#!/bin/bash

ffoo import core


is_integer() {
    #
    # True if $1 is integer value
    #
    # This is achieved by checking if 
    #
    local val="$1"
    test 0 -ge "$val" 2>/dev/null || test 0 -le "$val" 2>/dev/null
    case $? in
        0) return 0 ;;
        2) return 1 ;;
        *) warn "weird exit status in is_integer()"; return 2 ;;
    esac
}


bool() {
    #
    # True if $1 is true
    #
    #   bool [--like-sh|--like-c] value
    #
    # Returns with zero exit status for $1 values of "true",
    # "yes" or "y", 1 for for "false", "no" or "n" (only common
    # English is supported).  For any other non-integer value,
    # prints warning and exits with status of 2.
    #
    # For integer values, if --like-sh is specified (default),
    # zero produces zero, but any other value produces 1.  Use
    # --like-c to turn this logic around, i.e. as C works:
    # anything else than zero is considered true, resulting in
    # zero exit status.
    #
    local mode=sh
    while true; do case "$1" in
        --like-sh)  mode=sh; shift ;;
        --like-c)   mode=c;  shift ;;
        *)                   break ;;
    esac done
    local value="$1"
    local reset_shopt="$(shopt -p)"
    debug -v value
    if is_integer "$value";
    then
        case "$mode:$value" in
            c:0)       return 1 ;;
            c:*)       return 0 ;;
            sh:0)      return 0 ;;
            sh:[0-9]*) return 1 ;;  # positive bash exit status
            *)  warn "unexpected 'mode:value': $mode:$value"; return 2 ;;
        esac
    else
        case "${value,,}" in
            true|yes|y) return 0 ;;
            false|no|n) return 1 ;;
            "") usage_is -E "[-n] value"; return 2 ;;
            *)  warn "cannot determine true-ness: $value"; return 2 ;;
        esac
    fi
}