Add ImageDataUri class to convert image uri to file

Author: rossta

lib/image_data_uri.rb

@@ -0,0 +1,55 @@
+require "base64"
+require "pathname"
+
+class ImageDataUri
+  attr_reader :content_type, :encoding, :data
+
+  def initialize(data_uri)
+    parse_data_uri(data_uri)
+  end
+
+  def to_file(path)
+    path_with_extension = ensure_file_extension(path)
+    File.binwrite(path_with_extension, to_file_data)
+    path_with_extension
+  end
+
+  def to_file_data
+    Base64.decode64(@data)
+  end
+
+  private
+
+  def parse_data_uri(data_uri)
+    raise ArgumentError, "Invalid data URI format" unless data_uri.start_with?("data:")
+
+    parts = data_uri.split(",", 2)
+    raise ArgumentError, "Invalid data URI format" if parts.length != 2
+
+    metadata, @data = parts
+    metadata_parts = metadata.split(";")
+
+    @content_type = metadata_parts[0].split(":")[1]
+    @encoding = metadata_parts[1] if metadata_parts.length > 1
+
+    raise ArgumentError, "Unsupported encoding" if @encoding && @encoding != "base64"
+  end
+
+  def ensure_file_extension(path)
+    pathname = Pathname.new(path)
+    return path if pathname.extname.size > 1
+
+    extension = mime_to_extension(@content_type)
+    "#{path}#{extension}"
+  end
+
+  def mime_to_extension(mime_type)
+    {
+      "image/jpeg" => ".jpg",
+      "image/png" => ".png",
+      "image/gif" => ".gif",
+      "image/webp" => ".webp",
+      "image/svg+xml" => ".svg"
+    }.fetch(mime_type, ".bin")
+  end
+end

spec/lib/image_data_uri_spec.rb

@@ -0,0 +1,65 @@
+require "spec_helper"
+require_relative "../../lib/image_data_uri"
+
+RSpec.describe ImageDataUri do
+  let(:png_data_uri) { "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAACklEQVR4nGMAAQAABQABDQottAAAAABJRU5ErkJggg==" }
+  let(:jpeg_data_uri) { "data:image/jpeg;base64,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" }
+
+  describe "#initialize" do
+    it "parses a valid PNG data URI" do
+      image_uri = ImageDataUri.new(png_data_uri)
+      expect(image_uri.content_type).to eq("image/png")
+      expect(image_uri.encoding).to eq("base64")
+    end
+
+    it "parses a valid JPEG data URI" do
+      image_uri = ImageDataUri.new(jpeg_data_uri)
+      expect(image_uri.content_type).to eq("image/jpeg")
+      expect(image_uri.encoding).to eq("base64")
+    end
+
+    it "raises an error for invalid data URI format" do
+      expect { ImageDataUri.new("invalid_uri") }.to raise_error(ArgumentError, "Invalid data URI format")
+    end
+
+    it "raises an error for unsupported encoding" do
+      expect { ImageDataUri.new("data:image/png;base32,ABCDEF") }.to raise_error(ArgumentError, "Unsupported encoding")
+    end
+  end
+
+  describe "#to_file" do
+    let(:image_uri) { ImageDataUri.new(png_data_uri) }
+
+    before do
+      allow(File).to receive(:binwrite)
+    end
+
+    it "writes the file data to the specified path" do
+      path = "test_image"
+      expect(File).to receive(:binwrite).with("#{path}.png", kind_of(String))
+      image_uri.to_file(path)
+    end
+
+    it "appends the correct extension when not provided" do
+      expect(image_uri.to_file("image")).to eq("image.png")
+    end
+
+    it "does not modify the path when extension is provided" do
+      expect(image_uri.to_file("image.png")).to eq("image.png")
+    end
+
+    it "uses .bin extension for unknown mime types" do
+      unknown_data_uri = "data:image/unknown;base64,ABCDEF"
+      image_uri = ImageDataUri.new(unknown_data_uri)
+      expect(image_uri.to_file("image")).to eq("image.bin")
+    end
+  end
+
+  describe "#to_file_data" do
+    it "returns decoded file data" do
+      image_uri = ImageDataURI.new(png_data_uri)
+      expect(image_uri.to_file_data).to be_a(String)
+      expect(image_uri.to_file_data.bytesize).to be > 0
+    end
+  end
+end