<?php
declare(strict_types=1);

header('Content-Type: application/json; charset=utf-8');
header('Cache-Control: no-store');

require __DIR__ . '/im_web_bootstrap.php';

function detailPlaceholders(array $values): string
{
    return implode(',', array_fill(0, count($values), '?'));
}

function detailTimestampMs(?string $datetime, string $messageId = '0'): int
{
    $id = (int)$messageId;
    if ($id > 0) {
        return ($id >> 21) + 1514736000000;
    }

    if ($datetime !== null && $datetime !== '') {
        $date = DateTimeImmutable::createFromFormat(
            'Y-m-d H:i:s',
            $datetime,
            new DateTimeZone(IM_DB_TIMEZONE)
        );
        if ($date instanceof DateTimeImmutable) {
            return $date->getTimestamp() * 1000;
        }
    }

    return 0;
}

function detailResolveUserId(PDO $db, string $value): string
{
    if ($value === '') {
        return '';
    }

    $statement = $db->prepare(
        'select `_uid` from `t_user` where `_uid` = ? or `_mobile` = ? or `_name` = ? limit 1'
    );
    $statement->execute([$value, $value, $value]);
    $uid = $statement->fetchColumn();

    return is_string($uid) && $uid !== '' ? $uid : $value;
}

function detailConversationType(mixed $value): string
{
    $type = strtolower(trim((string)$value));
    return in_array($type, ['1', 'group', 'channel'], true) ? 'group' : 'single';
}

function detailDeliveryMap(PDO $db, array $userIds): array
{
    $userIds = array_values(array_unique(array_filter(array_map('strval', $userIds))));
    if (!$userIds) {
        return [];
    }

    $statement = $db->prepare(
        'select `_uid`, max(`_dt`) as `_dt` from `t_delivery_report`'
        . ' where `_uid` in (' . detailPlaceholders($userIds) . ') group by `_uid`'
    );
    $statement->execute($userIds);

    $items = [];
    foreach ($statement->fetchAll() as $row) {
        $items[(string)$row['_uid']] = (int)$row['_dt'];
    }

    return $items;
}

function detailReadAt(PDO $db, string $readerId, array $targets): int
{
    $targets = array_values(array_unique(array_filter(array_map('strval', $targets))));
    if ($readerId === '' || !$targets) {
        return 0;
    }

    $statement = $db->prepare(
        'select max(`_dt`) from `t_read_report`'
        . ' where `_uid` = ? and `_type` = 0 and `_line` = 0'
        . ' and `_target` in (' . detailPlaceholders($targets) . ')'
    );
    $statement->execute(array_merge([$readerId], $targets));
    $value = $statement->fetchColumn();

    return is_numeric($value) ? (int)$value : 0;
}

function detailSingleMessageVisible(PDO $db, string $userId, string $targetId, string $messageUid): bool
{
    $table = imUserMessagesTable($userId);
    $conversationKeys = [$userId . '|' . $targetId, $targetId . '|' . $userId];
    $statement = $db->prepare(
        'select 1 from `' . $table . '`'
        . ' where `_uid` = ? and `_mid` = ? and `_type` = 0 and `_line` = 0'
        . ' and `_target` in (' . detailPlaceholders($conversationKeys) . ') limit 1'
    );
    $statement->execute(array_merge([$userId, $messageUid], $conversationKeys));

    return (bool)$statement->fetchColumn();
}

function detailUserMap(PDO $imDb, PDO $appDb, array $userIds, string $ownerId, string $groupId = ''): array
{
    $userIds = array_values(array_unique(array_filter(array_map('strval', $userIds))));
    if (!$userIds) {
        return [];
    }

    $statement = $imDb->prepare(
        'select `_uid`, `_name`, `_display_name`, `_mobile`, `_portrait` from `t_user`'
        . ' where `_uid` in (' . detailPlaceholders($userIds) . ')'
    );
    $statement->execute($userIds);

    $users = [];
    foreach ($statement->fetchAll() as $row) {
        $uid = (string)$row['_uid'];
        $rawName = trim((string)($row['_display_name'] ?? ''))
            ?: trim((string)($row['_name'] ?? ''))
            ?: trim((string)($row['_mobile'] ?? ''))
            ?: $uid;
        $users[$uid] = [
            'uid' => $uid,
            'rawName' => $rawName,
            'mobile' => (string)($row['_mobile'] ?? ''),
            'portrait' => (string)($row['_portrait'] ?? ''),
            'contactAlias' => '',
            'remarkAlias' => '',
            'groupAlias' => '',
            'role' => '',
            'displayName' => $rawName,
        ];
    }

    if ($ownerId !== '') {
        $aliasStatement = $imDb->prepare(
            'select `_friend_uid`, `_alias` from `t_friend` where `_uid` = ?'
            . ' and `_friend_uid` in (' . detailPlaceholders($userIds) . ')'
        );
        $aliasStatement->execute(array_merge([$ownerId], $userIds));
        foreach ($aliasStatement->fetchAll() as $row) {
            $uid = (string)$row['_friend_uid'];
            if (isset($users[$uid])) {
                $users[$uid]['contactAlias'] = trim((string)($row['_alias'] ?? ''));
            }
        }

        try {
            $remarkMap = fetchWebUserRemarkMap($appDb, $ownerId, $userIds);
        } catch (Throwable) {
            $remarkMap = [];
        }
        foreach ($remarkMap as $uid => $alias) {
            if (isset($users[$uid])) {
                $users[$uid]['remarkAlias'] = trim((string)$alias);
            }
        }
    }

    if ($groupId !== '') {
        $memberStatement = $appDb->prepare(
            'select `user_id`, `alias`, `role` from `t_web_group_members`'
            . ' where `group_id` = ? and `user_id` in (' . detailPlaceholders($userIds) . ')'
        );
        $memberStatement->execute(array_merge([$groupId], $userIds));
        foreach ($memberStatement->fetchAll() as $row) {
            $uid = (string)$row['user_id'];
            if (isset($users[$uid])) {
                $users[$uid]['groupAlias'] = trim((string)($row['alias'] ?? ''));
                $users[$uid]['role'] = (string)($row['role'] ?? '');
            }
        }
    }

    foreach ($users as $uid => $user) {
        $alias = (string)$user['contactAlias'] !== ''
            ? (string)$user['contactAlias']
            : ((string)$user['remarkAlias'] !== '' ? (string)$user['remarkAlias'] : (string)$user['groupAlias']);
        $users[$uid]['displayName'] = $alias !== '' ? $alias : (string)$user['rawName'];
    }

    foreach ($userIds as $uid) {
        if (!isset($users[$uid])) {
            $users[$uid] = [
                'uid' => $uid,
                'rawName' => $uid,
                'mobile' => '',
                'portrait' => '',
                'contactAlias' => '',
                'remarkAlias' => '',
                'groupAlias' => '',
                'role' => '',
                'displayName' => $uid,
            ];
        }
    }

    return $users;
}

function detailMember(array $user, int $time = 0): array
{
    return [
        'uid' => (string)$user['uid'],
        'name' => (string)$user['displayName'],
        'rawName' => (string)$user['rawName'],
        'mobile' => (string)($user['mobile'] ?? ''),
        'portrait' => (string)($user['portrait'] ?? ''),
        'role' => (string)($user['role'] ?? ''),
        'time' => $time,
    ];
}

function singleDetail(PDO $imDb, string $userId, string $targetId, string $messageUid): array
{
    if (!preg_match('/^\d+$/', $messageUid)) {
        respond(400, '缺少可查询的消息ID');
    }

    $table = imMessageTable($messageUid);
    $statement = $imDb->prepare(
        'select `_mid`, `_from`, `_target`, `_dt`, `_content_type`, `_searchable_key`, `_to`'
        . ' from `' . $table . '` where `_mid` = ? limit 1'
    );
    $statement->execute([$messageUid]);
    $message = $statement->fetch();
    if (!is_array($message)) {
        respond(404, '没有找到该消息');
    }

    $senderId = (string)$message['_from'];
    if (!detailSingleMessageVisible($imDb, $userId, $targetId, $messageUid)) {
        respond(403, '没有权限查看该消息');
    }

    $receiverId = $senderId === $userId ? $targetId : $userId;
    if ($senderId !== $userId && $senderId !== $targetId) {
        respond(403, '没有权限查看该消息');
    }

    $sentAt = detailTimestampMs((string)($message['_dt'] ?? ''), $messageUid);
    $targets = [$senderId, $senderId . '|' . $receiverId, $receiverId . '|' . $senderId];
    $deliveredRaw = detailDeliveryMap($imDb, [$receiverId])[$receiverId] ?? 0;
    $readRaw = detailReadAt($imDb, $receiverId, $targets);
    $users = detailUserMap($imDb, imAppDb(), [$senderId, $receiverId], $userId);

    return [
        'messageUid' => $messageUid,
        'conversationType' => 'single',
        'sentAt' => $sentAt,
        'sender' => detailMember($users[$senderId]),
        'receiver' => detailMember($users[$receiverId]),
        'deliveredAt' => $deliveredRaw >= $sentAt ? $deliveredRaw : 0,
        'readAt' => $readRaw >= $sentAt ? $readRaw : 0,
    ];
}

function groupDetail(PDO $imDb, PDO $appDb, string $userId, string $groupId, string $messageUid): array
{
    ensureWebImAppTables();
    if (!preg_match('/^\d+$/', $messageUid)) {
        respond(400, '缺少可查询的消息ID');
    }

    $myMember = $appDb->prepare(
        'select `role` from `t_web_group_members` where `group_id` = ? and `user_id` = ? and `status` = 0 limit 1'
    );
    $myMember->execute([$groupId, $userId]);
    if (!$myMember->fetchColumn()) {
        respond(403, '你不在该群组中');
    }

    $messageStatement = $appDb->prepare(
        'select `message_uid`, `group_id`, `sender_uid`, `created_at_ms`, `edited_at_ms`, `recalled`'
        . ' from `t_web_group_messages` where `group_id` = ? and `message_uid` = ? limit 1'
    );
    $messageStatement->execute([$groupId, $messageUid]);
    $message = $messageStatement->fetch();
    if (!is_array($message)) {
        respond(404, '没有找到该群消息');
    }

    $sentAt = (int)$message['created_at_ms'];
    $editedAt = (int)($message['edited_at_ms'] ?? 0);
    $activityAt = max($sentAt, $editedAt);
    $senderId = (string)$message['sender_uid'];

    $memberStatement = $appDb->prepare(
        'select `user_id`, `role`, `alias`, `joined_at_ms` from `t_web_group_members`'
        . ' where `group_id` = ? and `status` = 0 and `joined_at_ms` <= ?'
        . ' order by (`role` = "owner") desc, (`role` = "admin") desc, `joined_at_ms` asc'
    );
    $memberStatement->execute([$groupId, $sentAt]);
    $members = array_values(array_filter($memberStatement->fetchAll(), static function (array $member) use ($senderId): bool {
        return (string)$member['user_id'] !== $senderId;
    }));

    $memberIds = array_values(array_unique(array_map(static fn(array $member): string => (string)$member['user_id'], $members)));
    $users = detailUserMap($imDb, $appDb, array_merge([$senderId], $memberIds), $userId, $groupId);
    $deliveryMap = detailDeliveryMap($imDb, $memberIds);

    $readMap = [];
    if ($memberIds) {
        $readStatement = $appDb->prepare(
            'select `user_id`, `read_at_ms` from `t_web_group_reads`'
            . ' where `group_id` = ? and `user_id` in (' . detailPlaceholders($memberIds) . ')'
        );
        $readStatement->execute(array_merge([$groupId], $memberIds));
        foreach ($readStatement->fetchAll() as $row) {
            $readMap[(string)$row['user_id']] = (int)$row['read_at_ms'];
        }
    }

    $read = [];
    $unread = [];
    $undelivered = [];
    foreach ($memberIds as $uid) {
        $readAt = (int)($readMap[$uid] ?? 0);
        $deliveredAt = (int)($deliveryMap[$uid] ?? 0);
        $member = detailMember($users[$uid], $readAt >= $activityAt ? $readAt : ($deliveredAt >= $sentAt ? $deliveredAt : 0));
        if ($readAt >= $activityAt) {
            $read[] = $member;
        } elseif ($deliveredAt >= $sentAt) {
            $unread[] = $member;
        } else {
            $undelivered[] = $member;
        }
    }

    return [
        'messageUid' => $messageUid,
        'conversationType' => 'group',
        'groupId' => $groupId,
        'sentAt' => $sentAt,
        'editedAt' => $editedAt,
        'recalled' => (bool)$message['recalled'],
        'sender' => detailMember($users[$senderId] ?? ['uid' => $senderId, 'displayName' => $senderId, 'rawName' => $senderId]),
        'group' => [
            'read' => $read,
            'unread' => $unread,
            'undelivered' => $undelivered,
            'counts' => [
                'read' => count($read),
                'unread' => count($unread),
                'undelivered' => count($undelivered),
                'total' => count($memberIds),
            ],
        ],
    ];
}

$payload = readJsonPayload();
$userId = trim((string)($payload['userId'] ?? ''));
$target = trim((string)($payload['target'] ?? ''));
$messageUid = trim((string)($payload['messageUid'] ?? $payload['messageId'] ?? ''));
$conversationType = detailConversationType($payload['conversationType'] ?? $payload['type'] ?? 'single');

if ($userId === '') {
    respond(400, '缺少用户ID');
}
if ($target === '') {
    respond(400, '缺少会话对象');
}
if ($messageUid === '') {
    respond(400, '缺少消息ID');
}

try {
    $imDb = imDb();
    $appDb = imAppDb();
    $userId = detailResolveUserId($imDb, $userId);
    if ($conversationType === 'group') {
        respond(0, 'success', ['detail' => groupDetail($imDb, $appDb, $userId, $target, $messageUid)]);
    }

    $targetId = detailResolveUserId($imDb, $target);
    respond(0, 'success', ['detail' => singleDetail($imDb, $userId, $targetId, $messageUid)]);
} catch (Throwable $error) {
    respond(500, $error->getMessage() ?: '消息详情加载失败');
}