module Danger
  # Enforces that .xcodeproj structure is tidy.
  # It wraps around [Synx](https://github.com/venmo/synx)
  # tool to perform the check.
  #
  # @example Ensure that all added / modified project files are synchronized
  #
  #          danger_synx.ensure_clean_structure
  #
  # @see  turekj/danger-synx
  # @tags synx, xcodeproj
  #
  class DangerSynx < Plugin
    # Ensures clean project structure. Runs Synx on all .xcodeproj
    # files that where either added or modified.
    #
    # @return   [void]
    #
    def ensure_clean_structure
      unless synx_installed?
        raise 'synx > 0.2.1 not found in PATH and failed to install'
      end

      generate_output synx_issues
    end

    # Checks whether Synx in a correct version is installed in the system.
    # If not, tries to recover by installing it.
    # Returns true if Synx is present or installation was successful.
    #
    # @return [bool]
    #
    def precheck_synx_installation?
      `gem install synx` unless synx_installed?
      synx_installed?
    end

    # Returns a command to run for synx
    #
    # @return [String]
    def synx
      "#{'bundle exec ' if File.exist?('Gemfile')}synx"
    end

    # Tests whether Synx is already installed and meets minimal
    # version requirements.
    #
    # @return [bool]
    #
    def synx_installed?
      match = `#{synx} --version`.match(/Synx (\d+)\.(\d+)\.(\d+)/i)
      if match
        major, minor, patch = match.captures.map { |c| Integer(c) }
        major > 0 || minor > 2 || (minor == 2 && patch > 1)
      else
        false
      end
    end

    # Triggers Synx on all projects that were modified or added
    # to the project. Returns accumulated list of issues
    # for those projects.
    #
    # @return [Array<(String, String)>]
    #
    def synx_issues
      (git.modified_files + git.added_files)
        .select { |f| f.include? '.xcodeproj' }
        .reduce([]) { |i, f| i + synx_project(f) }
    end

    # Triggers Synx in a dry-run mode on a project file.
    # Parses output and returns a list of issues.
    #
    # @param  [String] modified_file_path
    #         Path of file contained in .xcodeproj to Synx
    #
    # @return [(String, String)]
    #
    def synx_project(modified_file_path)
      path = project_path modified_file_path
      name = project_name path
      output = `#{synx} -w warning "#{path}" 2>&1`.lines
      output
        .map(&:strip)
        .select { |o| o.start_with? 'warning: ' }
        .map { |o| [name, strip_prefix(o)] }
    end

    private

    def project_path(modified_file_path)
      match = modified_file_path.match('(.+\.xcodeproj)*+')
      match[0] if match
    end

    def project_name(project_path)
      project_path.split('/').last
    end

    def strip_prefix(output_line)
      output_line.slice(9, output_line.size - 9)
    end

    def generate_output(issues)
      return if issues.empty?

      warn("Synx detected #{issues.size} structural issue(s)")

      message = "### Synx structural issues\n\n"
      message << "| Project file | Issue |\n"
      message << "| --- | --- |\n"

      issues.each do |(project, issue)|
        message << "| #{project} | #{issue} |\n"
      end

      markdown message
    end

  end
end