1 files changed, 119 insertions, 0 deletions
diff --git a/lib/bundler/compact_index_client/cache.rb b/lib/bundler/compact_index_client/cache.rb
new file mode 100644
index 0000000000..e44f05dc7e
--- /dev/null
+++ b/lib/bundler/compact_index_client/cache.rb
@@ -0,0 +1,119 @@
+# frozen_string_literal: true
+require "digest/md5"
+
+module Bundler
+  class CompactIndexClient
+    class Cache
+      attr_reader :directory
+
+      def initialize(directory)
+        @directory = Pathname.new(directory).expand_path
+        info_roots.each do |dir|
+          SharedHelpers.filesystem_access(dir) do
+            FileUtils.mkdir_p(dir)
+          end
+        end
+      end
+
+      def names
+        lines(names_path)
+      end
+
+      def names_path
+        directory.join("names")
+      end
+
+      def versions
+        versions_by_name = Hash.new {|hash, key| hash[key] = [] }
+        info_checksums_by_name = {}
+
+        lines(versions_path).each do |line|
+          name, versions_string, info_checksum = line.split(" ", 3)
+          info_checksums_by_name[name] = info_checksum || ""
+          versions_string.split(",").each do |version|
+            if version.start_with?("-")
+              version = version[1..-1].split("-", 2).unshift(name)
+              versions_by_name[name].delete(version)
+            else
+              version = version.split("-", 2).unshift(name)
+              versions_by_name[name] << version
+            end
+          end
+        end
+
+        [versions_by_name, info_checksums_by_name]
+      end
+
+      def versions_path
+        directory.join("versions")
+      end
+
+      def checksums
+        checksums = {}
+
+        lines(versions_path).each do |line|
+          name, _, checksum = line.split(" ", 3)
+          checksums[name] = checksum
+        end
+
+        checksums
+      end
+
+      def dependencies(name)
+        lines(info_path(name)).map do |line|
+          parse_gem(line)
+        end
+      end
+
+      def info_path(name)
+        name = name.to_s
+        if name =~ /[^a-z0-9_-]/
+          name += "-#{Digest::MD5.hexdigest(name).downcase}"
+          info_roots.last.join(name)
+        else
+          info_roots.first.join(name)
+        end
+      end
+
+      def specific_dependency(name, version, platform)
+        pattern = [version, platform].compact.join("-")
+        return nil if pattern.empty?
+
+        gem_lines = info_path(name).read
+        gem_line = gem_lines[/^#{Regexp.escape(pattern)}\b.*/, 0]
+        gem_line ? parse_gem(gem_line) : nil
+      end
+
+    private
+
+      def lines(path)
+        return [] unless path.file?
+        lines = SharedHelpers.filesystem_access(path, :read, &:read).split("\n")
+        header = lines.index("---")
+        header ? lines[header + 1..-1] : lines
+      end
+
+      def parse_gem(string)
+        version_and_platform, rest = string.split(" ", 2)
+        version, platform = version_and_platform.split("-", 2)
+        dependencies, requirements = rest.split("|", 2).map {|s| s.split(",") } if rest
+        dependencies = dependencies ? dependencies.map {|d| parse_dependency(d) } : []
+        requirements = requirements ? requirements.map {|r| parse_dependency(r) } : []
+        [version, platform, dependencies, requirements]
+      end
+
+      def parse_dependency(string)
+        dependency = string.split(":")
+        dependency[-1] = dependency[-1].split("&") if dependency.size > 1
+        dependency
+      end
+
+      def info_roots
+        [
+          directory.join("info"),
+          directory.join("info-special-characters"),
+        ]
+      end
+    end
+  end
+end