"""
Tests for POST /generate — LiteLLM gateway.
LiteLLM is mocked; no real network calls.
"""
import json
import pytest
import httpx
from unittest.mock import AsyncMock, patch
from httpx import AsyncClient, ASGITransport, Response

from main import app, PromptContext
from prompts import PROMPTS, get_prompt

_build_user_v1 = PROMPTS["v1"].build_user


def _litellm_response(candidates: list[dict]) -> Response:
    import httpx
    body = {
        "model": "tip-generator",
        "choices": [{"message": {"content": json.dumps(candidates)}}],
        "usage": {"prompt_tokens": 10, "completion_tokens": 20},
    }
    req = httpx.Request("POST", "http://litellm/chat/completions")
    return Response(200, json=body, request=req)


@pytest.mark.anyio
async def test_generate_returns_candidates():
    fake_items = [
        {"id": "tip-1", "content": "Do the overdue task now.", "rationale": "It's been waiting."},
        {"id": "tip-2", "content": "Take a 5-minute break.", "rationale": "You've been working long."},
    ]
    mock_resp = _litellm_response(fake_items)

    with patch("main.httpx.AsyncClient") as MockClient:
        instance = AsyncMock()
        instance.post = AsyncMock(return_value=mock_resp)
        instance.__aenter__ = AsyncMock(return_value=instance)
        instance.__aexit__ = AsyncMock(return_value=False)
        MockClient.return_value = instance

        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
            resp = await client.post("/generate", json={"user_id": "u1", "n": 2})

    assert resp.status_code == 200
    data = resp.json()
    assert len(data["candidates"]) == 2
    assert data["candidates"][0]["id"] == "tip-1"
    assert data["model"] == "tip-generator"


@pytest.mark.anyio
async def test_generate_strips_markdown_fence():
    fake_items = [{"id": "tip-a", "content": "Focus.", "rationale": "Now."}]
    fenced = "```json\n" + json.dumps(fake_items) + "\n```"
    body = {
        "model": "tip-generator",
        "choices": [{"message": {"content": fenced}}],
        "usage": {},
    }
    req = httpx.Request("POST", "http://litellm/chat/completions")
    mock_resp = Response(200, json=body, request=req)

    with patch("main.httpx.AsyncClient") as MockClient:
        instance = AsyncMock()
        instance.post = AsyncMock(return_value=mock_resp)
        instance.__aenter__ = AsyncMock(return_value=instance)
        instance.__aexit__ = AsyncMock(return_value=False)
        MockClient.return_value = instance

        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
            resp = await client.post("/generate", json={"user_id": "u1"})

    assert resp.status_code == 200
    assert resp.json()["candidates"][0]["id"] == "tip-a"


@pytest.mark.anyio
async def test_generate_503_on_unreachable():
    import httpx as _httpx

    with patch("main.httpx.AsyncClient") as MockClient:
        instance = AsyncMock()
        instance.post = AsyncMock(side_effect=_httpx.ConnectError("refused"))
        instance.__aenter__ = AsyncMock(return_value=instance)
        instance.__aexit__ = AsyncMock(return_value=False)
        MockClient.return_value = instance

        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
            resp = await client.post("/generate", json={"user_id": "u1"})

    assert resp.status_code == 503


def test_build_prompt_includes_tasks():
    ctx = PromptContext(
        tasks=[{"content": "Write report", "priority": 4, "is_overdue": True, "due_date": "2026-04-15"}],
        hour_of_day=9,
        day_of_week=2,
    )
    prompt = _build_user_v1(ctx, n=3)
    assert "Write report" in prompt
    assert "09:00" in prompt
    assert "Generate 3 tips" in prompt


def test_build_prompt_truncates_at_five():
    tasks = [{"content": f"Task {i}", "priority": 1, "is_overdue": False, "due_date": None} for i in range(8)]
    ctx = PromptContext(tasks=tasks, hour_of_day=12)
    prompt = _build_user_v1(ctx, n=2)
    assert "Task 4" in prompt
    assert "Task 5" not in prompt


def test_build_prompt_extra_fields():
    ctx = PromptContext(tasks=[], hour_of_day=8, extra={"mood": "focused", "energy": "high"})
    prompt = _build_user_v1(ctx, n=1)
    assert "mood: focused" in prompt
    assert "energy: high" in prompt


def test_build_prompt_empty_tasks_no_task_line():
    ctx = PromptContext(tasks=[], hour_of_day=10)
    prompt = _build_user_v1(ctx, n=2)
    assert "Tasks:" not in prompt
    assert "Generate 2 tips" in prompt


def test_build_prompt_tasks_sorted_overdue_first():
    tasks = [
        {"content": "Low priority", "priority": 1, "is_overdue": False, "task_age_days": 0},
        {"content": "Overdue task", "priority": 2, "is_overdue": True, "task_age_days": 3},
    ]
    ctx = PromptContext(tasks=tasks, hour_of_day=9)
    prompt = _build_user_v1(ctx, n=2)
    assert prompt.index("Overdue task") < prompt.index("Low priority")


def test_build_prompt_includes_profile_features():
    ctx = PromptContext(
        tasks=[],
        hour_of_day=14,
        profile_features={"completion_rate_30d": 0.75, "dismiss_rate_30d": 0.1, "preferred_hour": 9},
    )
    prompt = _build_user_v1(ctx, n=1)
    assert "User profile:" in prompt
    assert "completion_rate=75%" in prompt
    assert "dismiss_rate=10%" in prompt
    assert "preferred_hour=09:00" in prompt


def test_build_prompt_no_profile_line_when_empty():
    ctx = PromptContext(tasks=[], hour_of_day=10, profile_features={})
    prompt = _build_user_v1(ctx, n=1)
    assert "User profile:" not in prompt


def test_build_prompt_profile_partial_fields():
    ctx = PromptContext(
        tasks=[],
        hour_of_day=10,
        profile_features={"completion_rate_30d": 0.5},
    )
    prompt = _build_user_v1(ctx, n=1)
    assert "completion_rate=50%" in prompt
    assert "dismiss_rate" not in prompt


@pytest.mark.anyio
async def test_generate_retry_succeeds_on_second_attempt():
    """First response is invalid JSON; second is valid. Should return 200."""
    valid_items = [{"id": "tip-ok", "content": "Retry worked.", "rationale": "Second try."}]
    bad_req = httpx.Request("POST", "http://litellm/chat/completions")
    bad_resp = Response(200, json={
        "model": "tip-generator",
        "choices": [{"message": {"content": "this is not json"}}],
        "usage": {},
    }, request=bad_req)
    good_resp = _litellm_response(valid_items)

    with patch("main.httpx.AsyncClient") as MockClient:
        instance = AsyncMock()
        instance.post = AsyncMock(side_effect=[bad_resp, good_resp])
        instance.__aenter__ = AsyncMock(return_value=instance)
        instance.__aexit__ = AsyncMock(return_value=False)
        MockClient.return_value = instance

        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
            resp = await client.post("/generate", json={"user_id": "u1", "n": 1})

    assert resp.status_code == 200
    assert resp.json()["candidates"][0]["id"] == "tip-ok"
    assert instance.post.call_count == 2
    # Retry message should include the correction suffix
    second_call_messages = instance.post.call_args_list[1][1]["json"]["messages"]
    assert any("not valid JSON" in m["content"] for m in second_call_messages)


@pytest.mark.anyio
async def test_generate_502_after_all_retries_exhausted():
    """All attempts return invalid JSON → 502."""
    bad_req = httpx.Request("POST", "http://litellm/chat/completions")

    def _bad_resp():
        return Response(200, json={
            "model": "tip-generator",
            "choices": [{"message": {"content": "not json at all"}}],
            "usage": {},
        }, request=bad_req)

    from main import _MAX_GENERATE_RETRIES
    responses = [_bad_resp() for _ in range(1 + _MAX_GENERATE_RETRIES)]

    with patch("main.httpx.AsyncClient") as MockClient:
        instance = AsyncMock()
        instance.post = AsyncMock(side_effect=responses)
        instance.__aenter__ = AsyncMock(return_value=instance)
        instance.__aexit__ = AsyncMock(return_value=False)
        MockClient.return_value = instance

        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
            resp = await client.post("/generate", json={"user_id": "u1"})

    assert resp.status_code == 502
    assert "retries" in resp.json()["detail"]


@pytest.mark.anyio
async def test_generate_502_on_upstream_http_error():
    """LiteLLM returns 500 → HTTPStatusError → 502."""
    err_req = httpx.Request("POST", "http://litellm/chat/completions")
    err_resp = Response(500, text="internal error", request=err_req)

    with patch("main.httpx.AsyncClient") as MockClient:
        instance = AsyncMock()
        instance.post = AsyncMock(side_effect=httpx.HTTPStatusError(
            "500", request=err_req, response=err_resp
        ))
        instance.__aenter__ = AsyncMock(return_value=instance)
        instance.__aexit__ = AsyncMock(return_value=False)
        MockClient.return_value = instance

        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
            resp = await client.post("/generate", json={"user_id": "u1"})

    assert resp.status_code == 502
    assert "LiteLLM error" in resp.json()["detail"]


def test_parse_llm_json_bare_fence():
    from main import _parse_llm_json
    raw = "```\n[{\"id\":\"x\",\"content\":\"hi\"}]\n```"
    items = _parse_llm_json(raw)
    assert items[0]["id"] == "x"


def test_parse_llm_json_no_fence():
    from main import _parse_llm_json
    raw = '[{"id":"plain","content":"no fence"}]'
    items = _parse_llm_json(raw)
    assert items[0]["id"] == "plain"


def test_parse_llm_json_raises_on_invalid():
    from main import _parse_llm_json
    with pytest.raises((ValueError, Exception)):
        _parse_llm_json("this is not json")


# ── Prompt registry / selection (#84) ──────────────────────────────────────

def test_prompt_registry_contains_expected_versions():
    assert set(PROMPTS.keys()) >= {"v1", "v2-mentor", "v3-few-shot"}
    # v2-mentor must differ from v1 in tone — easiest assertion: different system prompt.
    assert PROMPTS["v1"].system != PROMPTS["v2-mentor"].system
    # v3-few-shot must include curated example content in its system prompt.
    assert "Examples" in PROMPTS["v3-few-shot"].system


def test_get_prompt_unknown_raises_keyerror():
    with pytest.raises(KeyError):
        get_prompt("does-not-exist")


def test_get_prompt_default_when_none():
    p = get_prompt(None)
    assert p.version == "v1"  # current DEFAULT_PROMPT_VERSION


@pytest.mark.anyio
async def test_generate_echoes_selected_prompt_version():
    """Server should report back which prompt_version it actually used."""
    fake_items = [{"id": "tip-1", "content": "x", "rationale": "y"}]
    mock_resp = _litellm_response(fake_items)

    with patch("main.httpx.AsyncClient") as MockClient:
        instance = AsyncMock()
        instance.post = AsyncMock(return_value=mock_resp)
        instance.__aenter__ = AsyncMock(return_value=instance)
        instance.__aexit__ = AsyncMock(return_value=False)
        MockClient.return_value = instance

        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
            resp = await client.post(
                "/generate",
                json={"user_id": "u1", "n": 1, "prompt_version": "v2-mentor"},
            )

    assert resp.status_code == 200
    assert resp.json()["prompt_version"] == "v2-mentor"


@pytest.mark.anyio
async def test_generate_passes_profile_features_to_prompt():
    """profile_features from GenerateRequest should appear in the user message sent to LiteLLM."""
    fake_items = [{"id": "tip-1", "content": "x", "rationale": "y"}]
    mock_resp = _litellm_response(fake_items)
    captured_payload: list[dict] = []

    async def _capture(url, *, json, headers):
        captured_payload.append(json)
        return mock_resp

    with patch("main.httpx.AsyncClient") as MockClient:
        instance = AsyncMock()
        instance.post = AsyncMock(side_effect=_capture)
        instance.__aenter__ = AsyncMock(return_value=instance)
        instance.__aexit__ = AsyncMock(return_value=False)
        MockClient.return_value = instance

        async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
            resp = await client.post("/generate", json={
                "user_id": "u1",
                "n": 1,
                "profile_features": {"completion_rate_30d": 0.8, "preferred_hour": 10},
            })

    assert resp.status_code == 200
    user_msg = captured_payload[0]["messages"][1]["content"]
    assert "User profile:" in user_msg
    assert "completion_rate=80%" in user_msg
    assert "preferred_hour=10:00" in user_msg


@pytest.mark.anyio
async def test_generate_422_on_unknown_prompt_version():
    async with AsyncClient(transport=ASGITransport(app=app), base_url="http://test") as client:
        resp = await client.post(
            "/generate",
            json={"user_id": "u1", "n": 1, "prompt_version": "nonsense"},
        )
    assert resp.status_code == 422
    assert "Unknown prompt_version" in resp.json()["detail"]