#!/bin/zsh
# Eryn Wells <eryn@erynwells.me>

MOTD_FILE=/etc/motd

binary_exists() {
    hash $1 1>/dev/null 2>&1
    return $?
}

if [[ ! -w "$MOTD_FILE" ]]; then
    echo "$MOTD_FILE is not wrtiable by $USER" >&2
    exit 1
fi

# If lolcat is installed, dump a colorful message to the MOTD file. :)
local cat_program=cat
local cat_args=''
if binary_exists lolcat; then
    echo "Enabling rainbows"
    cat_program=lolcat
    cat_args=-f
fi

local hello_message="\nThis machine is called `hostname`.\n"

local hardware_model=`sysctl -n hw.model`

if [[ -n "$hardware_model" ]]; then
    hello_message+="It’s a $hardware_model "
fi

local os_version=`sysctl -n kern.osproductversion`
local product_name=`sw_vers --productName`
local os_build=`sw_vers --buildVersion`

if [[ -n "$os_version" && -n "$os_build" ]]; then
    hello_message+="running $product_name $os_version ($os_build)."
elif [[ -n "$os_version" ]]; then
    hello_message+="running $product_name $os_version."
fi

hello_message+="\n"

echo "Writing MOTD"
print -P $hello_message | $cat_program $cat_args > $MOTD_FILE