from fastapi import APIRouter, Depends, Query
from app.core.auth import get_current_admin_user, get_current_user
from app.core.response import create_api_response
from app.core.database import get_db_connection
from app.models.models import (
    MenuInfo,
    MenuListResponse,
    RolePermissionInfo,
    UpdateRolePermissionsRequest,
    RoleInfo,
    CreateMenuRequest,
    UpdateMenuRequest,
    CreateRoleRequest,
    UpdateRoleRequest,
)
from typing import List
import time

router = APIRouter()
_USER_MENU_CACHE_TTL_SECONDS = 120
_USER_MENU_CACHE_VERSION = "menu-rules-v4"
_user_menu_cache_by_role = {}


def _get_cached_user_menus(role_id: int):
    cached = _user_menu_cache_by_role.get(role_id)
    if not cached:
        return None
    if cached.get("version") != _USER_MENU_CACHE_VERSION:
        _user_menu_cache_by_role.pop(role_id, None)
        return None
    if time.time() > cached["expires_at"]:
        _user_menu_cache_by_role.pop(role_id, None)
        return None
    return cached["menus"]


def _set_cached_user_menus(role_id: int, menus):
    _user_menu_cache_by_role[role_id] = {
        "version": _USER_MENU_CACHE_VERSION,
        "menus": menus,
        "expires_at": time.time() + _USER_MENU_CACHE_TTL_SECONDS,
    }


def _invalidate_user_menu_cache(role_id: int | None = None):
    if role_id is None:
        _user_menu_cache_by_role.clear()
        return
    _user_menu_cache_by_role.pop(role_id, None)


def _build_menu_index(menus):
    menu_by_id = {}
    children_by_parent = {}
    for menu in menus:
        menu_id = menu["menu_id"]
        menu_by_id[menu_id] = menu
        parent_id = menu.get("parent_id")
        if parent_id is not None:
            children_by_parent.setdefault(parent_id, []).append(menu_id)
    return menu_by_id, children_by_parent


def _get_descendants(menu_id, children_by_parent):
    result = set()
    stack = [menu_id]
    while stack:
        current = stack.pop()
        for child_id in children_by_parent.get(current, []):
            if child_id in result:
                continue
            result.add(child_id)
            stack.append(child_id)
    return result


def _normalize_permission_menu_ids(raw_menu_ids, all_menus):
    """
    对权限菜单ID做归一化：
    1. 选中父节点 => 自动包含全部子孙节点
    2. 选中子节点 => 自动包含全部祖先节点
    """
    menu_by_id, children_by_parent = _build_menu_index(all_menus)
    selected = {menu_id for menu_id in raw_menu_ids if menu_id in menu_by_id}

    expanded = set(selected)

    # 父 -> 子孙
    for menu_id in list(expanded):
        expanded.update(_get_descendants(menu_id, children_by_parent))

    # 子 -> 祖先
    for menu_id in list(expanded):
        cursor = menu_by_id[menu_id].get("parent_id")
        while cursor is not None and cursor in menu_by_id:
            if cursor in expanded:
                break
            expanded.add(cursor)
            cursor = menu_by_id[cursor].get("parent_id")

    return sorted(expanded)

# ========== 菜单权限管理接口 ==========

@router.get("/admin/menus")
async def get_all_menus(current_user=Depends(get_current_admin_user)):
    """
    获取所有菜单列表
    只有管理员才能访问
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)
            query = """
                SELECT menu_id, menu_code, menu_name, menu_icon, menu_url, menu_type,
                       parent_id, sort_order, is_active, description, created_at, updated_at
                FROM sys_menus
                ORDER BY
                  COALESCE(parent_id, menu_id) ASC,
                  CASE WHEN parent_id IS NULL THEN 0 ELSE 1 END ASC,
                  sort_order ASC,
                  menu_id ASC
            """
            cursor.execute(query)
            menus = cursor.fetchall()

            menu_list = [MenuInfo(**menu) for menu in menus]

            return create_api_response(
                code="200",
                message="获取菜单列表成功",
                data=MenuListResponse(menus=menu_list, total=len(menu_list))
            )
    except Exception as e:
        return create_api_response(code="500", message=f"获取菜单列表失败: {str(e)}")


@router.post("/admin/menus")
async def create_menu(request: CreateMenuRequest, current_user=Depends(get_current_admin_user)):
    """
    创建菜单
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)

            cursor.execute("SELECT menu_id FROM sys_menus WHERE menu_code = %s", (request.menu_code,))
            if cursor.fetchone():
                return create_api_response(code="400", message="菜单编码已存在")

            if request.parent_id is not None:
                cursor.execute("SELECT menu_id FROM sys_menus WHERE menu_id = %s", (request.parent_id,))
                if not cursor.fetchone():
                    return create_api_response(code="400", message="父菜单不存在")

            cursor.execute(
                """
                INSERT INTO sys_menus (menu_code, menu_name, menu_icon, menu_url, menu_type, parent_id, sort_order, is_active, description)
                VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s)
                """,
                (
                    request.menu_code,
                    request.menu_name,
                    request.menu_icon,
                    request.menu_url,
                    request.menu_type,
                    request.parent_id,
                    request.sort_order,
                    1 if request.is_active else 0,
                    request.description,
                ),
            )
            menu_id = cursor.lastrowid
            connection.commit()
            _invalidate_user_menu_cache()

            cursor.execute(
                """
                SELECT menu_id, menu_code, menu_name, menu_icon, menu_url, menu_type,
                       parent_id, sort_order, is_active, description, created_at, updated_at
                FROM sys_menus
                WHERE menu_id = %s
                """,
                (menu_id,),
            )
            created = cursor.fetchone()
            return create_api_response(code="200", message="创建菜单成功", data=created)
    except Exception as e:
        return create_api_response(code="500", message=f"创建菜单失败: {str(e)}")


@router.put("/admin/menus/{menu_id}")
async def update_menu(menu_id: int, request: UpdateMenuRequest, current_user=Depends(get_current_admin_user)):
    """
    更新菜单
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)

            cursor.execute("SELECT * FROM sys_menus WHERE menu_id = %s", (menu_id,))
            current = cursor.fetchone()
            if not current:
                return create_api_response(code="404", message="菜单不存在")

            updates = {}
            for field in [
                "menu_code",
                "menu_name",
                "menu_icon",
                "menu_url",
                "menu_type",
                "sort_order",
                "description",
            ]:
                value = getattr(request, field)
                if value is not None:
                    updates[field] = value

            if request.is_active is not None:
                updates["is_active"] = 1 if request.is_active else 0

            fields_set = getattr(request, "model_fields_set", getattr(request, "__fields_set__", set()))

            # parent_id 允许设为 null，且不允许设为自己
            if request.parent_id == menu_id:
                return create_api_response(code="400", message="父菜单不能为自身")
            if request.parent_id is not None:
                cursor.execute("SELECT menu_id FROM sys_menus WHERE menu_id = %s", (request.parent_id,))
                if not cursor.fetchone():
                    return create_api_response(code="400", message="父菜单不存在")

                # 防止形成环：父菜单不能是当前菜单的子孙
                cursor.execute("SELECT menu_id, parent_id FROM sys_menus")
                all_menus = cursor.fetchall()
                _, children_by_parent = _build_menu_index(all_menus)
                descendants = _get_descendants(menu_id, children_by_parent)
                if request.parent_id in descendants:
                    return create_api_response(code="400", message="父菜单不能设置为当前菜单的子孙菜单")

            if request.parent_id is not None or (request.parent_id is None and "parent_id" in fields_set):
                updates["parent_id"] = request.parent_id

            if "menu_code" in updates:
                cursor.execute(
                    "SELECT menu_id FROM sys_menus WHERE menu_code = %s AND menu_id != %s",
                    (updates["menu_code"], menu_id),
                )
                if cursor.fetchone():
                    return create_api_response(code="400", message="菜单编码已存在")

            if not updates:
                return create_api_response(code="200", message="没有变更内容", data=current)

            set_sql = ", ".join([f"{k} = %s" for k in updates.keys()])
            values = list(updates.values()) + [menu_id]
            cursor.execute(f"UPDATE sys_menus SET {set_sql} WHERE menu_id = %s", tuple(values))
            connection.commit()
            _invalidate_user_menu_cache()

            cursor.execute(
                """
                SELECT menu_id, menu_code, menu_name, menu_icon, menu_url, menu_type,
                       parent_id, sort_order, is_active, description, created_at, updated_at
                FROM sys_menus
                WHERE menu_id = %s
                """,
                (menu_id,),
            )
            updated = cursor.fetchone()
            return create_api_response(code="200", message="更新菜单成功", data=updated)
    except Exception as e:
        return create_api_response(code="500", message=f"更新菜单失败: {str(e)}")


@router.delete("/admin/menus/{menu_id}")
async def delete_menu(menu_id: int, current_user=Depends(get_current_admin_user)):
    """
    删除菜单（有子菜单时不允许删除）
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)

            cursor.execute("SELECT menu_id FROM sys_menus WHERE menu_id = %s", (menu_id,))
            if not cursor.fetchone():
                return create_api_response(code="404", message="菜单不存在")

            cursor.execute("SELECT COUNT(*) AS cnt FROM sys_menus WHERE parent_id = %s", (menu_id,))
            child_count = cursor.fetchone()["cnt"]
            if child_count > 0:
                return create_api_response(code="400", message="请先删除子菜单")

            cursor.execute("DELETE FROM sys_role_menu_permissions WHERE menu_id = %s", (menu_id,))
            cursor.execute("DELETE FROM sys_menus WHERE menu_id = %s", (menu_id,))
            connection.commit()
            _invalidate_user_menu_cache()
            return create_api_response(code="200", message="删除菜单成功")
    except Exception as e:
        return create_api_response(code="500", message=f"删除菜单失败: {str(e)}")

@router.get("/admin/roles")
async def get_all_roles(current_user=Depends(get_current_admin_user)):
    """
    获取所有角色列表及其权限统计
    只有管理员才能访问
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)

            # 查询所有角色及其权限数量
            query = """
                SELECT r.role_id, r.role_name, r.created_at,
                       COUNT(rmp.menu_id) as menu_count
                FROM sys_roles r
                LEFT JOIN sys_role_menu_permissions rmp ON r.role_id = rmp.role_id
                GROUP BY r.role_id
                ORDER BY r.role_id ASC
            """
            cursor.execute(query)
            roles = cursor.fetchall()

            return create_api_response(
                code="200",
                message="获取角色列表成功",
                data={"roles": roles, "total": len(roles)}
            )
    except Exception as e:
        return create_api_response(code="500", message=f"获取角色列表失败: {str(e)}")


@router.post("/admin/roles")
async def create_role(request: CreateRoleRequest, current_user=Depends(get_current_admin_user)):
    """
    创建角色
    """
    try:
        role_name = request.role_name.strip()
        if not role_name:
            return create_api_response(code="400", message="角色名称不能为空")

        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)
            cursor.execute("SELECT role_id FROM sys_roles WHERE role_name = %s", (role_name,))
            if cursor.fetchone():
                return create_api_response(code="400", message="角色名称已存在")

            cursor.execute("INSERT INTO sys_roles (role_name) VALUES (%s)", (role_name,))
            role_id = cursor.lastrowid
            connection.commit()

            cursor.execute("SELECT role_id, role_name, created_at FROM sys_roles WHERE role_id = %s", (role_id,))
            role = cursor.fetchone()
            return create_api_response(code="200", message="创建角色成功", data=role)
    except Exception as e:
        return create_api_response(code="500", message=f"创建角色失败: {str(e)}")


@router.put("/admin/roles/{role_id}")
async def update_role(role_id: int, request: UpdateRoleRequest, current_user=Depends(get_current_admin_user)):
    """
    更新角色
    """
    try:
        role_name = request.role_name.strip()
        if not role_name:
            return create_api_response(code="400", message="角色名称不能为空")

        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)
            cursor.execute("SELECT role_id FROM sys_roles WHERE role_id = %s", (role_id,))
            if not cursor.fetchone():
                return create_api_response(code="404", message="角色不存在")

            cursor.execute("SELECT role_id FROM sys_roles WHERE role_name = %s AND role_id != %s", (role_name, role_id))
            if cursor.fetchone():
                return create_api_response(code="400", message="角色名称已存在")

            cursor.execute("UPDATE sys_roles SET role_name = %s WHERE role_id = %s", (role_name, role_id))
            connection.commit()

            cursor.execute("SELECT role_id, role_name, created_at FROM sys_roles WHERE role_id = %s", (role_id,))
            role = cursor.fetchone()
            return create_api_response(code="200", message="更新角色成功", data=role)
    except Exception as e:
        return create_api_response(code="500", message=f"更新角色失败: {str(e)}")


@router.get("/admin/roles/{role_id}/users")
async def get_role_users(
    role_id: int,
    page: int = Query(1, ge=1),
    size: int = Query(10, ge=1, le=100),
    current_user=Depends(get_current_admin_user),
):
    """
    获取角色下用户列表
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)
            cursor.execute("SELECT role_id, role_name FROM sys_roles WHERE role_id = %s", (role_id,))
            role = cursor.fetchone()
            if not role:
                return create_api_response(code="404", message="角色不存在")

            cursor.execute(
                """
                SELECT COUNT(*) AS total
                FROM sys_users
                WHERE role_id = %s
                """,
                (role_id,),
            )
            total = cursor.fetchone()["total"]
            offset = (page - 1) * size

            cursor.execute(
                """
                SELECT user_id, username, caption, email, avatar_url, role_id, created_at
                FROM sys_users
                WHERE role_id = %s
                ORDER BY user_id ASC
                LIMIT %s OFFSET %s
                """,
                (role_id, size, offset),
            )
            users = cursor.fetchall()
            return create_api_response(
                code="200",
                message="获取角色用户成功",
                data={
                    "role_id": role_id,
                    "role_name": role["role_name"],
                    "users": users,
                    "total": total,
                    "page": page,
                    "size": size,
                },
            )
    except Exception as e:
        return create_api_response(code="500", message=f"获取角色用户失败: {str(e)}")


@router.get("/admin/roles/permissions/all")
async def get_all_role_permissions(current_user=Depends(get_current_admin_user)):
    """
    批量获取所有角色权限（用于减少N次请求）
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)
            cursor.execute(
                """
                SELECT rmp.role_id, rmp.menu_id
                FROM sys_role_menu_permissions rmp
                JOIN sys_menus m ON m.menu_id = rmp.menu_id
                WHERE m.is_active = 1
                ORDER BY rmp.role_id ASC, rmp.menu_id ASC
                """
            )
            rows = cursor.fetchall()

            result = {}
            for row in rows:
                result.setdefault(row["role_id"], []).append(row["menu_id"])
            return create_api_response(code="200", message="获取角色权限成功", data={"permissions": result})
    except Exception as e:
        return create_api_response(code="500", message=f"获取角色权限失败: {str(e)}")

@router.get("/admin/roles/{role_id}/permissions")
async def get_role_permissions(role_id: int, current_user=Depends(get_current_admin_user)):
    """
    获取指定角色的菜单权限
    只有管理员才能访问
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)

            # 检查角色是否存在
            cursor.execute("SELECT role_id, role_name FROM sys_roles WHERE role_id = %s", (role_id,))
            role = cursor.fetchone()
            if not role:
                return create_api_response(code="404", message="角色不存在")

            # 查询该角色的所有菜单权限
            query = """
                SELECT rmp.menu_id
                FROM sys_role_menu_permissions rmp
                JOIN sys_menus m ON m.menu_id = rmp.menu_id
                WHERE rmp.role_id = %s
                  AND m.is_active = 1
            """
            cursor.execute(query, (role_id,))
            permissions = cursor.fetchall()

            menu_ids = [p['menu_id'] for p in permissions]

            return create_api_response(
                code="200",
                message="获取角色权限成功",
                data=RolePermissionInfo(
                    role_id=role['role_id'],
                    role_name=role['role_name'],
                    menu_ids=menu_ids
                )
            )
    except Exception as e:
        return create_api_response(code="500", message=f"获取角色权限失败: {str(e)}")

@router.put("/admin/roles/{role_id}/permissions")
async def update_role_permissions(
    role_id: int,
    request: UpdateRolePermissionsRequest,
    current_user=Depends(get_current_admin_user)
):
    """
    更新指定角色的菜单权限
    只有管理员才能访问
    """
    try:
        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)

            # 检查角色是否存在
            cursor.execute("SELECT role_id FROM sys_roles WHERE role_id = %s", (role_id,))
            if not cursor.fetchone():
                return create_api_response(code="404", message="角色不存在")

            cursor.execute(
                """
                SELECT menu_id, parent_id
                FROM sys_menus
                WHERE is_active = 1
                """
            )
            all_menus = cursor.fetchall()
            menu_id_set = {menu["menu_id"] for menu in all_menus}

            # 验证所有menu_id是否有效
            invalid_menu_ids = [menu_id for menu_id in request.menu_ids if menu_id not in menu_id_set]
            if invalid_menu_ids:
                return create_api_response(code="400", message="包含无效的菜单ID")

            normalized_menu_ids = _normalize_permission_menu_ids(request.menu_ids, all_menus)

            # 删除该角色的所有现有权限
            cursor.execute("DELETE FROM sys_role_menu_permissions WHERE role_id = %s", (role_id,))

            # 插入新的权限
            if normalized_menu_ids:
                insert_values = [(role_id, menu_id) for menu_id in normalized_menu_ids]
                cursor.executemany(
                    "INSERT INTO sys_role_menu_permissions (role_id, menu_id) VALUES (%s, %s)",
                    insert_values
                )

            connection.commit()
            _invalidate_user_menu_cache(role_id)

            return create_api_response(
                code="200",
                message="更新角色权限成功",
                data={"role_id": role_id, "menu_count": len(normalized_menu_ids)}
            )
    except Exception as e:
        return create_api_response(code="500", message=f"更新角色权限失败: {str(e)}")

@router.get("/menus/user")
async def get_user_menus(current_user=Depends(get_current_user)):
    """
    获取当前用户可访问的菜单列表（用于渲染下拉菜单）
    所有登录用户都可以访问
    """
    try:
        role_id = current_user["role_id"]
        cached_menus = _get_cached_user_menus(role_id)
        if cached_menus is not None:
            return create_api_response(
                code="200",
                message="获取用户菜单成功",
                data={"menus": cached_menus}
            )

        with get_db_connection() as connection:
            cursor = connection.cursor(dictionary=True)

            # 根据用户的role_id查询可访问的菜单
            query = """
                SELECT m.menu_id, m.menu_code, m.menu_name, m.menu_icon,
                       m.menu_url, m.menu_type, m.parent_id, m.sort_order
                FROM sys_menus m
                JOIN sys_role_menu_permissions rmp ON m.menu_id = rmp.menu_id
                WHERE rmp.role_id = %s
                  AND m.is_active = 1
                  AND (m.is_visible = 1 OR m.is_visible IS NULL OR m.menu_code IN ('dashboard', 'desktop'))
                ORDER BY
                  COALESCE(m.parent_id, m.menu_id) ASC,
                  CASE WHEN m.parent_id IS NULL THEN 0 ELSE 1 END ASC,
                  m.sort_order ASC,
                  m.menu_id ASC
            """
            cursor.execute(query, (role_id,))
            menus = cursor.fetchall()

            # 仅在缺失父菜单时补查，减少不必要的SQL
            current_menu_ids = {menu["menu_id"] for menu in menus}
            missing_parent_ids = {
                menu["parent_id"] for menu in menus
                if menu.get("parent_id") is not None and menu["parent_id"] not in current_menu_ids
            }

            if missing_parent_ids:
                format_strings = ",".join(["%s"] * len(missing_parent_ids))
                cursor.execute(
                    f"""
                    SELECT menu_id, menu_code, menu_name, menu_icon, menu_url, menu_type, parent_id, sort_order
                    FROM sys_menus
                    WHERE is_active = 1 AND menu_id IN ({format_strings})
                    """,
                    tuple(missing_parent_ids),
                )
                parent_rows = cursor.fetchall()
                menus.extend(parent_rows)
                current_menu_ids.update(row["menu_id"] for row in parent_rows)

            menus = sorted(
                {menu["menu_id"]: menu for menu in menus}.values(),
                key=lambda m: (
                    m["parent_id"] if m["parent_id"] is not None else m["menu_id"],
                    0 if m["parent_id"] is None else 1,
                    m["sort_order"],
                    m["menu_id"],
                ),
            )
            _set_cached_user_menus(role_id, menus)

            return create_api_response(
                code="200",
                message="获取用户菜单成功",
                data={"menus": menus}
            )
    except Exception as e:
        return create_api_response(code="500", message=f"获取用户菜单失败: {str(e)}")