"""
Ollama endpoint resolver for non-critical workload placement.

ADR-110 gives AWOOOI three Ollama endpoints. This resolver is intentionally
small: it chooses the preferred endpoint by workload class, while health-aware
failover remains owned by ollama_failover_manager.py.
"""

from __future__ import annotations

from dataclasses import dataclass
from typing import Literal, Protocol

from src.core.config import settings

OllamaWorkloadType = Literal[
    "interactive",
    "healthcheck",
    "batch",
    "embedding",
    "rag",
    "code_review",
    "shadow",
    "canary",
    "local_required",
    "privacy_sensitive",
    "dr",
]

_GCP_B_PREFERRED_WORKLOADS = {
    "batch",
    "embedding",
    "rag",
    "code_review",
    "shadow",
    "canary",
}

_LOCAL_PREFERRED_WORKLOADS = {
    "local_required",
    "privacy_sensitive",
    "dr",
}


class _OllamaSettings(Protocol):
    OLLAMA_URL: str
    OLLAMA_SECONDARY_URL: str
    OLLAMA_FALLBACK_URL: str


@dataclass(frozen=True)
class OllamaEndpointSelection:
    url: str
    provider_name: str
    workload_type: OllamaWorkloadType
    reason: str


def resolve_ollama_selection(
    workload_type: OllamaWorkloadType = "interactive",
    *,
    config: _OllamaSettings | None = None,
) -> OllamaEndpointSelection:
    """Return the preferred Ollama endpoint for a workload class."""
    cfg = config or settings
    primary = cfg.OLLAMA_URL
    secondary = cfg.OLLAMA_SECONDARY_URL
    fallback = cfg.OLLAMA_FALLBACK_URL

    if workload_type in _GCP_B_PREFERRED_WORKLOADS and secondary:
        return OllamaEndpointSelection(
            url=secondary,
            provider_name="ollama_gcp_b",
            workload_type=workload_type,
            reason="gcp_b_batch_lane",
        )

    if workload_type in _LOCAL_PREFERRED_WORKLOADS and fallback:
        return OllamaEndpointSelection(
            url=fallback,
            provider_name="ollama_local",
            workload_type=workload_type,
            reason="local_privacy_or_dr_lane",
        )

    return OllamaEndpointSelection(
        url=primary,
        provider_name="ollama_gcp_a",
        workload_type=workload_type,
        reason="primary_interactive_lane",
    )


def resolve_ollama_endpoint(
    workload_type: OllamaWorkloadType = "interactive",
    *,
    config: _OllamaSettings | None = None,
) -> str:
    """Return only the preferred Ollama base URL."""
    return resolve_ollama_selection(workload_type, config=config).url