#!/usr/bin/env ruby

require 'optparse'
require 'slackit'

# -------------------------------------------------------------------------------- #
# Send Mssage to Slack                                                             #
# -------------------------------------------------------------------------------- #
# This function will take the input arguments and then send the message.           #
# -------------------------------------------------------------------------------- #

def send_message_to_slack(options)
    begin
        s = Slackit.new(webhook_url: options[:webhook_url], channel: options[:channel], username: options[:username], icon_emoji: options[:icon_emoji])
        s.send(options[:message])
    rescue ArgumentError
        puts "You must specify a webhook_url"
        exit(1)
    end
end

# -------------------------------------------------------------------------------- #
# Process Arguments                                                                #
# -------------------------------------------------------------------------------- #
# This function will process the input from the command line and work out what it  #
# is that the user wants to see.                                                   #
#                                                                                  #
# This is the main processing function where all the processing logic is handled.  #
# -------------------------------------------------------------------------------- #

def process_arguments
    options = {}
    # Enforce the presence of
    mandatory = %I[webhook_url message]

    optparse = OptionParser.new do |opts|
        opts.banner = "Usage: #{$PROGRAM_NAME}"

        opts.on('-h', '--help', 'Display this screen') do
            puts opts
            exit(1)
        end
        opts.on('-c', '--channel string', 'The channel to send the message to') do |channel|
            options[:channel] = channel
        end

        opts.on('-i', '--icon-emoji string', 'The emoji to use for the channel icon [default: :wolf:]') do |icon_emoji|
            options[:icon_emoji] = icon_emoji
        end

        opts.on('-m', '--message string', 'The message to send') do |message|
            options[:message] = message
        end

        opts.on('-w', '--webhook-url string', 'The slack incoming webhook url to use') do |webhook_url|
            options[:webhook_url] = webhook_url
        end

        opts.on('-u', '--username string', 'The username to send as [default: slackit]') do |username|
            options[:username] = username
        end
    end

    begin
        optparse.parse!
        options[:message] = ARGF.read if !STDIN.tty? # override message parameter if data is piped in
        missing = mandatory.select { |param| options[param].nil? }
        raise OptionParser::MissingArgument.new(missing.join(', ')) unless missing.empty?
    rescue OptionParser::InvalidOption, OptionParser::MissingArgument => e
        puts e.to_s
        puts optparse
        exit
    end

    exit 0 if send_message_to_slack(options)

    exit 1
end

# -------------------------------------------------------------------------------- #
# Main()                                                                           #
# -------------------------------------------------------------------------------- #
# The main function where all of the heavy lifting and script config is done.      #
# -------------------------------------------------------------------------------- #

def main
    process_arguments
end

main

# -------------------------------------------------------------------------------- #
# End of Script                                                                    #
# -------------------------------------------------------------------------------- #
# This is the end - nothing more to see here.                                      #
# -------------------------------------------------------------------------------- #