"""Chunker 切分器的单元测试"""

from app.core.chunker import Chunker


class TestStructuredChunking:
    """结构化文档按标题树切分"""

    def test_split_by_sections_and_section_path(self):
        """按 section 切分，section_path 为祖先标题链"""
        text = (
            "# 安装指南\n这是简介内容，介绍安装流程。\n\n"
            "## 环境准备\n准备 Python 环境与依赖。\n\n"
            "## 安装步骤\n执行安装命令完成部署。"
        )
        chunks = Chunker(max_chars=30).chunk(text, "doc-1")

        assert [c.chunk_index for c in chunks] == [0, 1, 2]
        assert [c.section_path for c in chunks] == ["安装指南", "安装指南 / 环境准备", "安装指南 / 安装步骤"]
        # chunk 文本含所属标题行本身
        assert chunks[0].text.startswith("# 安装指南")
        assert chunks[1].text.startswith("## 环境准备")
        assert chunks[2].text.startswith("## 安装步骤")
        assert all(c.doc_id == "doc-1" for c in chunks)

    def test_preamble_before_first_heading(self):
        """首个标题前的引导正文归入空 section_path 的 chunk"""
        text = "无标题的引导内容，描述文档主题。\n# 第一章\n章节正文内容。"
        chunks = Chunker(max_chars=20).chunk(text, "doc-1")

        assert len(chunks) == 2
        assert chunks[0].section_path == ""
        assert chunks[0].text == "无标题的引导内容，描述文档主题。"
        assert chunks[1].section_path == "第一章"

    def test_sibling_sections_reset_path(self):
        """同级标题弹栈，section_path 不含上一分支"""
        text = "# 甲\n内容甲。\n## 甲一\n内容甲一。\n# 乙\n内容乙。"
        chunks = Chunker(max_chars=20).chunk(text, "doc-1")

        assert [c.section_path for c in chunks] == ["甲", "甲 / 甲一", "乙"]


class TestLongSectionSplitting:
    """超长 section 二次切分"""

    def test_long_section_split_by_paragraphs(self):
        """超长 section 按空行段落累加切分，同 section 的 chunk 共享 section_path"""
        para1 = "第一段内容，" * 6  # 36 字符
        para2 = "第二段内容，" * 6
        text = f"# 大章节\n{para1}\n\n{para2}"
        chunks = Chunker(max_chars=60).chunk(text, "doc-1")

        assert len(chunks) == 2
        assert [c.chunk_index for c in chunks] == [0, 1]
        assert all(c.section_path == "大章节" for c in chunks)
        assert all(len(c.text) <= 60 for c in chunks)
        assert chunks[0].text.startswith("# 大章节")
        assert para1 in chunks[0].text
        assert para2 in chunks[1].text

    def test_long_paragraph_hard_split(self):
        """单段落仍超长时按 max_chars 硬切"""
        long_para = "长" * 150
        text = f"# 章节\n{long_para}"
        chunks = Chunker(max_chars=50).chunk(text, "doc-1")

        # section 文本为 "# 章节\n" + 150 字 = 156 字符，硬切为 4 段
        assert len(chunks) == 4
        assert [c.chunk_index for c in chunks] == [0, 1, 2, 3]
        assert all(len(c.text) <= 50 for c in chunks)
        assert all(c.section_path == "章节" for c in chunks)
        assert chunks[0].text.startswith("# 章节")


class TestPlainTextChunking:
    """无结构文本按段落切分"""

    def test_split_by_paragraphs(self):
        """按空行段落累加切分，section_path 为空"""
        para = "段落内容，" * 5  # 25 字符
        text = f"{para}\n\n{para}\n\n{para}"
        chunks = Chunker(max_chars=55).chunk(text, "doc-1")

        # 两段累加 52 字符 ≤ 55，再加一段超限，故切为 2 块
        assert len(chunks) == 2
        assert [c.chunk_index for c in chunks] == [0, 1]
        assert all(c.section_path == "" for c in chunks)
        assert all(len(c.text) <= 55 for c in chunks)

    def test_long_plain_text_hard_split(self):
        """无结构单段落超长时硬切"""
        text = "字" * 120
        chunks = Chunker(max_chars=50).chunk(text, "doc-1")

        assert len(chunks) == 3
        assert all(len(c.text) <= 50 for c in chunks)
        assert all(c.section_path == "" for c in chunks)


class TestShortAndEmptyText:
    """短文本与空文本"""

    def test_short_text_single_chunk(self):
        """全文不超过 max_chars 时整篇单 chunk"""
        chunks = Chunker(max_chars=100).chunk("# 标题\n短文本内容", "doc-1")

        assert len(chunks) == 1
        assert chunks[0].chunk_index == 0
        assert chunks[0].text == "# 标题\n短文本内容"
        assert chunks[0].section_path == ""

    def test_empty_text_returns_empty(self):
        assert Chunker(max_chars=100).chunk("", "doc-1") == []
        assert Chunker(max_chars=100).chunk("   \n  ", "doc-1") == []


class TestChunkIndexContinuity:
    """chunk_index 跨 section 连续递增"""

    def test_indices_continuous_across_sections(self):
        para = "内容段落，" * 6  # 30 字符
        text = f"# 第一章\n{para}\n\n{para}\n# 第二章\n{para}\n\n{para}"
        chunks = Chunker(max_chars=50).chunk(text, "doc-1")

        # 每个 section（标题行 + 两段）超 50，各切为 2 块，共 4 块
        assert len(chunks) == 4
        assert [c.chunk_index for c in chunks] == [0, 1, 2, 3]
        assert chunks[0].section_path == chunks[1].section_path == "第一章"
        assert chunks[2].section_path == chunks[3].section_path == "第二章"