#!/usr/bin/env python3
"""
OCR KIA service manual PDF → structured JSON.

Usage:
    python3 ocr_kia_pdf.py [--pages N] [--start N]
    
Output: kia_data/kia_ocr.json
"""

import pymupdf
import subprocess
import tempfile
import os
import json
import re
import sys
import argparse
from pathlib import Path

PDF_PATH = "/mnt/y/Torrents/KIA4_by_kiario.pdf"
OUT_DIR = Path(__file__).parent.parent / "kia_data"
OUT_JSON = OUT_DIR / "kia_ocr.json"

# OCR language: rus for Russian, eng for English terms
OCR_LANG = "rus+eng"
# Zoom factor for rendering (2 = 2x, better OCR quality)
ZOOM = 2


def ocr_page(pixmap, page_num=0) -> str:
    """Run tesseract on a pixmap, return text. Retry on timeout with explicit cleanup."""
    # Save pixmap to temp file, close before OCR
    fd, img_path = tempfile.mkstemp(suffix=".png")
    os.close(fd)
    pixmap.save(img_path)

    for attempt in range(3):
        proc = None
        try:
            proc = subprocess.Popen(
                ["tesseract", img_path, "stdout", "-l", OCR_LANG],
                stdout=subprocess.PIPE,
                stderr=subprocess.DEVNULL,
                text=True,
            )
            stdout, _ = proc.communicate(timeout=60)
            if proc.returncode != 0 and proc.returncode is not None:
                raise RuntimeError(f"tesseract exit {proc.returncode}")
            os.unlink(img_path)
            return stdout.strip()
        except subprocess.TimeoutExpired:
            if proc:
                proc.kill()
                try:
                    proc.wait(timeout=5)
                except subprocess.TimeoutExpired:
                    pass
            if attempt < 2:
                print(f"  p{page_num}: timeout, retry {attempt+2}/3...", flush=True)
            else:
                print(f"  p{page_num}: SKIP (timeout after 3 retries)", flush=True)
                os.unlink(img_path)
                return ""
        except Exception as e:
            if proc:
                proc.kill()
                try:
                    proc.wait(timeout=5)
                except subprocess.TimeoutExpired:
                    pass
            os.unlink(img_path)
            print(f"  p{page_num}: ERROR {e}", flush=True)
            return ""


def is_section_header(line: str) -> bool:
    """
    Heuristic: detect section/chapter headers.
    Examples:
      - "ГЛАВА 1. ОБЩИЕ СВЕДЕНИЯ"
      - "1. ТЕХНИЧЕСКОЕ ОБСЛУЖИВАНИЕ"
      - "ДВИГАТЕЛЬ"
    """
    line = line.strip()
    if not line or len(line) < 3:
        return False

    # Numbered chapter: "1.", "1.2", "ГЛАВА 1"
    if re.match(r"^(ГЛАВА|РАЗДЕЛ|ЧАСТЬ)\s+\d+", line, re.IGNORECASE):
        return True
    if re.match(r"^\d+\.\s+[А-ЯA-Z]", line):
        return True
    if re.match(r"^\d+\.\d+\.?\s+[А-ЯA-Z]", line):
        return True

    # ALL CAPS, 3+ words, reasonable length (not a full sentence)
    if line.isupper() and len(line.split()) >= 2 and 5 < len(line) < 100:
        return True

    return False


def parse_pdf(start_page=0, max_pages=None):
    """OCR all pages and structure into sections."""
    doc = pymupdf.open(PDF_PATH)
    total_pages = doc.page_count
    end_page = min(total_pages, start_page + max_pages) if max_pages else total_pages

    print(f"PDF: {total_pages} pages, processing {start_page}–{end_page-1}", flush=True)

    sections = []
    current_section = {"title": "Начало", "pages": [], "text": ""}
    mat = pymupdf.Matrix(ZOOM, ZOOM)

    for i in range(start_page, end_page):
        page = doc[i]
        pix = page.get_pixmap(matrix=mat)
        text = ocr_page(pix, page_num=i)

        if not text:
            print(f"  p{i}: [empty]")
            continue

        # Try to detect section header on this page
        lines = text.split("\n")
        header_found = False
        for line in lines[:5]:  # check first 5 lines
            if is_section_header(line):
                # Save previous section
                if current_section["text"].strip():
                    sections.append(current_section)
                current_section = {"title": line.strip(), "pages": [], "text": ""}
                header_found = True
                break

        current_section["pages"].append(i)
        current_section["text"] += text + "\n"

        if (i - start_page) % 20 == 0:
            print(f"  p{i}: {len(text)} chars, sections so far: {len(sections)}", flush=True)

    # Save last section
    if current_section["text"].strip():
        sections.append(current_section)

    doc.close()
    return {
        "source": PDF_PATH,
        "total_pages": total_pages,
        "pages_processed": end_page - start_page,
        "sections": sections,
    }


def main():
    parser = argparse.ArgumentParser(description="OCR KIA PDF → JSON")
    parser.add_argument("--pages", type=int, default=None, help="Max pages to process")
    parser.add_argument("--start", type=int, default=0, help="Start page")
    args = parser.parse_args()

    OUT_DIR.mkdir(parents=True, exist_ok=True)

    data = parse_pdf(start_page=args.start, max_pages=args.pages)

    print(f"\nSections: {len(data['sections'])}")
    total_chars = sum(len(s["text"]) for s in data["sections"])
    print(f"Total chars: {total_chars:,}")

    with open(OUT_JSON, "w", encoding="utf-8") as f:
        json.dump(data, f, ensure_ascii=False, indent=2)

    print(f"Saved: {OUT_JSON} ({os.path.getsize(OUT_JSON)/1024/1024:.1f} MB)")
    print("Done!")


if __name__ == "__main__":
    main()