# frozen_string_literal: true

require "stackprof"
require "tmpdir"

require "hotch/version"

class Hotch
  attr_reader :viewer, :filter, :options

  def initialize(name, viewer: nil, mode: :wall, filter: nil, options: {})
    @name = name
    @viewer = viewer
    @options = options
    @reports = []
    @mode = mode

    @options[:filter] = Regexp.new(filter) if filter
  end

  def start(**options)
    return if StackProf.running?

    stackprof = { mode: @mode }.merge(options)
    StackProf.start(**stackprof)
  end

  def stop
    return unless StackProf.running?

    StackProf.stop
    @reports << StackProf::Report.new(results)
  end

  def run(...)
    start(...)
    yield
  ensure
    stop
  end

  def results
    StackProf.results
  end

  def report
    report = @reports.inject(:+) or return

    dir = Dir.mktmpdir("hotch.#{name}.")

    report_dump(report, dir, "profile.dump")
    dot = report_dot(report, dir, "profile.dot")
    svg = convert_svg(dir, dot, "profile.svg")

    @reports.clear

    return report, svg unless block_given?

    yield report, svg
  end

  def report_at_exit
    return if defined? @at_exit_installed

    at_exit do
      stop

      report do |_, svg|
        if viewer
          puts "Profile SVG: #{svg}"
          Kernel.system viewer, svg
        else
          puts "Profile SVG: view #{svg} # no HOTCH_VIEWER set"
        end
      end
    end

    @at_exit_installed = true
  end

  private

  def name
    @name.gsub(/\W+/, "_")
  end

  def report_dump(report, dir, file)
    write_file(dir, file) do |fh|
      report.print_dump(fh)
    end
  end

  def report_dot(report, dir, file)
    write_file(dir, file) do |fh|
      report.print_graphviz(options, fh)
    end
  end

  def convert_svg(dir, dot, file)
    svg = File.join(dir, file)
    system("dot", "-Tsvg", "-o", svg, dot) or raise "dot: command not found. Please install graphviz"
    svg
  end

  def write_file(dir, file, &block)
    path = File.join(dir, file)
    File.open(path, "wb", &block)
    path
  end
end

# rubocop:disable Naming/MethodName
def Hotch(name: $PROGRAM_NAME, aggregate: true, viewer: ENV.fetch("HOTCH_VIEWER", nil), mode: :wall,
  filter: ENV.fetch("HOTCH_FILTER", nil), options: {}, &block)
  hotch = if aggregate
            $hotch ||= Hotch.new(name, viewer: viewer, mode: mode, filter: filter, options: options)
          else
            caller = Kernel.caller_locations(1).first
            name = "#{name}:#{caller.path}:#{caller.lineno}"
            Hotch.new(name, viewer: viewer, filter: filter, options: options)
          end

  hotch.report_at_exit
  hotch.run(&block)
end
# rubocop:enable Naming/MethodName