# encoding: utf-8
#  Phusion Passenger - https://www.phusionpassenger.com/
#  Copyright (c) 2013-2014 Phusion
#
#  "Phusion Passenger" is a trademark of Hongli Lai & Ninh Bui.
#
#  Permission is hereby granted, free of charge, to any person obtaining a copy
#  of this software and associated documentation files (the "Software"), to deal
#  in the Software without restriction, including without limitation the rights
#  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#  copies of the Software, and to permit persons to whom the Software is
#  furnished to do so, subject to the following conditions:
#
#  The above copyright notice and this permission notice shall be included in
#  all copies or substantial portions of the Software.
#
#  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#  THE SOFTWARE.

PhusionPassenger.require_passenger_lib 'platform_info'
require 'fileutils'
require 'shellwords'

module PhusionPassenger
module Utils

module Download
	extend self    # Make methods available as class methods.

	def self.included(klass)
		# When included into another class, make sure that Utils
		# methods are made private.
		public_instance_methods(false).each do |method_name|
			klass.send(:private, method_name)
		end
	end

	# Downloads a file from the given URL and saves it to the given filename.
	# Returns whether the download succeeded.
	# 
	# Options:
	#
	#   show_progress: whether to show download progress. Default: false.
	#   logger: the logger to use. If not given, this function will log to STDERR.
	#   cacert: a CA certificate file to use for verifying SSL websites.
	#           The default is to use the download tool's down CA database.
	#   use_cache: Whether to copy the file from the download cache, if available.
	#              Default: false.
	#   connect_timeout: The maximum amount of time to spend on DNS lookup
	#                    and establishing the TCP connection. Set to nil to
	#                    disable this timeout. Default: 4.
	#   idle_timeout: The maximum idle read time. Set to nil to set this timeout
	#                 to the default wget value, 900. Set to nil to disable this
	#                 timeout. Default: 5.
	#   total_timeout: The maximum amount of time spent on the whole download
	#                  operation, including connection time. Only has effect on curl.
	#                  Set to nil to disable this timeout. Default: nil.
	def download(url, output, options = {})
		options = {
			:connect_timeout => 4,
			:idle_timeout    => 5
		}.merge(options)
		logger = options[:logger] || Logger.new(STDERR)

		if options[:use_cache] && cache_dir = PhusionPassenger.download_cache_dir
			basename = basename_from_url(url)
			if File.exist?("#{cache_dir}/#{basename}")
				logger.info "Copying #{basename} from #{cache_dir}..."
				FileUtils.cp("#{cache_dir}/#{basename}", output)
				return true
			end
		end

		if PlatformInfo.find_command("curl")
			return download_with_curl(logger, url, output, options)
		elsif PlatformInfo.find_command("wget")
			return download_with_wget(logger, url, output, options)
		else
			logger.error "Could not download #{url}: no download tool found (curl or wget required)"
			return false
		end
	end

private
	def basename_from_url(url)
		return url.sub(/.*\//, '')
	end

	def download_with_curl(logger, url, output, options)
		command = ["curl", "-f", "-L", "-o", output]
		if options[:show_progress]
			command << "-#"
		else
			command << "-s"
			command << "-S"
		end
		if options[:cacert]
			command << "--cacert"
			command << options[:cacert]
		end
		if options[:connect_timeout]
			command << "--connect-timeout"
			command << options[:connect_timeout].to_s
		end
		if options[:idle_timeout]
			command << "--speed-time"
			command << options[:idle_timeout].to_s
			command << "--speed-limit"
			command << "1"
		end
		if options[:total_timeout]
			command << "--max-time"
			command << options[:total_timeout].to_s
		end
		command << url
		command_str = Shellwords.join(command)
		logger.info("Invoking: #{command_str}")

		if options[:show_progress]
			# If curl errors out we don't want it to display 'curl: ' prefixes,
			# so we parse its output.
			begin
				io = IO.popen("#{command_str} 2>&1", "r")
			rescue SystemCallError => e
				logger.error("Could not invoke curl: #{e}")
				return false
			end
			begin
				non_empty_line_encountered = false
				while !io.eof?
					# We split on "\r" because progress bar lines do not contain "\n".
					data = io.gets("\r")
					data = remove_curl_output_prefix(data)

					# If an error occurs then the first few lines may be empty.
					# Skip those.
					if !non_empty_line_encountered && data =~ /\A\n+/
						data.gsub!(/\A\n+/, '')
					end

					non_empty_line_encountered = true
					STDERR.write(data)
					STDERR.flush
				end
			ensure
				io.close
			end
			result = $?.exitstatus == 0
		else
			begin
				output = `#{command_str} 2>&1`
			rescue SystemCallError => e
				logger.error("Could not invoke curl: #{e}")
				return false
			end
			result = $?.exitstatus == 0
			if !result
				output = remove_curl_output_prefix(output)
				output.chomp!
				logger.error("Could not download #{url}: #{output}")
			end
		end

		return result
	end

	def remove_curl_output_prefix(line)
		return line.gsub(/^curl: (\([0-9]+\) )?/, '')
	end

	def download_with_wget(logger, url, output, options)
		command = ["wget", "--tries=1", "-O", output]
		if !options[:show_progress]
			command << "-nv"
		end
		if options[:cacert]
			command << "--ca-certificate=#{options[:cacert]}"
		end
		if options[:connect_timeout]
			command << "--dns-timeout=#{options[:connect_timeout]}"
			command << "--connect-timeout=#{options[:connect_timeout]}"
		end
		if options[:idle_timeout]
			command << "--timeout=#{options[:idle_timeout]}"
		end
		command << url
		command_str = Shellwords.join(command)
		logger.info("Invoking: #{command_str}")

		if options[:show_progress]
			begin
				result = system(*command)
			rescue SystemCallError => e
				logger.error("Could not invoke wget: #{e}")
				return false
			end
			if !result
				logger.error("Could not download #{url}: #{output}")
			end
		else
			begin
				output = `#{command_str} 2>&1`
			rescue SystemCallError => e
				logger.error("Could not invoke wget: #{e}")
				return false
			end
			result = $?.exitstatus == 0
			if !result
				# Error output may begin with "<URL>:\n" which is redundant.
				output.gsub!(/\A#{Regexp.escape url}:\n/, '')
				output.chomp!
				logger.error("Could not download #{url}: #{output}")
			end
		end

		return result
	end
end

end # module Utils
end # module PhusionPassenger
