"""Behavior tests for `llm_json_call` / `allm_json_call` (schema-driven LLM JSON)."""

from __future__ import annotations

import httpx
import pytest
from langchain_core.messages import AIMessage
from openai import APIStatusError
from pydantic import BaseModel, Field

from app.core.langchain_llm import ensure_json_object_prompt_has_json_keyword
from app.core.llm_call import LLMCallError, allm_json_call, llm_json_call


class _SmallOut(BaseModel):
    answer: str = Field(default="")
    score: int = 0


class _SyncFakeLlm:
    def __init__(self, contents: list[str]) -> None:
        self._contents = list(contents)
        self._i = 0

    def bind(self, **_kwargs: object):
        return self

    def invoke(self, _prompt: str):
        c = self._contents[min(self._i, len(self._contents) - 1)]
        self._i += 1
        return AIMessage(content=c)

    async def ainvoke(self, _prompt: str):
        return self.invoke(_prompt)


class _CapturePromptLlm:
    """Records the prompt passed to ``invoke`` (after ``bind`` noop)."""

    def __init__(self, content: str) -> None:
        self.content = content
        self.last_prompt: str | None = None

    def bind(self, **_kwargs: object):
        return self

    def invoke(self, prompt: str):
        self.last_prompt = prompt
        return AIMessage(content=self.content)

    async def ainvoke(self, prompt: str):
        return self.invoke(prompt)


def test_ensure_json_object_prompt_appends_when_no_json_substring() -> None:
    out = ensure_json_object_prompt_has_json_keyword("仅中文，无英文字样")
    assert "仅中文" in out
    assert "json" in out.casefold()


def test_ensure_json_object_prompt_unchanged_when_json_present() -> None:
    s = "只输出 JSON：{}"
    assert ensure_json_object_prompt_has_json_keyword(s) is s


def test_llm_json_call_injects_json_keyword_for_api_when_missing() -> None:
    llm = _CapturePromptLlm('{"answer": "ok", "score": 2}')
    llm_json_call(
        llm,
        '你是助手。输出：{"x":1}',
        _SmallOut,
        max_tokens=32,
        agent="test_agent",
    )
    assert llm.last_prompt is not None
    # 用户内容里含 JSON 示例但无字母 json，仍应追加合规后缀
    assert "json" in llm.last_prompt.casefold()


def test_llm_json_call_success() -> None:
    llm = _SyncFakeLlm(['{"answer": "ok", "score": 2}'])
    out = llm_json_call(
        llm,
        "prompt",
        _SmallOut,
        max_tokens=32,
        agent="test_agent",
    )
    assert out.answer == "ok"
    assert out.score == 2


def test_llm_json_call_empty_retry_then_success() -> None:
    llm = _SyncFakeLlm(["", '{"answer": "retry", "score": 0}'])
    out = llm_json_call(
        llm,
        "p",
        _SmallOut,
        max_tokens=8,
        agent="t",
    )
    assert out.answer == "retry"
    assert llm._i == 2


def test_llm_json_call_compat_strip() -> None:
    raw = '```json\n{"answer": "fenced", "score": 1}\n```'
    llm = _SyncFakeLlm([raw])
    out = llm_json_call(llm, "p", _SmallOut, max_tokens=8, agent="t")
    assert out.answer == "fenced"


def test_llm_json_call_validation_fallback() -> None:
    llm = _SyncFakeLlm(['{"answer": "x", "score": "not_an_int"}'])
    out = llm_json_call(
        llm,
        "p",
        _SmallOut,
        max_tokens=8,
        agent="t",
        fallback_factory=lambda: _SmallOut(answer="fb"),
    )
    assert out.answer == "fb"


def test_llm_json_call_no_fallback_raises() -> None:
    llm = _SyncFakeLlm(['{"answer": "x", "score": "not_an_int"}'])
    with pytest.raises(LLMCallError) as ei:
        llm_json_call(llm, "p", _SmallOut, max_tokens=8, agent="t")
    assert ei.value.kind == "validation"


def _api_status_402() -> APIStatusError:
    req = httpx.Request("POST", "https://api.deepseek.com/v1/chat/completions")
    resp = httpx.Response(
        402, request=req, json={"error": {"message": "Insufficient balance"}}
    )
    return APIStatusError("Payment required", response=resp, body=resp.json())


class _LlmInvokeRaises:
    def bind(self, **_kwargs: object):
        return self

    def invoke(self, _prompt: str) -> object:
        raise _api_status_402()

    async def ainvoke(self, _prompt: str) -> object:
        return self.invoke(_prompt)


def test_llm_json_call_openai_status_maps_to_friendly_chinese() -> None:
    with pytest.raises(LLMCallError) as ei:
        llm_json_call(
            _LlmInvokeRaises(),
            "p",
            _SmallOut,
            max_tokens=8,
            agent="t",
        )
    assert ei.value.kind == "invoke"
    s = str(ei.value)
    assert "402" in s
    assert "余额" in s
    assert "DeepSeek" in s


@pytest.mark.asyncio
async def test_allm_json_call_parity_with_sync() -> None:
    llm = _SyncFakeLlm(['{"answer": "async", "score": 7}'])
    out = await allm_json_call(llm, "p", _SmallOut, max_tokens=8, agent="at")
    assert out.answer == "async"
    assert out.score == 7


@pytest.mark.asyncio
async def test_allm_json_call_fallback_on_decode() -> None:
    llm = _SyncFakeLlm(["not json at all {{{"])
    out = await allm_json_call(
        llm,
        "p",
        _SmallOut,
        max_tokens=8,
        agent="at",
        fallback_factory=lambda: _SmallOut(answer="dec"),
    )
    assert out.answer == "dec"