"""
FastAPI 依赖注入 — Workspace 上下文、RBAC 权限检查
"""
from dataclasses import dataclass
import logging
from typing import Optional

from fastapi import Depends, HTTPException, Request
from sqlalchemy.orm import Session

from app.core.database import get_db
from app.core.security import decode_access_token
from app.models.user import User
from app.models.workspace import WorkspaceMembership

logger = logging.getLogger(__name__)


@dataclass
class WorkspaceContext:
    """工作区上下文 — 包装当前用户 + 当前工作区 ID"""
    user: User
    workspace_id: str


def get_current_workspace_id(request: Request) -> str:
    """从 JWT 的 `ws` 字段提取当前工作区 ID。"""
    auth_header = request.headers.get("Authorization", "")
    if not auth_header.startswith("Bearer "):
        raise HTTPException(status_code=401, detail="未提供有效的认证令牌")

    token = auth_header[7:]
    payload = decode_access_token(token)
    if payload is None:
        raise HTTPException(status_code=401, detail="无效的访问令牌")

    ws_id = payload.get("ws")
    if not ws_id:
        raise HTTPException(status_code=400, detail="令牌中未包含工作区信息，请重新登录")

    return ws_id


def get_workspace_context(
    request: Request,
    db: Session = Depends(get_db),
) -> WorkspaceContext:
    """获取完整的 Workspace 上下文（用户 + 工作区）。

    注意：此函数仅认证用户并提取 workspace_id，不验证 workspace 成员资格。
    用于跨 workspace 或 admin 端点。需要强制成员资格验证的端点请使用
    get_workspace_membership()。
    """
    auth_header = request.headers.get("Authorization", "")
    if not auth_header.startswith("Bearer "):
        raise HTTPException(status_code=401, detail="未提供有效的认证令牌")

    token = auth_header[7:]
    payload = decode_access_token(token)
    if payload is None:
        raise HTTPException(status_code=401, detail="无效的访问令牌")

    user_id = payload.get("sub")
    ws_id = payload.get("ws")

    if not user_id:
        raise HTTPException(status_code=401, detail="无效的访问令牌")

    user = db.query(User).filter(User.id == user_id).first()
    if not user:
        raise HTTPException(status_code=401, detail="用户不存在")

    if user.status == "deleted":
        raise HTTPException(status_code=403, detail="账号已注销")

    return WorkspaceContext(user=user, workspace_id=ws_id or "")


# ─── 多租户 RBAC 依赖 (v1.3) ───

def get_workspace_membership(
    request: Request,
    db: Session = Depends(get_db),
) -> WorkspaceContext:
    """认证用户 + 验证 workspace 成员资格。

    平台管理员（user.role == 'admin'）绕过 workspace 成员资格检查。
    普通用户必须属于 JWT 中 `ws` 指定的 workspace。
    """
    ctx = get_workspace_context(request, db)

    # 平台管理员可访问所有 workspace
    if ctx.user.role == "admin":
        return ctx

    if not ctx.workspace_id:
        raise HTTPException(status_code=400, detail="未选择工作区")

    membership = (
        db.query(WorkspaceMembership)
        .filter(
            WorkspaceMembership.workspace_id == ctx.workspace_id,
            WorkspaceMembership.user_id == ctx.user.id,
        )
        .first()
    )
    if not membership:
        logger.warning("用户 %s 尝试访问未加入的工作区 %s", ctx.user.id, ctx.workspace_id)
        raise HTTPException(status_code=403, detail="无权访问此工作区")

    return ctx


async def require_workspace_admin(
    ctx: WorkspaceContext = Depends(get_workspace_membership),
    db: Session = Depends(get_db),
) -> WorkspaceContext:
    """要求 workspace 管理员或平台管理员权限。

    用于删除/发布/修改工作区设置等敏感操作。
    """
    # 平台管理员
    if ctx.user.role == "admin":
        return ctx

    # workspace 管理员
    membership = (
        db.query(WorkspaceMembership)
        .filter(
            WorkspaceMembership.workspace_id == ctx.workspace_id,
            WorkspaceMembership.user_id == ctx.user.id,
        )
        .first()
    )
    if not membership or membership.role != "admin":
        raise HTTPException(status_code=403, detail="需要工作区管理员权限")

    return ctx


class WorkspacePermission:
    """细粒度权限检查依赖 — 桥接系统 RBAC 与 workspace 上下文。

    用法:
        @router.delete("/agents/{id}")
        async def delete_agent(
            ...,
            ctx: WorkspaceContext = Depends(WorkspacePermission("agent:delete")),
        ):
    """

    def __init__(self, permission_code: str):
        self.permission_code = permission_code

    async def __call__(
        self,
        ctx: WorkspaceContext = Depends(get_workspace_membership),
        db: Session = Depends(get_db),
    ) -> WorkspaceContext:
        # 平台管理员总是通过
        if ctx.user.role == "admin":
            return ctx

        # workspace 管理员拥有该 workspace 内所有权限
        membership = (
            db.query(WorkspaceMembership)
            .filter(
                WorkspaceMembership.workspace_id == ctx.workspace_id,
                WorkspaceMembership.user_id == ctx.user.id,
            )
            .first()
        )
        if membership and membership.role == "admin":
            return ctx

        # 检查系统级 RBAC 权限
        if _user_has_permission(db, ctx.user.id, self.permission_code):
            return ctx

        raise HTTPException(status_code=403, detail=f"缺少权限: {self.permission_code}")


def _user_has_permission(db: Session, user_id: str, permission_code: str) -> bool:
    """检查用户是否拥有指定权限（通过系统级 RBAC）。"""
    from app.models.permission import Role, Permission
    from app.models.user import User
    result = (
        db.query(Permission)
        .join(Permission.roles)
        .join(Role.users)
        .filter(
            Permission.code == permission_code,
            User.id == user_id,
        )
        .first()
    )
    return result is not None