table_merge.py

# Copyright (c) Opendatalab. All rights reserved.

from loguru import logger
from bs4 import BeautifulSoup

from mineru.utils.enum_class import BlockType, SplitFlag


def full_to_half(text: str) -> str:
    """Convert full-width characters to half-width characters using code point manipulation.

    Args:
        text: String containing full-width characters

    Returns:
        String with full-width characters converted to half-width
    """
    result = []
    for char in text:
        code = ord(char)
        # Full-width letters, numbers and punctuation (FF01-FF5E)
        if 0xFF01 <= code <= 0xFF5E:
            result.append(chr(code - 0xFEE0))  # Shift to ASCII range
        else:
            result.append(char)
    return ''.join(result)


def calculate_table_total_columns(soup):
    """计算表格的总列数，通过分析整个表格结构来处理rowspan和colspan

    Args:
        soup: BeautifulSoup解析的表格

    Returns:
        int: 表格的总列数
    """
    rows = soup.find_all("tr")
    if not rows:
        return 0

    # 创建一个矩阵来跟踪每个位置的占用情况
    max_cols = 0
    occupied = {}  # {row_idx: {col_idx: True}}

    for row_idx, row in enumerate(rows):
        col_idx = 0
        cells = row.find_all(["td", "th"])

        if row_idx not in occupied:
            occupied[row_idx] = {}

        for cell in cells:
            # 找到下一个未被占用的列位置
            while col_idx in occupied[row_idx]:
                col_idx += 1

            colspan = int(cell.get("colspan", 1))
            rowspan = int(cell.get("rowspan", 1))

            # 标记被这个单元格占用的所有位置
            for r in range(row_idx, row_idx + rowspan):
                if r not in occupied:
                    occupied[r] = {}
                for c in range(col_idx, col_idx + colspan):
                    occupied[r][c] = True

            col_idx += colspan
            max_cols = max(max_cols, col_idx)

    return max_cols


def calculate_row_columns(row):
    """
    计算表格行的实际列数，考虑colspan属性

    Args:
        row: BeautifulSoup的tr元素对象

    Returns:
        int: 行的实际列数
    """
    cells = row.find_all(["td", "th"])
    column_count = 0

    for cell in cells:
        colspan = int(cell.get("colspan", 1))
        column_count += colspan

    return column_count


def calculate_visual_columns(row):
    """
    计算表格行的视觉列数（实际td/th单元格数量，不考虑colspan）

    Args:
        row: BeautifulSoup的tr元素对象

    Returns:
        int: 行的视觉列数（实际单元格数）
    """
    cells = row.find_all(["td", "th"])
    return len(cells)


def detect_table_headers(soup1, soup2, max_header_rows=5):
    """
    检测并比较两个表格的表头

    Args:
        soup1: 第一个表格的BeautifulSoup对象
        soup2: 第二个表格的BeautifulSoup对象
        max_header_rows: 最大可能的表头行数

    Returns:
        tuple: (表头行数, 表头是否一致, 表头文本列表)
    """
    rows1 = soup1.find_all("tr")
    rows2 = soup2.find_all("tr")

    min_rows = min(len(rows1), len(rows2), max_header_rows)
    header_rows = 0
    headers_match = True
    header_texts = []

    for i in range(min_rows):
        # 提取当前行的所有单元格
        cells1 = rows1[i].find_all(["td", "th"])
        cells2 = rows2[i].find_all(["td", "th"])

        # 检查两行的结构和内容是否一致
        structure_match = True

        # 首先检查单元格数量
        if len(cells1) != len(cells2):
            structure_match = False
        else:
            # 然后检查单元格的属性和内容
            for cell1, cell2 in zip(cells1, cells2):
                colspan1 = int(cell1.get("colspan", 1))
                rowspan1 = int(cell1.get("rowspan", 1))
                colspan2 = int(cell2.get("colspan", 1))
                rowspan2 = int(cell2.get("rowspan", 1))

                text1 = full_to_half(cell1.get_text().strip())
                text2 = full_to_half(cell2.get_text().strip())

                if colspan1 != colspan2 or rowspan1 != rowspan2 or text1 != text2:
                    structure_match = False
                    break

        if structure_match:
            header_rows += 1
            row_texts = [full_to_half(cell.get_text().strip()) for cell in cells1]
            header_texts.append(row_texts)  # 添加表头文本
        else:
            headers_match = header_rows > 0  # 只有当至少匹配了一行时，才认为表头匹配
            break

    # 如果没有找到匹配的表头行，则返回失败
    if header_rows == 0:
        headers_match = False

    return header_rows, headers_match, header_texts


def can_merge_tables(current_table_block, previous_table_block):
    """判断两个表格是否可以合并"""
    # 检查表格是否有caption和footnote
    if any(block["type"] == BlockType.TABLE_CAPTION for block in current_table_block["blocks"]):
        return False, None, None, None, None

    if any(block["type"] == BlockType.TABLE_FOOTNOTE for block in previous_table_block["blocks"]):
        return False, None, None, None, None

    # 获取两个表格的HTML内容
    current_html = ""
    previous_html = ""

    for block in current_table_block["blocks"]:
        if (block["type"] == BlockType.TABLE_BODY and block["lines"] and block["lines"][0]["spans"]):
            current_html = block["lines"][0]["spans"][0].get("html", "")

    for block in previous_table_block["blocks"]:
        if (block["type"] == BlockType.TABLE_BODY and block["lines"] and block["lines"][0]["spans"]):
            previous_html = block["lines"][0]["spans"][0].get("html", "")

    if not current_html or not previous_html:
        return False, None, None, None, None

    # 检查表格宽度差异
    x0_t1, y0_t1, x1_t1, y1_t1 = current_table_block["bbox"]
    x0_t2, y0_t2, x1_t2, y1_t2 = previous_table_block["bbox"]
    table1_width = x1_t1 - x0_t1
    table2_width = x1_t2 - x0_t2

    if abs(table1_width - table2_width) / min(table1_width, table2_width) >= 0.1:
        return False, None, None, None, None

    # 解析HTML并检查表格结构
    soup1 = BeautifulSoup(previous_html, "html.parser")
    soup2 = BeautifulSoup(current_html, "html.parser")

    # 检查整体列数匹配
    table_cols1 = calculate_table_total_columns(soup1)
    table_cols2 = calculate_table_total_columns(soup2)
    # logger.debug(f"Table columns - Previous: {table_cols1}, Current: {table_cols2}")
    tables_match = table_cols1 == table_cols2

    # 检查首末行列数匹配
    rows_match = check_rows_match(soup1, soup2)

    return (tables_match or rows_match), soup1, soup2, current_html, previous_html


def check_rows_match(soup1, soup2):
    """检查表格行是否匹配"""
    rows1 = soup1.find_all("tr")
    rows2 = soup2.find_all("tr")

    if not (rows1 and rows2):
        return False

    # 获取第一个表的最后一行数据行
    last_row = None
    for row in reversed(rows1):
        if row.find_all(["td", "th"]):
            last_row = row
            break

    # 检测表头行数，以便获取第二个表的首个数据行
    header_count, _, _ = detect_table_headers(soup1, soup2)

    # 获取第二个表的首个数据行
    first_data_row = None
    if len(rows2) > header_count:
        first_data_row = rows2[header_count]  # 第一个非表头行

    if not (last_row and first_data_row):
        return False

    # 计算实际列数（考虑colspan）和视觉列数
    last_row_cols = calculate_row_columns(last_row)
    first_row_cols = calculate_row_columns(first_data_row)
    last_row_visual_cols = calculate_visual_columns(last_row)
    first_row_visual_cols = calculate_visual_columns(first_data_row)

    # logger.debug(f"行列数 - 前表最后一行: {last_row_cols}(视觉列数:{last_row_visual_cols}), 当前表首行: {first_row_cols}(视觉列数:{first_row_visual_cols})")

    # 同时考虑实际列数匹配和视觉列数匹配
    return last_row_cols == first_row_cols or last_row_visual_cols == first_row_visual_cols


def perform_table_merge(soup1, soup2, previous_table_block, wait_merge_table_footnotes):
    """执行表格合并操作"""
    # 检测表头有几行，并确认表头内容是否一致
    header_count, headers_match, header_texts = detect_table_headers(soup1, soup2)
    # logger.debug(f"检测到表头行数: {header_count}, 表头匹配: {headers_match}")
    # logger.debug(f"表头内容: {header_texts}")

    # 找到第一个表格的tbody，如果没有则查找table元素
    tbody1 = soup1.find("tbody") or soup1.find("table")

    # 找到第二个表格的tbody，如果没有则查找table元素
    tbody2 = soup2.find("tbody") or soup2.find("table")

    # 将第二个表格的行添加到第一个表格中
    if tbody1 and tbody2:
        rows2 = soup2.find_all("tr")
        # 将第二个表格的行添加到第一个表格中（跳过表头行）
        for row in rows2[header_count:]:
            # 从原来的位置移除行，并添加到第一个表格中
            row.extract()
            tbody1.append(row)

    # 添加待合并表格的footnote到前一个表格中
    for table_footnote in wait_merge_table_footnotes:
        temp_table_footnote = table_footnote.copy()
        temp_table_footnote[SplitFlag.CROSS_PAGE] = True
        previous_table_block["blocks"].append(temp_table_footnote)

    return str(soup1)


def merge_table(page_info_list):
    """合并跨页表格"""
    # 倒序遍历每一页
    for page_idx in range(len(page_info_list) - 1, -1, -1):
        # 跳过第一页，因为它没有前一页
        if page_idx == 0:
            continue

        page_info = page_info_list[page_idx]
        previous_page_info = page_info_list[page_idx - 1]

        # 检查当前页是否有表格块
        if not (page_info["para_blocks"] and page_info["para_blocks"][0]["type"] == BlockType.TABLE):
            continue

        current_table_block = page_info["para_blocks"][0]

        # 检查上一页是否有表格块
        if not (previous_page_info["para_blocks"] and previous_page_info["para_blocks"][-1]["type"] == BlockType.TABLE):
            continue

        previous_table_block = previous_page_info["para_blocks"][-1]

        # 收集待合并表格的footnote
        wait_merge_table_footnotes = [
            block for block in current_table_block["blocks"]
            if block["type"] == BlockType.TABLE_FOOTNOTE
        ]

        # 检查两个表格是否可以合并
        can_merge, soup1, soup2, current_html, previous_html = can_merge_tables(
            current_table_block, previous_table_block
        )

        if not can_merge:
            continue

        # 执行表格合并
        merged_html = perform_table_merge(
            soup1, soup2, previous_table_block, wait_merge_table_footnotes
        )

        # 更新previous_table_block的html
        for block in previous_table_block["blocks"]:
            if (block["type"] == BlockType.TABLE_BODY and block["lines"] and block["lines"][0]["spans"]):
                block["lines"][0]["spans"][0]["html"] = merged_html
                break

        # 删除当前页的table
        for block in current_table_block["blocks"]:
            block['lines'] = []
            block[SplitFlag.LINES_DELETED] = True