mpv-communicate

#!/usr/bin/env bash
# Sends commands to an mpv socket using socat
# First argument: mpv socket
# all other arguments are sent to the socket using socat

declare -a ARGS
GET_SOCKET=
PRINT=1
SOCKET=

usage() {
    cat <<-EOF
usage: ${0##*/} [options] [SOCKET] COMMAND

    Read about mpv IPC commands at mpv.io/manual/master/#json-ipc.

options:
    -q, --quiet           Print nothing, only return if COMMAND was successful.
EOF
}

abort() {
    if [[ "$PRINT" -eq 1 ]]; then
        usage
        echo "${0##*/}: $1" >&2
    fi

    exit 1
}

get_opts() {
    while [[ "$#" -ne 0 ]]; do
        SHIFT_COUNT=1
        case "$1" in
            -q | --quiet) PRINT=0 ;;
            -a | --ampv) GET_SOCKET="AMPV" ;;
            -m | --music) GET_SOCKET="MUSIC" ;;
            -u | --umpv) GET_SOCKET="UMPV" ;;
            *)
                if [[ -z "$GET_SOCKET" ]]; then
                    SOCKET="$1"
                else
                    ARGS+=("$1")
                fi
                ARGS+=("${@:2}")
                SHIFT_COUNT="$#"
                ;;
        esac
        shift "$SHIFT_COUNT"
    done
}

set_socket() {
    [[ -n "$SOCKET" ]] && return
    case "$GET_SOCKET" in
        AMPV) SOCKET="$(mpv-active-sockets --ampv | head -n1)" ;;
        MUSIC) SOCKET="$(mpv-active-sockets --music | head -n1)" ;;
        UMPV) SOCKET="$(mpv-active-sockets --umpv | head -n1)" ;;
        *) abort "unrecognized value in GET_SOCKET: $GET_SOCKET" ;;
    esac
}

validate_socket() {
    [[ ! -e "$SOCKET" ]] && abort "path doesn't exist: $SOCKET"
    [[ ! -S "$SOCKET" ]] && abort "path isn't a socket: $SOCKET"
}

mpv_communicate() {
    if [[ "$PRINT" -eq 1 ]]; then
        socat - "${SOCKET:?Socket is not set.}" <<<"${ARGS[@]}"
    else
        socat - "${SOCKET:?Socket is not set.}" <<<"${ARGS[@]}" >/dev/null 2>&1
    fi
}

main() {
    get_opts "$@"
    set_socket
    validate_socket
    mpv_communicate
}

main "$@"