process_documents.py

import math
import re
from statistics import median
from bs4 import BeautifulSoup
from langchain.docstore.document import Document
from langchain.document_loaders import PDFMinerPDFasHTMLLoader, WebBaseLoader
import tiktoken

deep_strip = lambda text: re.sub(r"\s+", " ", text or "").strip()


def process_documents(urls):
    snippets = []
    documents = {}
    for source_id, url in enumerate(urls):
        snippet = (
            process_pdf(url, source_id)
            if url.endswith(".pdf")
            else process_web(url, source_id)
        )
        snippets.extend(snippet)
        documents[str(source_id)] = Document(
            page_content="\n".join([snip.page_content for snip in snippet]),
            metadata={
                "source_url": url,
                "source_type": "pdf" if url.endswith(".pdf") else "web",
                "source_id": source_id,
                "chunk_id": source_id,
            },
        )
        for snip in snippet:
            documents[snip.metadata["chunk_id"]] = snip
    return snippets, documents


def process_web(url, source_id):
    data = WebBaseLoader(url).load()[0]
    document_snippets = [
        Document(
            page_content=deep_strip(data.page_content),
            metadata={
                "header": data.metadata["title"],
                "source_url": url,
                "source_type": "web",
                "chunk_id": source_id,
                "source_id": source_id,
            },
        )
    ]
    return document_snippets


def process_pdf(url, source_id):
    data = PDFMinerPDFasHTMLLoader(url).load()[0]
    content = BeautifulSoup(data.page_content, "html.parser").find_all("div")
    snippets = get_pdf_snippets(content)
    filtered_snippets = filter_pdf_snippets(snippets, new_line_threshold_ratio=0.4)
    median_font_size = math.ceil(
        median([font_size for _, font_size in filtered_snippets])
    )
    semantic_snippets = get_pdf_semantic_snippets(filtered_snippets, median_font_size)
    document_snippets = [
        Document(
            page_content=deep_strip(snip[1]["header_text"]) + " " + deep_strip(snip[0]),
            metadata={
                "header": " ".join(snip[1]["header_text"].split()[:10]),
                "source_url": url,
                "source_type": "pdf",
                "chunk_id": f"{source_id}_{i:02d}",
                "source_id": source_id,
            },
        )
        for i, snip in enumerate(semantic_snippets)
    ]
    return document_snippets


def get_pdf_snippets(content):
    current_font_size = None
    current_text = ""
    snippets = []
    for cntnt in content:
        span = cntnt.find("span")
        if not span:
            continue
        style = span.get("style")
        if not style:
            continue
        font_size = re.findall("font-size:(\d+)px", style)
        if not font_size:
            continue
        font_size = int(font_size[0])

        if not current_font_size:
            current_font_size = font_size
        if font_size == current_font_size:
            current_text += cntnt.text
        else:
            snippets.append((current_text, current_font_size))
            current_font_size = font_size
            current_text = cntnt.text
    snippets.append((current_text, current_font_size))
    return snippets


def filter_pdf_snippets(content_list, new_line_threshold_ratio):
    filtered_list = []
    for e, (content, font_size) in enumerate(content_list):
        newline_count = content.count("\n")
        total_chars = len(content)
        ratio = newline_count / total_chars
        if ratio <= new_line_threshold_ratio:
            filtered_list.append((content, font_size))
    return filtered_list


def get_pdf_semantic_snippets(filtered_snippets, median_font_size):
    semantic_snippets = []
    current_header = None
    current_content = []
    header_font_size = None
    content_font_sizes = []

    for content, font_size in filtered_snippets:
        if font_size > median_font_size:
            if current_header is not None:
                metadata = {
                    "header_font_size": header_font_size,
                    "content_font_size": (
                        median(content_font_sizes) if content_font_sizes else None
                    ),
                    "header_text": current_header,
                }
                semantic_snippets.append((current_content, metadata))
                current_content = []
                content_font_sizes = []

            current_header = content
            header_font_size = font_size
        else:
            content_font_sizes.append(font_size)
            if current_content:
                current_content += " " + content
            else:
                current_content = content

    if current_header is not None:
        metadata = {
            "header_font_size": header_font_size,
            "content_font_size": (
                median(content_font_sizes) if content_font_sizes else None
            ),
            "header_text": current_header,
        }
        semantic_snippets.append((current_content, metadata))
    return semantic_snippets


def num_tokens(string):
    return len(tiktoken.get_encoding("cl100k_base").encode(string))