"""
Tests for RoutingPolicy (FR-2).
"""

import pytest

from llm_connect.routing import RoutingPolicy, RoutingRule
from llm_connect.adapter import MockLLMAdapter


class TestRoutingPolicy:
    def _adapters(self, n: int = 3):
        return [MockLLMAdapter(mock_response=f"resp-{i}") for i in range(n)]

    def test_rule_match_returns_prefer(self):
        prefer, *_ = self._adapters()
        policy = RoutingPolicy(rules=[RoutingRule("triage", prefer=prefer)])
        assert policy.resolve("triage") is prefer

    def test_first_matching_rule_wins(self):
        a, b = self._adapters(2)
        policy = RoutingPolicy(rules=[
            RoutingRule("triage", prefer=a),
            RoutingRule("triage", prefer=b),
        ])
        assert policy.resolve("triage") is a

    def test_cost_cap_within_limit_returns_prefer(self):
        prefer, fallback = self._adapters(2)
        policy = RoutingPolicy(rules=[
            RoutingRule("triage", prefer=prefer, max_cost_per_1k=1.0, fallback=fallback)
        ])
        assert policy.resolve("triage", estimated_cost_per_1k=0.5) is prefer

    def test_cost_cap_exceeded_returns_fallback(self):
        prefer, fallback = self._adapters(2)
        policy = RoutingPolicy(rules=[
            RoutingRule("triage", prefer=prefer, max_cost_per_1k=1.0, fallback=fallback)
        ])
        assert policy.resolve("triage", estimated_cost_per_1k=2.0) is fallback

    def test_cost_cap_exceeded_no_fallback_returns_prefer(self):
        """When cost exceeds cap but no fallback is set, still return prefer."""
        prefer, *_ = self._adapters()
        policy = RoutingPolicy(rules=[
            RoutingRule("triage", prefer=prefer, max_cost_per_1k=0.1)
        ])
        assert policy.resolve("triage", estimated_cost_per_1k=5.0) is prefer

    def test_no_estimated_cost_ignores_cap(self):
        prefer, fallback = self._adapters(2)
        policy = RoutingPolicy(rules=[
            RoutingRule("triage", prefer=prefer, max_cost_per_1k=0.01, fallback=fallback)
        ])
        # No cost estimate → cap not applied
        assert policy.resolve("triage") is prefer

    def test_unknown_task_type_returns_default(self):
        prefer, default = self._adapters(2)
        policy = RoutingPolicy(
            rules=[RoutingRule("triage", prefer=prefer)],
            default=default,
        )
        assert policy.resolve("unknown") is default

    def test_no_match_no_default_raises_lookup_error(self):
        prefer, *_ = self._adapters()
        policy = RoutingPolicy(rules=[RoutingRule("triage", prefer=prefer)])
        with pytest.raises(LookupError, match="unknown"):
            policy.resolve("unknown")

    def test_empty_rules_with_default_returns_default(self):
        default, *_ = self._adapters()
        policy = RoutingPolicy(default=default)
        assert policy.resolve("anything") is default

    def test_empty_policy_raises(self):
        policy = RoutingPolicy()
        with pytest.raises(LookupError):
            policy.resolve("triage")

    def test_multiple_task_types(self):
        a, b, c = self._adapters(3)
        policy = RoutingPolicy(rules=[
            RoutingRule("fast", prefer=a),
            RoutingRule("smart", prefer=b),
            RoutingRule("cheap", prefer=c),
        ])
        assert policy.resolve("fast") is a
        assert policy.resolve("smart") is b
        assert policy.resolve("cheap") is c