"""鉴权依赖：从 Authorization header 解析当前用户，提供权限校验。"""
from __future__ import annotations

from typing import Any

from fastapi import Depends, HTTPException, Query, Request, status

from app.db.platform_store import get_platform_store

# 无需鉴权的路径前缀（健康检查、登录等）
PUBLIC_PATHS = ("/health", "/login", "/system-info")
OWNER_TABLES = {
    "dataset": ("datasets", "created_by"), "model": ("models", "created_by"),
    "trained_model": ("trained_models", "created_by"), "eval": ("eval_tasks", "created_by"),
    "fine-tune": ("fine_tune_tasks", "payload"), "fine_tune_task": ("fine_tune_tasks", "payload"),
    "compare": ("compare_tasks", "payload"), "inference": ("compare_tasks", "payload"),
    "project": ("projects", "created_by"), "data_process": ("data_process_tasks", "created_by"),
}


def _extract_token(request: Request) -> str | None:
    """从 Authorization header 提取 token（格式: Bearer platform-token-{user_id}）。"""
    auth = request.headers.get("Authorization", "")
    token = auth.replace("Bearer ", "").strip()
    if token.startswith("platform-token-"):
        return token[len("platform-token-"):]
    return None

def _session_token(user_id: str, session_id: str) -> str:
    return f"platform-token-{user_id}.{session_id}"


def get_current_user(request: Request) -> dict[str, Any]:
    """
    FastAPI 依赖：解析当前登录用户。
    - 公开路径（/health, /login 等）直接放行，返回匿名用户。
    - 无 token 或 token 无效时抛 401。
    - admin 用户标记为超级管理员，拥有全部权限。
    """
    path = request.url.path
    # 去掉路由前缀后判断
    for prefix in PUBLIC_PATHS:
        if path.endswith(prefix):
            return {"id": None, "username": "anonymous", "role": "viewer", "permissions": [], "protected": False}

    token_value = _extract_token(request)
    if not token_value:
        raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="missing or invalid token")

    store = get_platform_store()
    user_id, _, session_id = token_value.partition(".")
    if session_id:
        with store.connect() as conn:
            session = conn.execute(
                "SELECT user_id, logout_at, expires_at FROM sessions WHERE id=?", (session_id,)
            ).fetchone()
        if not session or session["user_id"] != user_id or session["logout_at"]:
            raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="session expired")
        if session["expires_at"]:
            from datetime import datetime, timezone
            try:
                if datetime.fromisoformat(str(session["expires_at"]).replace("Z", "+00:00")) <= datetime.now(timezone.utc):
                    raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="session expired")
            except ValueError:
                pass
    with store.connect() as conn:
        user_row = conn.execute("SELECT * FROM users WHERE id=?", (user_id,)).fetchone()
    if user_row:
        return store._user(user_row)
    raise HTTPException(status_code=status.HTTP_401_UNAUTHORIZED, detail="user not found")


def require_admin(current_user: dict[str, Any] = Depends(get_current_user)) -> dict[str, Any]:
    """FastAPI 依赖：要求当前用户是管理员（role=admin 或 protected）。"""
    if current_user.get("role") == "admin" or current_user.get("protected"):
        return current_user
    raise HTTPException(status_code=status.HTTP_403_FORBIDDEN, detail="admin permission required")


def is_admin(user: dict[str, Any]) -> bool:
    """判断用户是否为管理员（admin 角色或 protected 标记）。"""
    return user.get("role") == "admin" or user.get("protected", False)


def has_resource_access(
    resource_type: str,
    resource_id: str,
    user: dict[str, Any],
    permission: str = "read",
) -> bool:
    """
    检查用户对某资源是否有指定权限。
    - admin/protected 用户直接放行（旁路）。
    - 其他用户检查 acls 表中是否有对应授权。
    """
    if user.get("role") == "admin" or user.get("protected"):
        return True

    store = get_platform_store()
    acls = store.get_acl(resource_type, resource_id)
    user_id = user.get("id")
    user_role = user.get("role")

    owner_tables = OWNER_TABLES
    table_info = owner_tables.get(resource_type)
    if table_info and user_id:
        table, column = table_info
        with store.connect() as conn:
            row = conn.execute(f"SELECT {column} FROM {table} WHERE id=?", (resource_id,)).fetchone()
        if row:
            owner = row[column]
            if column == "payload":
                try:
                    import json
                    owner = json.loads(owner or "{}").get("created_by")
                except (TypeError, ValueError):
                    owner = None
            if owner == user_id:
                return True

    for entry in acls:
        # 按 user 授权
        if entry.get("principal_type") == "user" and entry.get("principal_id") == user_id:
            if _permission_covers(entry.get("permission"), permission):
                return True
        # 按 role 授权
        if entry.get("principal_type") == "role" and entry.get("principal_id") == user_role:
            if _permission_covers(entry.get("permission"), permission):
                return True
    return False


def _permission_covers(granted: str | None, required: str) -> bool:
    """权限覆盖判断：write/execute 覆盖 read；admin 覆盖一切。"""
    if not granted:
        return False
    if granted == "admin":
        return True
    if granted == required:
        return True
    # write 覆盖 read
    if required == "read" and granted in ("write", "execute"):
        return True
    return False


def filter_accessible_resource_ids(
    resource_type: str,
    all_ids: list[str],
    user: dict[str, Any],
) -> list[str]:
    """
    从全部资源 ID 中过滤出当前用户可访问的 ID 列表。
    - admin 直接返回全部。
    - 普通用户查 acls 表取交集。
    """
    if user.get("role") == "admin" or user.get("protected"):
        return all_ids

    if not all_ids:
        return []

    store = get_platform_store()
    user_id = user.get("id")
    user_role = user.get("role")

    # 查询该用户在该资源类型下有 read 权限的所有 resource_id
    with store.connect() as conn:
        rows = conn.execute(
            """
            SELECT DISTINCT resource_id FROM acls
            WHERE resource_type=? AND (
                (principal_type='user' AND principal_id=?)
                OR (principal_type='role' AND principal_id=?)
            )
            """,
            (resource_type, user_id, user_role),
        ).fetchall()

    accessible = {r["resource_id"] for r in rows}
    if resource_type in owner_tables:
        table, column = owner_tables[resource_type]
        with store.connect() as conn:
            owned = conn.execute(f"SELECT id FROM {table} WHERE {column}=?", (user_id,)).fetchall()
        accessible.update(row["id"] for row in owned)
    return [rid for rid in all_ids if rid in accessible]


def filter_accessible_resource_ids_batch(
    resource_type: str,
    resource_ids: list[str],
    user: dict[str, Any],
) -> set[str]:
    """Filter a list endpoint with one ACL query instead of one query per row."""
    if is_admin(user):
        return set(resource_ids)
    if not resource_ids:
        return set()
    store = get_platform_store()
    placeholders = ",".join("?" for _ in resource_ids)
    with store.connect() as conn:
        rows = conn.execute(
            f"SELECT DISTINCT resource_id FROM acls WHERE resource_type=? AND resource_id IN ({placeholders}) "
            "AND ((principal_type='user' AND principal_id=?) OR (principal_type='role' AND principal_id=?))",
            (resource_type, *resource_ids, user.get("id"), user.get("role")),
        ).fetchall()
    accessible = {row["resource_id"] for row in rows}
    table_info = OWNER_TABLES.get(resource_type)
    if table_info and user.get("id"):
        table, column = table_info
        with store.connect() as conn:
            owned = conn.execute(
                f"SELECT id FROM {table} WHERE id IN ({placeholders}) AND {column}=?",
                (*resource_ids, user["id"]),
            ).fetchall()
        accessible.update(row["id"] for row in owned)
    return accessible