require 'open-uri'
require 'csv'
require 'date'
require 'nokogiri'


module YQuotes

	COOKIE_URL = 'https://finance.yahoo.com/quote/AAPL/history?p=AAPL'
	CRUMB_PATTERN = /\"CrumbStore\":{\"crumb\":\"(?<crumb>[^"]+)/
	QUOTE_ENDPOINT = "https://query1.finance.yahoo.com/v7/finance/download/%{symbol}?"

	class Yahoo

		# Get cookie and crumb
		def initialize
			fetch_credentials
		end

		# fetch_csv: fetch historical quotes in csv format
		def fetch_csv(ticker, start_date=nil, end_date=nil, period='d')
			connection = nil

			# retry 3-times in case it sends unauthorized
			3.times do |i|
				begin
					url = build_url(ticker, start_date, end_date, period)
					connection = open(url, 'Cookie' => @cookie)
					break
				rescue OpenURI::HTTPError => e
					fetch_credentials
				end
			end

			data = CSV.parse(connection.read, :converters => :numeric)

			raise "Yahoo.fetch_csv unable to fetch data" unless data.is_a? Array
			return data
		end

		alias_method :get_csv, :fetch_csv
		alias_method :get_data, :fetch_csv

		private

		def fetch_credentials
			# get cookie
			page = open(COOKIE_URL)
			@cookie = page.meta['set-cookie'].split('; ', 2).first

			# get crumb
			scripts = Nokogiri::HTML(page).css('script')
			scripts.each do |s|
				if s.text.include? 'CrumbStore'
					pattern = s.text.match(CRUMB_PATTERN) 
					@crumb = pattern['crumb']
					break
				end
			end
		end

		# build_params: build parameters for get query
		def build_url(ticker, start_date=nil, end_date=nil, period='d')

			url = QUOTE_ENDPOINT
			url = url %{:symbol => URI.escape(ticker.upcase)}

			params = {
				:crumb => URI.escape(@crumb),
				:events => 'history',
				:interval => '1d'
			}

			# sanitize date
			params[:period1] = get_date(start_date).to_i unless start_date.nil?
			params[:period2] = get_date(end_date).to_i unless end_date.nil?

			params[:interval] = "1d" if period == "d"
			params[:interval] = "1mo" if period == "m"
			params[:interval] = "1wk" if period == "w"
			
			url + "#{params.map  { |k,v|  "#{k}=#{v}" }.join("&")}"
		end

		# get_date: get date from String
		def get_date(d)
			return nil if d.nil?
			return d.to_time if d.is_a? DateTime

			if d.is_a? String

				begin
					dt = DateTime.parse(d).to_time
				rescue Exception => e
					raise "invalid param #{d} - date should be in yyyy-mm-dd format"
				end
			end
		end

	end

end