#!/usr/bin/env bash

usage() {
    cat <<EOS >&2
    $(help_synopsis "${BASE_SOURCE[0]}" "[options] <command> <commandoptions>")

    -l | --list-commands    List all available commands
    -v                      Be verbose
    -h                      Show this help and exit

$(help_end)
EOS
}

LIST_COMMANDS=0
VERBOSE=0

source $(dirname ${BASH_SOURCE[0]})/nix-utils.sh

#
# Get the name of the script file for the command passed as argument
#
# Does not check whether the file exists.
#
script_for() {
    echo "$(dirname ${BASH_SOURCE[0]})/nix-script-${1}.sh"
}

SHIFT_ARGS=0

#
# Increase the SHIFT_ARGS variable
#
shift_one_more() {
    SHIFT_ARGS=$(( SHIFT_ARGS + 1 ))
}

#
# Shift N times the arguments, so:
#
#  shift_n 5 a b c d e f
#
# will print "f"
#
shift_n() {
    for n in `seq 0 $1`; do shift; done
    echo $*
}

#
# List all available commands
#
all_commands() {
    find $(dirname ${BASH_SOURCE[0]}) -type f -name "nix-script-*.sh"
}

#
# Parse the arguments for this script
#
for cmd
do
    case $cmd in
    "--list-commands" )
        LIST_COMMANDS=1
        shift_one_more
        ;;

    "-l" )
        LIST_COMMANDS=1
        shift_one_more
        ;;

    "-v" )
        export VERBOSE=1
        stdout "Verbose now"
        shift_one_more
        ;;

    "-h" )
        usage
        exit 1
        ;;

    * )
        if [ ! -n $(script_for $cmd) ]
        then
            stderr "Unknown flag / command '$cmd'"
            exit 1
        else
            if [ -z "$COMMAND" ]
            then
                stdout "Found command: '$cmd'"
                COMMAND=$cmd
                shift_one_more
            fi
            break
        fi
    esac
done

if [ $LIST_COMMANDS -eq 1 ]
then
    stdout "Listing commands"
    for cmd in $(all_commands)
    do
        echo $(scriptname_to_command $cmd)
    done
    exit 0
fi

[ -z "$COMMAND" ] && stderr "No command given" && exit 1

stdout "Searching for script for '$COMMAND'"
SCRIPT=$(script_for $COMMAND)

#
# Error checking whether the script is available and executable.
#
[ ! -f $SCRIPT ]   && stderr "Not available: $COMMAND -> $SCRIPT" && exit 1
[[ ! -x $SCRIPT ]] && stderr "Not executeable: $SCRIPT"           && exit 1

stdout "Parsing args for '$COMMAND'"
SCRIPT_ARGS=$(shift_n $SHIFT_ARGS $*)

#
# execute the script with its arguments
#
stdout "Calling: '$SCRIPT $SCRIPT_ARGS'"
exec bash $SCRIPT $SCRIPT_ARGS