"""Application configuration split by architecture component."""

from decimal import Decimal
from functools import lru_cache
from pathlib import Path
import sys
from typing import Any

from pydantic import BaseModel, Field
from pydantic_settings import (
    BaseSettings,
    PydanticBaseSettingsSource,
    SettingsConfigDict,
    YamlConfigSettingsSource,
)

DEFAULT_CONFIG_FILE = "/config.yaml"
TEST_CONFIG_FILE = "config.test.yaml"


class ControllerConfig(BaseModel):
    api_prefix: str = "/api/v1"
    request_id_header: str = "X-Request-ID"


class ServiceConfig(BaseModel):
    provider_timeout_seconds: float = 10.0
    max_parallel_providers: int = 8


class BusinessLogicConfig(BaseModel):
    weight_round_scale: int = 2
    provider_price_multiplier: Decimal = Field(..., gt=0)


class RepositoryConfig(BaseModel):
    redis_dsn: str = "redis://localhost:6379/0"
    price_cache_ttl_seconds: int = 900


class AdapterConfig(BaseModel):
    cdek_base_url: str = "https://api.cdek.ru/v2"
    cdek_client_id: str = ""
    cdek_client_secret: str = ""
    cdek_retry_attempts: int = Field(default=2, ge=0)
    cdek_retry_backoff_seconds: float = Field(default=0.2, ge=0)
    cdek_timeout_seconds: float = Field(default=10.0, gt=0)
    cdek_cache_ttl_seconds: int = Field(default=900, gt=0)


class ObservabilityConfig(BaseModel):
    enabled: bool = False
    service_name: str = Field(..., min_length=1)
    otlp_endpoint: str = Field(..., min_length=1)
    otlp_insecure: bool = True


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        extra="ignore",
    )

    controller: ControllerConfig = Field(default_factory=ControllerConfig)
    service: ServiceConfig = Field(default_factory=ServiceConfig)
    business_logic: BusinessLogicConfig = Field(default_factory=BusinessLogicConfig)
    repository: RepositoryConfig = Field(default_factory=RepositoryConfig)
    adapter: AdapterConfig = Field(default_factory=AdapterConfig)
    observability: ObservabilityConfig

    @classmethod
    def settings_customise_sources(
        cls,
        settings_cls: type[BaseSettings],
        init_settings: PydanticBaseSettingsSource,
        env_settings: PydanticBaseSettingsSource,
        dotenv_settings: PydanticBaseSettingsSource,
        file_secret_settings: PydanticBaseSettingsSource,
    ) -> tuple[PydanticBaseSettingsSource, ...]:
        config_file = _resolve_runtime_config_file()
        yaml_source = YamlConfigSettingsSource(
            settings_cls,
            yaml_file=config_file,
        )
        return (
            init_settings,
            yaml_source,
        )


class _RequiredYamlSections(BaseModel):
    controller: dict[str, Any]
    service: dict[str, Any]
    business_logic: dict[str, Any]
    repository: dict[str, Any]
    adapter: dict[str, Any]
    observability: dict[str, Any]


def _resolve_runtime_config_file() -> str:
    test_config_path = Path(TEST_CONFIG_FILE)
    if "pytest" in sys.modules and test_config_path.is_file():
        return TEST_CONFIG_FILE
    return DEFAULT_CONFIG_FILE


def _validate_required_yaml_sections() -> None:
    config_file = _resolve_runtime_config_file()
    config_path = Path(config_file)
    if not config_path.is_file():
        return

    yaml_source = YamlConfigSettingsSource(Settings, yaml_file=config_file)
    yaml_data = yaml_source.yaml_data
    if not isinstance(yaml_data, dict):
        yaml_data = {}
    _RequiredYamlSections.model_validate(yaml_data)


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