#!/usr/bin/env python3
"""
ocr_screenshots.py – OCR screenshot images and store results in SQLite database.

Usage:
    ocr_screenshots.py [--db <path>] [--screenshots-dir <path>]

Arguments:
    --db              Path to the SQLite database file.
                      Default: $XDG_DATA_HOME/screenshot-gallery/screenshot_ocr.db
                               (~/.local/share/screenshot-gallery/screenshot_ocr.db)
    --screenshots-dir Directory containing screenshot images to process.
                      Default: ~/Screenshots
"""

import argparse
import glob
import os
import shutil
import signal
import sqlite3
import subprocess
import sys
import tempfile
from datetime import datetime

# ---------------------------------------------------------------------------
# Globals used by the signal handler to stop processing gracefully
# ---------------------------------------------------------------------------
_current_proc: subprocess.Popen | None = None
_shutdown = False


def _handle_signal(signum, frame):
    """Terminate any running tesseract child, then exit."""
    global _shutdown
    _shutdown = True
    if _current_proc is not None:
        try:
            _current_proc.terminate()
        except OSError:
            pass
    print("\nCancelled.", flush=True)
    sys.exit(1)


signal.signal(signal.SIGTERM, _handle_signal)
signal.signal(signal.SIGINT,  _handle_signal)


# ---------------------------------------------------------------------------
# Argument parsing
# ---------------------------------------------------------------------------
def parse_args() -> argparse.Namespace:
    xdg_data = os.environ.get("XDG_DATA_HOME", os.path.expanduser("~/.local/share"))
    default_db  = os.path.join(xdg_data, "screenshot-gallery", "screenshot_ocr.db")
    default_dir = os.path.expanduser("~/Screenshots")

    parser = argparse.ArgumentParser(
        description="OCR screenshot images and store results in a SQLite database."
    )
    parser.add_argument(
        "--db",
        default=default_db,
        metavar="PATH",
        help=f"Path to the SQLite database (default: {default_db})",
    )
    parser.add_argument(
        "--screenshots-dir",
        default=default_dir,
        metavar="DIR",
        help=f"Directory containing screenshots (default: {default_dir})",
    )
    return parser.parse_args()


# ---------------------------------------------------------------------------
# Dependency / environment checks
# ---------------------------------------------------------------------------
def check_dependencies(screenshots_dir: str) -> bool:
    ok = True

    if shutil.which("tesseract") is None:
        print(
            "Error: tesseract is not installed. Please install it with:\n"
            "  sudo pacman -S tesseract tesseract-data-eng   # Arch\n"
            "  sudo apt install tesseract-ocr                # Debian/Ubuntu",
            file=sys.stderr,
        )
        ok = False

    if not os.path.isdir(screenshots_dir):
        print(
            f"Error: screenshots directory not found: {screenshots_dir}",
            file=sys.stderr,
        )
        ok = False

    return ok


# ---------------------------------------------------------------------------
# Database helpers
# ---------------------------------------------------------------------------
def init_database(db_path: str) -> None:
    """Create the database file and table if they do not already exist."""
    os.makedirs(os.path.dirname(db_path), exist_ok=True)
    conn = sqlite3.connect(db_path)
    conn.execute("""
        CREATE TABLE IF NOT EXISTS ocr_results (
            id           INTEGER PRIMARY KEY AUTOINCREMENT,
            filename     TEXT UNIQUE,
            full_path    TEXT,
            ocr_text     TEXT,
            file_size    INTEGER,
            created_date TEXT,
            ocr_date     TEXT
        )
    """)
    conn.commit()
    conn.close()
    print(f"Database ready: {db_path}", flush=True)


def get_processed_files(db_path: str) -> set:
    conn = sqlite3.connect(db_path)
    rows = conn.execute("SELECT filename FROM ocr_results").fetchall()
    conn.close()
    return {row[0] for row in rows}


def remove_deleted_files(db_path: str, db_filenames: set, fs_filenames: set) -> int:
    """Delete DB rows for files that no longer exist on the filesystem.

    Returns the number of rows removed.
    """
    deleted = db_filenames - fs_filenames
    if not deleted:
        return 0

    conn = sqlite3.connect(db_path)
    removed = 0
    try:
        for filename in sorted(deleted):
            conn.execute("DELETE FROM ocr_results WHERE filename = ?", (filename,))
            print(f"Removed (file deleted): {filename}", flush=True)
            removed += 1
        conn.commit()
    except Exception as exc:
        print(f"Error removing deleted entries: {exc}", file=sys.stderr, flush=True)
        conn.rollback()
    finally:
        conn.close()

    return removed


def get_total_count(db_path: str) -> int:
    conn = sqlite3.connect(db_path)
    count = conn.execute("SELECT COUNT(*) FROM ocr_results").fetchone()[0]
    conn.close()
    return count


def insert_result(db_path: str, filename: str, full_path: str,
                  ocr_text: str, file_size: int, created_date: str) -> None:
    conn = sqlite3.connect(db_path)
    try:
        conn.execute(
            """
            INSERT INTO ocr_results
                (filename, full_path, ocr_text, file_size, created_date, ocr_date)
            VALUES (?, ?, ?, ?, ?, ?)
            """,
            (filename, full_path, ocr_text, file_size, created_date,
             datetime.now().isoformat()),
        )
        conn.commit()
        print(f"Added: {filename}", flush=True)
    except sqlite3.IntegrityError:
        print(f"Skipping (already in database): {filename}", flush=True)
    except Exception as exc:
        print(f"Error adding {filename}: {exc}", file=sys.stderr, flush=True)
    finally:
        conn.close()


# ---------------------------------------------------------------------------
# OCR
# ---------------------------------------------------------------------------
def perform_ocr(image_path: str) -> str:
    """Run tesseract on image_path and return the extracted text (may be empty)."""
    global _current_proc

    try:
        with tempfile.NamedTemporaryFile(suffix=".txt", delete=False) as tmp:
            tmp_txt  = tmp.name
        tmp_base = tmp_txt[:-4]  # tesseract appends .txt itself

        _current_proc = subprocess.Popen(
            ["tesseract", image_path, tmp_base],
            stdout=subprocess.DEVNULL,
            stderr=subprocess.PIPE,
        )
        _, stderr = _current_proc.communicate()
        returncode = _current_proc.returncode
        _current_proc = None

        if returncode != 0:
            print(
                f"tesseract error on {os.path.basename(image_path)}: "
                f"{stderr.decode(errors='replace').strip()}",
                file=sys.stderr,
                flush=True,
            )
            return ""

        with open(tmp_txt, "r", encoding="utf-8", errors="replace") as fh:
            return fh.read().strip()

    except Exception as exc:
        _current_proc = None
        print(f"Error processing {os.path.basename(image_path)}: {exc}",
              file=sys.stderr, flush=True)
        return ""
    finally:
        # Clean up temp file if it exists
        try:
            os.remove(tmp_txt)
        except OSError:
            pass


# ---------------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------------
def main() -> int:
    args = parse_args()
    db_path        = args.db
    screenshots_dir = args.screenshots_dir

    print(f"Database:          {db_path}",        flush=True)
    print(f"Screenshots dir:   {screenshots_dir}", flush=True)

    if not check_dependencies(screenshots_dir):
        return 1

    init_database(db_path)

    processed_files = get_processed_files(db_path)
    print(f"Already processed: {len(processed_files)} files", flush=True)

    image_files: list[str] = []
    for ext in ("*.png", "*.jpg", "*.jpeg", "*.PNG", "*.JPG", "*.JPEG"):
        image_files.extend(glob.glob(os.path.join(screenshots_dir, ext)))
    image_files = sorted(set(image_files))  # deduplicate (case-insensitive FS edge case)

    print(f"Found:             {len(image_files)} image files", flush=True)

    # Remove DB entries for screenshots that no longer exist on disk
    fs_filenames = {os.path.basename(p) for p in image_files}
    removed_count = remove_deleted_files(db_path, processed_files, fs_filenames)
    if removed_count:
        print(f"Removed:           {removed_count} stale entries", flush=True)
        # Keep processed_files in sync so skip logic below is accurate
        processed_files -= (processed_files - fs_filenames)

    processed_count = 0
    skipped_count   = 0
    error_count     = 0

    for image_path in image_files:
        if _shutdown:
            break

        filename = os.path.basename(image_path)

        if filename in processed_files:
            skipped_count += 1
            continue

        print(f"Processing: {filename}", flush=True)

        stat        = os.stat(image_path)
        file_size   = stat.st_size
        created_date = datetime.fromtimestamp(stat.st_mtime).isoformat()

        ocr_text = perform_ocr(image_path)

        if _shutdown:
            break

        if ocr_text:
            insert_result(db_path, filename, image_path,
                          ocr_text, file_size, created_date)
            processed_count += 1
        else:
            print(f"No text extracted: {filename}", flush=True)
            error_count += 1

    total = get_total_count(db_path)
    print("", flush=True)
    print("OCR process completed:", flush=True)
    print(f"  Processed:                     {processed_count}", flush=True)
    print(f"  Skipped (already in database): {skipped_count}", flush=True)
    print(f"  Removed (files deleted):       {removed_count}", flush=True)
    print(f"  Errors:                        {error_count}", flush=True)
    print(f"  Total records in database:     {total}", flush=True)

    return 0


if __name__ == "__main__":
    sys.exit(main())