from __future__ import annotations

from functools import lru_cache
from typing import List, Literal
import os
from dotenv import load_dotenv, find_dotenv
from pydantic import AliasChoices, Field, field_validator, model_validator
from pydantic_settings import BaseSettings, SettingsConfigDict
from src.infrastructure.vault import create_hvac_client_from_approle, read_kv2_secret

env_file = find_dotenv(".env")
if env_file:
    load_dotenv(env_file)


def normalize_vault_base_url(raw: str) -> str:
    u = raw.strip().rstrip('/')
    if not u:
        return raw.strip()
    if '://' not in u:
        return f'https://{u}'
    return u


class Settings(BaseSettings):
    VAULT_ADDR: str = Field(default='http://localhost:8200')
    VAULT_ROLE_ID: str = Field(..., description='AppRole role_id')
    VAULT_SECRET_ID: str = Field(
        ...,
        description='AppRole secret_id',
        validation_alias=AliasChoices('VAULT_SECRET_ID', 'VAULT_SECRET_TOKEN'),
    )
    VAULT_NAMESPACE: str | None = Field(default=None)
    VAULT_MOUNT_POINT: str = Field(default='dev-secrets')

    VAULT_JWT_KID_PATH: str = 'jwt/kid'
    VAULT_JWT_KIDS_PREFIX: str = 'jwt/kids'
    JWT_KEYS_REFRESH_SECONDS: int = 3600

    DATABASE_HOST: str
    DATABASE_PORT: int = Field(default=5432, ge=1, le=65535)
    DATABASE_NAME: str
    DATABASE_USER: str
    DATABASE_PASSWORD: str

    DATABASE_POOL_SIZE: int = 10
    DATABASE_MAX_OVERFLOW: int = 20
    DATABASE_POOL_TIMEOUT: int = 30
    DATABASE_POOL_RECYCLE: int = 3600
    DATABASE_ECHO: bool = False

    CSRF_SECRET_KEY: str = Field(min_length=32)

    CSRF_COOKIE_SECURE: bool = False
    CSRF_COOKIE_HTTPONLY: bool = True
    CSRF_COOKIE_SAMESITE: Literal['Lax', 'Strict', 'None'] = 'Lax'
    CSRF_COOKIE_PATH: str = '/'
    CSRF_COOKIE_DOMAIN: str | None = None

    DOCS_USERNAME: str = 'admin'
    DOCS_PASSWORD: str = 'admin'

    JWT_ACCESS_TTL_SECONDS: int = 15 * 60
    JWT_REFRESH_TTL_SECONDS: int = 30 * 24 * 60 * 60
    JWT_ISSUER: str | None = None
    JWT_AUDIENCE: str | None = None
    JWT_ALGORITHM: str = 'RS256'

    REDIS_HOST: str = 'localhost'
    REDIS_PORT: int = 6379
    REDIS_PASSWORD: str | None = None
    REDIS_DB: int = 0

    RABBIT_HOST: str = 'localhost'
    RABBIT_PORT: int = 5672
    RABBIT_USER: str = 'guest'
    RABBIT_PASSWORD: str = 'guest'
    RABBIT_VHOST: str = '/'

    RABBIT_PUBLISH_PERSIST: bool = True
    RABBIT_CONNECT_TIMEOUT: int = 5
    RABBIT_EMAIL_CODE_QUEUE: str = 'email.verification_code'

    CORS_ORIGINS: str = 'http://localhost:3000'
    CORS_ALLOW_CREDENTIALS: bool = True

    RATE_LIMIT_REQUESTS: int = 60
    RATE_LIMIT_WINDOW: int = 60

    LOG_LEVEL: Literal['DEBUG', 'INFO', 'WARNING', 'ERROR', 'CRITICAL'] = 'INFO'
    LOG_FORMAT: Literal['JSON', 'TEXT'] = 'TEXT'

    @field_validator('VAULT_ADDR', mode='before')
    @classmethod
    def vault_addr_scheme(cls, v):
        if v is None or not isinstance(v, str):
            return v
        return normalize_vault_base_url(v)

    @field_validator('CSRF_COOKIE_DOMAIN', mode='before')
    @classmethod
    def empty_csrf_domain_to_none(cls, v):
        if v is None or (isinstance(v, str) and not v.strip()):
            return None
        return v

    model_config = SettingsConfigDict(
        env_file='.env',
        env_file_encoding='utf-8',
        case_sensitive=True,
        extra='ignore',
        populate_by_name=True,
    )

    @model_validator(mode='before')
    @classmethod
    def load_from_vault(cls, data: dict):
        if not isinstance(data, dict):
            return data
        addr_raw = data.get('VAULT_ADDR') or os.getenv('VAULT_ADDR') or 'http://localhost:8200'
        addr = normalize_vault_base_url(addr_raw)
        data['VAULT_ADDR'] = addr
        role_id = data.get('VAULT_ROLE_ID') or os.getenv('VAULT_ROLE_ID')
        secret_id = (
            data.get('VAULT_SECRET_ID')
            or data.get('VAULT_SECRET_TOKEN')
            or os.getenv('VAULT_SECRET_ID')
            or os.getenv('VAULT_SECRET_TOKEN')
        )
        namespace = data.get('VAULT_NAMESPACE')
        if namespace is None:
            namespace = os.getenv('VAULT_NAMESPACE')
        namespace = namespace if namespace else None
        mount = data.get('VAULT_MOUNT_POINT') or os.getenv('VAULT_MOUNT_POINT') or 'dev-secrets'

        if not role_id or not secret_id:
            raise RuntimeError(
                'VAULT_ROLE_ID and VAULT_SECRET_ID (or VAULT_SECRET_TOKEN) are required for Vault AppRole'
            )

        data['VAULT_ROLE_ID'] = str(role_id).strip()
        data['VAULT_SECRET_ID'] = str(secret_id).strip()

        client = create_hvac_client_from_approle(
            url=addr,
            role_id=role_id,
            secret_id=secret_id,
            namespace=namespace,
            timeout=5,
        )

        def read_secret(path: str) -> dict:
            return read_kv2_secret(client=client, mount_point=mount, path=path)

        def read_secret_optional(path: str) -> dict:
            try:
                return read_secret(path)
            except Exception:
                return {}

        database = read_secret('database')
        csrf = read_secret('csrf')

        db_ci = {str(k).lower(): v for k, v in database.items()}

        def db_nonempty(key: str) -> bool:
            v = db_ci.get(key)
            if v is None:
                return False
            if isinstance(v, str) and not v.strip():
                return False
            return True

        required_db = ['host', 'name', 'user', 'password', 'port']
        missing_db = [k for k in required_db if not db_nonempty(k)]
        if missing_db:
            raise RuntimeError(f'Vault secret database missing non-empty keys: {missing_db}')

        data['DATABASE_HOST'] = str(db_ci['host']).strip()
        data['DATABASE_PORT'] = int(db_ci['port'])
        data['DATABASE_NAME'] = str(db_ci['name']).strip()
        data['DATABASE_USER'] = str(db_ci['user']).strip()
        data['DATABASE_PASSWORD'] = str(db_ci['password']).strip()

        csrf_secret = None
        for entry_key, entry_val in csrf.items():
            if str(entry_key).lower() == 'key' and entry_val is not None and str(entry_val).strip():
                csrf_secret = str(entry_val).strip()
                break
        if not csrf_secret:
            raise RuntimeError(
                'Vault secret at csrf must contain a non-empty field named key (e.g. key=...)'
            )

        data['CSRF_SECRET_KEY'] = csrf_secret

        rabbit = read_secret_optional('rabbitmq')
        if rabbit:
            r_ci = {str(k).lower(): v for k, v in rabbit.items()}

            def rb_set(field: str, env_key: str, *, as_int: bool = False) -> None:
                v = r_ci.get(field)
                if v is None:
                    return
                if isinstance(v, str) and not v.strip():
                    return
                if as_int:
                    data[env_key] = int(v)
                else:
                    data[env_key] = str(v).strip()

            rb_set('host', 'RABBIT_HOST')
            rb_set('port', 'RABBIT_PORT', as_int=True)
            rb_set('user', 'RABBIT_USER')
            rb_set('password', 'RABBIT_PASSWORD')
            rb_set('vhost', 'RABBIT_VHOST')

        return data


    def cors_origins_list(self) -> List[str]:
        return [o.strip() for o in self.CORS_ORIGINS.split(',') if o.strip()]


    @property
    def DATABASE_URL(self) -> str:
        return (
            f"postgresql+asyncpg://{self.DATABASE_USER}:{self.DATABASE_PASSWORD}"
            f"@{self.DATABASE_HOST}:{self.DATABASE_PORT}/{self.DATABASE_NAME}"
        )

    @property
    def REDIS_URL(self) -> str:
        auth = f":{self.REDIS_PASSWORD}@" if self.REDIS_PASSWORD else ""
        return f"redis://{auth}{self.REDIS_HOST}:{self.REDIS_PORT}/{self.REDIS_DB}"

    @property
    def RABBIT_URL(self) -> str:
        vhost = "%2F" if self.RABBIT_VHOST == "/" else self.RABBIT_VHOST.lstrip("/")
        return f"amqp://{self.RABBIT_USER}:{self.RABBIT_PASSWORD}@{self.RABBIT_HOST}:{self.RABBIT_PORT}/{vhost}"

    @property
    def EXCLUDED_PATHS(self) -> List[str]:
        return ['/docs', '/redoc', '/openapi.json', '/ping', '/health']


@lru_cache(maxsize=1)
def get_settings() -> Settings:
    return Settings()


settings = get_settings()