require 'excon'
require 'json'

require 'strutta-api/api_object.rb'
require 'strutta-api/entries.rb'
require 'strutta-api/errors.rb'
require 'strutta-api/flow.rb'
require 'strutta-api/games.rb'
require 'strutta-api/participants.rb'
require 'strutta-api/points.rb'
require 'strutta-api/moderation.rb'
require 'strutta-api/judging.rb'
require 'strutta-api/rounds.rb'
require 'strutta-api/version.rb'

module Strutta
  # Strutta API engine
  # Handles API requests and errors
  class API
    include Strutta::Version
    attr_accessor :host, :path, :token, :debug, :session

    # Initializes the Strutta API wrapper
    #
    # @param token [String] your Strutta API token
    # @param host [String] Strutta API host URL - used to switched between prod/staging
    # @param path [String] Strutta API host path - used to switched between versions
    # @return [Strutta::API] instantiated Strutta API object
    def initialize(token, host = 'http://strutta-api.herokuapp.com/', path = Version::VERSION_PATH)
      fail Error, 'You must provide a Strutta API key' unless token

      @host = host
      @path = path
      @token = token
      @session = Excon.new @host
      @debug = debug
    end

    # Makes an API call
    #
    # @param method [String] the required HTTP method
    # @param url [String] URL for the call
    # @param params [Hash] Parameters for the call
    # @return [Hash] Parsed body of the response
    def call(method, url, params = {})
      params = JSON.generate(params)
      r = @session.send(method, path: "#{@path}#{url}", headers: api_headers, body: params)

      # Delete calls have no JSON return
      return true if r.status == 204

      # Raise exceptions on error response codes
      cast_error(r.status, r.body) if r.status >= 400

      JSON.parse(r.body)
    end

    # Instantiates a Strutta::Games object
    #
    # @param id [Integer, nil] the ID of the Strutta game
    # @return [Strutta::Games] The instantiated Strutta::Games object
    def games(id = nil)
      Games.new id, self
    end

    private

    # Utility: build the Headers hash
    # @return [Hash] Headers for an API call
    def api_headers
      {
        'Content-Type' => 'application/json',
        'Authorization' => "Token token=#{@token}"
      }
    end

    # Throws exceptions based on HTTP responses
    #
    # @param status [Integer] the HTTP response status
    # @param body [JSON] the HTTP response body
    # @return [Error] An appropriate exception
    def cast_error(status, body)
      error_info = JSON.parse(body)
      msg = error_info['error'] && error_info['message'] ? "#{error_info['error']} - #{error_info['message']}" : "We received an unexpected error: #{body}"
      fail error_map(status), msg
    rescue JSON::ParserError
      raise Errors::Error, "We received an unexpected error: #{body}"
    end

    # Map errors to HTTP statuses
    #
    # @param status [Integer] the HTTP response status
    # @return [Error] The associated exception
    def error_map(status)
      case status
      when 401
        Errors::Unauthorized
      when 400
        Errors::BadRequestError
      when 404
        Errors::ObjectNotFoundError
      when 422
        Errors::UnprocessableEntityError
      else
        Errors::Error
      end
    end
  end
end