#!/bin/sh
# shellcheck source=/dev/null
#
# pfetch - Simple POSIX sh fetch script.

die() {
    printf '\033[31;1merror\033[m: %s.\n' "$@" >&2
    exit 1
}

log() {
    printf '\033[3%s;1m%s\033[m%s%s\n' "$1" "$2" "$3" "${4:-unknown}"
}

get_os() {
    case $kernel_name in
        Linux|GNU*) os=linux ;;

        *)
            die "Unknown OS detected '$kernel_name'" \
                "Open an issue on GitHub to add support for your OS"
        ;;
    esac
}

get_distro() {
    case $os in
        linux)
            . /etc/os-release && distro=$PRETTY_NAME
        ;;
    esac

    log 1 os " " "$distro"
}

get_kernel() {
    log 1 kernel " " "$kernel_version"
}

get_uptime() {
    # Uptime works by retrieving the data in total seconds and then
    # converting that data into days, hours and minutes using simple
    # math.
    case $os in
        linux)
            IFS=. read -r s _ < /proc/uptime
        ;;
    esac

    # Convert the uptime from seconds into days, hours and minutes.
    d=$((s / 60 / 60 / 24))
    h=$((s / 60 / 60 % 24))
    m=$((s / 60 % 60))

    # Only append days, hours and minutes if they're non-zero.
    [ "$d" = 0 ] || uptime="${uptime}${d}d "
    [ "$h" = 0 ] || uptime="${uptime}${h}h "
    [ "$m" = 0 ] || uptime="${uptime}${m}m "

    log 1 uptime " " "${uptime:-0m}"
}

main() {
    # Hide 'stderr' unless the first argument is '-v'. This saves
    # polluting the script with '2>/dev/null'.
    [ "$1" = -v ] || exec 2>/dev/null

    # Store the output of 'uname' to avoid calling it multiple times
    # throughout the script. 'read <<EOF' is the simplest way of reading
    # a command into a list of variables.
    read -r kernel_name kernel_version kernel_machine <<EOF
        $(uname -srm)
EOF

    get_os
    get_distro
    get_kernel
    get_uptime
}

main "$@"