lpl - Read entries from RetroArch .lpl playlist files in JSON format (powered by jq)

lpl

#!/bin/env bash

# lpl - Read entries from RetroArch .lpl playlist files in JSON format
#
# USAGE
#   See `lpl -h`
#
# DEPENDENCIES
#   getopts - Arguments parser (Bash built-in function)
#   readlink - Get fullpath from path (standard program)
#   jq - JSON parser (external program)

# DEFAULTS
QUERY="path"
FILE="$HOME/.config/retroarch/content_history.lpl"
INDEX=""

# PARSE ARGUMENTS
while getopts  "hq:f:i:" flag
do
    if [ "$flag" == "h" ]
    then
        echo "lpl [-h] [-q QUERY] [-f FILE] [-i INDEX]"
        echo ""
        echo "EXAMPLES:"
        echo "    lpl"
        echo "    lpl -q core_path"
        echo "    lpl -f "$HOME/.config/retroarch/playlists/Atari - 2600.lpl" -i 0"
        echo ""
        echo "QUERY:"
        echo "    keyname to read values from: 'path', 'label', 'core_path'," \
             "'core_name', 'crc32', 'db_name', 'default_core_path'," \
             "'default_core_name', defaults to: '$QUERY'"
        echo ""
        echo "FILE:"
        echo "    path to RetroArch .lpl playlist file in JSON format," \
             "defaults to: '$FILE'"
        echo ""
        echo "INDEX:"
        echo "    integer to limit output of entries, 0=first, 1=second," \
             "-1=last, an empty value will get all entries," \
             "defaults to: '$INDEX'"
        echo ""
        echo "2021 Tuncay D."
        exit 0
    fi

    if [ "$flag" == "q" ]
    then
        QUERY="$OPTARG"
    fi

    if [ "$flag" == "f" ]
    then
        FILE="$OPTARG"
    fi

    if [ "$flag" == "i" ]
    then
        INDEX="$OPTARG"
    fi
done

FILE=$(readlink -f "$FILE")

if [ "$QUERY" == "default_core_path" ]
then
    QUERY_EXPANDED=".default_core_path"
elif [ "$QUERY" == "default_core_name" ]
then
    QUERY_EXPANDED=".default_core_name"
else
    QUERY_EXPANDED=".items[$INDEX]? | select(.$QUERY != null) | .$QUERY"
fi

jq --raw-output "$QUERY_EXPANDED" "$FILE"