para_split_v2.py

from sklearn.cluster import DBSCAN
import numpy as np
from loguru import logger
import re
from magic_pdf.libs.boxbase import _is_in_or_part_overlap_with_area_ratio as is_in_layout
from magic_pdf.libs.ocr_content_type import ContentType, BlockType
from magic_pdf.model.magic_model import MagicModel
from magic_pdf.libs.Constants import *

LINE_STOP_FLAG = ['.', '!', '?', '。', '！', '？', "：", ":", ")", "）", ";"]
INLINE_EQUATION = ContentType.InlineEquation
INTERLINE_EQUATION = ContentType.InterlineEquation
TEXT = ContentType.Text
debug_able = False


def __get_span_text(span):
    c = span.get('content', '')
    if len(c) == 0:
        c = span.get('image_path', '')

    return c


def __detect_list_lines(lines, new_layout_bboxes, lang):
    global debug_able
    """
    探测是否包含了列表，并且把列表的行分开.
    这样的段落特点是，顶格字母大写/数字，紧跟着几行缩进的。缩进的行首字母含小写的。
    """

    def find_repeating_patterns2(lst):
        indices = []
        ones_indices = []
        i = 0
        while i < len(lst):  # Loop through the entire list
            if lst[i] == 1:  # If we encounter a '1', we might be at the start of a pattern
                start = i
                ones_in_this_interval = [i]
                i += 1
                # Traverse elements that are 1, 2 or 3, until we encounter something else
                while i < len(lst) and lst[i] in [1, 2, 3]:
                    if lst[i] == 1:
                        ones_in_this_interval.append(i)
                    i += 1
                if len(ones_in_this_interval) > 1 or (
                        start < len(lst) - 1 and ones_in_this_interval and lst[start + 1] in [2, 3]):
                    indices.append((start, i - 1))
                    ones_indices.append(ones_in_this_interval)
            else:
                i += 1
        return indices, ones_indices

    def find_repeating_patterns(lst):
        indices = []
        ones_indices = []
        i = 0
        while i < len(lst) - 1:  # 确保余下元素至少有2个
            if lst[i] == 1 and lst[i + 1] in [2, 3]:  # 额外检查以防止连续出现的1
                start = i
                ones_in_this_interval = [i]
                i += 1
                while i < len(lst) and lst[i] in [2, 3]:
                    i += 1
                # 验证下一个序列是否符合条件
                if i < len(lst) - 1 and lst[i] == 1 and lst[i + 1] in [2, 3] and lst[i - 1] in [2, 3]:
                    while i < len(lst) and lst[i] in [1, 2, 3]:
                        if lst[i] == 1:
                            ones_in_this_interval.append(i)
                        i += 1
                    indices.append((start, i - 1))
                    ones_indices.append(ones_in_this_interval)
                else:
                    i += 1
            else:
                i += 1
        return indices, ones_indices

    """===================="""

    def split_indices(slen, index_array):
        result = []
        last_end = 0

        for start, end in sorted(index_array):
            if start > last_end:
                # 前一个区间结束到下一个区间开始之间的部分标记为"text"
                result.append(('text', last_end, start - 1))
            # 区间内标记为"list"
            result.append(('list', start, end))
            last_end = end + 1

        if last_end < slen:
            # 如果最后一个区间结束后还有剩余的字符串，将其标记为"text"
            result.append(('text', last_end, slen - 1))

        return result

    """===================="""

    if lang != 'en':
        return lines, None

    total_lines = len(lines)
    line_fea_encode = []
    """
    对每一行进行特征编码，编码规则如下：
    1. 如果行顶格，且大写字母开头或者数字开头，编码为1
    2. 如果顶格，其他非大写开头编码为4
    3. 如果非顶格，首字符大写，编码为2
    4. 如果非顶格，首字符非大写编码为3
    """
    if len(lines) > 0:
        x_map_tag_dict, min_x_tag = cluster_line_x(lines)
    for l in lines:
        span_text = __get_span_text(l['spans'][0])
        if not span_text:
            line_fea_encode.append(0)
            continue
        first_char = span_text[0]
        layout = __find_layout_bbox_by_line(l['bbox'], new_layout_bboxes)
        if not layout:
            line_fea_encode.append(0)
        else:
            #
            if x_map_tag_dict[round(l['bbox'][0])] == min_x_tag:
                # if first_char.isupper() or first_char.isdigit() or not first_char.isalnum():
                if not first_char.isalnum() or if_match_reference_list(span_text):
                    line_fea_encode.append(1)
                else:
                    line_fea_encode.append(4)
            else:
                if first_char.isupper():
                    line_fea_encode.append(2)
                else:
                    line_fea_encode.append(3)

    # 然后根据编码进行分段, 选出来 1,2,3连续出现至少2次的行，认为是列表。

    list_indice, list_start_idx = find_repeating_patterns2(line_fea_encode)
    if len(list_indice) > 0:
        if debug_able:
            logger.info(f"发现了列表，列表行数：{list_indice}， {list_start_idx}")

    # TODO check一下这个特列表里缩进的行左侧是不是对齐的。
    segments = []
    for start, end in list_indice:
        for i in range(start, end + 1):
            if i > 0:
                if line_fea_encode[i] == 4:
                    if debug_able:
                        logger.info(f"列表行的第{i}行不是顶格的")
                    break
        else:
            if debug_able:
                logger.info(f"列表行的第{start}到第{end}行是列表")

    return split_indices(total_lines, list_indice), list_start_idx


def cluster_line_x(lines: list) -> dict:
    """
    对一个block内所有lines的bbox的x0聚类
    """
    min_distance = 5
    min_sample = 1
    x0_lst = np.array([[round(line['bbox'][0]), 0] for line in lines])
    x0_clusters = DBSCAN(eps=min_distance, min_samples=min_sample).fit(x0_lst)
    x0_uniq_label = np.unique(x0_clusters.labels_)
    #x1_lst = np.array([[line['bbox'][2], 0] for line in lines])
    x0_2_new_val = {}  # 存储旧值对应的新值映射
    min_x0 = round(lines[0]["bbox"][0])
    for label in x0_uniq_label:
        if label == -1:
            continue
        x0_index_of_label = np.where(x0_clusters.labels_ == label)
        x0_raw_val = x0_lst[x0_index_of_label][:, 0]
        x0_new_val = np.min(x0_lst[x0_index_of_label][:, 0])
        x0_2_new_val.update({round(raw_val): round(x0_new_val) for raw_val in x0_raw_val})
        if x0_new_val < min_x0:
            min_x0 = x0_new_val
    return x0_2_new_val, min_x0


def if_match_reference_list(text: str) -> bool:
    pattern = re.compile(r'^\d+\..*')
    if pattern.match(text):
        return True
    else:
        return False


def __valign_lines(blocks, layout_bboxes):
    """
    在一个layoutbox内对齐行的左侧和右侧。
    扫描行的左侧和右侧，如果x0, x1差距不超过一个阈值，就强行对齐到所处layout的左右两侧（和layout有一段距离）。
    3是个经验值，TODO，计算得来，可以设置为1.5个正文字符。
    """

    min_distance = 3
    min_sample = 2
    new_layout_bboxes = []

    for layout_box in layout_bboxes:
        blocks_in_layoutbox = [b for b in blocks if
                               b["type"] == BlockType.Text and is_in_layout(b['bbox'], layout_box['layout_bbox'])]
        if len(blocks_in_layoutbox) == 0 or len(blocks_in_layoutbox[0]["lines"]) == 0:
            new_layout_bboxes.append(layout_box['layout_bbox'])
            continue

        x0_lst = np.array([[line['bbox'][0], 0] for block in blocks_in_layoutbox for line in block['lines']])
        x1_lst = np.array([[line['bbox'][2], 0] for block in blocks_in_layoutbox for line in block['lines']])
        x0_clusters = DBSCAN(eps=min_distance, min_samples=min_sample).fit(x0_lst)
        x1_clusters = DBSCAN(eps=min_distance, min_samples=min_sample).fit(x1_lst)
        x0_uniq_label = np.unique(x0_clusters.labels_)
        x1_uniq_label = np.unique(x1_clusters.labels_)

        x0_2_new_val = {}  # 存储旧值对应的新值映射
        x1_2_new_val = {}
        for label in x0_uniq_label:
            if label == -1:
                continue
            x0_index_of_label = np.where(x0_clusters.labels_ == label)
            x0_raw_val = x0_lst[x0_index_of_label][:, 0]
            x0_new_val = np.min(x0_lst[x0_index_of_label][:, 0])
            x0_2_new_val.update({idx: x0_new_val for idx in x0_raw_val})
        for label in x1_uniq_label:
            if label == -1:
                continue
            x1_index_of_label = np.where(x1_clusters.labels_ == label)
            x1_raw_val = x1_lst[x1_index_of_label][:, 0]
            x1_new_val = np.max(x1_lst[x1_index_of_label][:, 0])
            x1_2_new_val.update({idx: x1_new_val for idx in x1_raw_val})

        for block in blocks_in_layoutbox:
            for line in block['lines']:
                x0, x1 = line['bbox'][0], line['bbox'][2]
                if x0 in x0_2_new_val:
                    line['bbox'][0] = int(x0_2_new_val[x0])

                if x1 in x1_2_new_val:
                    line['bbox'][2] = int(x1_2_new_val[x1])
            # 其余对不齐的保持不动

        # 由于修改了block里的line长度，现在需要重新计算block的bbox
        for block in blocks_in_layoutbox:
            if len(block["lines"]) > 0:
                block['bbox'] = [min([line['bbox'][0] for line in block['lines']]),
                                 min([line['bbox'][1] for line in block['lines']]),
                                 max([line['bbox'][2] for line in block['lines']]),
                                 max([line['bbox'][3] for line in block['lines']])]

        """新计算layout的bbox，因为block的bbox变了。"""
        layout_x0 = min([block['bbox'][0] for block in blocks_in_layoutbox])
        layout_y0 = min([block['bbox'][1] for block in blocks_in_layoutbox])
        layout_x1 = max([block['bbox'][2] for block in blocks_in_layoutbox])
        layout_y1 = max([block['bbox'][3] for block in blocks_in_layoutbox])
        new_layout_bboxes.append([layout_x0, layout_y0, layout_x1, layout_y1])

    return new_layout_bboxes


def __align_text_in_layout(blocks, layout_bboxes):
    """
    由于ocr出来的line，有时候会在前后有一段空白，这个时候需要对文本进行对齐，超出的部分被layout左右侧截断。
    """
    for layout in layout_bboxes:
        lb = layout['layout_bbox']
        blocks_in_layoutbox = [block for block in blocks if
                               block["type"] == BlockType.Text and is_in_layout(block['bbox'], lb)]
        if len(blocks_in_layoutbox) == 0:
            continue

        for block in blocks_in_layoutbox:
            for line in block.get("lines", []):
                x0, x1 = line['bbox'][0], line['bbox'][2]
                if x0 < lb[0]:
                    line['bbox'][0] = lb[0]
                if x1 > lb[2]:
                    line['bbox'][2] = lb[2]


def __common_pre_proc(blocks, layout_bboxes):
    """
    不分语言的，对文本进行预处理
    """
    # __add_line_period(blocks, layout_bboxes)
    __align_text_in_layout(blocks, layout_bboxes)
    aligned_layout_bboxes = __valign_lines(blocks, layout_bboxes)

    return aligned_layout_bboxes


def __pre_proc_zh_blocks(blocks, layout_bboxes):
    """
    对中文文本进行分段预处理
    """
    pass


def __pre_proc_en_blocks(blocks, layout_bboxes):
    """
    对英文文本进行分段预处理
    """
    pass


def __group_line_by_layout(blocks, layout_bboxes):
    """
    每个layout内的行进行聚合
    """
    # 因为只是一个block一行目前, 一个block就是一个段落
    blocks_group = []
    for lyout in layout_bboxes:
        blocks_in_layout = [block for block in blocks if is_in_layout(block['bbox'], lyout['layout_bbox'])]
        blocks_group.append(blocks_in_layout)
    return blocks_group


def __split_para_in_layoutbox(blocks_group, new_layout_bbox, lang="en"):
    """
    lines_group 进行行分段——layout内部进行分段。lines_group内每个元素是一个Layoutbox内的所有行。
    1. 先计算每个group的左右边界。
    2. 然后根据行末尾特征进行分段。
        末尾特征：以句号等结束符结尾。并且距离右侧边界有一定距离。
        且下一行开头不留空白。

    """
    list_info = []  # 这个layout最后是不是列表,记录每一个layout里是不是列表开头，列表结尾
    for blocks in blocks_group:
        is_start_list = None
        is_end_list = None
        if len(blocks) == 0:
            list_info.append([False, False])
            continue
        if blocks[0]["type"] != BlockType.Text and blocks[-1]["type"] != BlockType.Text:
            list_info.append([False, False])
            continue
        if blocks[0]["type"] != BlockType.Text:
            is_start_list = False
        if blocks[-1]["type"] != BlockType.Text:
            is_end_list = False

        lines = [line for block in blocks if
                 block["type"] == BlockType.Text for line in
                 block['lines']]
        total_lines = len(lines)
        if total_lines == 1 or total_lines == 0:
            list_info.append([False, False])
            continue
        """在进入到真正的分段之前，要对文字块从统计维度进行对齐方式的探测，
                    对齐方式分为以下：
                    1. 左对齐的文本块(特点是左侧顶格，或者左侧不顶格但是右侧顶格的行数大于非顶格的行数，顶格的首字母有大写也有小写)
                        1) 右侧对齐的行，单独成一段
                        2) 中间对齐的行，按照字体/行高聚合成一段
                    2. 左对齐的列表块（其特点是左侧顶格的行数小于等于非顶格的行数，非定格首字母会有小写，顶格90%是大写。并且左侧顶格行数大于1，大于1是为了这种模式连续出现才能称之为列表）
                        这样的文本块，顶格的为一个段落开头，紧随其后非顶格的行属于这个段落。
        """
        text_segments, list_start_line = __detect_list_lines(lines, new_layout_bbox, lang)
        """根据list_range，把lines分成几个部分

        """
        for list_start in list_start_line:
            if len(list_start) > 1:
                for i in range(0, len(list_start)):
                    index = list_start[i] - 1
                    if index >= 0:
                        if "content" in lines[index]["spans"][-1]:
                            lines[index]["spans"][-1]["content"] += '\n\n'
        layout_list_info = [False, False]  # 这个layout最后是不是列表,记录每一个layout里是不是列表开头，列表结尾
        for content_type, start, end in text_segments:
            if content_type == 'list':
                if start == 0 and is_start_list is None:
                    layout_list_info[0] = True
                if end == total_lines - 1 and is_end_list is None:
                    layout_list_info[1] = True

        list_info.append(layout_list_info)
    return list_info


def __split_para_lines(lines: list, text_blocks: list) -> list:
    text_paras = []
    other_paras = []
    text_lines = []
    for line in lines:

        spans_types = [span["type"] for span in line]
        if ContentType.Table in spans_types:
            other_paras.append([line])
            continue
        if ContentType.Image in spans_types:
            other_paras.append([line])
            continue
        if ContentType.InterlineEquation in spans_types:
            other_paras.append([line])
            continue
        text_lines.append(line)

    for block in text_blocks:
        block_bbox = block["bbox"]
        para = []
        for line in text_lines:
            bbox = line["bbox"]
            if is_in_layout(bbox, block_bbox):
                para.append(line)
        if len(para) > 0:
            text_paras.append(para)
    paras = other_paras.extend(text_paras)
    paras_sorted = sorted(paras, key=lambda x: x[0]["bbox"][1])
    return paras_sorted


def __connect_list_inter_layout(blocks_group, new_layout_bbox, layout_list_info, page_num, lang):
    global debug_able
    """
    如果上个layout的最后一个段落是列表，下一个layout的第一个段落也是列表，那么将他们连接起来。 TODO 因为没有区分列表和段落，所以这个方法暂时不实现。
    根据layout_list_info判断是不是列表。，下个layout的第一个段如果不是列表，那么看他们是否有几行都有相同的缩进。
    """
    if len(blocks_group) == 0 or len(blocks_group) == 0:  # 0的时候最后的return 会出错
        return blocks_group, [False, False]

    for i in range(1, len(blocks_group)):
        if len(blocks_group[i]) == 0 or len(blocks_group[i - 1]) == 0:
            continue
        pre_layout_list_info = layout_list_info[i - 1]
        next_layout_list_info = layout_list_info[i]
        pre_last_para = blocks_group[i - 1][-1].get("lines", [])
        next_paras = blocks_group[i]
        next_first_para = next_paras[0]

        if pre_layout_list_info[1] and not next_layout_list_info[0] and next_first_para[
            "type"] == BlockType.Text:  # 前一个是列表结尾，后一个是非列表开头，此时检测是否有相同的缩进
            if debug_able:
                logger.info(f"连接page {page_num} 内的list")
            # 向layout_paras[i] 寻找开头具有相同缩进的连续的行
            may_list_lines = []
            lines = next_first_para.get("lines", [])

            for line in lines:
                if line['bbox'][0] > __find_layout_bbox_by_line(line['bbox'], new_layout_bbox)[0]:
                    may_list_lines.append(line)
                else:
                    break
            # 如果这些行的缩进是相等的，那么连到上一个layout的最后一个段落上。
            if len(may_list_lines) > 0 and len(set([x['bbox'][0] for x in may_list_lines])) == 1:
                pre_last_para.extend(may_list_lines)
                next_first_para["lines"] = next_first_para["lines"][len(may_list_lines):]

    return blocks_group, [layout_list_info[0][0], layout_list_info[-1][1]]  # 同时还返回了这个页面级别的开头、结尾是不是列表的信息


def __connect_list_inter_page(pre_page_paras, next_page_paras, pre_page_layout_bbox, next_page_layout_bbox,
                              pre_page_list_info, next_page_list_info, page_num, lang):
    """
    如果上个layout的最后一个段落是列表，下一个layout的第一个段落也是列表，那么将他们连接起来。 TODO 因为没有区分列表和段落，所以这个方法暂时不实现。
    根据layout_list_info判断是不是列表。，下个layout的第一个段如果不是列表，那么看他们是否有几行都有相同的缩进。
    """
    if len(pre_page_paras) == 0 or len(next_page_paras) == 0:  # 0的时候最后的return 会出错
        return False
    if len(pre_page_paras[-1]) == 0 or len(next_page_paras[0]) == 0:
        return False
    if pre_page_paras[-1][-1]["type"] != BlockType.Text or next_page_paras[0][0]["type"] != BlockType.Text:
        return False
    if pre_page_list_info[1] and not next_page_list_info[0]:  # 前一个是列表结尾，后一个是非列表开头，此时检测是否有相同的缩进
        if debug_able:
            logger.info(f"连接page {page_num} 内的list")
        # 向layout_paras[i] 寻找开头具有相同缩进的连续的行
        may_list_lines = []
        next_page_first_para = next_page_paras[0][0]
        if next_page_first_para["type"] == BlockType.Text:
            lines = next_page_first_para["lines"]
            for line in lines:
                if line['bbox'][0] > __find_layout_bbox_by_line(line['bbox'], next_page_layout_bbox)[0]:
                    may_list_lines.append(line)
                else:
                    break
        # 如果这些行的缩进是相等的，那么连到上一个layout的最后一个段落上。
        if len(may_list_lines) > 0 and len(set([x['bbox'][0] for x in may_list_lines])) == 1:
            #pre_page_paras[-1].append(may_list_lines)
            # 下一页合并到上一页最后一段，打一个cross_page的标签
            for line in may_list_lines:
                for span in line["spans"]:
                    span[CROSS_PAGE] = True
            pre_page_paras[-1][-1]["lines"].extend(may_list_lines)
            next_page_first_para["lines"] = next_page_first_para["lines"][len(may_list_lines):]
            return True

    return False


def __find_layout_bbox_by_line(line_bbox, layout_bboxes):
    """
    根据line找到所在的layout
    """
    for layout in layout_bboxes:
        if is_in_layout(line_bbox, layout):
            return layout
    return None


def __connect_para_inter_layoutbox(blocks_group, new_layout_bbox):
    """
    layout之间进行分段。
    主要是计算前一个layOut的最后一行和后一个layout的第一行是否可以连接。
    连接的条件需要同时满足：
    1. 上一个layout的最后一行沾满整个行。并且没有结尾符号。
    2. 下一行开头不留空白。

    """
    connected_layout_blocks = []
    if len(blocks_group) == 0:
        return connected_layout_blocks

    connected_layout_blocks.append(blocks_group[0])
    for i in range(1, len(blocks_group)):
        try:
            if len(blocks_group[i]) == 0:
                continue
            if len(blocks_group[i - 1]) == 0:  # TODO 考虑连接问题，
                connected_layout_blocks.append(blocks_group[i])
                continue
            # text类型的段才需要考虑layout间的合并
            if blocks_group[i - 1][-1]["type"] != BlockType.Text or blocks_group[i][0]["type"] != BlockType.Text:
                connected_layout_blocks.append(blocks_group[i])
                continue
            if len(blocks_group[i - 1][-1]["lines"]) == 0 or len(blocks_group[i][0]["lines"]) == 0:
                connected_layout_blocks.append(blocks_group[i])
                continue
            pre_last_line = blocks_group[i - 1][-1]["lines"][-1]
            next_first_line = blocks_group[i][0]["lines"][0]
        except Exception as e:
            logger.error(f"page layout {i} has no line")
            continue
        pre_last_line_text = ''.join([__get_span_text(span) for span in pre_last_line['spans']])
        pre_last_line_type = pre_last_line['spans'][-1]['type']
        next_first_line_text = ''.join([__get_span_text(span) for span in next_first_line['spans']])
        next_first_line_type = next_first_line['spans'][0]['type']
        if pre_last_line_type not in [TEXT, INLINE_EQUATION] or next_first_line_type not in [TEXT, INLINE_EQUATION]:
            #connected_layout_paras.append(layout_paras[i])
            connected_layout_blocks.append(blocks_group[i])
            continue
        pre_layout = __find_layout_bbox_by_line(pre_last_line['bbox'], new_layout_bbox)
        next_layout = __find_layout_bbox_by_line(next_first_line['bbox'], new_layout_bbox)

        pre_x2_max = pre_layout[2] if pre_layout else -1
        next_x0_min = next_layout[0] if next_layout else -1

        pre_last_line_text = pre_last_line_text.strip()
        next_first_line_text = next_first_line_text.strip()
        if pre_last_line['bbox'][2] == pre_x2_max and pre_last_line_text and pre_last_line_text[
            -1] not in LINE_STOP_FLAG and \
                next_first_line['bbox'][0] == next_x0_min:  # 前面一行沾满了整个行，并且没有结尾符号.下一行没有空白开头。
            """连接段落条件成立，将前一个layout的段落和后一个layout的段落连接。"""
            #connected_layout_paras[-1][-1].extend(layout_paras[i][0])
            connected_layout_blocks[-1][-1]["lines"].extend(blocks_group[i][0]["lines"])
            #layout_paras[i].pop(0)  # 删除后一个layout的第一个段落， 因为他已经被合并到前一个layout的最后一个段落了。
            blocks_group[i][0]["lines"] = []  #删除后一个layout第一个段落中的lines，因为他已经被合并到前一个layout的最后一个段落了
            blocks_group[i][0][LINES_DELETED] = True
            # if len(layout_paras[i]) == 0:
            #     layout_paras.pop(i)
            # else:
            #     connected_layout_paras.append(layout_paras[i])
            connected_layout_blocks.append(blocks_group[i])
        else:
            """连接段落条件不成立，将前一个layout的段落加入到结果中。"""
            #connected_layout_paras.append(layout_paras[i])
            connected_layout_blocks.append(blocks_group[i])
    return connected_layout_blocks


def __connect_para_inter_page(pre_page_paras, next_page_paras, pre_page_layout_bbox, next_page_layout_bbox, page_num,
                              lang):
    """
    连接起来相邻两个页面的段落——前一个页面最后一个段落和后一个页面的第一个段落。
    是否可以连接的条件：
    1. 前一个页面的最后一个段落最后一行沾满整个行。并且没有结尾符号。
    2. 后一个页面的第一个段落第一行没有空白开头。
    """
    # 有的页面可能压根没有文字
    if len(pre_page_paras) == 0 or len(next_page_paras) == 0 or len(pre_page_paras[0]) == 0 or len(
            next_page_paras[0]) == 0:  # TODO [[]]为什么出现在pre_page_paras里？
        return False
    pre_last_block = pre_page_paras[-1][-1]
    next_first_block = next_page_paras[0][0]
    if pre_last_block["type"] != BlockType.Text or next_first_block["type"] != BlockType.Text:
        return False
    if len(pre_last_block["lines"]) == 0 or len(next_first_block["lines"]) == 0:
        return False
    pre_last_para = pre_last_block["lines"]
    next_first_para = next_first_block["lines"]
    pre_last_line = pre_last_para[-1]
    next_first_line = next_first_para[0]
    pre_last_line_text = ''.join([__get_span_text(span) for span in pre_last_line['spans']])
    pre_last_line_type = pre_last_line['spans'][-1]['type']
    next_first_line_text = ''.join([__get_span_text(span) for span in next_first_line['spans']])
    next_first_line_type = next_first_line['spans'][0]['type']

    if pre_last_line_type not in [TEXT, INLINE_EQUATION] or next_first_line_type not in [TEXT,
                                                                                         INLINE_EQUATION]:  # TODO，真的要做好，要考虑跨table, image, 行间的情况
        # 不是文本，不连接
        return False

    pre_x2_max_bbox = __find_layout_bbox_by_line(pre_last_line['bbox'], pre_page_layout_bbox)
    if not pre_x2_max_bbox:
        return False
    next_x0_min_bbox = __find_layout_bbox_by_line(next_first_line['bbox'], next_page_layout_bbox)
    if not next_x0_min_bbox:
        return False

    pre_x2_max = pre_x2_max_bbox[2]
    next_x0_min = next_x0_min_bbox[0]

    pre_last_line_text = pre_last_line_text.strip()
    next_first_line_text = next_first_line_text.strip()
    if pre_last_line['bbox'][2] == pre_x2_max and pre_last_line_text[-1] not in LINE_STOP_FLAG and \
            next_first_line['bbox'][0] == next_x0_min:  # 前面一行沾满了整个行，并且没有结尾符号.下一行没有空白开头。
        """连接段落条件成立，将前一个layout的段落和后一个layout的段落连接。"""
        # 下一页合并到上一页最后一段，打一个cross_page的标签
        for line in next_first_para:
            for span in line["spans"]:
                span[CROSS_PAGE] = True
        pre_last_para.extend(next_first_para)

        #next_page_paras[0].pop(0)  # 删除后一个页面的第一个段落， 因为他已经被合并到前一个页面的最后一个段落了。
        next_page_paras[0][0]["lines"] = []
        next_page_paras[0][0][LINES_DELETED] = True
        return True
    else:
        return False


def find_consecutive_true_regions(input_array):
    start_index = None  # 连续True区域的起始索引
    regions = []  # 用于保存所有连续True区域的起始和结束索引

    for i in range(len(input_array)):
        # 如果我们找到了一个True值，并且当前并没有在连续True区域中
        if input_array[i] and start_index is None:
            start_index = i  # 记录连续True区域的起始索引

        # 如果我们找到了一个False值，并且当前在连续True区域中
        elif not input_array[i] and start_index is not None:
            # 如果连续True区域长度大于1，那么将其添加到结果列表中
            if i - start_index > 1:
                regions.append((start_index, i - 1))
            start_index = None  # 重置起始索引

    # 如果最后一个元素是True，那么需要将最后一个连续True区域加入到结果列表中
    if start_index is not None and len(input_array) - start_index > 1:
        regions.append((start_index, len(input_array) - 1))

    return regions


def __connect_middle_align_text(page_paras, new_layout_bbox, page_num, lang):
    global debug_able
    """
    找出来中间对齐的连续单行文本，如果连续行高度相同，那么合并为一个段落。
    一个line居中的条件是：
    1. 水平中心点跨越layout的中心点。
    2. 左右两侧都有空白
    """

    for layout_i, layout_para in enumerate(page_paras):
        layout_box = new_layout_bbox[layout_i]
        single_line_paras_tag = []
        for i in range(len(layout_para)):
            #single_line_paras_tag.append(len(layout_para[i]) == 1 and layout_para[i][0]['spans'][0]['type'] == TEXT)
            single_line_paras_tag.append(layout_para[i]['type'] == BlockType.Text and len(layout_para[i]["lines"]) == 1)
        """找出来连续的单行文本，如果连续行高度相同，那么合并为一个段落。"""
        consecutive_single_line_indices = find_consecutive_true_regions(single_line_paras_tag)
        if len(consecutive_single_line_indices) > 0:
            #index_offset = 0
            """检查这些行是否是高度相同的，居中的"""
            for start, end in consecutive_single_line_indices:
                #start += index_offset
                #end += index_offset
                line_hi = np.array([block["lines"][0]['bbox'][3] - block["lines"][0]['bbox'][1] for block in
                                    layout_para[start:end + 1]])
                first_line_text = ''.join([__get_span_text(span) for span in layout_para[start]["lines"][0]['spans']])
                if "Table" in first_line_text or "Figure" in first_line_text:
                    pass
                if debug_able:
                    logger.info(line_hi.std())

                if line_hi.std() < 2:
                    """行高度相同，那么判断是否居中"""
                    all_left_x0 = [block["lines"][0]['bbox'][0] for block in layout_para[start:end + 1]]
                    all_right_x1 = [block["lines"][0]['bbox'][2] for block in layout_para[start:end + 1]]
                    layout_center = (layout_box[0] + layout_box[2]) / 2
                    if all([x0 < layout_center < x1 for x0, x1 in zip(all_left_x0, all_right_x1)]) \
                            and not all([x0 == layout_box[0] for x0 in all_left_x0]) \
                            and not all([x1 == layout_box[2] for x1 in all_right_x1]):
                        merge_para = [block["lines"][0] for block in layout_para[start:end + 1]]
                        para_text = ''.join([__get_span_text(span) for line in merge_para for span in line['spans']])
                        if debug_able:
                            logger.info(para_text)
                        layout_para[start]["lines"] = merge_para
                        for i_para in range(start + 1, end + 1):
                            layout_para[i_para]["lines"] = []
                            layout_para[i_para][LINES_DELETED] = True
                        #layout_para[start:end + 1] = [merge_para]

                        #index_offset -= end - start

    return


def __merge_signle_list_text(page_paras, new_layout_bbox, page_num, lang):
    """
    找出来连续的单行文本，如果首行顶格，接下来的几个单行段落缩进对齐，那么合并为一个段落。
    """

    pass


def __do_split_page(blocks, layout_bboxes, new_layout_bbox, page_num, lang):
    """
    根据line和layout情况进行分段
    先实现一个根据行末尾特征分段的简单方法。
    """
    """
    算法思路：
    1. 扫描layout里每一行，找出来行尾距离layout有边界有一定距离的行。
    2. 从上述行中找到末尾是句号等可作为断行标志的行。
    3. 参照上述行尾特征进行分段。
    4. 图、表，目前独占一行，不考虑分段。
    """
    blocks_group = __group_line_by_layout(blocks, layout_bboxes)  # block内分段
    layout_list_info = __split_para_in_layoutbox(blocks_group, new_layout_bbox, lang)  # layout内分段
    blocks_group, page_list_info = __connect_list_inter_layout(blocks_group, new_layout_bbox, layout_list_info,
                                                               page_num, lang)  # layout之间连接列表段落
    connected_layout_blocks = __connect_para_inter_layoutbox(blocks_group, new_layout_bbox)  # layout间链接段落

    return connected_layout_blocks, page_list_info


def para_split(pdf_info_dict, debug_mode, lang="en"):
    global debug_able
    debug_able = debug_mode
    new_layout_of_pages = []  # 数组的数组，每个元素是一个页面的layoutS
    all_page_list_info = []  # 保存每个页面开头和结尾是否是列表
    for page_num, page in pdf_info_dict.items():
        blocks = page['preproc_blocks']
        layout_bboxes = page['layout_bboxes']
        new_layout_bbox = __common_pre_proc(blocks, layout_bboxes)
        new_layout_of_pages.append(new_layout_bbox)
        splited_blocks, page_list_info = __do_split_page(blocks, layout_bboxes, new_layout_bbox, page_num, lang)
        all_page_list_info.append(page_list_info)
        page['para_blocks'] = splited_blocks

    """连接页面与页面之间的可能合并的段落"""
    pdf_infos = list(pdf_info_dict.values())
    for page_num, page in enumerate(pdf_info_dict.values()):
        if page_num == 0:
            continue
        pre_page_paras = pdf_infos[page_num - 1]['para_blocks']
        next_page_paras = pdf_infos[page_num]['para_blocks']
        pre_page_layout_bbox = new_layout_of_pages[page_num - 1]
        next_page_layout_bbox = new_layout_of_pages[page_num]

        is_conn = __connect_para_inter_page(pre_page_paras, next_page_paras, pre_page_layout_bbox,
                                            next_page_layout_bbox, page_num, lang)
        if debug_able:
            if is_conn:
                logger.info(f"连接了第{page_num - 1}页和第{page_num}页的段落")

        is_list_conn = __connect_list_inter_page(pre_page_paras, next_page_paras, pre_page_layout_bbox,
                                                 next_page_layout_bbox, all_page_list_info[page_num - 1],
                                                 all_page_list_info[page_num], page_num, lang)
        if debug_able:
            if is_list_conn:
                logger.info(f"连接了第{page_num - 1}页和第{page_num}页的列表段落")

    """接下来可能会漏掉一些特别的一些可以合并的内容，对他们进行段落连接
    1. 正文中有时出现一个行顶格，接下来几行缩进的情况。
    2. 居中的一些连续单行，如果高度相同，那么可能是一个段落。
    """
    for page_num, page in enumerate(pdf_info_dict.values()):
        page_paras = page['para_blocks']
        new_layout_bbox = new_layout_of_pages[page_num]
        __connect_middle_align_text(page_paras, new_layout_bbox, page_num, lang)
        __merge_signle_list_text(page_paras, new_layout_bbox, page_num, lang)

    # layout展平
    for page_num, page in enumerate(pdf_info_dict.values()):
        page_paras = page['para_blocks']
        page_blocks = [block for layout in page_paras for block in layout]
        page["para_blocks"] = page_blocks