Generate config

closes #17

src/ameba/cli/cmd.cr

@@ -6,8 +6,9 @@ module Ameba::Cli
   extend self
 
   private class Opts
-    property config : String?
+    property config = Ameba::Config::PATH
     property silent : Bool = false
+    property generate : Bool = false
     property files : Array(String)?
     property only : Array(String)?
     property except : Array(String)?
@@ -33,6 +34,10 @@ module Ameba::Cli
       parser.on("--except RULE1,RULE2,...", "Disable the given rules") do |rules|
         opts.except = rules.split ","
       end
+
+      parser.on("--gen-config", "Generate a configuration file acting as a TODO list") do
+        opts.generate = true
+      end
     end
 
     run_ameba opts
@@ -45,7 +50,9 @@ module Ameba::Cli
 
     configure_rules(config, opts)
 
-    exit 1 unless Ameba.run(config).success?
+    runner = Ameba.run(config)
+    generate_config_file(config, runner, opts) if opts.generate
+    exit 1 unless runner.success?
   rescue e
     puts "Error: #{e.message}"
     exit 255
@@ -64,6 +71,16 @@ module Ameba::Cli
     end
   end
 
+  private def generate_config_file(config, runner, opts)
+    failed_rules =
+      runner.sources
+            .map { |s| s.errors.map &.rule.name }
+            .flatten
+            .uniq!
+    failed_rules.each { |rule| config.update_rule rule, enabled: false }
+    File.write(opts.config, config.to_yaml)
+  end
+
   private def print_version
     puts Ameba::VERSION
     exit 0

src/ameba/config.cr

@@ -12,6 +12,7 @@ require "yaml"
 # By default config loads `.ameba.yml` file in a current directory.
 #
 class Ameba::Config
+  PATH = ".ameba.yml"
   setter formatter : Formatter::BaseFormatter?
   setter files : Array(String)?
   getter rules : Array(Rule::Base)
@@ -19,7 +20,7 @@ class Ameba::Config
   # Creates a new instance of `Ameba::Config` based on YAML parameters.
   #
   # `Config.load` uses this constructor to instantiate new config by YAML file.
-  protected def initialize(config : YAML::Any)
+  protected def initialize(@config : Hash(YAML::Type, YAML::Type))
     @rules = Rule.rules.map &.new(config)
   end
 
@@ -29,10 +30,11 @@ class Ameba::Config
   # config = Ameba::Config.load
   # ```
   #
-  def self.load(path = nil)
-    path ||= ".ameba.yml"
+  def self.load(path = PATH)
     content = File.exists?(path) ? File.read path : "{}"
-    Config.new YAML.parse(content)
+    Config.new YAML.parse(content).as_h
+  rescue e
+    raise "Config file is invalid"
   end
 
   # Returns a list of paths (with wildcards) to files.
@@ -78,6 +80,15 @@ class Ameba::Config
     @rules[index] = rule
   end
 
+  def to_yaml(yaml : YAML::Builder)
+    yaml.mapping do
+      rules.each do |rule|
+        rule.name.to_yaml(yaml)
+        rule.to_yaml(yaml)
+      end
+    end
+  end
+
   private def default_files
     Dir["**/*.cr"].reject(&.starts_with? "lib/")
   end

src/ameba/runner.cr

@@ -15,7 +15,7 @@ module Ameba
     @rules : Array(Rule::Base)
 
     # A list of sources to run inspection on.
-    @sources : Array(Source)
+    getter sources : Array(Source)
 
     # A formatter to prepare report.
     @formatter : Formatter::BaseFormatter