#!/usr/bin/env ruby

require 'cgi'
require 'httparty'
require 'date'

module Agents
  class JiraAgent < Agent
    cannot_receive_events!

    description <<-MD
      The Jira Agent subscribes to Jira issue updates.

      `jira_url` specidies the full URL of the jira installation, including https://
      `jql` is an optional Jira Query Language-based filter to limit the flow of events. See [JQL Docs](https://confluence.atlassian.com/display/JIRA/Advanced+Searching) for details. 
      `username` and `password` are optional, and may need to be specified if your Jira instance is read-protected

      The agent does periodical queries and emits the events containing the updated issues in JSON format.
      NOTE: upon the first execution, the agent will fetch everything available by the JQL query. So if it's not desirable, limit the `jql` query by date.
    MD

    event_description <<-MD
      Events are the raw JSON generated by Jira REST API

      {
        "expand": "editmeta,renderedFields,transitions,changelog,operations",
        "id": "80127",
        "self": "https://jira.atlassian.com/rest/api/2/issue/80127",
        "key": "BAM-3512",
        "fields": {
          ...
        }
      }
    MD

    default_schedule "every_10m"

    def default_options
      {
        'username'  => '',
        'password' => '',
        'jira_url' => 'https://jira.atlassian.com',
        'jql' => '' 
      }
    end

    def validate_options
        errors.add(:base, "you need to specify your jira URL") unless options['jira_url'].present?
    end

    def working?
      (events_count.present? && events_count > 0)
    end

    def check
      last_run = nil

      current_run = Time.now.utc.iso8601
      last_run = Time.parse(memory[:last_run]) if memory[:last_run]
      begin
        issues = get_issues(last_run)

        issues.each do |issue|
          updated = Time.parse(issue['fields']['updated'])

          # this check is more precise than in get_issues()
          # see get_issues() for explanation
          if updated > last_run then
            create_event :payload => issue
          end
        end

        memory[:last_run] = current_run
      rescue Exception => e
        log(e.message)
      end
    end

  private
    def request_url(jql, start_at)
      "#{options[:jira_url]}/rest/api/2/search?jql=#{CGI::escape(jql)}&fields=*all&startAt=#{start_at}"
    end

    def request_options
      ropts = {:headers => {"User-Agent" => "Huginn (https://github.com/cantino/huginn)"}}

      if !options[:username].empty?  then
        ropts = ropts.merge({:basic_auth => {:username =>options[:username], :password=>options[:password]}})
      end

      ropts
    end


    def get_issues(since)
      startAt = 0
      issues = []

      # JQL doesn't have an ability to specify timezones
      # Because of this we have to fetch issues 24 h
      # earlier and filter out unnecessary ones at a later
      # stage. Fortunately, the 'updated' field has GMT
      # offset
      since -= 24*60*60

      jql = ""

      if !options[:jql].empty? && since then 
        jql = "(#{options[:jql]}) and updated >= '#{since.strftime('%Y-%m-%d %H:%M')}'"
      else
        jql = options[:jql] if !options[:jql].empty?
        jql = "updated >= '#{since.strftime('%Y-%m-%d %H:%M')} GMT'" if since
      end


      loop do
        response = HTTParty.get(request_url(jql, startAt), request_options)

        if response.code == 400 then
          raise RuntimeError.new("Jira error: #{response['errorMessages']}") 
        elsif response.code == 403 then
          raise RuntimeError.new("Authentication failed: Forbidden (403)")
        elsif response.code != 200 then
          raise RuntimeError.new("Request failed: #{response}")
        end

        issues += response['issues']
        startAt += response['issues'].length
 
        break if startAt >= response['total']
      end

      issues
    end

  end
end