#!/usr/bin/env bash

#
# igex(1): Run a command and ignore specified exit values, translating them to
# 0. Don't touch any stderr, though. Good for wrapping around rsync(1), like to
# ignore exit value 24.
#
# -h gives help, -v gives you stderr specifying success or failure, -i specifies
# the signals to ignore; you must specify at least one none-zero integer.
#
# Author: Tom Ryder <tom@sanctum.geek.nz>
# Copyright: 2016
# License: Public domain
#
self=igex

# Print usage information
usage() {
    printf '%s: usage: %s [-hv] -i IGNORE1[,IGNORE2...] [--] COMMAND [ARG1...]\n' \
        "$self" "$self"
}

# Array with exit values to ignore
declare -a ignores
ignores=()

# Flag for whether to print diagnostics to stderr or not; defaults to off
declare -i verbose
verbose=0

# Process options
while getopts 'hvi:' opt ; do
    case $opt in

        # -h: Print help
        h)
            usage
            exit 0
            ;;

        # -v: Print diagnostics to stderr
        v)
            verbose=1
            ;;

        # Specify the comma-delimited signals to ignore
        i)
            IFS=, read -a ignores < <(printf '%s\n' "$OPTARG")
            ;;

        # Unknown option
        \?)
            usage >&2
            exit 2
            ;;
    esac
done
shift "$((OPTIND-1))"

# Check we have at least one ignore value
if ! ((${#ignores[@]})) ; then
    usage >&2
    exit 2
fi

# Check that all the ignore values are non-zero
for ignore in "${ignores[@]}" ; do
    ((ignore != 0)) && continue
    usage >&2
    exit 2
done

# Check we have some arguments left to run a command
if ! (($#)) ; then
    usage >&2
    exit 2
fi

# Run the command and save its exit value
"$@"
ret=$?

# Iterate through the ignored exit values and reset the exit value to 0 if it
# matches any of them, including a warning to stderr if -v was specified
for ignore in "${ignores[@]}" ; do
    ((ret != ignore)) && continue
    ((verbose)) && printf '%s: Ignoring exit value %u\n' \
        "$self" "$ignore" >&2
    ret=0
    break
done

# Exit with the determined value
exit "$ret"