File size: 4,793 Bytes
d473af5
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
81a53ea
 
d473af5
 
81a53ea
 
 
 
 
 
 
 
 
 
 
d473af5
 
 
 
 
 
81a53ea
 
d473af5
 
81a53ea
d473af5
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
import os
import re
from pathlib import Path
from typing import List, Tuple

import fitz  # pymupdf
from pdf2image import convert_from_path
import pytesseract
from PIL import ImageOps, ImageEnhance

OCR_LANG = "eng+ara"
OCR_DPI = 180
NATIVE_MIN_CHARS_PER_PAGE = 60  # if native extracted text < this => OCR that page

_SENT_BOUNDARY_RE = re.compile(r"(?<=[\.\!\?\u061F\u06D4\u061B…])\s+")  # . ! ? ؟ ۔ ؛ …

def normalize_text(text: str) -> str:
    """Normalizes text by removing excessive whitespace and fixing newlines."""
    text = text.replace("\r\n", "\n").replace("\r", "\n")
    text = re.sub(r"[ \t]+", " ", text)
    text = re.sub(r"\n{3,}", "\n\n", text)
    return text.strip()

def ocr_image_pil(img):
    """Applies light preprocessing to improve OCR accuracy."""
    img = img.convert("RGB")
    img = ImageOps.grayscale(img)
    img = ImageEnhance.Contrast(img).enhance(1.6)
    return img

def ocr_pdf_page(pdf_path: str, page_number_1based: int, dpi: int = OCR_DPI, lang: str = OCR_LANG) -> str:
    """OCRs a single PDF page."""
    images = convert_from_path(
        str(pdf_path),
        dpi=dpi,
        first_page=page_number_1based,
        last_page=page_number_1based,
        fmt="png",
        thread_count=2,
    )
    if not images:
        return ""
    img = images[0]
    img = ocr_image_pil(img)
    return pytesseract.image_to_string(img, lang=lang)

def pdf_to_text_smart(pdf_path: str, native_min_chars_per_page: int = NATIVE_MIN_CHARS_PER_PAGE) -> str:
    """Extracts text from PDF, falling back to OCR for scanned pages.
       Optimized to avoid OCR on native PDFs with sparse pages (like title pages)."""
    doc = fitz.open(str(pdf_path))
    parts = []
    
    # Quick check: is this likely a native PDF?
    # Sample up to 10 pages to see if any has a good amount of native text.
    is_native_pdf = False
    sample_pages = min(10, doc.page_count)
    for i in range(sample_pages):
        page = doc.load_page(i)
        native = (page.get_text("text") or "").strip()
        if len(re.sub(r"\s+", "", native)) > 200:
            is_native_pdf = True
            break

    for i in range(doc.page_count):
        page = doc.load_page(i)
        native = (page.get_text("text") or "").strip()
        native_compact_len = len(re.sub(r"\s+", "", native))

        if native_compact_len >= native_min_chars_per_page or is_native_pdf:
            # If we know it's a native PDF, even sparse pages (like titles/blank pages) don't need OCR
            parts.append(native)
        else:
            # Only OCR if it's not a known native PDF and native text is sparse (could be a scanned page)
            ocr = ocr_pdf_page(pdf_path, page_number_1based=i+1)
            parts.append(ocr)

    doc.close()
    return normalize_text("\n\n".join(parts))

def extract_text_from_file(file_path: str) -> str:
    """Extracts text from a .txt or .pdf file."""
    path = Path(file_path)
    suf = path.suffix.lower()

    if suf == ".txt":
        raw = path.read_text(encoding="utf-8", errors="ignore")
        return normalize_text(raw)
    
    if suf == ".pdf":
        return pdf_to_text_smart(str(path))
        
    raise ValueError(f"Unsupported file type '{suf}'. Please upload .pdf or .txt only.")

def split_into_chapters(text: str) -> List[Tuple[str, str]]:
    """
    Best effort chapter split:
    - Detect lines that look like: CHAPTER 1 / Chapter One / CHAPTER ONE etc.
    - If not found, return one chapter = full text.
    Returns: list of (title, body)
    """
    text = normalize_text(text)
    lines = text.splitlines()

    chapter_re = re.compile(r"^\s*(chapter|CHAPTER)\s+([0-9]+|[IVXLC]+|[A-Za-z]+)\b.*$", re.IGNORECASE)

    idxs = []
    titles = []
    for i, ln in enumerate(lines):
        if chapter_re.match(ln.strip()):
            idxs.append(i)
            titles.append(ln.strip())

    if len(idxs) < 2:
        return [("BOOK", text)]

    chapters = []
    for k in range(len(idxs)):
        start = idxs[k]
        end = idxs[k+1] if k+1 < len(idxs) else len(lines)
        title = titles[k]
        body = "\n".join(lines[start:end]).strip()
        chapters.append((title, body))
    return chapters

def split_sentences(paragraph: str) -> List[str]:
    """Splits a paragraph into sentences."""
    paragraph = paragraph.strip()
    if not paragraph:
        return []
    if not any(ch in paragraph for ch in ".!?\u061F\u06D4\u061B…"):
        ls = [ln.strip() for ln in paragraph.split("\n") if ln.strip()]
        return ls if ls else [paragraph]
    return [s.strip() for s in _SENT_BOUNDARY_RE.split(paragraph) if s.strip()]

def iter_paragraphs(text: str):
    """Yields paragraphs from text."""
    for p in re.split(r"\n\s*\n+", text):
        p = p.strip()
        if p:
            yield p