Merge pull request #361 from crystal-ameba/issue-275

Support hierarchical loading of the config file

spec/ameba/cli/cmd_spec.cr

@@ -21,7 +21,7 @@ module Ameba::Cli
       %w(-c --config).each do |f|
         it "accepts #{f} flag" do
           c = Cli.parse_args [f, "config.yml"]
-          c.config.should eq "config.yml"
+          c.config.should eq Path["config.yml"]
         end
       end
 
@@ -82,12 +82,6 @@ module Ameba::Cli
         c.colors?.should be_true
       end
 
-      it "ignores --config if --gen-config flag passed" do
-        c = Cli.parse_args %w(--gen-config --config my_config.yml)
-        c.formatter.should eq :todo
-        c.config.should eq ""
-      end
-
       describe "-e/--explain" do
         it "configures file/line/column" do
           c = Cli.parse_args %w(--explain src/file.cr:3:5)
@@ -166,7 +160,7 @@ module Ameba::Cli
         c.globs.should be_nil
         c.only.should be_nil
         c.except.should be_nil
-        c.config.should eq Config::PATH
+        c.config.should be_nil
       end
     end
   end

spec/ameba/formatter/todo_formatter_spec.cr

@@ -20,7 +20,7 @@ module Ameba
 
   describe Formatter::TODOFormatter do
     ::Spec.after_each do
-      FileUtils.rm_rf(Ameba::Config::PATH)
+      FileUtils.rm_rf(Ameba::Config::DEFAULT_PATH)
     end
 
     context "problems not found" do
@@ -45,7 +45,7 @@ module Ameba
           s = Source.new "a = 1", "source.cr"
           s.add_issue DummyRule.new, {1, 2}, "message"
           formatter.finished([s])
-          io.to_s.should contain "Created .ameba.yml"
+          io.to_s.should contain "Created #{Config::DEFAULT_PATH}"
         end
       end
 

src/ameba/cli/cmd.cr

@@ -44,7 +44,7 @@ module Ameba::Cli
   end
 
   private class Opts
-    property config = Config::PATH
+    property config : Path?
     property formatter : Symbol | String | Nil
     property globs : Array(String)?
     property only : Array(String)?
@@ -76,7 +76,7 @@ module Ameba::Cli
 
       parser.on("-c", "--config PATH",
         "Specify a configuration file") do |path|
-        opts.config = path unless opts.config.empty?
+        opts.config = Path[path] unless path.empty?
       end
 
       parser.on("-f", "--format FORMATTER",
@@ -105,7 +105,6 @@ module Ameba::Cli
       parser.on("--gen-config",
         "Generate a configuration file acting as a TODO list") do
         opts.formatter = :todo
-        opts.config = ""
       end
 
       parser.on("--fail-level SEVERITY",

src/ameba/config.cr

@@ -10,8 +10,30 @@ require "./glob_utils"
 # config.formatter = my_formatter
 # ```
 #
-# By default config loads `.ameba.yml` file in a current directory.
+# By default config loads `.ameba.yml` file located in a current
+# working directory.
 #
+# If it cannot be found until reaching the root directory, then it will be
+# searched for in the user’s global config locations, which consists of a
+# dotfile or a config file inside the XDG Base Directory specification.
+#
+# - `~/.ameba.yml`
+# - `$XDG_CONFIG_HOME/ameba/config.yml` (expands to `~/.config/ameba/config.yml`
+#   if `$XDG_CONFIG_HOME` is not set)
+#
+# If both files exist, the dotfile will be selected.
+#
+# As an example, if Ameba is invoked from inside `/path/to/project/lib/utils`,
+# then it will use the config as specified inside the first of the following files:
+#
+# - `/path/to/project/lib/utils/.ameba.yml`
+# - `/path/to/project/lib/.ameba.yml`
+# - `/path/to/project/.ameba.yml`
+# - `/path/to/.ameba.yml`
+# - `/path/.ameba.yml`
+# - `/.ameba.yml`
+# - `~/.ameba.yml`
+# - `~/.config/ameba/config.yml`
 class Ameba::Config
   include GlobUtils
 
@@ -24,7 +46,14 @@ class Ameba::Config
     json:     Formatter::JSONFormatter,
   }
 
-  PATH = ".ameba.yml"
+  XDG_CONFIG_HOME = ENV.fetch("XDG_CONFIG_HOME", "~/.config")
+
+  FILENAME      = ".ameba.yml"
+  DEFAULT_PATH  = Path[Dir.current] / FILENAME
+  DEFAULT_PATHS = {
+    Path["~"] / FILENAME,
+    Path[XDG_CONFIG_HOME] / "ameba/config.yml",
+  }
 
   DEFAULT_GLOBS = %w(
     **/*.cr
@@ -77,14 +106,36 @@ class Ameba::Config
   # ```
   # config = Ameba::Config.load
   # ```
-  def self.load(path = PATH, colors = true)
+  def self.load(path = nil, colors = true)
     Colorize.enabled = colors
-    content = File.exists?(path) ? File.read path : "{}"
+    content = read_config(path) || "{}"
     Config.new YAML.parse(content)
   rescue e
     raise "Config file is invalid: #{e.message}"
   end
 
+  protected def self.read_config(path = nil)
+    if path
+      return File.exists?(path) ? File.read(path) : nil
+    end
+    each_config_path do |config_path|
+      return File.read(config_path) if File.exists?(config_path)
+    end
+  end
+
+  protected def self.each_config_path(&)
+    path = Path[DEFAULT_PATH].expand(home: true)
+
+    search_paths = path.parents
+    search_paths.reverse_each do |search_path|
+      yield search_path / FILENAME
+    end
+
+    DEFAULT_PATHS.each do |default_path|
+      yield default_path
+    end
+  end
+
   def self.formatter_names
     AVAILABLE_FORMATTERS.keys.join('|')
   end

src/ameba/formatter/todo_formatter.cr

@@ -26,7 +26,7 @@ module Ameba::Formatter
     end
 
     private def generate_todo_config(issues)
-      file = File.new(Config::PATH, mode: "w")
+      file = File.new(Config::DEFAULT_PATH, mode: "w")
       file << header
       rule_issues_map(issues).each do |rule, rule_issues|
         file << "\n# Problems found: #{rule_issues.size}"