ais/ais_query.sh

#!/bin/sh

# AIS Stream Ship Position Query Script
# Uses websocat to connect to aisstream.io and query ship position data
# Requires: websocat command-line tool and a valid aisstream.io API key

# Configuration variables - Edit these as needed
API_KEY="${AIS_API_KEY:-8d32f42f3d7fa506ed5ed549d29279580b99303b}"
WEBSOCKET_URL="wss://stream.aisstream.io/v0/stream"

# Default bounding box (worldwide coverage)
# Format: [[lat1, lon1], [lat2, lon2]]
# Current setting covers the entire world
BOUNDING_BOX='[[[-90, -180], [90, 180]]]'

# Optional: Filter by specific ship MMSI numbers (up to 50)
# Leave empty for all ships
SHIP_MMSI_FILTER='["227397210"]'

# Optional: Filter by message types (default: PositionReport)
# Available types: PositionReport, ShipStaticData, BaseStationReport, etc.
MESSAGE_TYPE_FILTER='["PositionReport"]'

# Output file for logging (optional)
DateFichier=`date +"%Y%m%d-%H%M%S"`
OUTPUT_FILE="raw_ais_"$DateFichier".log"

# Function to display usage information
show_usage() {
    cat << EOF
Usage: $0 [OPTIONS]
Query AIS ship position data from aisstream.io using websocat

OPTIONS:
    -k, --api-key KEY       Set API key (can also use AIS_API_KEY environment variable)
    -b, --bbox BBOX         Set bounding box in JSON format
                           Example: '[[[25.0, -80.0], [26.0, -79.0]]]'
    -m, --mmsi MMSI_LIST    Filter by MMSI numbers in JSON array format
                           Example: '["123456789", "987654321"]'
    -t, --types TYPES       Filter by message types in JSON array format
                           Example: '["PositionReport", "ShipStaticData"]'
    -o, --output FILE       Save output to file (in addition to stdout)
    -h, --help             Show this help message

EXAMPLES:
    # Basic usage with API key from environment
    export AIS_API_KEY="your_api_key_here"
    $0

    # Query specific region (Miami area)
    $0 -k "your_api_key" -b '[[[25.6, -80.3], [25.8, -80.1]]]'

    # Filter specific ships
    $0 -k "your_api_key" -m '["368207620", "367719770"]'

    # Save output to file
    $0 -k "your_api_key" -o ship_positions.json

NOTES:
    - API key is required and can be obtained free from aisstream.io
    - Subscription message must be sent within 3 seconds of connection
    - Bounding box format: [[[lat1, lon1], [lat2, lon2]]]
    - Coordinates: latitude (-90 to 90), longitude (-180 to 180)
    - Press Ctrl+C to stop the stream

EOF
}

# Function to validate JSON format
validate_json() {
    echo "$1" | python3 -c "import sys, json; json.load(sys.stdin)" 2>/dev/null
    return $?
}

# Parse command line arguments
while [ $# -gt 0 ]; do
    case $1 in
        -k|--api-key)
            API_KEY="$2"
            shift 2
            ;;
        -b|--bbox)
            BOUNDING_BOX="$2"
            shift 2
            ;;
        -m|--mmsi)
            SHIP_MMSI_FILTER="$2"
            shift 2
            ;;
        -t|--types)
            MESSAGE_TYPE_FILTER="$2"
            shift 2
            ;;
        -o|--output)
            OUTPUT_FILE="$2"
            shift 2
            ;;
        -h|--help)
            show_usage
            exit 0
            ;;
        *)
            echo "Error: Unknown option $1" >&2
            show_usage
            exit 1
            ;;
    esac
done

# Validate required tools
if ! command -v websocat >/dev/null 2>&1; then
    echo "Error: websocat is not installed or not in PATH" >&2
    echo "Install websocat from: https://github.com/vi/websocat" >&2
    exit 1
fi

# Validate API key
if [ "$API_KEY" = "YOUR_API_KEY_HERE" ] || [ -z "$API_KEY" ]; then
    echo "Error: API key is required" >&2
    echo "Set AIS_API_KEY environment variable or use -k option" >&2
    echo "Get free API key from: https://aisstream.io/authenticate" >&2
    exit 1
fi

# Validate JSON formats
if ! validate_json "$BOUNDING_BOX"; then
    echo "Error: Invalid bounding box JSON format" >&2
    exit 1
fi

if ! validate_json "$SHIP_MMSI_FILTER"; then
    echo "Error: Invalid MMSI filter JSON format" >&2
    exit 1
fi

if ! validate_json "$MESSAGE_TYPE_FILTER"; then
    echo "Error: Invalid message type filter JSON format" >&2
    exit 1
fi

# Create subscription message
create_subscription_message() {
echo "{\"APIKey\":\"$API_KEY\",\"BoundingBoxes\":$BOUNDING_BOX,\"FiltersShipMMSI\":$SHIP_MMSI_FILTER}"
}

# Function to process AIS messages
process_message() {
    if [ -n "$OUTPUT_FILE" ]; then
        # Output to both stdout and file
        tee -a "$OUTPUT_FILE"
    else
        # Output to stdout only
        cat
    fi
}

# Display connection information
echo "Connecting to AIS Stream..."
echo "WebSocket URL: $WEBSOCKET_URL"
echo "Bounding Box: $BOUNDING_BOX"
echo "MMSI Filter: $SHIP_MMSI_FILTER"
echo "Message Types: $MESSAGE_TYPE_FILTER"
if [ -n "$OUTPUT_FILE" ]; then
    echo "Output File: $OUTPUT_FILE"
    # Create output file with timestamp header
    echo "# AIS Stream Data - $(date)" > "$OUTPUT_FILE"
fi
echo "Press Ctrl+C to stop..."
echo "----------------------------------------"

# Setup cleanup on script exit
cleanup() {
    echo ""
    echo "Connection closed."
    if [ -n "$OUTPUT_FILE" ]; then
        echo "Data saved to: $OUTPUT_FILE"
    fi
}
trap cleanup EXIT INT TERM

# Create subscription message and connect
SUBSCRIPTION_MSG=$(create_subscription_message)

# Connect to websocket and send subscription message
echo "$SUBSCRIPTION_MSG" | websocat -n -H "Sec-WebSocket-Protocol: json"  -v "$WEBSOCKET_URL" - | process_message