require "../common"
require "mime/media_type"

class HTTP::Client
  class Response
    getter version : String
    getter status : HTTP::Status
    getter status_message : String?
    getter headers : Headers
    getter! body_io : IO
    @cookies : Cookies?

    def initialize(@status : HTTP::Status, @body : String? = nil, @headers : Headers = Headers.new, status_message : String? = nil, @version = "HTTP/1.1", @body_io : IO? = nil)
      @status_message = status_message || @status.description

      if Response.mandatory_body?(@status)
        @body = "" unless @body || @body_io
      else
        if (@body || @body_io) && (headers["Content-Length"]? != "0")
          raise ArgumentError.new("Status #{status.code} should not have a body")
        end
      end
    end

    def self.new(status_code : Int32, body : String? = nil, headers : Headers = Headers.new, status_message : String? = nil, version : String = "HTTP/1.1", body_io : IO? = nil) : self
      new(HTTP::Status.new(status_code), body, headers, status_message, version, body_io)
    end

    def body : String
      @body || ""
    end

    def body? : String?
      @body
    end

    # Returns `true` if the response status code is between 200 and 299.
    def success? : Bool
      @status.success?
    end

    # Returns a convenience wrapper around querying and setting cookie related
    # headers, see `HTTP::Cookies`.
    def cookies : HTTP::Cookies
      @cookies ||= Cookies.from_server_headers(headers)
    end

    def keep_alive? : Bool
      HTTP.keep_alive?(self)
    end

    def content_type : String?
      mime_type.try &.media_type
    end

    # Convenience method to retrieve the HTTP status code.
    def status_code : Int32
      status.code
    end

    def charset : String?
      mime_type.try &.["charset"]?
    end

    def mime_type : MIME::MediaType?
      if content_type = headers["Content-Type"]?.presence
        MIME::MediaType.parse(content_type)
      end
    end

    def to_io(io : IO) : Nil
      io << @version << ' ' << @status.code << ' ' << @status_message << "\r\n"
      cookies = @cookies
      headers = cookies ? cookies.add_response_headers(@headers) : @headers
      HTTP.serialize_headers_and_body(io, headers, @body, @body_io, @version)
    end

    # :nodoc:
    def consume_body_io : Nil
      if io = @body_io
        @body = io.gets_to_end
        @body_io = nil
      end
    end

    def self.mandatory_body?(status : HTTP::Status) : Bool
      !(status.informational? || status.no_content? || status.not_modified?)
    end

    def self.supports_chunked?(version : String) : Bool
      version == "HTTP/1.1"
    end

    def self.from_io(io : IO, ignore_body : Bool = false, decompress : Bool = true) : self
      from_io?(io, ignore_body, decompress) ||
        raise("Unexpected end of http request")
    end

    # Parses an `HTTP::Client::Response` from the given `IO`.
    # Might return `nil` if there's no data in the `IO`,
    # which probably means that the connection was closed.
    def self.from_io?(io : IO, ignore_body : Bool = false, decompress : Bool = true) : self?
      from_io?(io, ignore_body: ignore_body, decompress: decompress) do |response|
        if response
          response.consume_body_io
          return response
        else
          return nil
        end
      end
    end

    def self.from_io(io, ignore_body = false, decompress = true, &)
      from_io?(io, ignore_body, decompress) do |response|
        if response
          yield response
        else
          raise("Unexpected end of http request")
        end
      end
    end

    # Parses an `HTTP::Client::Response` from the given `IO` and yields
    # it to the block. Might yield `nil` if there's no data in the `IO`,
    # which probably means that the connection was closed.
    def self.from_io?(io, ignore_body = false, decompress = true, &block)
      line = io.gets(4096, chomp: true)
      return yield nil unless line

      pieces = line.split(3)
      raise "Invalid HTTP response" if pieces.size < 2

      http_version = pieces[0]
      raise "Unsupported HTTP version: #{http_version}" unless HTTP::SUPPORTED_VERSIONS.includes?(http_version)

      status_code = pieces[1].to_i?

      unless status_code && 100 <= status_code < 1000
        raise "Invalid HTTP status code: #{pieces[1]}"
      end

      status = HTTP::Status.new(status_code)
      status_message = pieces[2]? ? pieces[2].chomp : ""

      body_type = HTTP::BodyType::OnDemand
      body_type = HTTP::BodyType::Mandatory if mandatory_body?(status)
      body_type = HTTP::BodyType::Prohibited if ignore_body

      HTTP.parse_headers_and_body(io, body_type: body_type, decompress: decompress) do |headers, body|
        return yield new status, nil, headers, status_message, http_version, body
      end

      nil
    end
  end
end
