"""Unit tests for the AI 改写 prompt builder (app.gateway.routers.writing).

Focus: the 仿写 (imitate) action injects the reference sample into the prompt,
and existing actions are unaffected.
"""

from pathlib import Path
from types import SimpleNamespace

import pytest

from app.gateway.routers.writing import (
    _REFERENCE_MAX_CHARS,
    RewriteRequest,
    SelectionInfo,
    _release_document_rewrite,
    _reserve_document_rewrite,
    build_rewrite_messages,
)


def _req(**kwargs) -> RewriteRequest:
    base = {
        "selection": SelectionInfo(**{"from": 0, "to": 4, "text": "原始文字"}),
    }
    base.update(kwargs)
    return RewriteRequest(**base)


def test_imitate_injects_reference_text():
    body = _req(action="imitate", reference_text="这是一段范文，节奏明快，排比有力。")
    action, messages = build_rewrite_messages(body)

    assert action == "imitate"
    human = messages[1].content
    assert "范文" in human
    assert "这是一段范文，节奏明快，排比有力。" in human
    assert "原始文字" in human


def test_imitate_without_reference_has_no_reference_block():
    body = _req(action="imitate", reference_text="   ")
    action, messages = build_rewrite_messages(body)

    assert action == "imitate"
    # No reference → the 范文 block is not appended
    assert "【范文】" not in messages[1].content


def test_imitate_reference_is_truncated():
    long_ref = "甲" * (_REFERENCE_MAX_CHARS + 500)
    body = _req(action="imitate", reference_text=long_ref)
    _, messages = build_rewrite_messages(body)

    human = messages[1].content
    # The reference is capped — the 500 extra chars are dropped
    assert human.count("甲") == _REFERENCE_MAX_CHARS


def test_polish_action_unaffected_by_reference_field():
    # A stray reference_text on a non-imitate action must be ignored
    body = _req(action="polish", reference_text="不应出现的范文")
    action, messages = build_rewrite_messages(body)

    assert action == "polish"
    assert "范文" not in messages[1].content
    assert "不应出现的范文" not in messages[1].content


def test_unknown_action_falls_back_to_polish():
    body = _req(action="not-a-real-action")
    action, _ = build_rewrite_messages(body)
    assert action == "polish"


def test_imitate_follow_up_preserves_reference_and_previous_result():
    body = _req(
        action="imitate",
        reference_text="范文样例",
        previous_result="上一版仿写结果",
        follow_up_instruction="再正式一点",
    )
    _, messages = build_rewrite_messages(body)

    # system, human(original w/ reference), ai(previous), human(follow-up)
    assert len(messages) == 4
    assert "范文样例" in messages[1].content
    assert messages[2].content == "上一版仿写结果"
    assert messages[3].content == "再正式一点"


@pytest.mark.asyncio
async def test_full_document_rewrite_reservation_rejects_a_second_live_request(tmp_path: Path):
    """Two streams must never generate competing commits for one real file."""
    path = tmp_path / "report.md"
    path.write_text("# report", encoding="utf-8")

    assert await _reserve_document_rewrite(path) is True
    try:
        assert await _reserve_document_rewrite(path) is False
    finally:
        await _release_document_rewrite(path)

    assert await _reserve_document_rewrite(path) is True
    await _release_document_rewrite(path)


@pytest.mark.asyncio
async def test_full_document_rewrite_keeps_committed_file_when_undo_snapshot_fails(
    monkeypatch,
    tmp_path: Path,
):
    """Undo persistence is best effort and must not restore a valid rewrite."""
    from app.gateway.routers import writing

    path = tmp_path / "report.md"
    path.write_text("# 原文\n\n正文", encoding="utf-8")

    class _Model:
        async def astream(self, *_args, **_kwargs):
            yield "# 改写后\n\n新正文"

    class _BrokenVersionStore:
        async def create(self, **_kwargs):
            raise RuntimeError("version store unavailable")

    class _Config:
        models: list[object] = []

        @staticmethod
        def get_model_config(_name):
            return None

    async def resolve_path(*_args):
        return path

    async def current_user(*_args):
        return "user-a"

    async def requirements(*_args, **_kwargs):
        yield "保留事实。"

    monkeypatch.setattr(writing, "aresolve_thread_virtual_path", resolve_path)
    monkeypatch.setattr(writing, "get_current_user", current_user)
    monkeypatch.setattr(writing, "create_chat_model", lambda **_kwargs: _Model())
    monkeypatch.setattr(writing, "_astream_rewrite_requirements", requirements)
    monkeypatch.setattr(writing, "_extract_chunk_parts", lambda chunk: ("", chunk))
    response = await writing.rewrite_document(
        body=writing.DocumentRewriteRequest(
            threadId="thread-a",
            path="/mnt/user-data/report.md",
            instruction="统一表达风格",
        ),
        request=SimpleNamespace(
            _deerflow_test_bypass_auth=True,
            app=SimpleNamespace(state=SimpleNamespace(document_rewrite_version_store=_BrokenVersionStore())),
        ),
        config=_Config(),
    )

    events = "".join([frame async for frame in response.body_iterator])

    assert path.read_text(encoding="utf-8") == "# 改写后\n\n新正文"
    assert "event: committed" in events
    assert '"versionSnapshotFailed": true' in events
    assert "event: error" not in events