"""VDL2 aircraft datalink routes."""

from __future__ import annotations

import json
import queue
import shutil
import subprocess
import threading
import time
from datetime import datetime
from typing import Generator

from flask import Blueprint, jsonify, request, Response

import app as app_module
from utils.logging import sensor_logger as logger
from utils.validation import validate_device_index, validate_gain, validate_ppm
from utils.sdr import SDRFactory, SDRType
from utils.sse import format_sse
from utils.event_pipeline import process_event
from utils.constants import (
    PROCESS_TERMINATE_TIMEOUT,
    SSE_KEEPALIVE_INTERVAL,
    SSE_QUEUE_TIMEOUT,
    PROCESS_START_WAIT,
)
from utils.process import register_process, unregister_process

vdl2_bp = Blueprint('vdl2', __name__, url_prefix='/vdl2')

# Default VDL2 frequencies (MHz) - common worldwide
DEFAULT_VDL2_FREQUENCIES = [
    '136975000',  # Primary worldwide
    '136725000',  # Europe
    '136775000',  # Europe
    '136800000',  # Multi-region
    '136875000',  # Multi-region
]

# Message counter for statistics
vdl2_message_count = 0
vdl2_last_message_time = None

# Track which device is being used
vdl2_active_device: int | None = None


def find_dumpvdl2():
    """Find dumpvdl2 binary."""
    return shutil.which('dumpvdl2')


def stream_vdl2_output(process: subprocess.Popen) -> None:
    """Stream dumpvdl2 JSON output to queue."""
    global vdl2_message_count, vdl2_last_message_time

    try:
        app_module.vdl2_queue.put({'type': 'status', 'status': 'started'})

        for line in iter(process.stdout.readline, b''):
            line = line.decode('utf-8', errors='replace').strip()
            if not line:
                continue

            try:
                data = json.loads(line)

                # Add our metadata
                data['type'] = 'vdl2'
                data['timestamp'] = datetime.utcnow().isoformat() + 'Z'

                # Update stats
                vdl2_message_count += 1
                vdl2_last_message_time = time.time()

                app_module.vdl2_queue.put(data)

                # Log if enabled
                if app_module.logging_enabled:
                    try:
                        with open(app_module.log_file_path, 'a') as f:
                            ts = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
                            f.write(f"{ts} | VDL2 | {json.dumps(data)}\n")
                    except Exception:
                        pass

            except json.JSONDecodeError:
                # Not JSON - could be status message
                if line:
                    logger.debug(f"dumpvdl2 non-JSON: {line[:100]}")

    except Exception as e:
        logger.error(f"VDL2 stream error: {e}")
        app_module.vdl2_queue.put({'type': 'error', 'message': str(e)})
    finally:
        global vdl2_active_device
        # Ensure process is terminated
        try:
            process.terminate()
            process.wait(timeout=2)
        except Exception:
            try:
                process.kill()
            except Exception:
                pass
        unregister_process(process)
        app_module.vdl2_queue.put({'type': 'status', 'status': 'stopped'})
        with app_module.vdl2_lock:
            app_module.vdl2_process = None
        # Release SDR device
        if vdl2_active_device is not None:
            app_module.release_sdr_device(vdl2_active_device)
            vdl2_active_device = None


@vdl2_bp.route('/tools')
def check_vdl2_tools() -> Response:
    """Check for VDL2 decoding tools."""
    has_dumpvdl2 = find_dumpvdl2() is not None

    return jsonify({
        'dumpvdl2': has_dumpvdl2,
        'ready': has_dumpvdl2
    })


@vdl2_bp.route('/status')
def vdl2_status() -> Response:
    """Get VDL2 decoder status."""
    running = False
    if app_module.vdl2_process:
        running = app_module.vdl2_process.poll() is None

    return jsonify({
        'running': running,
        'message_count': vdl2_message_count,
        'last_message_time': vdl2_last_message_time,
        'queue_size': app_module.vdl2_queue.qsize()
    })


@vdl2_bp.route('/start', methods=['POST'])
def start_vdl2() -> Response:
    """Start VDL2 decoder."""
    global vdl2_message_count, vdl2_last_message_time, vdl2_active_device

    with app_module.vdl2_lock:
        if app_module.vdl2_process and app_module.vdl2_process.poll() is None:
            return jsonify({
                'status': 'error',
                'message': 'VDL2 decoder already running'
            }), 409

    # Check for dumpvdl2
    dumpvdl2_path = find_dumpvdl2()
    if not dumpvdl2_path:
        return jsonify({
            'status': 'error',
            'message': 'dumpvdl2 not found. Install from: https://github.com/szpajder/dumpvdl2'
        }), 400

    data = request.json or {}

    # Validate inputs
    try:
        device = validate_device_index(data.get('device', '0'))
        gain = validate_gain(data.get('gain', '40'))
        ppm = validate_ppm(data.get('ppm', '0'))
    except ValueError as e:
        return jsonify({'status': 'error', 'message': str(e)}), 400

    # Check if device is available
    device_int = int(device)
    error = app_module.claim_sdr_device(device_int, 'vdl2')
    if error:
        return jsonify({
            'status': 'error',
            'error_type': 'DEVICE_BUSY',
            'message': error
        }), 409

    vdl2_active_device = device_int

    # Get frequencies - use provided or defaults
    # dumpvdl2 expects frequencies in Hz (integers)
    frequencies = data.get('frequencies', DEFAULT_VDL2_FREQUENCIES)
    if isinstance(frequencies, str):
        frequencies = [f.strip() for f in frequencies.split(',')]

    # Clear queue
    while not app_module.vdl2_queue.empty():
        try:
            app_module.vdl2_queue.get_nowait()
        except queue.Empty:
            break

    # Reset stats
    vdl2_message_count = 0
    vdl2_last_message_time = None

    # Resolve SDR type for device selection
    sdr_type_str = data.get('sdr_type', 'rtlsdr')
    try:
        sdr_type = SDRType(sdr_type_str)
    except ValueError:
        sdr_type = SDRType.RTL_SDR

    is_soapy = sdr_type not in (SDRType.RTL_SDR,)

    # Build dumpvdl2 command
    # dumpvdl2 --output decoded:json --rtlsdr <device> --gain <gain> --correction <ppm> <freq1> <freq2> ...
    cmd = [dumpvdl2_path]
    cmd.extend(['--output', 'decoded:json:file:path=-'])

    if is_soapy:
        # SoapySDR device
        sdr_device = SDRFactory.create_default_device(sdr_type, index=device_int)
        builder = SDRFactory.get_builder(sdr_type)
        device_str = builder._build_device_string(sdr_device)
        cmd.extend(['--soapysdr', device_str])
    else:
        cmd.extend(['--rtlsdr', str(device)])

    # Add gain
    if gain and str(gain) != '0':
        cmd.extend(['--gain', str(gain)])

    # Add PPM correction if specified
    if ppm and str(ppm) != '0':
        cmd.extend(['--correction', str(ppm)])

    # Add frequencies (dumpvdl2 takes them as positional args in Hz)
    cmd.extend(frequencies)

    logger.info(f"Starting VDL2 decoder: {' '.join(cmd)}")

    try:
        process = subprocess.Popen(
            cmd,
            stdout=subprocess.PIPE,
            stderr=subprocess.PIPE,
            start_new_session=True
        )

        # Wait briefly to check if process started
        time.sleep(PROCESS_START_WAIT)

        if process.poll() is not None:
            # Process died - release device
            if vdl2_active_device is not None:
                app_module.release_sdr_device(vdl2_active_device)
                vdl2_active_device = None
            stderr = ''
            if process.stderr:
                stderr = process.stderr.read().decode('utf-8', errors='replace')
            error_msg = 'dumpvdl2 failed to start'
            if stderr:
                error_msg += f': {stderr[:200]}'
            logger.error(error_msg)
            return jsonify({'status': 'error', 'message': error_msg}), 500

        app_module.vdl2_process = process
        register_process(process)

        # Start output streaming thread
        thread = threading.Thread(
            target=stream_vdl2_output,
            args=(process,),
            daemon=True
        )
        thread.start()

        return jsonify({
            'status': 'started',
            'frequencies': frequencies,
            'device': device,
            'gain': gain
        })

    except Exception as e:
        # Release device on failure
        if vdl2_active_device is not None:
            app_module.release_sdr_device(vdl2_active_device)
            vdl2_active_device = None
        logger.error(f"Failed to start VDL2 decoder: {e}")
        return jsonify({'status': 'error', 'message': str(e)}), 500


@vdl2_bp.route('/stop', methods=['POST'])
def stop_vdl2() -> Response:
    """Stop VDL2 decoder."""
    global vdl2_active_device

    with app_module.vdl2_lock:
        if not app_module.vdl2_process:
            return jsonify({
                'status': 'error',
                'message': 'VDL2 decoder not running'
            }), 400

        try:
            app_module.vdl2_process.terminate()
            app_module.vdl2_process.wait(timeout=PROCESS_TERMINATE_TIMEOUT)
        except subprocess.TimeoutExpired:
            app_module.vdl2_process.kill()
        except Exception as e:
            logger.error(f"Error stopping VDL2: {e}")

        app_module.vdl2_process = None

    # Release device from registry
    if vdl2_active_device is not None:
        app_module.release_sdr_device(vdl2_active_device)
        vdl2_active_device = None

    return jsonify({'status': 'stopped'})


@vdl2_bp.route('/stream')
def stream_vdl2() -> Response:
    """SSE stream for VDL2 messages."""
    def generate() -> Generator[str, None, None]:
        last_keepalive = time.time()

        while True:
            try:
                msg = app_module.vdl2_queue.get(timeout=SSE_QUEUE_TIMEOUT)
                last_keepalive = time.time()
                try:
                    process_event('vdl2', msg, msg.get('type'))
                except Exception:
                    pass
                yield format_sse(msg)
            except queue.Empty:
                now = time.time()
                if now - last_keepalive >= SSE_KEEPALIVE_INTERVAL:
                    yield format_sse({'type': 'keepalive'})
                    last_keepalive = now

    response = Response(generate(), mimetype='text/event-stream')
    response.headers['Cache-Control'] = 'no-cache'
    response.headers['X-Accel-Buffering'] = 'no'
    return response


@vdl2_bp.route('/frequencies')
def get_frequencies() -> Response:
    """Get default VDL2 frequencies."""
    return jsonify({
        'default': DEFAULT_VDL2_FREQUENCIES,
        'regions': {
            'north_america': ['136975000', '136100000', '136650000', '136700000', '136800000'],
            'europe': ['136975000', '136675000', '136725000', '136775000', '136825000'],
            'asia_pacific': ['136975000', '136900000'],
        }
    })