#!/bin/bash
#
# Checks that an internet connection exists.
# Return value is 0 on success, or another number on failure (see also: 'curl-exit-code-to-string').
#
# Examples:
#    eos-connection-checker -t=20 && echo connection exists || echo no connection
#    eos-connection-checker || curl-exit-code-to-string $?

# FastestMirror assumes the list was created with eos-rankmirrors.
# Both functions below return the URLs in format: https://mirror.moson.org/endeavouros/repo/state
FastestMirror() { grep -m1 "^# https://" $ml | sed 's|# \([^$]*\)/\$.*|\1/state|' ; }
AllMirrors()    { grep "^Server[ ]*=[ ]*https://" $ml | sed 's|^Server[ ]*=[ ]*\([^$]*\)/\$.*|\1/state|' ; }

Test() {
    local url="$1"
    /bin/curl --silent --fail --connect-timeout $timeout "$url" >/dev/null  # download the 'state' file from a mirror
    retval=$?
    if [ $retval -eq 0 ] ; then
        [ "$verbose" = "yes" ] && echo "==> Mirror = $url" >&2
        exit 0                     # connection exists
    fi
}

CheckTimeout() {
    case "$timeout" in
        "") timeout=$default_timeout; return ;;                     # must have a value
        0)  timeout=1; return ;;                                    # don't allow zero timeout
        0*) timeout=$(echo "$timeout" | sed -E 's|[0]+(.+)|\1|') ;; # remove leading zeros
    esac
    [ "${timeout//[0-9]/}" ] && timeout=$default_timeout            # only numbers allowed
}

Help() {
    local progname=${0##*/}
    cat <<EOF
Usage: $progname [options]
Options:
       -h,  --help         This help.
       -v,  --verbose      Be more verbose.
       -t*, --timeout=*    Max time in seconds to wait for each internet check to fail.
                           Option --timeout requires a '=' and a number.
                           Examples: '-t10', '-t=10', '--timeout=10' mean the same.
                           Default timeout is $default_timeout.
EOF
}

Main() {
    local -r ml=/etc/pacman.d/endeavouros-mirrorlist
    local fastest=""
    local URLs=()
    local URL
    local retval=201                                    # 201 means internal error, should never happen
    local fallback="https://forum.endeavouros.com/faq"  # fallback if no mirrors in $ml
    local -r default_timeout=8
    local timeout="$default_timeout"
    local verbose=no

    for arg in "$@" ; do
        case "$arg" in
            -v   | --verbose)    verbose=yes ;;
            -t=* | --timeout=*)  timeout=${arg#*=}; CheckTimeout ;;
            -t*)                 timeout=${arg/-t}; CheckTimeout ;;
            -h   | --help)       Help; exit 0 ;;
        esac
    done
    [ $verbose = yes ] && echo "==> Timeout = $timeout" >&2

    if [ -e $ml ] ; then
        fastest="$(FastestMirror)"                        # Try the fastest ranking mirror first.
        if [ "$fastest" ] ; then
            Test "$fastest"
            URLs=($(AllMirrors | grep -v "$fastest"))     # Fastest failed, use the actual mirrorlist without then $fastest.
        else
            URLs=("$(AllMirrors)")                        # Fastest not found, use the actual mirrorlist.
        fi
    fi
    URLs+=("$fallback")                                   # Fallback URL if no mirrors configured.

    for URL in "${URLs[@]}" ; do
        Test "$URL"
    done
    exit $retval                                          # all tested URLs failed, exit with the last curl error
}

Main "$@"