"""Unit tests for LLM batch-matching scenarios.

Covers:
- Empty input returns immediately without LLM calls
- All errors: no exception, complete error list
- Default max_concurrency value is 5
- Single error does not affect other candidates

Anforderungen: 4.2, 4.3, 4.4, 5.3
"""

from __future__ import annotations

import asyncio
import json

from teamlandkarte_mcp.azure.openai_client import AzureAPIError
from teamlandkarte_mcp.matching.llm_fulltext_matcher import LlmFulltextMatcher
from teamlandkarte_mcp.matching.profiles import TaskProfile
from teamlandkarte_mcp.models import Capacity

_CATEGORIES = ("Top", "Good", "Partial", "Low", "Irrelevant")


# ---------------------------------------------------------------------------
# Test doubles
# ---------------------------------------------------------------------------


class _StubDb:
    def batch_get_capacity_descriptions(self, capacity_ids):
        return {str(i): None for i in capacity_ids}

    def batch_get_capacity_certificates(self, capacity_ids):
        return {str(i): [] for i in capacity_ids}

    def batch_get_capacity_references(self, capacity_ids):
        return {str(i): [] for i in capacity_ids}


class _StaticLlm:
    """Always returns the same response or raises."""

    def __init__(self, response=None, exc=None):
        self._response = response
        self._exc = exc
        self.call_count = 0

    async def chat_completion(self, system, user):
        self.call_count += 1
        if self._exc:
            raise self._exc
        return self._response


class _FailOneLlm:
    """Fails on a specific call index, succeeds on others."""

    def __init__(self, fail_index: int):
        self._fail_index = fail_index
        self._call_index = 0

    async def chat_completion(self, system, user):
        idx = self._call_index
        self._call_index += 1
        if idx == self._fail_index:
            raise AzureAPIError("simulated failure")
        return json.dumps({"category": "Top", "rationale": "ok"})


# ---------------------------------------------------------------------------
# Helpers
# ---------------------------------------------------------------------------


def _make_capacities(n: int) -> list[Capacity]:
    return [
        Capacity(
            id=i + 1,
            owner_name=f"owner{i + 1}",
            role_name="Engineer",
            role_level=None,
            begin_date=None,
            end_date=None,
            competences=[],
        )
        for i in range(n)
    ]


def _task_profile() -> TaskProfile:
    return TaskProfile(id="t1", title="Task", description="Desc", skills=[])


# ---------------------------------------------------------------------------
# Tests
# ---------------------------------------------------------------------------


def test_empty_input_returns_immediately_without_llm_calls():
    """Empty capacities list returns empty result, no LLM calls made."""
    llm = _StaticLlm(response=json.dumps({"category": "Top", "rationale": "x"}))
    matcher = LlmFulltextMatcher(db=_StubDb(), client=llm)

    result = asyncio.run(
        matcher.match_capacities(task_profile=_task_profile(), capacities=[])
    )

    # All 5 categories present but empty
    assert set(result.by_category.keys()) == set(_CATEGORIES)
    for cat in _CATEGORIES:
        assert result.by_category[cat] == []

    # No errors
    assert result.errors == []

    # No LLM calls were made
    assert llm.call_count == 0


def test_all_errors_no_exception_complete_error_list():
    """When all LLM calls fail, no exception is thrown and errors list is complete."""
    n = 5
    llm = _StaticLlm(exc=AzureAPIError("total failure"))
    matcher = LlmFulltextMatcher(db=_StubDb(), client=llm)
    capacities = _make_capacities(n)

    result = asyncio.run(
        matcher.match_capacities(task_profile=_task_profile(), capacities=capacities)
    )

    # All categories empty
    for cat in _CATEGORIES:
        assert result.by_category[cat] == []

    # All candidates appear in errors
    assert len(result.errors) == n
    error_ids = {e.item_id for e in result.errors}
    expected_ids = {str(i + 1) for i in range(n)}
    assert error_ids == expected_ids


def test_default_max_concurrency_is_five():
    """LlmFulltextMatcher without explicit max_concurrency uses 5."""
    llm = _StaticLlm()
    matcher = LlmFulltextMatcher(db=_StubDb(), client=llm)

    assert matcher._max_concurrency == 5


def test_single_error_does_not_affect_others():
    """One failing LLM call does not prevent other candidates from being categorized."""
    n = 5
    fail_index = 2  # The 3rd call (index 2) will fail
    llm = _FailOneLlm(fail_index=fail_index)
    matcher = LlmFulltextMatcher(db=_StubDb(), client=llm)
    capacities = _make_capacities(n)

    result = asyncio.run(
        matcher.match_capacities(task_profile=_task_profile(), capacities=capacities)
    )

    # Exactly one error
    assert len(result.errors) == 1

    # The other 4 are categorized (all in "Top" per _FailOneLlm)
    categorized_items = []
    for items in result.by_category.values():
        categorized_items.extend(items)
    assert len(categorized_items) == n - 1

    # Total partition is preserved
    assert len(categorized_items) + len(result.errors) == n

    # All categorized items are in "Top"
    for item in categorized_items:
        assert item.category == "Top"