '') jsonResponse(['error' => 'body required'], 400);

    $recipient = getTenantByUsername($db, $recipientName);
    if (!$recipient) jsonResponse(['error' => "no such user: $recipientName"], 404);

    $interKey = getInterTenantKey($db, $MASTER_KEY);
    if (!$interKey) jsonResponse(['error' => 'relay super-shared key not set'], 500);
    $storedTitle = clientEncrypt($title, $interKey);
    $storedBody = clientEncrypt($body, $interKey);

    $db->prepare('INSERT INTO messages (recipient_id, sender_id, sender_username, title, body, color, tags, relay_uid) VALUES (:r, :s, :sn, :t, :b, :c, :tg, :uid)')
        ->execute([
            'r' => $recipient['id'],
            's' => $sessionTenant['id'],
            'sn' => $sessionTenant['username'],
            't' => $storedTitle,
            'b' => $storedBody,
            'c' => $input['color'] ?? '#38bdf8',
            'tg' => $input['tags'] ?? '',
            'uid' => $input['relay_uid'] ?? null,
        ]);
    jsonResponse(['ok' => true, 'id' => (int)$db->lastInsertId(), 'recipient' => $recipientName]);
}

// ── Client API auth (X-Relay-User + X-Relay-Key) ──

$clientTenant = authClient($db);

if ($route === '/api/messages' && $method === 'POST') {
    if (!$clientTenant) jsonResponse(['error' => 'unauthorized'], 401);

    $input = json_decode(file_get_contents('php://input'), true) ?: [];
    $encryptedTitle = (string)($input['title'] ?? '');
    $encryptedBody = (string)($input['body'] ?? '');
    $recipientName = trim((string)($input['recipient'] ?? $clientTenant['username']));
    if ($encryptedBody === '') jsonResponse(['error' => 'body required'], 400);

    $recipient = getTenantByUsername($db, $recipientName);
    if (!$recipient) jsonResponse(['error' => "no such user: $recipientName"], 404);

    // Decrypt with sender's secret
    if (empty($clientTenant['secret_encrypted'])) {
        jsonResponse(['error' => 'sender has no client secret set — log into the relay UI and configure one in your account'], 400);
    }
    $senderSecret = masterDecrypt($clientTenant['secret_encrypted'], $MASTER_KEY);
    if (!$senderSecret) jsonResponse(['error' => 'sender secret unavailable'], 500);
    $plainTitle = clientDecrypt($encryptedTitle, $senderSecret);
    $plainBody = clientDecrypt($encryptedBody, $senderSecret);

    // Re-encrypt with the inter-tenant (super-shared) key for at-rest storage
    $interKey = getInterTenantKey($db, $MASTER_KEY);
    if (!$interKey) jsonResponse(['error' => 'relay super-shared key not set — admin must complete setup'], 500);
    $storedTitle = clientEncrypt($plainTitle, $interKey);
    $storedBody = clientEncrypt($plainBody, $interKey);

    $db->prepare('INSERT INTO messages (recipient_id, sender_id, sender_username, title, body, color, tags, relay_uid) VALUES (:r, :s, :sn, :t, :b, :c, :tg, :uid)')
        ->execute([
            'r' => $recipient['id'],
            's' => $clientTenant['id'],
            'sn' => $clientTenant['username'],
            't' => $storedTitle,
            'b' => $storedBody,
            'c' => $input['color'] ?? '#38bdf8',
            'tg' => $input['tags'] ?? '',
            'uid' => $input['relay_uid'] ?? null,
        ]);
    jsonResponse(['ok' => true, 'id' => (int)$db->lastInsertId(), 'recipient' => $recipientName]);
}

if ($route === '/api/messages' && $method === 'GET') {
    if (!$clientTenant) jsonResponse(['error' => 'unauthorized'], 401);
    if (empty($clientTenant['secret_encrypted'])) {
        jsonResponse(['error' => 'no client secret set — log into the relay UI and configure one in your account'], 400);
    }

    $since = $_GET['since'] ?? null;
    if ($since) {
        $stmt = $db->prepare("SELECT * FROM messages WHERE recipient_id = :r AND created_at > :s ORDER BY created_at ASC");
        $stmt->execute(['r' => $clientTenant['id'], 's' => $since]);
    } else {
        $stmt = $db->prepare("SELECT * FROM messages WHERE recipient_id = :r ORDER BY created_at ASC");
        $stmt->execute(['r' => $clientTenant['id']]);
    }
    $msgs = $stmt->fetchAll();

    // Decrypt with inter-tenant key, re-encrypt with recipient's secret
    $interKey = getInterTenantKey($db, $MASTER_KEY);
    if (!$interKey) jsonResponse(['error' => 'relay super-shared key not set'], 500);
    $recipientSecret = masterDecrypt($clientTenant['secret_encrypted'], $MASTER_KEY);
    if (!$recipientSecret) jsonResponse(['error' => 'recipient secret unavailable'], 500);

    $out = [];
    foreach ($msgs as $msg) {
        $plainTitle = clientDecrypt($msg['title'] ?? '', $interKey);
        $plainBody = clientDecrypt($msg['body'] ?? '', $interKey);
        $msg['title'] = clientEncrypt($plainTitle, $recipientSecret);
        $msg['body'] = clientEncrypt($plainBody, $recipientSecret);
        $out[] = $msg;
    }
    $db->prepare("UPDATE messages SET fetched = 1 WHERE recipient_id = :r AND fetched = 0")
        ->execute(['r' => $clientTenant['id']]);
    jsonResponse($out);
}

if (preg_match('#^/api/messages/(\d+)$#', $route, $m) && $method === 'DELETE') {
    $tenant = $clientTenant ?: $sessionTenant;
    if (!$tenant) jsonResponse(['error' => 'unauthorized'], 401);
    $id = (int)$m[1];
    $db->prepare('DELETE FROM messages WHERE id = :id AND recipient_id = :r')
        ->execute(['id' => $id, 'r' => $tenant['id']]);
    jsonResponse(['ok' => true]);
}

if ($route === '/api/attachments' && $method === 'POST') {
    if (!$clientTenant) jsonResponse(['error' => 'unauthorized'], 401);
    $input = json_decode(file_get_contents('php://input'), true) ?: [];
    $relayUid = (string)($input['relay_uid'] ?? '');
    $filename = (string)($input['filename'] ?? '');
    $data = (string)($input['data'] ?? '');
    $recipientName = trim((string)($input['recipient'] ?? $clientTenant['username']));
    if (!$relayUid || !$filename || !$data) jsonResponse(['error' => 'relay_uid, filename, and data required'], 400);

    $recipient = getTenantByUsername($db, $recipientName);
    if (!$recipient) jsonResponse(['error' => "no such user: $recipientName"], 404);

    // Decrypt-reencrypt hop, same shape as messages: arrives encrypted with
    // sender's secret, gets stored at-rest under the inter-tenant key.
    if (empty($clientTenant['secret_encrypted'])) {
        jsonResponse(['error' => 'sender has no client secret set — log into the relay UI and configure one in your account'], 400);
    }
    $senderSecret = masterDecrypt($clientTenant['secret_encrypted'], $MASTER_KEY);
    if (!$senderSecret) jsonResponse(['error' => 'sender secret unavailable'], 500);
    $interKey = getInterTenantKey($db, $MASTER_KEY);
    if (!$interKey) jsonResponse(['error' => 'relay super-shared key not set — admin must complete setup'], 500);

    $plainBytes = clientDecrypt($data, $senderSecret);
    if ($plainBytes === '') jsonResponse(['error' => 'attachment decrypt failed (sender secret mismatch?)'], 400);
    $storedData = clientEncrypt($plainBytes, $interKey);

    $db->prepare('DELETE FROM attachments WHERE recipient_id = :r AND relay_uid = :uid AND filename = :fn')
        ->execute(['r' => $recipient['id'], 'uid' => $relayUid, 'fn' => $filename]);
    $db->prepare('INSERT INTO attachments (recipient_id, relay_uid, filename, data) VALUES (:r, :uid, :fn, :data)')
        ->execute(['r' => $recipient['id'], 'uid' => $relayUid, 'fn' => $filename, 'data' => $storedData]);
    jsonResponse(['ok' => true, 'id' => (int)$db->lastInsertId()]);
}

if ($route === '/api/attachments' && $method === 'GET') {
    if (!$clientTenant) jsonResponse(['error' => 'unauthorized'], 401);
    if (empty($clientTenant['secret_encrypted'])) {
        jsonResponse(['error' => 'no client secret set — log into the relay UI and configure one in your account'], 400);
    }
    $relayUid = $_GET['relay_uid'] ?? '';
    if (!$relayUid) jsonResponse(['error' => 'relay_uid required'], 400);

    $interKey = getInterTenantKey($db, $MASTER_KEY);
    if (!$interKey) jsonResponse(['error' => 'relay super-shared key not set'], 500);
    $recipientSecret = masterDecrypt($clientTenant['secret_encrypted'], $MASTER_KEY);
    if (!$recipientSecret) jsonResponse(['error' => 'recipient secret unavailable'], 500);

    $stmt = $db->prepare('SELECT id, relay_uid, filename, data, created_at FROM attachments WHERE recipient_id = :r AND relay_uid = :uid');
    $stmt->execute(['r' => $clientTenant['id'], 'uid' => $relayUid]);
    $rows = $stmt->fetchAll();

    $out = [];
    foreach ($rows as $row) {
        $plainBytes = clientDecrypt($row['data'] ?? '', $interKey);
        $row['data'] = clientEncrypt($plainBytes, $recipientSecret);
        $out[] = $row;
    }
    jsonResponse($out);
}