#!/bin/bash

WPDIR="$HOME/pictures/wallpapers"
LAST_WP_FILE="$HOME/.config/random-wall_last_wp.txt"
CURRENT_WP_FILE="$HOME/.config/nitrogen/bg-saved.cfg"

random=true
apply=true
wpfile=""

function usage {
    local stream exitcode
    if [ "$1" -eq 1 ]; then
        stream=2
        exitcode=255
    else
        stream=1
        exitcode=0
    fi
    echo "Usage: $(basename "$0") [-n|--noapply] [-h|--help] [wallpaper_location]" >&"$stream"
    echo "If wallpaper location is not given, a random wallpaper from $WPDIR will be chosen" >&"$stream"
    exit "$exitcode"
}

# Check if last wallpaper file exists and get its content
if [ -f "$LAST_WP_FILE" ]; then
    LAST_WP=$(<"$LAST_WP_FILE")
else
    LAST_WP=""
fi

# Function to get a random wallpaper from $WPDIR, excluding the last and current wallpapers
function get_random_wallpaper {
    local wallpapers
    shopt -s nullglob
    wallpapers=("$WPDIR"/*.jpg)
    if [ ${#wallpapers[@]} -eq 0 ]; then
        echo "No wallpapers found in $WPDIR" >&2
        exit 1
    fi

    # If there is only one wallpaper, return it
    if [ ${#wallpapers[@]} -eq 1 ]; then
        echo "${wallpapers[0]}"
        return
    fi

    local exclude=()
    if [ "$LAST_WP" != "" ]; then
        exclude+=("$LAST_WP")
    fi
    if [ "$CURRENT_WP" != "" ]; then
        exclude+=("$CURRENT_WP")
    fi

    local random_wallpaper
    while true; do
        random_wallpaper="${wallpapers[RANDOM % ${#wallpapers[@]}]}"
        if [[ ! " ${exclude[@]} " =~ " ${random_wallpaper} " ]]; then
            echo "$random_wallpaper"
            return
        fi
    done
}

# handle arguments
while [ $# -gt 0 ]; do
    case "$1" in
        "--help" | "-h")
            usage 0
            ;;
        "--noapply" | "-n")
            apply=false
            ;;
        *)
            if ! "$random"; then
                usage 1
            elif [ ! -f "$1" ]; then
                echo "File '$1' not found" >&2
                exit 1
            fi
            random=false
            wpfile="$1"
            ;;
    esac
    shift
done

# Choose a random wallpaper if necessary
if "$random"; then
    wpfile=$(get_random_wallpaper)
    echo "Chose: $wpfile" >&2
fi

# Set the desktop wallpaper
cat >"$HOME/.config/nitrogen/bg-saved.cfg" <<EOF
[xin_-1]
file=$wpfile
mode=4
bgcolor=#000000
EOF

# Set the lock screen wallpaper
"$HOME/.scripts/lockscreen-wallpaper" "$wpfile" &

# Set the LightDM wallpaper
cp "$wpfile" "/usr/share/lightdm-webkit/themes/glorious/assets/bg.jpg"

# Save the last chosen wallpaper
echo "$wpfile" >"$LAST_WP_FILE"

# Sync wallpaper using AccountsService D-Bus
if [ "$wpfile" != "" ]; then
    dbus-send \
        --print-reply \
        --system \
        --dest=org.freedesktop.Accounts \
        /org/freedesktop/Accounts/User"$(id -u)" \
        org.freedesktop.DBus.Properties.Set \
        string:org.freedesktop.DisplayManager.AccountsService \
        string:BackgroundFile \
        variant:string:"$wpfile"
fi

# Apply the desktop wallpaper if requested
if "$apply"; then
    nitrogen --restore
fi