from __future__ import annotations

from functools import lru_cache

from pydantic_settings import BaseSettings, SettingsConfigDict


def parse_allowed_mcp_clients(raw: str) -> dict[str, set[str]]:
    out: dict[str, set[str]] = {}
    for part in raw.split(","):
        part = part.strip()
        if not part:
            continue
        client_id, _, redirect_uri = part.partition("|")
        client_id = client_id.strip()
        redirect_uri = redirect_uri.strip()
        if not client_id or not redirect_uri:
            continue
        out.setdefault(client_id, set()).add(redirect_uri)
    return out


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

    public_base_url: str = "http://127.0.0.1:48080"
    listen_host: str = "0.0.0.0"
    listen_port: int = 48080
    upstream_mcp_url: str = "http://gitea-mcp:8080/mcp"
    oidc_issuer: str = ""
    oidc_client_id: str = ""
    oidc_client_secret: str = ""
    oidc_scopes: str = (
        "openid profile email write:repository write:issue write:user"
        " write:organization write:notification write:package write:misc"
    )
    allowed_mcp_clients: str = ""
    token_encryption_key: str = ""
    data_dir: str = "./data"
    dcr_enabled: bool = True
    dcr_max_clients: int = 2000
    # Forward bearer tokens the bridge did not issue (e.g. Gitea PATs) unchanged.
    passthrough_unknown_tokens: bool = True
    # Optional Host header for the upstream request (gitea-mcp rejects other hosts).
    upstream_host_header: str = ""

    @property
    def issuer(self) -> str:
        return self.public_base_url.rstrip("/")

    @property
    def mcp_resource_url(self) -> str:
        return f"{self.issuer}/mcp"

    @property
    def allowed_clients(self) -> dict[str, set[str]]:
        return parse_allowed_mcp_clients(self.allowed_mcp_clients)

    @property
    def session_secret(self) -> bytes:
        return self.token_encryption_key.encode("utf-8")


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