#!/bin/bash

##### FUNCTIONS #####

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

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 $?
}

check_volume() {
    # Check if the volume value is valid
    if [ $1 -gt 100 ] || [ $1 -lt 0 ]; then
        echo "Invalid volume value"
        exit 1
    fi
}

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

    # The right music at the righ volume. Nothing's more perfect.
    set_volume $2
}

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"
}

##### PROGRAM #####

if [[ $# -eq 0 || ! -f $1 ]]; then
    echo "I need a config file as first argument"
    exit 1
fi

config_file=$1

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")

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

log "Initialisation complete"

while true; do
    # Lock file
    lock_file="/etc/welcomehome/home.lck"

    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"
            play_stream $stream $volume
            touch $lock_file
        fi
    else
        if [ -f $lock_file ]; then
            log "Device lost"
            stop_stream
            rm $lock_file
        fi
    fi
done