"""Routing engine configuration with environment variable loading."""
from __future__ import annotations

import os
from dataclasses import dataclass
from typing import Self


@dataclass(frozen=True)
class RoutingConfig:
    """Configuration for self-hosted routing engines (OSRM + OTP).

    Attributes:
        osrm_foot_url: URL for OSRM walking profile instance.
        osrm_bicycle_url: URL for OSRM cycling profile instance.
        otp_url: URL for OpenTripPlanner instance.
        osrm_batch_size: Number of origins per OSRM /table request.
        otp_max_concurrent: Max concurrent OTP requests.
    """

    osrm_foot_url: str = "http://osrm-foot:5000"
    osrm_bicycle_url: str = "http://osrm-bicycle:5000"
    otp_url: str = "http://otp:8080"
    osrm_batch_size: int = 50
    otp_max_concurrent: int = 10

    @classmethod
    def from_env(cls) -> Self:
        """Load configuration from environment variables.

        Environment variables:
            OSRM_FOOT_URL: OSRM walking instance URL (default: http://osrm-foot:5000)
            OSRM_BICYCLE_URL: OSRM cycling instance URL (default: http://osrm-bicycle:5000)
            OTP_URL: OpenTripPlanner URL (default: http://otp:8080)
            OSRM_BATCH_SIZE: Origins per /table request (default: 50)
            OTP_MAX_CONCURRENT: Max concurrent OTP requests (default: 10)
        """
        return cls(
            osrm_foot_url=os.environ.get("OSRM_FOOT_URL", "http://osrm-foot:5000"),
            osrm_bicycle_url=os.environ.get("OSRM_BICYCLE_URL", "http://osrm-bicycle:5000"),
            otp_url=os.environ.get("OTP_URL", "http://otp:8080"),
            osrm_batch_size=int(os.environ.get("OSRM_BATCH_SIZE", "50")),
            otp_max_concurrent=int(os.environ.get("OTP_MAX_CONCURRENT", "10")),
        )

    def get_osrm_url(self, profile: str) -> str:
        """Get the OSRM URL for a given profile."""
        if profile == "foot":
            return self.osrm_foot_url
        elif profile == "bicycle":
            return self.osrm_bicycle_url
        raise ValueError(f"Unknown OSRM profile: {profile}")