#!/bin/bash

##### SNIPPETS #####

log() {
    # Beautiful logs
    date=`date +"%d/%m/%Y - %H:%M:%S"`
    echo "[$date]" $1
}

display_err_arg() {
    echo "Usage: welcomehome --start $(tput smul)configuration file$(tput rmul)"
    echo "OR"
    echo "Usage: welcomehome --stop"
}

parse_arg() {
    # Echoes the value of a given parameter in a given configuration file
    value=$(cat $1 | grep -E "^$2" | cut -d"=" -f2)
    value=$(echo $value | sed "s,^\s+,,")
    echo $value
}

check_url() {
    # Check if URL is starting with "http(s)://"
    # Returns the same code as grep, which is 1 if incorrect,
    # 0 if correct
    echo $1 | grep -E "^https?\://"
    return $?
}

##### STREAM CONTROL #####

set_volume() {
    # Set the volume to the right value
    volume=$1
    log "Set volume to $volume"

    data='{"jsonrpc": "2.0", "id": 1, "method": "core.mixer.set_volume", "params": [VOLUME]}'
    # Using sed cuz simple quotes
    data=`echo $data | sed "s/VOLUME/${volume}/"`

    # Send the load
    curl -s -d "$data" http://localhost:6680/mopidy/rpc > /dev/null
}

play_stream() {
    # Reset playback state
    curl -s -d '{"jsonrpc": "2.0", "id": 1, "method": "core.playback.stop"}' http://localhost:6680/mopidy/rpc > /dev/null
    curl -s -d '{"jsonrpc": "2.0", "id": 1, "method": "core.tracklist.clear"}' http://localhost:6680/mopidy/rpc > /dev/null

    # Add track infos
    stream=$1
    log "Playing stream $stream"

    data='{"jsonrpc": "2.0", "id": 1, "method": "core.tracklist.add", "params": [ [ { "__model__": "Track", "uri": "STREAM" } ] ] }'
    # Using sed cuz simple quotes
    data=`echo $data | sed "s,STREAM,${stream},"`

    # Play dat sound
    curl -s -d "$data" http://localhost:6680/mopidy/rpc > /dev/null
    curl -s -d '{"jsonrpc": "2.0", "id": 1, "method": "core.playback.play"}' http://localhost:6680/mopidy/rpc > /dev/null
}

stop_stream() {
    # Stop dat sound
    curl -s -d '{"jsonrpc": "2.0", "id": 1, "method": "core.playback.stop"}' http://localhost:6680/mopidy/rpc > /dev/null
    log "Stream stopped"
}

##### CONTROLLERS #####

start_playing() {
    touch $lock_file
    play_stream $stream
}

stop_playing() {
    if [ -f $lock_file ]; then
        rm $lock_file
    fi
    stop_stream
}

##### MAIN FUNCTIONS #####

init() {
    # Initialise the variables
    config_file=$1

    # Check if the config file exists
    if [ ! -f $config_file ]; then
        echo "$config_file is not a file"
        exit 1
    fi

    log "Parsing the configuration file"

    # Get parameters from the given configuration file
    volume=$(parse_arg $config_file "volume")
    stream=$(parse_arg $config_file "stream")
    threshold=$(parse_arg $config_file "device_threshold")
    address=$(parse_arg $config_file "device_address")

    # Check stream URL validity
    if [ ! $(check_url $stream) ]; then
        echo "Incorrect stream address"
        exit 1
    fi

    # Check volume value validity
    if [ $volume -gt 100 ] || [ $volume -lt 0 ]; then
        echo "Invalid volume value"
        exit 1
    fi

    # Set volume to the right value
    set_volume $volume

    # Removing lock file in case of ungraceful shutdown
    if [ ! -f $lock_file ]; then
        rm $lock_file
    fi

    log "Initialisation complete"
}

main() {
    #Main loop
    log "Looking for device"
    while true; do
        # Polling the device's IP address
        count=$(ping -W 1 -c $threshold $address | grep ttl | wc -l)

        if [ $count -gt 0 ]; then
            # Lock file present = music already playing
            if [ ! -f $lock_file ]; then
                log "Device detected"
                start_playing
            fi
        else
            if [ -f $lock_file ]; then
                log "Device lost"
                stop_playing
            fi
        fi
    done
}

##### PROGRAM #####

if [ $# -eq 0 ] || [ $# -gt 2 ]; then
    echo "Wrong arguments number"
    display_err_arg
    exit 1
fi

# Setting lock file path
lock_file="/etc/welcomehome/home.lck"

# Check if we know the requested feature
case "$1" in
    "--start") init $2
               main
               ;;
    "--stop") stop_playing
              ;;
    *) echo "Unknown argument $1"
       display_err_arg
       ;;
esac