"""分层配置：dev / prod 全部走环境变量，启动即校验。"""

from __future__ import annotations

import os
from functools import lru_cache
from typing import Literal

from pydantic import Field, field_validator
from pydantic_settings import BaseSettings, SettingsConfigDict

DEV_JWT_SECRET = "dev-only-change-me"  # noqa: S105 - 仅开发默认值，生产启动时会被校验拦下


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        env_file=".env", env_file_encoding="utf-8", extra="ignore", case_sensitive=False
    )

    # ── 基础 ──────────────────────────────────────────────
    app_name: str = "达道Task"
    env: Literal["dev", "test", "prod"] = "dev"
    api_prefix: str = "/api/v1"
    cors_origins: list[str] = Field(
        default_factory=lambda: ["http://localhost:5180", "http://127.0.0.1:5180"]
    )

    # ── 数据库 ────────────────────────────────────────────
    # 应用角色：受 RLS 约束，非 owner、非 superuser
    database_url: str = "postgresql+asyncpg://dadao_app:dadao_dev_pw@127.0.0.1:5433/dadaotask"
    # 迁移角色：owner，可绕过 RLS，仅 alembic / 运维脚本使用
    migration_database_url: str = (
        "postgresql+asyncpg://dadao_owner:dadao_dev_pw@127.0.0.1:5433/dadaotask"
    )
    db_echo: bool = False
    db_pool_size: int = 10

    # ── Redis ─────────────────────────────────────────────
    redis_url: str = "redis://127.0.0.1:6380/0"

    # ── 认证 ──────────────────────────────────────────────
    jwt_secret: str = DEV_JWT_SECRET
    jwt_algorithm: str = "HS256"
    access_token_minutes: int = 30
    refresh_token_days: int = 14
    sms_code_ttl_seconds: int = 300
    # 同一手机号两次发码的最小间隔；测试里设为 0 可关闭节流
    sms_throttle_seconds: int = 60
    sms_dev_code: str = "123456"
    sms_provider: Literal["dev", "aliyun", "tencent"] = "dev"

    # ── 幂等 ──────────────────────────────────────────────
    idempotency_enabled: bool = True
    idempotency_ttl_seconds: int = 86_400

    # ── 构建标记（部署校验用）──────────────────────────────
    build_commit: str = "unknown"
    build_time: str = "unknown"

    @field_validator("cors_origins", mode="before")
    @classmethod
    def _split_origins(cls, value: object) -> object:
        """支持 CORS_ORIGINS="a,b" 这种写法。"""
        if isinstance(value, str) and not value.startswith("["):
            return [item.strip() for item in value.split(",") if item.strip()]
        return value

    def validate_runtime(self) -> None:
        """生产环境的致命配置错误，必须在启动时炸掉，而不是等待请求。"""
        if self.env != "prod":
            return
        problems: list[str] = []
        if self.jwt_secret == DEV_JWT_SECRET or len(self.jwt_secret) < 32:
            problems.append("JWT_SECRET 仍是开发默认值或长度不足 32")
        if "dadao_dev_pw" in self.database_url:
            problems.append("DATABASE_URL 仍在用开发默认口令")
        if self.sms_provider == "dev":
            problems.append("生产环境不允许 SMS_PROVIDER=dev（任意验证码可登录）")
        if problems:
            raise RuntimeError("配置校验失败：" + "；".join(problems))


@lru_cache
def get_settings() -> Settings:
    return Settings()


def build_commit() -> str:
    """优先读环境变量（CI/镜像注入），退回 git。"""
    env_value = os.getenv("BUILD_COMMIT")
    if env_value:
        return env_value
    return get_settings().build_commit