class RubyIndexer::Configuration

def apply_config(config)
  @excluded_gems.concat(config["excluded_gems"]) if config["excluded_gems"]
  @included_gems.concat(config["included_gems"]) if config["included_gems"]
  @excluded_patterns.concat(config["excluded_patterns"]) if config["excluded_patterns"]
  @included_patterns.concat(config["included_patterns"]) if config["included_patterns"]
  @excluded_magic_comments.concat(config["excluded_magic_comments"]) if config["excluded_magic_comments"]
end

def indexables
  excluded_gems = @excluded_gems - @included_gems
  locked_gems = Bundler.locked_gems&.specs
  # NOTE: indexing the patterns (both included and excluded) needs to happen before indexing gems, otherwise we risk
  # having duplicates if BUNDLE_PATH is set to a folder inside the project structure
  # Add user specified patterns
  indexables = @included_patterns.flat_map do |pattern|
    load_path_entry = T.let(nil, T.nilable(String))
    Dir.glob(pattern, File::FNM_PATHNAME | File::FNM_EXTGLOB).map! do |path|
      # All entries for the same pattern match the same $LOAD_PATH entry. Since searching the $LOAD_PATH for every
      # entry is expensive, we memoize it until we find a path that doesn't belong to that $LOAD_PATH. This happens
      # on repositories that define multiple gems, like Rails. All frameworks are defined inside the Dir.pwd, but
      # each one of them belongs to a different $LOAD_PATH entry
      if load_path_entry.nil? || !path.start_with?(load_path_entry)
        load_path_entry = $LOAD_PATH.find { |load_path| path.start_with?(load_path) }
      end
      IndexablePath.new(load_path_entry, path)
    end
  end
  # Remove user specified patterns
  indexables.reject! do |indexable|
    @excluded_patterns.any? do |pattern|
      File.fnmatch?(pattern, indexable.full_path, File::FNM_PATHNAME | File::FNM_EXTGLOB)
    end
  end
  # Add default gems to the list of files to be indexed
  Dir.glob(File.join(RbConfig::CONFIG["rubylibdir"], "*")).each do |default_path|
    # The default_path might be a Ruby file or a folder with the gem's name. For example:
    #   bundler/
    #   bundler.rb
    #   psych/
    #   psych.rb
    pathname = Pathname.new(default_path)
    short_name = pathname.basename.to_s.delete_suffix(".rb")
    # If the gem name is excluded, then we skip it
    next if excluded_gems.include?(short_name)
    # If the default gem is also a part of the bundle, we skip indexing the default one and index only the one in
    # the bundle, which won't be in `default_path`, but will be in `Bundler.bundle_path` instead
    next if locked_gems&.any? do |locked_spec|
      locked_spec.name == short_name &&
        !Gem::Specification.find_by_name(short_name).full_gem_path.start_with?(RbConfig::CONFIG["rubylibprefix"])
    rescue Gem::MissingSpecError
      # If a default gem is scoped to a specific platform, then `find_by_name` will raise. We want to skip those
      # cases
      true
    end
    if pathname.directory?
      # If the default_path is a directory, we index all the Ruby files in it
      indexables.concat(
        Dir.glob(File.join(default_path, "**", "*.rb"), File::FNM_PATHNAME | File::FNM_EXTGLOB).map! do |path|
          IndexablePath.new(RbConfig::CONFIG["rubylibdir"], path)
        end,
      )
    elsif pathname.extname == ".rb"
      # If the default_path is a Ruby file, we index it
      indexables << IndexablePath.new(RbConfig::CONFIG["rubylibdir"], default_path)
    end
  end
  # Add the locked gems to the list of files to be indexed
  locked_gems&.each do |lazy_spec|
    next if excluded_gems.include?(lazy_spec.name)
    spec = Gem::Specification.find_by_name(lazy_spec.name)
    # When working on a gem, it will be included in the locked_gems list. Since these are the project's own files,
    # we have already included and handled exclude patterns for it and should not re-include or it'll lead to
    # duplicates or accidentally ignoring exclude patterns
    next if spec.full_gem_path == Dir.pwd
    indexables.concat(
      spec.require_paths.flat_map do |require_path|
        load_path_entry = File.join(spec.full_gem_path, require_path)
        Dir.glob(File.join(load_path_entry, "**", "*.rb")).map! { |path| IndexablePath.new(load_path_entry, path) }
      end,
    )
  rescue Gem::MissingSpecError
    # If a gem is scoped only to some specific platform, then its dependencies may not be installed either, but they
    # are still listed in locked_gems. We can't index them because they are not installed for the platform, so we
    # just ignore if they're missing
  end
  indexables.uniq!(&:full_path)
  indexables
end

def initial_excluded_gems
  excluded, others = Bundler.definition.dependencies.partition do |dependency|
    dependency.groups == [:development]
  end
  # When working on a gem, we need to make sure that its gemspec dependencies can't be excluded. This is necessary
  # because Bundler doesn't assign groups to gemspec dependencies
  #
  # If the dependency is prerelease, `to_spec` may return `nil` due to a bug in older version of Bundler/RubyGems:
  # https://github.com/Shopify/ruby-lsp/issues/1246
  this_gem = Bundler.definition.dependencies.find do |d|
    d.to_spec&.full_gem_path == Dir.pwd
  rescue Gem::MissingSpecError
    false
  end
  others.concat(this_gem.to_spec.dependencies) if this_gem
  excluded.each do |dependency|
    next unless dependency.runtime?
    spec = dependency.to_spec
    next unless spec
    spec.dependencies.each do |transitive_dependency|
      # If the transitive dependency is included in other groups, skip it
      next if others.any? { |d| d.name == transitive_dependency.name }
      # If the transitive dependency is included as a transitive dependency of a gem outside of the development
      # group, skip it
      next if others.any? { |d| d.to_spec&.dependencies&.include?(transitive_dependency) }
      excluded << transitive_dependency
    end
  rescue Gem::MissingSpecError
    # If a gem is scoped only to some specific platform, then its dependencies may not be installed either, but they
    # are still listed in dependencies. We can't index them because they are not installed for the platform, so we
    # just ignore if they're missing
  end
  excluded.uniq!
  excluded.map(&:name)
end

def initialize
  @excluded_gems = T.let(initial_excluded_gems, T::Array[String])
  @included_gems = T.let([], T::Array[String])
  @excluded_patterns = T.let([File.join("**", "*_test.rb")], T::Array[String])
  path = Bundler.settings["path"]
  @excluded_patterns << File.join(File.expand_path(path, Dir.pwd), "**", "*.rb") if path
  @included_patterns = T.let([File.join(Dir.pwd, "**", "*.rb")], T::Array[String])
  @excluded_magic_comments = T.let(
    [
      "frozen_string_literal:",
      "typed:",
      "compiled:",
      "encoding:",
      "shareable_constant_value:",
      "warn_indent:",
      "rubocop:",
      "nodoc:",
      "doc:",
      "coding:",
      "warn_past_scope:",
    ],
    T::Array[String],
  )
end

def load_config
  return unless File.exist?(".index.yml")
  config = YAML.parse_file(".index.yml")
  return unless config
  config_hash = config.to_ruby
  validate_config!(config_hash)
  apply_config(config_hash)
rescue Psych::SyntaxError => e
  raise e, "Syntax error while loading .index.yml configuration: #{e.message}"
end

def magic_comment_regex
  @magic_comment_regex ||= T.let(/^#\s*#{@excluded_magic_comments.join("|")}/, T.nilable(Regexp))
end

def validate_config!(config)
  errors = config.filter_map do |key, value|
    type = CONFIGURATION_SCHEMA[key]
    if type.nil?
      "Unknown configuration option: #{key}"
    elsif !value.is_a?(type)
      "Expected #{key} to be a #{type}, but got #{value.class}"
    end
  end
  raise ArgumentError, errors.join("\n") if errors.any?
end