#!/usr/bin/env ruby
# frozen_string_literal: true

require 'English'
require 'optparse'
require 'readline'

require 'rpl'

class RplRepl
  def initialize( interpreter )
    interpreter ||= Rpl.new

    @interpreter = interpreter
  end

  def run
    print_stack unless @interpreter.stack.empty?

    Readline.completion_proc = proc do |s|
      ( @interpreter.dictionary.words.keys + @interpreter.dictionary.vars.keys ).grep(/^#{Regexp.escape(s)}/)
    end
    Readline.completion_append_character = ' '

    loop do
      input = Readline.readline( ' ', true )
      break if input.nil? || input == 'quit'

      pp Readline::HISTORY if input == 'history'

      # Remove blank lines from history
      Readline::HISTORY.pop if input.empty?

      begin
        @interpreter.run( input )
      rescue ArgumentError => e
        pp e
      end

      print_stack
    end
  end

  def print_stack
    stack_size = @interpreter.stack.size

    @interpreter.stack.each_with_index do |elt, i|
      puts "#{stack_size - i}: #{elt}"
    end
  end
end

options = { run_REPL: ARGV.empty?,
            files: [],
            programs: [] }

OptionParser.new do |opts|
  opts.on('-c', '--code "program"', ' ') do |program|
    options[:programs] << program
  end

  opts.on('-f', '--file program.rpl', 'load program.rpl') do |filename|
    options[:files] << filename
  end

  opts.on('-i', '--interactive', 'launch interactive REPL') do
    options[:run_REPL] = true
  end
end.parse!

# Instantiate interpreter
interpreter = Rpl.new

# first run provided files if any
options[:files].each do |filename|
  interpreter.run "\"#{filename}\" feval"
end

# second run provided code if any
options[:programs].each do |program|
  interpreter.run program
end

# third launch REPL if (explicitely or implicitely) asked
RplRepl.new( interpreter ).run if options[:run_REPL]

# last print resulting stack on exit (formatted so that it can be fed back later to interpreter)
pp interpreter.export_stack