# frozen-string-literal: true

require "open-uri"
require "net/https"

require "down/backend"

require "tempfile"
require "fileutils"
require "cgi"

module Down
  class NetHttp < Backend
    def initialize(options = {})
      @options = {
        "User-Agent" => "Down/#{Down::VERSION}",
        max_redirects: 2,
        open_timeout:  30,
        read_timeout:  30,
      }.merge(options)
    end

    def download(url, options = {})
      options = @options.merge(options)

      max_size            = options.delete(:max_size)
      max_redirects       = options.delete(:max_redirects)
      progress_proc       = options.delete(:progress_proc)
      content_length_proc = options.delete(:content_length_proc)
      destination         = options.delete(:destination)

      open_uri_options = {
        content_length_proc: proc { |size|
          if size && max_size && size > max_size
            raise Down::TooLarge, "file is too large (max is #{max_size/1024/1024}MB)"
          end
          content_length_proc.call(size) if content_length_proc
        },
        progress_proc: proc { |current_size|
          if max_size && current_size > max_size
            raise Down::TooLarge, "file is too large (max is #{max_size/1024/1024}MB)"
          end
          progress_proc.call(current_size) if progress_proc
        },
        redirect: false,
      }

      if options[:proxy]
        proxy    = URI(options.delete(:proxy))
        user     = proxy.user
        password = proxy.password

        if user || password
          proxy.user     = nil
          proxy.password = nil

          open_uri_options[:proxy_http_basic_authentication] = [proxy.to_s, user, password]
        else
          open_uri_options[:proxy] = proxy.to_s
        end
      end

      open_uri_options.merge!(options)

      uri = ensure_uri(url)

      if uri.user || uri.password
        open_uri_options[:http_basic_authentication] ||= [uri.user, uri.password]
        uri.user = nil
        uri.password = nil
      end

      open_uri_file = open_uri(uri, open_uri_options, follows_remaining: max_redirects)

      tempfile = ensure_tempfile(open_uri_file, File.extname(open_uri_file.base_uri.path))
      OpenURI::Meta.init tempfile, open_uri_file # add back open-uri methods
      tempfile.extend Down::NetHttp::DownloadedFile

      download_result(tempfile, destination)
    end

    def open(url, options = {})
      options = @options.merge(options)

      uri = ensure_uri(url)

      request = Fiber.new do
        net_http_request(uri, options) do |response|
          Fiber.yield response
        end
      end

      response = request.resume

      response_error!(response) unless response.is_a?(Net::HTTPSuccess)

      Down::ChunkedIO.new(
        chunks:     enum_for(:stream_body, response),
        size:       response["Content-Length"] && response["Content-Length"].to_i,
        encoding:   response.type_params["charset"],
        rewindable: options.fetch(:rewindable, true),
        on_close:   -> { request.resume }, # close HTTP connnection
        data: {
          status:   response.code.to_i,
          headers:  response.each_header.inject({}) { |headers, (downcased_name, value)|
                      name = downcased_name.split("-").map(&:capitalize).join("-")
                      headers.merge!(name => value)
                    },
          response: response,
        },
      )
    end

    private

    def open_uri(uri, options, follows_remaining: 0)
      downloaded_file = uri.open(options)
    rescue OpenURI::HTTPRedirect => exception
      raise Down::TooManyRedirects, "too many redirects" if follows_remaining == 0

      uri = exception.uri

      if !exception.io.meta["set-cookie"].to_s.empty?
        options["Cookie"] = exception.io.meta["set-cookie"]
      end

      follows_remaining -= 1
      retry
    rescue OpenURI::HTTPError => exception
      code, message = exception.io.status
      response_class = Net::HTTPResponse::CODE_TO_OBJ.fetch(code)
      response = response_class.new(nil, code, message)
      exception.io.metas.each do |name, values|
        values.each { |value| response.add_field(name, value) }
      end

      response_error!(response)
    rescue => exception
      request_error!(exception)
    end

    # Converts the given IO into a Tempfile if it isn't one already (open-uri
    # returns a StringIO when there is less than 10KB of content), and gives
    # it the specified file extension.
    def ensure_tempfile(io, extension)
      tempfile = Tempfile.new(["down-net_http", extension], binmode: true)

      if io.is_a?(Tempfile)
        # Windows requires file descriptors to be closed before files are moved
        io.close
        tempfile.close
        FileUtils.mv io.path, tempfile.path
      else
        IO.copy_stream(io, tempfile)
        io.close
      end

      tempfile.open
      tempfile
    end

    def net_http_request(uri, options, follows_remaining: options.fetch(:max_redirects, 2), &block)
      http, request = create_net_http(uri, options)

      begin
        response = http.start do
          http.request(request) do |response|
            unless response.is_a?(Net::HTTPRedirection)
              yield response
              response.instance_variable_set("@read", true) # mark response as read
            end
          end
        end
      rescue => exception
        request_error!(exception)
      end

      if response.is_a?(Net::HTTPRedirection)
        raise Down::TooManyRedirects if follows_remaining == 0

        location = URI.parse(response["Location"])
        location = uri + location if location.relative?

        net_http_request(location, options, follows_remaining: follows_remaining - 1, &block)
      end
    end

    def create_net_http(uri, options)
      http_class = Net::HTTP

      if options[:proxy]
        proxy = URI(options[:proxy])
        http_class = Net::HTTP::Proxy(proxy.hostname, proxy.port, proxy.user, proxy.password)
      end

      http = http_class.new(uri.host, uri.port)

      # taken from open-uri implementation
      if uri.is_a?(URI::HTTPS)
        http.use_ssl = true
        http.verify_mode = options[:ssl_verify_mode] || OpenSSL::SSL::VERIFY_PEER
        store = OpenSSL::X509::Store.new
        if options[:ssl_ca_cert]
          Array(options[:ssl_ca_cert]).each do |cert|
            File.directory?(cert) ? store.add_path(cert) : store.add_file(cert)
          end
        else
          store.set_default_paths
        end
        http.cert_store = store
      end

      http.read_timeout = options[:read_timeout] if options.key?(:read_timeout)
      http.open_timeout = options[:open_timeout] if options.key?(:open_timeout)

      request_headers = options.select { |key, value| key.is_a?(String) }
      request_headers["Accept-Encoding"] = "" # otherwise FiberError can be raised

      get = Net::HTTP::Get.new(uri.request_uri, request_headers)
      get.basic_auth(uri.user, uri.password) if uri.user || uri.password

      [http, get]
    end

    def stream_body(response, &block)
      response.read_body(&block)
    rescue => exception
      request_error!(exception)
    end

    def ensure_uri(url)
      uri = URI(url)
      raise Down::InvalidUrl, "URL scheme needs to be http or https" unless uri.is_a?(URI::HTTP)
      uri
    rescue URI::InvalidURIError => exception
      raise Down::InvalidUrl, exception.message
    end

    def response_error!(response)
      code    = response.code.to_i
      message = response.message.split(" ").map(&:capitalize).join(" ")

      args = ["#{code} #{message}", response: response]

      case response.code.to_i
      when 400..499 then raise Down::ClientError.new(*args)
      when 500..599 then raise Down::ServerError.new(*args)
      else               raise Down::ResponseError.new(*args)
      end
    end

    def request_error!(exception)
      case exception
      when Net::OpenTimeout
        raise Down::TimeoutError, "timed out waiting for connection to open"
      when Net::ReadTimeout
        raise Down::TimeoutError, "timed out while reading data"
      when EOFError, IOError, SocketError, SystemCallError
        raise Down::ConnectionError, exception.message
      when OpenSSL::SSL::SSLError
        raise Down::SSLError, exception.message
      else
        raise exception
      end
    end

    module DownloadedFile
      def original_filename
        filename_from_content_disposition || filename_from_uri
      end

      def content_type
        super unless meta["content-type"].to_s.empty?
      end

      private

      def filename_from_content_disposition
        content_disposition = meta["content-disposition"].to_s
        filename = content_disposition[/filename="([^"]*)"/, 1] || content_disposition[/filename=(.+)/, 1]
        filename = CGI.unescape(filename.to_s.strip)
        filename unless filename.empty?
      end

      def filename_from_uri
        path = base_uri.path
        filename = path.split("/").last
        CGI.unescape(filename) if filename
      end
    end
  end
end