# frozen_string_literal: true

require 'parser/all'
require_relative 'ruby_minimum_version/version'

class RubyMinimumVersion
  PARSERS = [18, 19,
             20, 21, 22, 23, 24, 25, 26, 27,
             30, 31, 32, 33, 34]
            .map { |ver| "Parser::Ruby#{ver}" }
            .select { |ver| const_defined?(ver) }
            .map { |ver| const_get(ver) }

  def initialize(given_source, verbose: false)
    @given_source = given_source
    @verbose = verbose
  end

  def minimum_version
    @minimum_version or parse
    @minimum_version
  end

  def document
    @document or parse
    @document
  end

  private

  def parse
    PARSERS.find do |parser|
      @parser = parser = parser.new # parser.reset if needed

      success = true
      parser.diagnostics.consumer = lambda do |diagnostic|
        success and @verbose and warn "Parsing with version #{parser.version}..."
        success = false
        highlight = ' ' * diagnostic.location.source_line.length
        diagnostic.highlights.each do |high|
          highlight[high.column_range] = '~' * highlight.size
        end
        highlight[diagnostic.location.column_range] = '^' * diagnostic.location.size
        highlight.rstrip!

        @verbose and warn <<~TEXT
          #{diagnostic.level}: #{diagnostic.message}
          #{diagnostic.location.source_line}
          #{highlight}
        TEXT
      end

      @document = parser.parse(buffer)
      success or next
      @minimum_version = parser.version
    end
  end

  def buffer
    @buffer and return @buffer

    buffer = case @given_source
             in String
               Parser::Source::Buffer.new(source)
             in IO
               Parser::Source::Buffer.new('(fragment)')
             end

    if @parser.is_a? Parser::Ruby18
      buffer.raw_source = source
    else
      buffer.source = source
    end

    @buffer = buffer
  end

  def source
    @source and return @source

    # Force encode given source?
    case @given_source
    in String
      @source = File.read(@given_source)
    in IO
      @source = @given_source.read
    end
  end
end