-- =====================================================
-- 消息系统完整权限策略配置
-- 配合 supabase_auth_complete_setup.sql 使用
-- =====================================================

-- 清理所有现有权限策略
DO $$
DECLARE
    r RECORD;
BEGIN
    -- 删除所有消息相关表的策略
    FOR r IN 
        SELECT schemaname, tablename, policyname 
        FROM pg_policies 
        WHERE schemaname = 'public' 
        AND tablename IN ('ak_messages', 'ak_message_recipients', 'ak_message_groups', 
                         'ak_message_group_members', 'ak_message_templates', 
                         'ak_user_message_preferences', 'ak_message_stats', 'ak_message_types')
    LOOP
        EXECUTE format('DROP POLICY IF EXISTS %I ON %I.%I', 
                      r.policyname, r.schemaname, r.tablename);
    END LOOP;
    
    RAISE NOTICE '🧹 已清理所有现有权限策略';
END $$;

-- 启用行级安全策略
ALTER TABLE public.ak_message_types ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.ak_messages ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.ak_message_recipients ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.ak_message_groups ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.ak_message_group_members ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.ak_message_templates ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.ak_user_message_preferences ENABLE ROW LEVEL SECURITY;
ALTER TABLE public.ak_message_stats ENABLE ROW LEVEL SECURITY;

-- =====================================================
-- 1. 消息类型权限策略 (ak_message_types)
-- =====================================================

-- 所有认证用户可以查看消息类型
CREATE POLICY "authenticated_users_can_view_message_types" ON public.ak_message_types
    FOR SELECT USING (
        auth.role() = 'authenticated'
    );

-- 管理员和教师可以管理消息类型
CREATE POLICY "admins_teachers_can_manage_message_types" ON public.ak_message_types
    FOR ALL USING (
        public.get_user_role(auth.uid()) IN ('admin', 'teacher')
    );

-- =====================================================
-- 2. 消息主表权限策略 (ak_messages)
-- =====================================================

-- 用户可以查看相关的消息
CREATE POLICY "users_can_view_relevant_messages" ON public.ak_messages
    FOR SELECT USING (
        -- 管理员可以查看所有消息
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 用户是发送者
        (sender_type = 'user' AND sender_id = auth.uid()) 
        OR
        -- 用户是接收者（单用户消息）
        (receiver_type = 'user' AND receiver_id = auth.uid())
        OR
        -- 群组消息（检查是否为群组成员）
        (receiver_type = 'group' AND receiver_id IN (
            SELECT group_id FROM public.ak_message_group_members 
            WHERE user_id = auth.uid() AND status = 'active'
        ))
        OR
        -- 广播消息所有人可见
        (receiver_type = 'broadcast')
        OR
        -- 教师可以查看学生发送的消息（如果在同一个班级）
        (public.get_user_role(auth.uid()) = 'teacher' 
         AND sender_type = 'user' 
         AND EXISTS (
             SELECT 1 FROM public.user_roles teacher_role
             JOIN public.user_roles student_role ON teacher_role.class_id = student_role.class_id
             WHERE teacher_role.user_id = auth.uid() 
             AND teacher_role.role = 'teacher'
             AND student_role.user_id = sender_id
             AND student_role.role = 'student'
             AND teacher_role.class_id IS NOT NULL
         ))
    );

-- 用户可以发送消息
CREATE POLICY "users_can_send_messages" ON public.ak_messages
    FOR INSERT WITH CHECK (
        -- 认证用户可以以自己的身份发送消息
        (auth.role() = 'authenticated' AND sender_type = 'user' AND sender_id = auth.uid())
        OR
        -- 管理员可以发送系统消息
        (public.get_user_role(auth.uid()) = 'admin' AND sender_type = 'system')
        OR
        -- 教师可以发送广播消息（如果有权限）
        (public.get_user_role(auth.uid()) = 'teacher' 
         AND receiver_type = 'broadcast'
         AND public.user_has_permission('can_send_broadcasts', auth.uid()))
    );

-- 用户可以更新自己发送的消息
CREATE POLICY "users_can_update_own_messages" ON public.ak_messages
    FOR UPDATE USING (
        -- 管理员可以更新所有消息
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 用户可以更新自己发送的消息
        (sender_type = 'user' AND sender_id = auth.uid())
        OR
        -- 教师可以更新发送给自己班级的消息
        (public.get_user_role(auth.uid()) = 'teacher' 
         AND public.user_has_permission('can_moderate', auth.uid())
         AND receiver_type = 'group'
         AND receiver_id IN (
             SELECT group_id FROM public.ak_message_group_members mgm
             JOIN public.user_roles ur ON ur.user_id = mgm.user_id
             WHERE mgm.user_id = auth.uid() AND ur.role = 'teacher'
         ))
    );

-- 用户可以删除自己发送的消息
CREATE POLICY "users_can_delete_own_messages" ON public.ak_messages
    FOR DELETE USING (
        -- 管理员可以删除所有消息
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 用户可以删除自己发送的消息
        (sender_type = 'user' AND sender_id = auth.uid())
        OR
        -- 教师可以删除不当消息（如果有权限）
        (public.get_user_role(auth.uid()) = 'teacher' 
         AND public.user_has_permission('can_moderate', auth.uid()))
    );

-- =====================================================
-- 3. 消息接收者权限策略 (ak_message_recipients)
-- =====================================================

-- 用户可以查看自己的接收记录
CREATE POLICY "users_can_view_own_recipients" ON public.ak_message_recipients
    FOR SELECT USING (
        -- 管理员可以查看所有记录
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 用户可以查看自己的接收记录
        user_id = auth.uid()
        OR
        -- 发送者可以查看接收状态
        message_id IN (
            SELECT id FROM public.ak_messages 
            WHERE sender_type = 'user' AND sender_id = auth.uid()
        )
        OR
        -- 教师可以查看学生的接收状态（同班级）
        (public.get_user_role(auth.uid()) = 'teacher' 
         AND user_id IN (
             SELECT student_role.user_id FROM public.user_roles teacher_role
             JOIN public.user_roles student_role ON teacher_role.class_id = student_role.class_id
             WHERE teacher_role.user_id = auth.uid() 
             AND teacher_role.role = 'teacher'
             AND student_role.role = 'student'
             AND teacher_role.class_id IS NOT NULL
         ))
    );

-- 系统自动创建接收记录
CREATE POLICY "system_can_create_recipients" ON public.ak_message_recipients
    FOR INSERT WITH CHECK (
        -- 管理员可以创建记录
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 消息发送者可以创建接收记录
        message_id IN (
            SELECT id FROM public.ak_messages 
            WHERE sender_type = 'user' AND sender_id = auth.uid()
        )
        OR
        -- 用户可以为自己创建接收记录
        user_id = auth.uid()
    );

-- 用户可以更新自己的接收状态
CREATE POLICY "users_can_update_own_recipients" ON public.ak_message_recipients
    FOR UPDATE USING (
        user_id = auth.uid()
        OR
        public.get_user_role(auth.uid()) = 'admin'
    );

-- =====================================================
-- 4. 消息群组权限策略 (ak_message_groups)
-- =====================================================

-- 用户可以查看相关的群组
CREATE POLICY "users_can_view_relevant_groups" ON public.ak_message_groups
    FOR SELECT USING (
        -- 管理员可以查看所有群组
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 群组创建者可以查看
        created_by = auth.uid()
        OR
        -- 群组成员可以查看
        id IN (
            SELECT group_id FROM public.ak_message_group_members 
            WHERE user_id = auth.uid() AND status = 'active'
        )
        OR
        -- 教师可以查看公开群组
        (public.get_user_role(auth.uid()) = 'teacher' AND is_public = true)
    );

-- 用户可以创建群组
CREATE POLICY "users_can_create_groups" ON public.ak_message_groups
    FOR INSERT WITH CHECK (
        -- 认证用户可以创建群组
        auth.role() = 'authenticated' AND created_by = auth.uid()
        AND (
            -- 教师默认可以创建群组
            public.get_user_role(auth.uid()) = 'teacher'
            OR
            -- 学生需要特定权限
            (public.get_user_role(auth.uid()) = 'student' 
             AND public.user_has_permission('can_create_groups', auth.uid()))
            OR
            -- 管理员可以创建群组
            public.get_user_role(auth.uid()) = 'admin'
        )
    );

-- 群组创建者和管理员可以更新群组
CREATE POLICY "creators_admins_can_update_groups" ON public.ak_message_groups
    FOR UPDATE USING (
        created_by = auth.uid()
        OR
        public.get_user_role(auth.uid()) = 'admin'
    );

-- 群组创建者和管理员可以删除群组
CREATE POLICY "creators_admins_can_delete_groups" ON public.ak_message_groups
    FOR DELETE USING (
        created_by = auth.uid()
        OR
        public.get_user_role(auth.uid()) = 'admin'
    );

-- =====================================================
-- 5. 群组成员权限策略 (ak_message_group_members)
-- =====================================================

-- 用户可以查看相关的群组成员
CREATE POLICY "users_can_view_relevant_group_members" ON public.ak_message_group_members
    FOR SELECT USING (
        -- 管理员可以查看所有成员
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 用户可以查看自己的成员关系
        user_id = auth.uid()
        OR
        -- 群组成员可以查看同群组的其他成员
        group_id IN (
            SELECT group_id FROM public.ak_message_group_members 
            WHERE user_id = auth.uid() AND status = 'active'
        )
        OR
        -- 群组创建者可以查看所有成员
        group_id IN (
            SELECT id FROM public.ak_message_groups 
            WHERE created_by = auth.uid()
        )
    );

-- 群组创建者和管理员可以添加成员
CREATE POLICY "creators_admins_can_add_members" ON public.ak_message_group_members
    FOR INSERT WITH CHECK (
        -- 管理员可以添加成员
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 群组创建者可以添加成员
        group_id IN (
            SELECT id FROM public.ak_message_groups 
            WHERE created_by = auth.uid()
        )
        OR
        -- 用户可以申请加入群组（pending状态）
        (user_id = auth.uid() AND status = 'pending')
    );

-- 群组创建者、管理员和用户本人可以更新成员状态
CREATE POLICY "authorized_users_can_update_members" ON public.ak_message_group_members
    FOR UPDATE USING (
        -- 管理员可以更新所有成员
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 群组创建者可以更新成员
        group_id IN (
            SELECT id FROM public.ak_message_groups 
            WHERE created_by = auth.uid()
        )
        OR
        -- 用户可以更新自己的成员状态（如退出群组）
        user_id = auth.uid()
    );

-- 群组创建者、管理员和用户本人可以删除成员
CREATE POLICY "authorized_users_can_remove_members" ON public.ak_message_group_members
    FOR DELETE USING (
        -- 管理员可以删除所有成员
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 群组创建者可以删除成员
        group_id IN (
            SELECT id FROM public.ak_message_groups 
            WHERE created_by = auth.uid()
        )
        OR
        -- 用户可以删除自己的成员关系
        user_id = auth.uid()
    );

-- =====================================================
-- 6. 消息模板权限策略 (ak_message_templates)
-- =====================================================

-- 用户可以查看相关的消息模板
CREATE POLICY "users_can_view_relevant_templates" ON public.ak_message_templates
    FOR SELECT USING (
        -- 管理员可以查看所有模板
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 用户可以查看自己创建的模板
        created_by = auth.uid()
        OR
        -- 用户可以查看公开模板
        is_public = true
        OR
        -- 教师可以查看教师模板
        (public.get_user_role(auth.uid()) = 'teacher' AND category = 'teacher')
    );

-- 用户可以创建模板
CREATE POLICY "users_can_create_templates" ON public.ak_message_templates
    FOR INSERT WITH CHECK (
        auth.role() = 'authenticated' AND created_by = auth.uid()
    );

-- 用户可以更新自己的模板
CREATE POLICY "users_can_update_own_templates" ON public.ak_message_templates
    FOR UPDATE USING (
        created_by = auth.uid()
        OR
        public.get_user_role(auth.uid()) = 'admin'
    );

-- 用户可以删除自己的模板
CREATE POLICY "users_can_delete_own_templates" ON public.ak_message_templates
    FOR DELETE USING (
        created_by = auth.uid()
        OR
        public.get_user_role(auth.uid()) = 'admin'
    );

-- =====================================================
-- 7. 用户偏好权限策略 (ak_user_message_preferences)
-- =====================================================

-- 用户可以查看和管理自己的偏好
CREATE POLICY "users_can_manage_own_preferences" ON public.ak_user_message_preferences
    FOR ALL USING (
        user_id = auth.uid()
        OR
        public.get_user_role(auth.uid()) = 'admin'
    );

-- =====================================================
-- 8. 消息统计权限策略 (ak_message_stats)
-- =====================================================

-- 用户可以查看相关的统计信息
CREATE POLICY "users_can_view_relevant_stats" ON public.ak_message_stats
    FOR SELECT USING (
        -- 管理员可以查看所有统计
        public.get_user_role(auth.uid()) = 'admin'
        OR
        -- 用户可以查看自己相关的统计
        (entity_type = 'user' AND entity_id = auth.uid())
        OR
        -- 群组成员可以查看群组统计
        (entity_type = 'group' AND entity_id IN (
            SELECT group_id FROM public.ak_message_group_members 
            WHERE user_id = auth.uid() AND status = 'active'
        ))
        OR
        -- 教师可以查看班级统计
        (entity_type = 'class' AND public.get_user_role(auth.uid()) = 'teacher'
         AND entity_id IN (
             SELECT class_id FROM public.user_roles 
             WHERE user_id = auth.uid() AND role = 'teacher'
         ))
    );

-- 系统和管理员可以更新统计
CREATE POLICY "system_can_update_stats" ON public.ak_message_stats
    FOR ALL USING (
        public.get_user_role(auth.uid()) = 'admin'
    );

-- =====================================================
-- 9. 安全函数和辅助策略
-- =====================================================

-- 创建安全的消息发送函数
CREATE OR REPLACE FUNCTION public.send_secure_message(
    message_type_id UUID,
    receiver_type TEXT,
    receiver_id UUID,
    title TEXT,
    content TEXT,
    metadata_json JSONB DEFAULT '{}'::jsonb
)
RETURNS UUID AS $$
DECLARE
    new_message_id UUID;
    sender_role TEXT;
BEGIN
    -- 检查发送者角色
    sender_role := public.get_user_role(auth.uid());
    
    -- 权限检查
    IF sender_role IS NULL OR sender_role = 'anonymous' THEN
        RAISE EXCEPTION 'Authentication required to send messages';
    END IF;
    
    -- 检查广播权限
    IF receiver_type = 'broadcast' AND NOT public.user_has_permission('can_send_broadcasts', auth.uid()) THEN
        RAISE EXCEPTION 'Permission denied: Cannot send broadcast messages';
    END IF;
    
    -- 插入消息
    INSERT INTO public.ak_messages (
        message_type_id, sender_type, sender_id, receiver_type, receiver_id,
        title, content, metadata, created_by
    ) VALUES (
        message_type_id, 'user', auth.uid(), receiver_type, receiver_id,
        title, content, metadata_json, auth.uid()
    ) RETURNING id INTO new_message_id;
    
    RETURN new_message_id;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

-- 创建安全的群组加入函数
CREATE OR REPLACE FUNCTION public.join_message_group(
    target_group_id UUID,
    join_message TEXT DEFAULT NULL
)
RETURNS BOOLEAN AS $$
DECLARE
    group_info RECORD;
    user_role TEXT;
BEGIN
    -- 获取群组信息
    SELECT * INTO group_info FROM public.ak_message_groups WHERE id = target_group_id;
    
    IF NOT FOUND THEN
        RAISE EXCEPTION 'Group not found';
    END IF;
    
    user_role := public.get_user_role(auth.uid());
    
    -- 检查加入权限
    IF NOT group_info.is_public AND group_info.created_by != auth.uid() 
       AND user_role != 'admin' THEN
        -- 非公开群组需要申请
        INSERT INTO public.ak_message_group_members (group_id, user_id, status, joined_at)
        VALUES (target_group_id, auth.uid(), 'pending', NOW())
        ON CONFLICT (group_id, user_id) DO UPDATE SET
            status = 'pending',
            updated_at = NOW();
        RETURN false; -- 返回false表示需要审批
    ELSE
        -- 公开群组或有权限直接加入
        INSERT INTO public.ak_message_group_members (group_id, user_id, status, joined_at)
        VALUES (target_group_id, auth.uid(), 'active', NOW())
        ON CONFLICT (group_id, user_id) DO UPDATE SET
            status = 'active',
            joined_at = NOW(),
            updated_at = NOW();
        RETURN true; -- 返回true表示成功加入
    END IF;
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

-- =====================================================
-- 10. 权限验证和测试查询
-- =====================================================

-- 创建权限测试函数
CREATE OR REPLACE FUNCTION public.test_message_permissions(test_user_id UUID)
RETURNS TABLE(
    test_name TEXT,
    permission_check TEXT,
    result BOOLEAN,
    details TEXT
) AS $$
BEGIN
    -- 测试角色获取
    RETURN QUERY SELECT 
        'Role Check'::TEXT,
        'get_user_role'::TEXT,
        (public.get_user_role(test_user_id) IS NOT NULL),
        format('User role: %s', public.get_user_role(test_user_id));
    
    -- 测试发送消息权限
    RETURN QUERY SELECT 
        'Send Message Permission'::TEXT,
        'user_has_permission'::TEXT,
        public.user_has_permission('send_message', test_user_id),
        format('Can send messages: %s', public.user_has_permission('send_message', test_user_id));
    
    -- 测试创建群组权限
    RETURN QUERY SELECT 
        'Create Group Permission'::TEXT,
        'user_has_permission'::TEXT,
        public.user_has_permission('create_group', test_user_id),
        format('Can create groups: %s', public.user_has_permission('create_group', test_user_id));
    
    -- 测试消息访问权限（检查用户能访问的消息数量）
    RETURN QUERY SELECT 
        'Message Access Count'::TEXT,
        'message_access'::TEXT,
        true,
        format('Accessible messages: %s', (
            SELECT COUNT(*) FROM public.ak_messages
            WHERE (sender_type = 'user' AND sender_id = test_user_id)
               OR (receiver_type = 'user' AND receiver_id = test_user_id)
               OR receiver_type = 'broadcast'
        ));
END;
$$ LANGUAGE plpgsql SECURITY DEFINER;

-- =====================================================
-- 完成消息和使用示例
-- =====================================================

/*
-- 测试权限系统
SELECT * FROM public.test_message_permissions('7bf7378e-a027-473e-97ac-3460ed3f170a');
SELECT * FROM public.test_message_permissions('eed3824b-bba1-4309-8048-19d17367c084');

-- 发送安全消息示例
SELECT public.send_secure_message(
    (SELECT id FROM public.ak_message_types WHERE type_name = 'announcement' LIMIT 1),
    'user',
    'eed3824b-bba1-4309-8048-19d17367c084',
    'Test Message',
    'This is a test message',
    '{"priority": "normal"}'::jsonb
);

-- 加入群组示例
SELECT public.join_message_group(
    (SELECT id FROM public.ak_message_groups LIMIT 1),
    'I would like to join this group'
);

-- 检查用户可访问的消息
SELECT m.id, m.title, m.created_at
FROM public.ak_messages m
WHERE (
    -- 用户相关的消息
    (m.sender_type = 'user' AND m.sender_id = auth.uid())
    OR (m.receiver_type = 'user' AND m.receiver_id = auth.uid())
    OR (m.receiver_type = 'broadcast')
    OR (m.receiver_type = 'group' AND m.receiver_id IN (
        SELECT group_id FROM public.ak_message_group_members
        WHERE user_id = auth.uid() AND status = 'active'
    ))
)
ORDER BY m.created_at DESC
LIMIT 10;
*/

-- 完成提示
SELECT 
    '✅ 消息系统权限策略配置完成' as status,
    (SELECT COUNT(*) FROM pg_policies WHERE schemaname = 'public' 
     AND tablename LIKE 'ak_%') as total_policies,
    'RLS已启用，权限控制已生效' as message;