require 'json'
require 'net/http'
require 'fileutils'
require 'digest/md5'

module Filbunke
  class Client

    attr_reader :repository

    UPDATES_ACTION = 'updates'
    FILES_ACTION = 'files'
    URL_KEY = 'url'
    FROM_CHECKPOINT_KEY = 'from_checkpoint'
    HASH_KEY = 'hash'

    def initialize(repository, logger, callbacks = [])
      @repository = repository
      @logger = logger
      @callbacks = callbacks
    end

    def with_updated_files(last_checkpoint)
      updates = get_updated_file_list(last_checkpoint)
      updated_files = updates["files"] || []
      failure = false
      updated_files.each do |raw_file|
        file = File.new(raw_file)

        local_file_path = ::File.join(repository.local_path, file.path)
        if file_needs_update?(file, local_file_path)
          if file.url =~ /^http:\/\//
            if update_http_file!(file, local_file_path) then
              @callbacks.each do |callback|
                callback.on_update(file)
              end
              yield file
            else
              @logger.log "Unable to get file #{file.url}/#{file.path}!"
              failure = true
            end
          else
            raise "Unsupported protocol for file: #{file.inspect}"
          end
        end
      end
      failure ? last_checkpoint : (updates["checkpoint"] || last_checkpoint)
    end

    def update_files!(last_checkpoint)
      with_updated_files(last_checkpoint) {}
    end

    def register_updated_file!(path, url, hash = nil)
      register_http = Net::HTTP.new(@repository.host, @repository.port)
      register_http.start do |http|
        register_path = "/#{FILES_ACTION}/#{@repository.name}/#{path}?#{URL_KEY}=#{url}"
        register_path += "&#{HASH_KEY}=#{hash}" if hash
        request = Net::HTTP::Put.new(register_path)
        response = http.request(request)
        if response.code.to_i != 204
          raise "Failed to register updated file: #{path}"
        end
      end
    end

    def register_deleted_file!(path)
      register_http = Net::HTTP.new(@repository.host, @repository.port)
      register_http.start do |http|
        register_path = "/#{FILES_ACTION}/#{@repository.name}/#{path}"
        request = Net::HTTP::Delete.new(register_path)
        response = http.request(request)
        if response.code.to_i != 204
          raise "Failed to register deleted file: #{path}"
        end
      end
    end

    private

    def file_needs_update?(file, local_file_path)
      return true if file.hash.nil? || file.hash == ""

      return true unless File.exists?(local_file_path)

      local_hash = Digest::MD5.hexdigest(File.read(local_file_path))
      local_hash != file.hash
    end

    def get_updated_file_list(last_checkpoint)

      begin
        updates_http = Net::HTTP.new(@repository.host, @repository.port)
        updates_http.start do |http|
          begin
            updates_path = "/#{UPDATES_ACTION}/#{@repository.name}?#{FROM_CHECKPOINT_KEY}=#{last_checkpoint}"
            request = Net::HTTP::Get.new(updates_path)
            response = http.request(request)
            if response.code.to_i == 200
              JSON.parse(response.body)
            else
              @logger.log "Failed to download updates for #{@repository.name}, error code = #{response.code}"
              {}
            end
          rescue StandardError => e
            @logger.log "Error getting file list: #{e.message}! Retrying later.."
            {}
          end
        end
      rescue StandardError => e
        @logger.log "Unable to create HTTP connection to #{@repository.host}:#{@repository.port} (#{e.message})!"
        return {}
      end        
    end

    def update_http_file!(file, local_file_path)
      begin
        uri = URI.parse(file.url)
        file_http=Net::HTTP.new(uri.host, uri.port)
        file_http.start do |http|
          request = Net::HTTP::Get.new(uri.path)
          request.basic_auth @repository.user, @repository.pass if @repository.user
          response = http.request(request)
          if response.code.to_i == 200
            write_file!(local_file_path, response.body)
          elsif response.code.to_i == 404
            delete_file!(local_file_path)
          else
            @logger.log "Failed to update file #{uri}, error code = #{response.code}"
          end
          return true
        end
      rescue StandardError => e
        return false
      end
    end

    def write_file!(file_path, contents)
      @logger.log("Writing: #{file_path}")
      ::FileUtils.mkdir_p(::File.dirname(file_path))
      ::File.open(file_path, 'w') do |file|
        file.write(contents);
        file.close
      end
    end

    def delete_file!(file_path)
      ::File.delete(file_path)
    end

  end
end