#!/bin/bash

browser="/usr/bin/firefox -new-tab"
viewer="/usr/bin/youtube-viewer"
args="--non-interactive --really-quiet -id"
youtube=(
    "http://www.youtube.com.tw/watch?v="
    "http://www.youtube.com/watch?v="
    "http://youtu.be/"
)
url=$1
percent=( 10 12 15 17 20 23 28 33 41 50 61 78 100 )

function fadeout(){
    #Specify gap time by assign decimal to gap in seconds
    #You may use expenential fade. Comment the linear one and uncomment the exponential one
    gap=1.6     #gap time
    for((i=0; i < $((${#percent[@]} - 1)); i++)); do
        mpc -q volume $(( $1 - ($1/(${#percent[@]} - 1)) * ( $i + 1 ) ))
        sleep $(echo "scale=4; $gap / (${#percent[@]} - 1)" | bc)       #linear
                #sleep $(echo "scale=4; $gap * $((${percent[$((i+1))]}-${percent[$i]})) /100" | bc) #exponential
    done
    mpc -q volume 0
}

function fadein(){
    gap=1.6     #gap time
    for((i=$((${#percent[@]} - 1)); i > 0; i--)); do
        mpc -q volume $(( $1 - ($1/(${#percent[@]} - 1)) * $i ))
        sleep $(echo "scale=4; $gap / (${#percent[@]} - 1)" | bc)       #linear
        #sleep $(echo "scale=4; $gap * $((${percent[$i]}-${percent[$(($i-1))]})) /100" | bc)    #exponential
    done
    mpc -q volume $1
}



for((i=0; i < ${#youtube[@]}; i++)); do
    if [[ ${url} == ${youtube[i]}* ]]; then
        id=${url#${youtube[i]}}
        id=${id:0:11}
        if [[ ${#id} = 11 ]]; then
            vol=$(mpc | tail -1 | cut -d "%" -f 1 | cut -d ":" -f 2)
            fadeout ${vol}      #comment this line to disable fadeout
            ${viewer} ${args} ${id}
            fadein ${vol}       #comment this line to disable fadein
            break
        fi
    fi
done

if [[ $i = ${#youtube[@]} ]]; then
    ${browser} $1
fi