Add basic client for the GitHub API

11 files changed, 250 insertions, 0 deletions

diff --git a/lib/github/client.rb b/lib/github/client.rb
new file mode 100644
index 00000000000..2511523bf6a
--- /dev/null
+++ b/lib/github/client.rb
@@ -0,0 +1,21 @@
+module Github
+  class Client
+    attr_reader :connection
+
+    def initialize(token)
+      @connection = Faraday.new(url: 'https://api.github.com') do |faraday|
+        faraday.adapter :net_http_persistent
+        faraday.response :json, content_type: /\bjson$/
+        faraday.authorization 'token', token
+        faraday.response :logger
+      end
+    end
+
+    def get(url, query = {})
+      rate_limit = RateLimit.new(connection)
+      sleep rate_limit.reset_in if rate_limit.exceed?
+
+      Github::Response.new(connection.get(url, query))
+    end
+  end
+end
diff --git a/lib/github/collection.rb b/lib/github/collection.rb
new file mode 100644
index 00000000000..bbca12a1c84
--- /dev/null
+++ b/lib/github/collection.rb
@@ -0,0 +1,26 @@
+module Github
+  class Collection
+    def initialize(url)
+      @url = url
+    end
+
+    def fetch(query = {})
+      return [] if @url.blank?
+
+      Enumerator.new do |yielder|
+        loop do
+          response = client.get(@url, query)
+          response.body.each { |item| yielder << item }
+          raise StopIteration unless response.rels.key?(:next)
+          @url = response.rels[:next]
+        end
+      end.lazy
+    end
+
+    private
+
+    def client
+      @client ||= Github::Client.new
+    end
+  end
+end
diff --git a/lib/github/issues.rb b/lib/github/issues.rb
new file mode 100644
index 00000000000..27843e1cdd8
--- /dev/null
+++ b/lib/github/issues.rb
@@ -0,0 +1,20 @@
+module Github
+  class Issues
+    attr_reader :owner, :repo
+
+    def initialize(owner, repo)
+      @owner = owner
+      @repo  = repo
+    end
+
+    def fetch
+      Collection.new(issues_url).fetch(state: :all, sort: :created, direction: :asc, per_page: 10)
+    end
+
+    private
+
+    def issues_url
+      "/repos/#{owner}/#{repo}/issues"
+    end
+  end
+end
diff --git a/lib/github/labels.rb b/lib/github/labels.rb
new file mode 100644
index 00000000000..0ea023888b3
--- /dev/null
+++ b/lib/github/labels.rb
@@ -0,0 +1,20 @@
+module Github
+  class Labels
+    attr_reader :owner, :repo
+
+    def initialize(owner, repo)
+      @owner = owner
+      @repo  = repo
+    end
+
+    def fetch
+      Collection.new(labels_url).fetch
+    end
+
+    private
+
+    def labels_url
+      "/repos/#{owner}/#{repo}/labels"
+    end
+  end
+end
diff --git a/lib/github/milestones.rb b/lib/github/milestones.rb
new file mode 100644
index 00000000000..d50278105db
--- /dev/null
+++ b/lib/github/milestones.rb
@@ -0,0 +1,20 @@
+module Github
+  class Milestones
+    attr_reader :owner, :repo
+
+    def initialize(owner, repo)
+      @owner = owner
+      @repo  = repo
+    end
+
+    def fetch
+      Collection.new(milestones_url).fetch
+    end
+
+    private
+
+    def milestones_url
+      "/repos/#{owner}/#{repo}/milestones"
+    end
+  end
+end
diff --git a/lib/github/pull_requests.rb b/lib/github/pull_requests.rb
new file mode 100644
index 00000000000..af04c90d454
--- /dev/null
+++ b/lib/github/pull_requests.rb
@@ -0,0 +1,20 @@
+module Github
+  class PullRequests
+    attr_reader :owner, :repo
+
+    def initialize(owner, repo)
+      @owner = owner
+      @repo  = repo
+    end
+
+    def fetch
+      Collection.new(pull_requests_url).fetch(state: :all, sort: :created, direction: :asc)
+    end
+
+    private
+
+    def pull_requests_url
+      "/repos/#{owner}/#{repo}/pulls"
+    end
+  end
+end
diff --git a/lib/github/rate_limit.rb b/lib/github/rate_limit.rb
new file mode 100644
index 00000000000..30b000f8a9a
--- /dev/null
+++ b/lib/github/rate_limit.rb
@@ -0,0 +1,41 @@
+module Github
+  class RateLimit
+    SAFE_REMAINING_REQUESTS = 100.freeze
+    SAFE_RESET_TIME         = 500.freeze
+
+    attr_reader :connection
+
+    def initialize(connection)
+      @connection = connection
+    end
+
+    def exceed?
+      return false unless enabled?
+
+      remaining <= SAFE_REMAINING_REQUESTS
+    end
+
+    def remaining
+      @remaining ||= response.body.dig('rate', 'remaining').to_i
+    end
+
+    def reset_in
+      @reset ||= response.body.dig('rate', 'reset').to_i
+    end
+
+    private
+
+    def rate_limit_url
+      '/rate_limit'
+    end
+
+    def response
+      @response ||= connection.get(rate_limit_url)
+    end
+
+    # GitHub Rate Limit API returns 404 when the rate limit is disabled
+    def enabled?
+      response.status != 404
+    end
+  end
+end
diff --git a/lib/github/releases.rb b/lib/github/releases.rb
new file mode 100644
index 00000000000..026ef4e6853
--- /dev/null
+++ b/lib/github/releases.rb
@@ -0,0 +1,20 @@
+module Github
+  class Releases
+    attr_reader :owner, :repo
+
+    def initialize(owner, repo)
+      @owner = owner
+      @repo  = repo
+    end
+
+    def fetch
+      Collection.new(releases_url).fetch
+    end
+
+    private
+
+    def releases_url
+      "/repos/#{owner}/#{repo}/releases"
+    end
+  end
+end
diff --git a/lib/github/repositories.rb b/lib/github/repositories.rb
new file mode 100644
index 00000000000..42342471102
--- /dev/null
+++ b/lib/github/repositories.rb
@@ -0,0 +1,17 @@
+module Github
+  class Repositories
+    def initialize(username)
+      @username = username
+    end
+
+    def fetch
+      Collection.new(repos_url).fetch
+    end
+
+    private
+
+    def repos_url
+      '/user/repos'
+    end
+  end
+end
diff --git a/lib/github/response.rb b/lib/github/response.rb
new file mode 100644
index 00000000000..c34b69aa4ea
--- /dev/null
+++ b/lib/github/response.rb
@@ -0,0 +1,22 @@
+module Github
+  class Response
+    attr_reader :raw, :headers, :body, :status
+
+    def initialize(response)
+      @raw     = response
+      @headers = response.headers
+      @body    = response.body
+      @status  = response.status
+    end
+
+    def rels
+      links = headers['Link'].to_s.split(', ').map do |link|
+        href, name = link.match(/<(.*?)>; rel="(\w+)"/).captures
+
+        [name.to_sym, href]
+      end
+
+      Hash[*links.flatten]
+    end
+  end
+end
diff --git a/lib/github/user.rb b/lib/github/user.rb
new file mode 100644
index 00000000000..19fe6230820
--- /dev/null
+++ b/lib/github/user.rb
@@ -0,0 +1,23 @@
+module Github
+  class User
+    attr_reader :username
+
+    def initialize(username)
+      @username = username
+    end
+
+    def get
+      client.get(user_url).body
+    end
+
+    private
+
+    def client
+      @client ||= Github::Client.new
+    end
+
+    def user_url
+      "/users/#{username}"
+    end
+  end
+end