from functools import lru_cache

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


def split_usernames(raw: str) -> list[str]:
    usernames: list[str] = []
    seen: set[str] = set()
    for part in raw.split(","):
        username = part.strip()
        if not username or username in seen:
            continue
        seen.add(username)
        usernames.append(username)
    return usernames


class Settings(BaseSettings):
    model_config = SettingsConfigDict(env_file=".env", case_sensitive=False)

    github_username: str = Field(alias="GITHUB_USERNAME")
    github_token: str | None = Field(default=None, alias="GITHUB_TOKEN")

    gitea_base_url: str = Field(alias="GITEA_BASE_URL")
    gitea_username: str = Field(alias="GITEA_USERNAME")
    gitea_token: str | None = Field(default=None, alias="GITEA_TOKEN")

    cache_ttl_seconds: int | None = Field(default=None, alias="CACHE_TTL_SECONDS")
    cache_dir: str | None = Field(default=None, alias="CACHE_DIR")

    default_theme: str = Field(default="light", alias="DEFAULT_THEME")
    service_title: str = Field(default="git-activity-merge", alias="SERVICE_TITLE")

    @field_validator("github_username", "gitea_username")
    @classmethod
    def _validate_username_list(cls, value: str) -> str:
        if not split_usernames(value):
            raise ValueError("must contain at least one username")
        return value

    @property
    def github_usernames(self) -> list[str]:
        return split_usernames(self.github_username)

    @property
    def gitea_usernames(self) -> list[str]:
        return split_usernames(self.gitea_username)


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