"""Markdown 后处理模块，包含所有格式共享的工具函数。"""

import re
import zipfile
from typing import List, Optional, Tuple

IMAGE_PATTERN = re.compile(r"!\[[^\]]*\]\([^)]+\)")
_CONSECUTIVE_BLANK_LINES = re.compile(r"\n{3,}")

# unstructured 噪声匹配: pptx 中的 RGB 颜色值（如 "R:255 G:128 B:0"）
_RGB_PATTERN = re.compile(r"^R:\d+\s+G:\d+\s+B:\d+$")
# unstructured 噪声匹配: 破折号页码（如 "— 3 —"）
_PAGE_NUMBER_PATTERN = re.compile(r"^—\s*\d+\s*—$")


def parse_with_markitdown(
    file_path: str,
) -> Tuple[Optional[str], Optional[str]]:
    """使用 MarkItDown 库解析文件"""
    try:
        from markitdown import MarkItDown

        md = MarkItDown()
        result = md.convert(file_path)
        if not result.text_content.strip():
            return None, "文档为空"
        return result.text_content, None
    except ImportError:
        return None, "MarkItDown 库未安装"
    except Exception as e:
        return None, f"MarkItDown 解析失败: {str(e)}"


def parse_with_docling(file_path: str) -> Tuple[Optional[str], Optional[str]]:
    """使用 docling 库解析文件"""
    try:
        from docling.document_converter import DocumentConverter
    except ImportError:
        return None, "docling 库未安装"

    try:
        converter = DocumentConverter()
        result = converter.convert(file_path)
        markdown_content = result.document.export_to_markdown()
        if not markdown_content.strip():
            return None, "文档为空"
        return markdown_content, None
    except Exception as e:
        return None, f"docling 解析失败: {str(e)}"


def build_markdown_table(rows_data: List[List[str]]) -> str:
    """将二维列表转换为 Markdown 表格格式"""
    if not rows_data or not rows_data[0]:
        return ""

    md_lines = []
    for i, row_data in enumerate(rows_data):
        row_text = [cell if cell else "" for cell in row_data]
        md_lines.append("| " + " | ".join(row_text) + " |")
        if i == 0:
            md_lines.append("| " + " | ".join(["---"] * len(row_text)) + " |")
    return "\n".join(md_lines) + "\n\n"


def flush_list_stack(list_stack: List[str], target: List[str]) -> None:
    """将列表堆栈中的非空项添加到目标列表并清空堆栈"""
    for item in list_stack:
        if item:
            target.append(item + "\n")
    list_stack.clear()


def safe_open_zip(zip_file: zipfile.ZipFile, name: str) -> Optional[zipfile.ZipExtFile]:
    """安全地从 ZipFile 中打开文件，防止路径遍历攻击"""
    if not name:
        return None
    if name.startswith("/") or name.startswith(".."):
        return None
    if "/../" in name or name.endswith("/.."):
        return None
    if "\\" in name:
        return None
    return zip_file.open(name)


def normalize_markdown_whitespace(content: str) -> str:
    """规范化 Markdown 空白字符，保留单行空行"""
    return _CONSECUTIVE_BLANK_LINES.sub("\n\n", content)


def remove_markdown_images(markdown_text: str) -> str:
    """移除 Markdown 文本中的图片标记"""
    return IMAGE_PATTERN.sub("", markdown_text)


def get_heading_level(line: str) -> int:
    """获取 Markdown 行的标题级别（1-6），非标题返回 0"""
    stripped = line.lstrip()
    if not stripped.startswith("#"):
        return 0
    without_hash = stripped.lstrip("#")
    level = len(stripped) - len(without_hash)
    if not (1 <= level <= 6):
        return 0
    if len(stripped) == level:
        return level
    if stripped[level] != " ":
        return 0
    return level


def extract_titles(markdown_text: str) -> List[str]:
    """提取 markdown 文本中的所有标题行（1-6级）"""
    title_lines = []
    for line in markdown_text.split("\n"):
        if get_heading_level(line) > 0:
            title_lines.append(line.lstrip())
    return title_lines


def extract_title_content(markdown_text: str, title_name: str) -> Optional[str]:
    """提取所有指定标题及其下级内容（每个包含上级标题）"""
    lines = markdown_text.split("\n")
    match_indices = []

    for i, line in enumerate(lines):
        level = get_heading_level(line)
        if level > 0:
            stripped = line.lstrip()
            title_text = stripped[level:].strip()
            if title_text == title_name:
                match_indices.append(i)

    if not match_indices:
        return None

    result_lines = []
    for match_num, idx in enumerate(match_indices):
        if match_num > 0:
            result_lines.append("\n---\n")

        target_level = get_heading_level(lines[idx])

        parent_titles = []
        current_level = target_level
        for i in range(idx - 1, -1, -1):
            line_level = get_heading_level(lines[i])
            if line_level > 0 and line_level < current_level:
                parent_titles.append(lines[i])
                current_level = line_level
                if current_level == 1:
                    break

        parent_titles.reverse()
        result_lines.extend(parent_titles)

        result_lines.append(lines[idx])
        for i in range(idx + 1, len(lines)):
            line = lines[i]
            line_level = get_heading_level(line)
            if line_level == 0 or line_level > target_level:
                result_lines.append(line)
            else:
                break

    return "\n".join(result_lines)


def search_markdown(
    content: str, pattern: str, context_lines: int = 0
) -> Optional[str]:
    """使用正则表达式搜索 markdown 文档，返回匹配结果及其上下文"""
    try:
        regex = re.compile(pattern)
    except re.error:
        return None

    lines = content.split("\n")

    non_empty_indices = []
    non_empty_to_original = {}
    for i, line in enumerate(lines):
        if line.strip():
            non_empty_indices.append(i)
            non_empty_to_original[i] = len(non_empty_indices) - 1

    matched_non_empty_indices = []
    for orig_idx in non_empty_indices:
        if regex.search(lines[orig_idx]):
            matched_non_empty_indices.append(non_empty_to_original[orig_idx])

    if not matched_non_empty_indices:
        return None

    merged_ranges = []
    current_start = matched_non_empty_indices[0]
    current_end = matched_non_empty_indices[0]

    for idx in matched_non_empty_indices[1:]:
        if idx - current_end <= context_lines * 2:
            current_end = idx
        else:
            merged_ranges.append((current_start, current_end))
            current_start = idx
            current_end = idx
    merged_ranges.append((current_start, current_end))

    results = []
    for start, end in merged_ranges:
        context_start_idx = max(0, start - context_lines)
        context_end_idx = min(len(non_empty_indices) - 1, end + context_lines)

        start_line_idx = non_empty_indices[context_start_idx]
        end_line_idx = non_empty_indices[context_end_idx]

        result_lines = [
            line
            for i, line in enumerate(lines)
            if start_line_idx <= i <= end_line_idx
        ]
        results.append("\n".join(result_lines))

    return "\n---\n".join(results)


def _unstructured_elements_to_markdown(
    elements: list, trust_titles: bool = True
) -> str:
    """将 unstructured 解析出的元素列表转换为 Markdown 文本"""
    try:
        import markdownify as md_lib
        from unstructured.documents.elements import (
            Footer,
            Header,
            Image,
            ListItem,
            PageBreak,
            PageNumber,
            Table,
            Title,
        )
    except ImportError:
        return "\n\n".join(
            el.text for el in elements if hasattr(el, "text") and el.text and el.text.strip()
        )

    skip_types = (Header, Footer, PageBreak, PageNumber)
    parts = []

    for el in elements:
        if isinstance(el, skip_types):
            continue
        text = el.text.strip() if hasattr(el, "text") else str(el).strip()
        if not text or _RGB_PATTERN.match(text) or _PAGE_NUMBER_PATTERN.match(text):
            continue

        if isinstance(el, Table):
            html = getattr(el.metadata, "text_as_html", None)
            if html:
                parts.append(md_lib.markdownify(html, strip=["img"]).strip())
            else:
                parts.append(str(el))
        elif isinstance(el, Title) and trust_titles:
            depth = getattr(el.metadata, "category_depth", None) or 1
            depth = min(max(depth, 1), 4)
            parts.append(f"{'#' * depth} {text}")
        elif isinstance(el, ListItem):
            parts.append(f"- {text}")
        elif isinstance(el, Image):
            path = getattr(el.metadata, "image_path", None) or ""
            if path:
                parts.append(f"![image]({path})")
        else:
            parts.append(text)

    return "\n\n".join(parts)