generate-shares.rb

require "httparty"
require 'yaml'
require 'digest/sha1'
require 'slop'

########################################################################################################################
# CLI Parsing
# $varname = global variable  (dollar sign = global var, accessible in functions)
$opts = Slop.parse do |o|
    o.string '-d', '--dest', 'destination', default: "_data/shares.yml"
    o.bool '-D', '--dry-run', "Do a dry-run (don't write to file)"
    o.bool '--debug', "Print debug output"
    o.on '-h', '--help' do
        puts o
        exit
    end
end
if $opts.debug?
    puts "DEBUG MODE"
end
if $opts.dry_run?
    puts "DRY RUN"
end
########################################################################################################################

# Make sure all required env vars are set
required_env_vars = ['SLACK_API_TOKEN', 'SLACK_CHANNEL_ID']
required_env_vars.each do |env_var|
    unless ENV.has_key?(env_var)
        puts "Please set the '%s' environment variable." % [env_var]
        puts "Exiting."
        exit 1
    end
end
########################################################################################################################
dst = $opts[:dest]
puts "Loading existing shares from #{dst}"
all_shares = YAML.load_file(dst)
all_ids = all_shares.map{|share| share['id']}

########################################################################################################################
# HELPER FUNCTIONS

def print_share(share)
    puts "\tTITLE: #{share['title']}"
    puts "\tURL: #{share['url']}"
    puts "\tTIMESTAMP: #{share['timestamp']}"
    puts "\tID: #{share['id']}"
    puts "\t----"
end

def debug(msg)
    if $opts.debug?
        puts "DEBUG: #{msg}"
    end
end 

########################################################################################################################


puts "Making API Request to Slack"

url = "https://slack.com/api/conversations.history?token=%s&channel=%s" %  \
      [ENV["SLACK_API_TOKEN"], ENV["SLACK_CHANNEL_ID"]]
response = HTTParty.get(url, format: JSON)

# Basic response errpr handling
if response.code != 200
    puts "ERROR: HTTP Reponse code: #{response.code} (#{url})"
    exit 1
end

body = JSON.parse(response.body)
if body.has_key?('error')
    puts "ERROR: API error: #{body['error']}"
    exit 1
end

new_shares = []
messages = body['messages']
messages.each do |message|
    debug(message)
    # Skip messages that have a subtype, these are channel notifications like 'x joined channel'
    unless message.has_key?('subtype')
        # We will only parse slack messages that are of the format:
        # text
        # <url>
        lines = message['text'].split("\n")
        debug(lines)
        # Messages where we have set an explicit title
        if lines.length() == 2 and lines[0] != ""
            share_url = lines[1][1..-2] # remove leading and trailing angular brackets
            share_id = Digest::SHA1.hexdigest(share_url)
            unless all_ids.include?(share_id)
                title = lines[0]
                puts "TITLELINE: #{title}"
                ['·',' - ',' – ', ' | '].each{|split_mark| title = title.partition(split_mark).first}
                title = title.strip
                share = {
                    'title' => title,
                    'url' => share_url,
                    'id' => share_id,
                    'timestamp' => message['ts']
                }
                print_share(share)
                new_shares.push(share)
            end
        # Only URL is shared, determine title from attachment
        elsif message.has_key?('attachments')
            # Message is 2 lines, but title line is empty
            if lines.length() == 2 and lines[0] == ""
                lines.shift()
            end
            share_url = lines[0][1..-2] # remove leading and trailing angular brackets
            share_id = Digest::SHA1.hexdigest(share_url)
            unless all_ids.include?(share_id)
                puts "URL ONLY"
                title = message['attachments'][0]['title']
                share = {
                    'title' => title,
                    'url' => share_url,
                    'id' => share_id,
                    'timestamp' => message['ts']
                }
                print_share(share)
                new_shares.push(share)
            end
        end
    end
end

########################################################################################################################
puts "Writing #{new_shares.length()} new share(s) to %s" % dst
all_shares = new_shares + all_shares # Prepend the new shares -> they are newer
unless $opts.dry_run?
    File.open(dst, "w") { |file| file.write(all_shares.to_yaml) }
else
    puts "DRY RUN: skipping filewrite"
end
puts "DONE"