#!/usr/bin/env ruby

# This is a Ruby client library for the Dojo Learning REST API.
#
# For more info and documentation, visit:
#
# http://www.dojolearning.com/developers
#
# Requires simplehttp and json libraries from RubyForge, available
# via:
#
# gem install json
# gem install simplehttp
#
# or from here:
#
# http://json.rubyforge.org/
# http://simplehttp.rubyforge.org/
#
# Example usage:
#
# require 'dojolearning'
#
# dojo = DojoLearning.new('user', 'apikey')
#
# topics = dojo.lesson_topics ();
#
# topics.each { |topic|
#	puts '<h2>%s</h2>' % [topic['name']]
#
#	lessons = dojo.lesson_list(topic['id'], 0)
#
#	lessons.each { |lesson|
#		puts '<a href="%s">%s</a><br />' % [lesson['url'], lesson['title']]
#	}
# }
#
# Author:: John Luxford (mailto:lux@dojolearning.com)
# Copyright:: Copyright (c) 2008 Dojo Learning
# License:: LGPL, http://opensource.org/licenses/lgpl-2.1.php

require 'cgi'
require 'rubygems'
require 'simple_http'
require 'json'

# Dojo Learning client class.
class DojoLearning
	attr_reader :user, :apikey, :errno, :error
	attr_writer :user, :apikey, :errno, :error

	# Constructor method.
	def initialize(user, apikey)
		@uri = 'http://api.dojolearning.com/rest-action/%s?user=%s&apikey=%s%s'
		@post_uri = 'http://api.dojolearning.com/rest-action/%s'
		@post_args = 'user=%s&apikey=%s%s'
		@user = user
		@apikey = apikey
		@errno = 0
		@error = ''

		# Generate the dynamic methods
		@method_list = self.send_and_receive('', '')
		@method_list.each { |k, v|
			self.add_method(k, v)
		}
	end

	# Send, receive and parse the request.
	def send_and_receive(request, params)
		# determine request type
		if (@method_list && @method_list[request])
			method = @method_list[request]['method']
		else
			method = 'GET'
		end

		if (method == 'GET')
			# handle GET requests
			url = @uri % [request, @user, @apikey, params]
			res = SimpleHttp.get(url)
		else
			# handle POST requests
			url = @post_uri % request
			params = @post_args % [@user, @apikey, params]
			res = SimpleHttp.post(url, params)
		end

		if res.class == Net::HTTPUnauthorized
			@errno = 401
			@error = 'Unauthorized'
			return false
		end

		# JSON package doesn't seem to handle simple types properly...
		if (res == 'true')
			return true
		elsif (res == 'false')
			return false
		elsif (res.match(/^".*"$/))
			return res.gsub('\\"', '"').slice(1..-2)
		end

		return JSON.parse(res)
	end

	# Dynamically add methods to the object
	def add_method(name, data)
		code = "def self." + name.gsub(/\./, '_') + '('
		sep = ''
		data['parameters'].each { |param|
			code += sep + param
			sep = ', '
		}
		code += ")\n"

		code += "\tm = '" + name + "'\n"
		code += "\tp = ''\n"
		if (data['parameters'].length > 0)
			data['parameters'].each { |k|
				code += "\tp += '&" + k + "=' + CGI.escape(" + k + ".to_s)\n"
			}
		end
		code += "\treturn self.send_and_receive(m, p)\n"

		code += "end\n\n"

		eval(code)
	end
end

#--
if $0 == __FILE__
	dojo = DojoLearning.new('user', 'apikey')

	topics = dojo.lesson_topics()

	topics.each { |topic|
		puts '<h2>%s</h2>' % [topic['name']]

		lessons = dojo.lesson_list(topic['id'], 0)

		lessons.each { |lesson|
			puts '<a href="%s">%s</a><br />' % [lesson['url'], lesson['title']]
		}
	}
end