squirt: upload a file to a slack channel from the cli

## squirt
#!/usr/bin/env ruby

require 'json'

if ARGV.length < 3 then
  puts "Usage: squirt <filename> <channel> <comment>"
  exit
end

token = ""

if token == "" then
  puts "Get an API token at https://api.slack.com/web#basics and enter it above"
  exit
end

filename = ARGV[0]
channel = ARGV[1]
comment = ARGV[2]

# get channel list
channel_raw_data = `curl -s -F token=#{token} https://slack.com/api/channels.list`
channel_data = JSON.parse(channel_raw_data)

#find channel ID for channel name
channel_id = channel_data["channels"].map {|c| c['id'] if c['name']==channel}.compact.first

if not channel_id then
  puts "Channel ID not found"
  exit 1
end

output = `curl -s -F file=@#{filename} -F channels=#{channel_id} -F initial_comment=\"#{comment}\" -F token=#{token} https://slack.com/api/files.upload`
result = JSON.parse(output)

if not result['ok'] then
  puts "Upload failed: #{result['error']}"
  exit 1
end