intercept/utils/sstv.py

"""SSTV (Slow-Scan Television) decoder for ISS transmissions.

This module provides SSTV decoding capabilities for receiving images
from the International Space Station during special events.

ISS SSTV typically transmits on 145.800 MHz FM.
"""

from __future__ import annotations

import os
import queue
import subprocess
import threading
import time
from dataclasses import dataclass, field
from datetime import datetime, timezone
from pathlib import Path
from typing import Callable

from utils.logging import get_logger

logger = get_logger('intercept.sstv')

# ISS SSTV frequency
ISS_SSTV_FREQ = 145.800  # MHz

# Common SSTV modes used by ISS
SSTV_MODES = ['PD120', 'PD180', 'Martin1', 'Martin2', 'Scottie1', 'Scottie2', 'Robot36']


@dataclass
class SSTVImage:
    """Decoded SSTV image."""
    filename: str
    path: Path
    mode: str
    timestamp: datetime
    frequency: float
    size_bytes: int = 0

    def to_dict(self) -> dict:
        return {
            'filename': self.filename,
            'path': str(self.path),
            'mode': self.mode,
            'timestamp': self.timestamp.isoformat(),
            'frequency': self.frequency,
            'size_bytes': self.size_bytes,
            'url': f'/sstv/images/{self.filename}'
        }


@dataclass
class DecodeProgress:
    """SSTV decode progress update."""
    status: str  # 'detecting', 'decoding', 'complete', 'error'
    mode: str | None = None
    progress_percent: int = 0
    message: str | None = None
    image: SSTVImage | None = None

    def to_dict(self) -> dict:
        result = {
            'type': 'sstv_progress',
            'status': self.status,
            'progress': self.progress_percent,
        }
        if self.mode:
            result['mode'] = self.mode
        if self.message:
            result['message'] = self.message
        if self.image:
            result['image'] = self.image.to_dict()
        return result


class SSTVDecoder:
    """SSTV decoder using external tools (slowrx or qsstv)."""

    def __init__(self, output_dir: str | Path | None = None):
        self._process = None
        self._running = False
        self._lock = threading.Lock()
        self._callback: Callable[[DecodeProgress], None] | None = None
        self._output_dir = Path(output_dir) if output_dir else Path('instance/sstv_images')
        self._images: list[SSTVImage] = []
        self._reader_thread = None
        self._frequency = ISS_SSTV_FREQ
        self._device_index = 0

        # Ensure output directory exists
        self._output_dir.mkdir(parents=True, exist_ok=True)

        # Detect available decoder
        self._decoder = self._detect_decoder()

    @property
    def is_running(self) -> bool:
        return self._running

    @property
    def decoder_available(self) -> str | None:
        """Return name of available decoder or None."""
        return self._decoder

    def _detect_decoder(self) -> str | None:
        """Detect which SSTV decoder is available."""
        # Check for slowrx (command-line SSTV decoder)
        try:
            result = subprocess.run(['which', 'slowrx'], capture_output=True, timeout=5)
            if result.returncode == 0:
                return 'slowrx'
        except Exception:
            pass

        # Check for qsstv (if available as CLI)
        try:
            result = subprocess.run(['which', 'qsstv'], capture_output=True, timeout=5)
            if result.returncode == 0:
                return 'qsstv'
        except Exception:
            pass

        # Check for Python sstv package
        try:
            import sstv
            return 'python-sstv'
        except ImportError:
            pass

        logger.warning("No SSTV decoder found. Install slowrx or python sstv package.")
        return None

    def set_callback(self, callback: Callable[[DecodeProgress], None]) -> None:
        """Set callback for decode progress updates."""
        self._callback = callback

    def start(self, frequency: float = ISS_SSTV_FREQ, device_index: int = 0) -> bool:
        """
        Start SSTV decoder listening on specified frequency.

        Args:
            frequency: Frequency in MHz (default: 145.800 for ISS)
            device_index: RTL-SDR device index

        Returns:
            True if started successfully
        """
        with self._lock:
            if self._running:
                return True

            if not self._decoder:
                logger.error("No SSTV decoder available")
                self._emit_progress(DecodeProgress(
                    status='error',
                    message='No SSTV decoder installed. Install slowrx: apt install slowrx'
                ))
                return False

            self._frequency = frequency
            self._device_index = device_index

            try:
                if self._decoder == 'slowrx':
                    self._start_slowrx()
                elif self._decoder == 'python-sstv':
                    self._start_python_sstv()
                else:
                    logger.error(f"Unsupported decoder: {self._decoder}")
                    return False

                self._running = True
                logger.info(f"SSTV decoder started on {frequency} MHz")
                self._emit_progress(DecodeProgress(
                    status='detecting',
                    message=f'Listening on {frequency} MHz...'
                ))
                return True

            except Exception as e:
                logger.error(f"Failed to start SSTV decoder: {e}")
                self._emit_progress(DecodeProgress(
                    status='error',
                    message=str(e)
                ))
                return False

    def _start_slowrx(self) -> None:
        """Start slowrx decoder with rtl_fm piped input."""
        # Convert frequency to Hz
        freq_hz = int(self._frequency * 1_000_000)

        # Build rtl_fm command for FM demodulation
        rtl_cmd = [
            'rtl_fm',
            '-d', str(self._device_index),
            '-f', str(freq_hz),
            '-M', 'fm',
            '-s', '48000',
            '-r', '48000',
            '-l', '0',  # No squelch
            '-'
        ]

        # slowrx reads from stdin and outputs images to directory
        slowrx_cmd = [
            'slowrx',
            '-o', str(self._output_dir),
            '-'
        ]

        logger.info(f"Starting rtl_fm: {' '.join(rtl_cmd)}")
        logger.info(f"Piping to slowrx: {' '.join(slowrx_cmd)}")

        # Start rtl_fm
        self._rtl_process = subprocess.Popen(
            rtl_cmd,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE
        )

        # Start slowrx reading from rtl_fm
        self._process = subprocess.Popen(
            slowrx_cmd,
            stdin=self._rtl_process.stdout,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE
        )

        # Start reader thread to monitor output
        self._reader_thread = threading.Thread(target=self._read_slowrx_output, daemon=True)
        self._reader_thread.start()

        # Start image watcher thread
        self._watcher_thread = threading.Thread(target=self._watch_images, daemon=True)
        self._watcher_thread.start()

    def _start_python_sstv(self) -> None:
        """Start Python SSTV decoder (requires audio file input)."""
        # Python sstv package typically works with audio files
        # For real-time decoding, we'd need to record audio first
        # This is a simplified implementation
        logger.warning("Python SSTV package requires audio file input")
        self._emit_progress(DecodeProgress(
            status='error',
            message='Python SSTV decoder requires audio files. Use slowrx for real-time decoding.'
        ))
        raise NotImplementedError("Real-time Python SSTV not implemented")

    def _read_slowrx_output(self) -> None:
        """Read slowrx stderr for progress updates."""
        if not self._process:
            return

        try:
            for line in iter(self._process.stderr.readline, b''):
                if not self._running:
                    break

                line_str = line.decode('utf-8', errors='ignore').strip()
                if not line_str:
                    continue

                logger.debug(f"slowrx: {line_str}")

                # Parse slowrx output for mode detection and progress
                if 'Detected' in line_str or 'mode' in line_str.lower():
                    for mode in SSTV_MODES:
                        if mode.lower() in line_str.lower():
                            self._emit_progress(DecodeProgress(
                                status='decoding',
                                mode=mode,
                                message=f'Decoding {mode} image...'
                            ))
                            break

        except Exception as e:
            logger.error(f"Error reading slowrx output: {e}")

    def _watch_images(self) -> None:
        """Watch output directory for new images."""
        known_files = set(f.name for f in self._output_dir.glob('*.png'))

        while self._running:
            time.sleep(1)

            try:
                current_files = set(f.name for f in self._output_dir.glob('*.png'))
                new_files = current_files - known_files

                for filename in new_files:
                    filepath = self._output_dir / filename
                    if filepath.exists():
                        # New image detected
                        image = SSTVImage(
                            filename=filename,
                            path=filepath,
                            mode='Unknown',  # Would need to parse from slowrx output
                            timestamp=datetime.now(timezone.utc),
                            frequency=self._frequency,
                            size_bytes=filepath.stat().st_size
                        )
                        self._images.append(image)

                        logger.info(f"New SSTV image: {filename}")
                        self._emit_progress(DecodeProgress(
                            status='complete',
                            message='Image decoded',
                            image=image
                        ))

                known_files = current_files

            except Exception as e:
                logger.error(f"Error watching images: {e}")

    def stop(self) -> None:
        """Stop SSTV decoder."""
        with self._lock:
            self._running = False

            if hasattr(self, '_rtl_process') and self._rtl_process:
                try:
                    self._rtl_process.terminate()
                    self._rtl_process.wait(timeout=5)
                except Exception:
                    self._rtl_process.kill()
                self._rtl_process = None

            if self._process:
                try:
                    self._process.terminate()
                    self._process.wait(timeout=5)
                except Exception:
                    self._process.kill()
                self._process = None

            logger.info("SSTV decoder stopped")

    def get_images(self) -> list[SSTVImage]:
        """Get list of decoded images."""
        # Also scan directory for any images we might have missed
        self._scan_images()
        return list(self._images)

    def _scan_images(self) -> None:
        """Scan output directory for images."""
        known_filenames = {img.filename for img in self._images}

        for filepath in self._output_dir.glob('*.png'):
            if filepath.name not in known_filenames:
                try:
                    stat = filepath.stat()
                    image = SSTVImage(
                        filename=filepath.name,
                        path=filepath,
                        mode='Unknown',
                        timestamp=datetime.fromtimestamp(stat.st_mtime, tz=timezone.utc),
                        frequency=ISS_SSTV_FREQ,
                        size_bytes=stat.st_size
                    )
                    self._images.append(image)
                except Exception as e:
                    logger.warning(f"Error scanning image {filepath}: {e}")

    def _emit_progress(self, progress: DecodeProgress) -> None:
        """Emit progress update to callback."""
        if self._callback:
            try:
                self._callback(progress)
            except Exception as e:
                logger.error(f"Error in progress callback: {e}")

    def decode_file(self, audio_path: str | Path) -> list[SSTVImage]:
        """
        Decode SSTV image from audio file.

        Args:
            audio_path: Path to WAV audio file

        Returns:
            List of decoded images
        """
        audio_path = Path(audio_path)
        if not audio_path.exists():
            raise FileNotFoundError(f"Audio file not found: {audio_path}")

        images = []

        if self._decoder == 'slowrx':
            # Use slowrx with file input
            output_file = self._output_dir / f"sstv_{datetime.now().strftime('%Y%m%d_%H%M%S')}.png"

            cmd = ['slowrx', '-o', str(self._output_dir), str(audio_path)]
            result = subprocess.run(cmd, capture_output=True, timeout=300)

            if result.returncode == 0:
                # Check for new images
                for filepath in self._output_dir.glob('*.png'):
                    stat = filepath.stat()
                    if stat.st_mtime > time.time() - 60:  # Created in last minute
                        image = SSTVImage(
                            filename=filepath.name,
                            path=filepath,
                            mode='Unknown',
                            timestamp=datetime.now(timezone.utc),
                            frequency=0,
                            size_bytes=stat.st_size
                        )
                        images.append(image)

        elif self._decoder == 'python-sstv':
            # Use Python sstv library
            try:
                from sstv.decode import SSTVDecoder as PythonSSTVDecoder
                from PIL import Image

                decoder = PythonSSTVDecoder(str(audio_path))
                img = decoder.decode()

                if img:
                    output_file = self._output_dir / f"sstv_{datetime.now().strftime('%Y%m%d_%H%M%S')}.png"
                    img.save(output_file)

                    image = SSTVImage(
                        filename=output_file.name,
                        path=output_file,
                        mode=decoder.mode or 'Unknown',
                        timestamp=datetime.now(timezone.utc),
                        frequency=0,
                        size_bytes=output_file.stat().st_size
                    )
                    images.append(image)

            except ImportError:
                logger.error("Python sstv package not properly installed")
            except Exception as e:
                logger.error(f"Error decoding with Python sstv: {e}")

        return images


# Global decoder instance
_decoder: SSTVDecoder | None = None


def get_sstv_decoder() -> SSTVDecoder:
    """Get or create the global SSTV decoder instance."""
    global _decoder
    if _decoder is None:
        _decoder = SSTVDecoder()
    return _decoder


def is_sstv_available() -> bool:
    """Check if SSTV decoding is available."""
    decoder = get_sstv_decoder()
    return decoder.decoder_available is not None