from __future__ import annotations

from functools import lru_cache
from typing import Literal

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


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

    app_name: str = Field(default="Rastro", alias="APP_NAME")
    app_description: str = Field(
        default="Observatorio publico de trackers BitTorrent",
        alias="APP_DESCRIPTION",
    )
    app_version: str = Field(default="0.1.0", alias="APP_VERSION")
    public_url: str = Field(default="http://localhost:8090", alias="PUBLIC_URL")
    repository_url: str = Field(default="", alias="REPOSITORY_URL")

    database_url: str = Field(
        default="sqlite+aiosqlite:///data/rastro.db",
        alias="DATABASE_URL",
    )
    host: str = Field(default="0.0.0.0", alias="HOST")
    port: int = Field(default=8090, alias="PORT", ge=1, le=65535)
    log_level: str = Field(default="INFO", alias="LOG_LEVEL")

    run_scheduler: bool = Field(default=True, alias="RUN_SCHEDULER")
    # Source lists refresh on a weekly cron (UTC). A startup import still runs
    # when the inventory is empty or the last successful import is stale.
    import_day_of_week: str = Field(default="sun", alias="IMPORT_DAY_OF_WEEK")
    import_hour_utc: int = Field(default=4, alias="IMPORT_HOUR_UTC", ge=0, le=23)
    import_max_age_hours: int = Field(default=144, alias="IMPORT_MAX_AGE_HOURS", ge=1)
    default_probe_interval_seconds: int = Field(
        default=10800, alias="DEFAULT_PROBE_INTERVAL_SECONDS", ge=60
    )
    min_probe_interval_seconds: int = Field(default=1800, alias="MIN_PROBE_INTERVAL_SECONDS", ge=60)
    probe_concurrency: int = Field(default=10, alias="PROBE_CONCURRENCY", ge=1, le=100)
    probe_timeout_seconds: float = Field(default=10.0, alias="PROBE_TIMEOUT_SECONDS", gt=0, le=120)
    max_response_bytes: int = Field(default=1_048_576, alias="MAX_RESPONSE_BYTES", ge=1024)
    raw_result_retention_days: int = Field(default=90, alias="RAW_RESULT_RETENTION_DAYS", ge=1)

    enable_ipv4: bool = Field(default=True, alias="ENABLE_IPV4")
    enable_ipv6: Literal["true", "false", "auto"] | bool = Field(
        default="auto", alias="ENABLE_IPV6"
    )
    geoip_asn_db: str = Field(default="", alias="GEOIP_ASN_DB")

    # Source URLs (overridable for tests)
    trackerslist_all_url: str = Field(
        default=("https://raw.githubusercontent.com/ngosang/trackerslist/master/trackers_all.txt"),
        alias="TRACKERSLIST_ALL_URL",
    )
    trackerslist_best_url: str = Field(
        default=("https://raw.githubusercontent.com/ngosang/trackerslist/master/trackers_best.txt"),
        alias="TRACKERSLIST_BEST_URL",
    )
    newtrackon_all_url: str = Field(
        default="https://newtrackon.com/api/all",
        alias="NEWTRACKON_ALL_URL",
    )
    newtrackon_stable_url: str = Field(
        default="https://newtrackon.com/api/stable",
        alias="NEWTRACKON_STABLE_URL",
    )
    newtrackon_live_url: str = Field(
        default="https://newtrackon.com/api/live",
        alias="NEWTRACKON_LIVE_URL",
    )
    jokepool710_all_url: str = Field(
        default=(
            "https://raw.githubusercontent.com/jokepool710/Torrent-_Trackers/main/trackers_all.txt"
        ),
        alias="JOKEPOOL710_ALL_URL",
    )
    xiu2_all_url: str = Field(
        default="https://raw.githubusercontent.com/XIU2/TrackersListCollection/master/all.txt",
        alias="XIU2_ALL_URL",
    )
    xiu2_best_url: str = Field(
        default="https://raw.githubusercontent.com/XIU2/TrackersListCollection/master/best.txt",
        alias="XIU2_BEST_URL",
    )

    @field_validator("enable_ipv6", mode="before")
    @classmethod
    def normalize_ipv6(cls, value: object) -> object:
        if isinstance(value, str):
            lowered = value.strip().lower()
            if lowered in {"1", "yes", "true"}:
                return True
            if lowered in {"0", "no", "false"}:
                return False
            if lowered == "auto":
                return "auto"
        return value

    @model_validator(mode="after")
    def validate_intervals(self) -> Settings:
        if self.min_probe_interval_seconds > self.default_probe_interval_seconds:
            raise ValueError(
                "MIN_PROBE_INTERVAL_SECONDS cannot exceed DEFAULT_PROBE_INTERVAL_SECONDS"
            )
        return self

    def user_agent(self) -> str:
        base = f"{self.app_name}/{self.app_version}"
        url = (self.public_url or "").strip()
        if url:
            return f"{base} (+{url})"
        return base

    def peer_id_prefix(self) -> bytes:
        """Return a 8-byte BitTorrent peer_id style prefix derived from app name."""
        slug = "".join(c for c in self.app_name.upper() if c.isalnum())[:6] or "RASTRO"
        slug = slug.ljust(6, "X")[:6]
        return f"-{slug}-".encode("ascii")

    def ipv6_mode(self) -> Literal["true", "false", "auto"]:
        if self.enable_ipv6 is True:
            return "true"
        if self.enable_ipv6 is False:
            return "false"
        return "auto"


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