module Mozo
  module Counter
    extend ActiveSupport::Autoload
    autoload :Redis

    mattr_accessor :connection

    # mainly for testing purposes
    def self.set(key, value)
      connection.set(key, value) rescue value
    end

    def self.get(key)
      connection.get(key, quiet: true).to_i rescue 0
    end

    def self.incr(key, options = {})
      options[:initial] ||= 1
      connection.incr(key, options) rescue 1
    end

    def self.decr(key, options = {})
      options[:initial] ||= 0
      connection.decr(key, options) rescue 0
    end

    # Provision Redis counters from CouchDB aggregated data.
    # Reads the Order.by_supplier_id_and_state view (reduce, grouped),
    # and sets the corresponding Redis keys.
    #
    # Invoke via: rails runner 'Mozo::Counter.provision!'
    #
    def self.provision!
      require 'couchrest'

      db = Order.database
      design = '_design/order_counter'
      view   = 'by_supplier_id_and_state'

      # Ensure the design doc exists
      unless db.get(design) rescue nil
        puts "[Counter.provision!] Creating design doc #{design}"
        doc = YAML.safe_load(
          File.read(Rails.root.join('drb_counter/couchdb_design.yml')),
          permitted_classes: [Symbol]
        )
        doc['_id'] = design
        doc['language'] ||= 'javascript'
        db.save_doc(doc)
      end

      # Query with reduce + group to get per-supplier/per-state counts
      result = db.view("#{design}/_view/#{view}", reduce: true, group: true, group_level: 2)
      rows = result['rows'] || []

      puts "[Counter.provision!] #{rows.size} counter keys to set"

      rows.each do |row|
        supplier_id, state = row['key']
        count = row['value']

        case state
        when 'placed'
          key = "supplier_counter:#{supplier_id}:orders_placed"
        when 'active'
          key = "supplier_counter:#{supplier_id}:orders_in_process"
        else
          next
        end

        set(key, count)
        puts "  #{key} = #{count}"
      end

      puts "[Counter.provision!] Done."
      rows.size
    end
  end
end