Add frequently used accessors to HeadObjectOutput

src/awscr-s3/client.cr

@@ -268,6 +268,8 @@ module Awscr::S3
     # p resp.size          # => 123
     # p resp.status        # => HTTP::Status::OK
     # p resp.last_modified # => "Wed, 19 Jun 2019 11:55:33 GMT"
+    # p resp.etag          # => ""
+    # p resp.meta          # => {"my_tag" => "my_value"}
     # ```
     def head_object(bucket, object : String, headers : Hash(String, String) = Hash(String, String).new)
       resp = http.head("/#{bucket}/#{Util.encode(object)}", headers: headers)

src/awscr-s3/responses/head_object_output.cr

@@ -0,0 +1,54 @@
+module Awscr::S3::Response
+  class HeadObjectOutput
+    DATE_FORMAT = "%a, %d %b %Y %H:%M:%S %Z"
+
+    # The body of the request object
+    getter status : HTTP::Status
+    getter status_message : String | Nil
+    getter headers : HTTP::Headers
+
+    # Create a `GetObjectOutput` response from an
+    # `HTTP::Client::Response` object
+    def self.from_response(response : HTTP::Client::Response)
+      new(
+        status: response.status,
+        status_message: response.status_message,
+        headers: response.headers
+      )
+    end
+
+    def initialize(@status, @status_message, @headers)
+    end
+
+    {% for f in ["Cache-Control", "Content-Disposition", "Content-Encoding", "Content-Language", "Content-Type",] %}
+      def {{ f.id.stringify.underscore.gsub(/-/, "_").id }} : String?
+        headers["{{ f.id }}"]?
+      end
+    {% end %}
+
+    def last_modified : Time
+      parse_date(headers["Last-Modified"])
+    end
+
+    def size : UInt64
+      headers["Content-Length"].to_u64
+    end
+
+    def etag : String?
+      headers["ETag"].try{|v| v.strip('"')}
+    end
+
+    def meta : Hash(String, String)
+      meta = {} of String => String
+      response.headers.each do |k, v|
+        next unless k.starts_with?("x-amz-meta-")
+        meta[k.lchop("x-amz-meta-")] = v.first
+      end
+      meta
+    end
+
+    private def parse_date(date : String)
+      Time.parse!(date.gsub(/\s{2,}/, ' '), DATE_FORMAT)
+    end
+  end
+end