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

require 'English'
require 'optparse'
require 'reline'

require 'rpl'

class RplRepl
  def initialize( interpreter: Rpl.new )
    begin
      @stty_save = `stty -g`.chomp
    rescue Error => e
      puts "Couldn't get terminal characteristics"
      pp e
    end

    @interpreter = interpreter
  end

  def run!
    print_stack unless @interpreter.stack.empty?

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

    prefill = ''
    loop do
      unless prefill.empty?
        Reline.pre_input_hook = lambda do
          Reline.insert_text( prefill.to_s )
          Reline.redisplay

          Reline.pre_input_hook = nil
        end
      end

      input = Reline.readline( ' ', true )

      break if input.nil? || input.strip == 'quit'

      prefill = ''

      if input.strip == 'edit'
        prefill = @interpreter.stack.pop.to_s
      elsif input.strip == 'history'
        history = Reline::HISTORY.map { |line| "\"#{line}\"" }.join(' ')
        @interpreter.run!( "{ #{history} }" )
      elsif input.empty?
        # Remove blank lines from history
        Reline::HISTORY.pop
      else
        begin
          @interpreter.run!( input )
        rescue ArgumentError => e
          pp e
        end
      end

      print_display if @interpreter.show_display

      print_stack
    rescue Interrupt
      puts '^C'
      `stty #{@stty_save}` if @stty_save
      exit 0
    end
  end

  def print_display
    puts @interpreter.display_grob.to_text
  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

def persistence_filename
  persistence_dir = ENV.fetch('XDG_DATA_HOME', nil)
  persistence_dir ||= '~/.local/share'
  persistence_dir += '/rpl.rb'

  File.expand_path( "#{persistence_dir}/env.rpl" )
end

options = { run_REPL: false,
            persistence: true,
            live_persistence: true,
            persistence_filename:,
            files: [],
            programs: [],
            verbosity: :critical }

Version = Rpl::VERSION

OptionParser.new do |opts|
  opts.on('-s', '--state filename', "persist state in filename (default: #{options[:persistence_filename]}) (will be created if needed)") do |filename|
    options[:persistence_filename] = File.expand_path( filename )
  end

  opts.on('-q', '--no-state', 'Do not load nor save persisted state') do
    warn "Not loading #{options[:persistence_filename]}." if options[:verbosity] == :debug

    options[:persistence_filename] = nil
    options[:live_persistence] = false
    options[:persistence] = false
  end

  opts.on('-d', '--no-persist', 'Do not persist state') do
    warn 'Not persisting this session.' if options[:verbosity] == :debug

    options[:live_persistence] = false
    options[:persistence] = false
  end

  opts.on('-c', '--code "program"', 'run provided "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
    warn 'Will load REPL.' if options[:verbosity] == :debug

    options[:run_REPL] = true
  end

  opts.on('-V', '--verbose "level"', 'set verbosity level') do |level|
    options[:verbosity] = level.to_sym

    warn "Setting verbosity to #{level.to_sym}" if options[:verbosity] == :debug
  end
end.parse!

options[:run_REPL] = options[:files].empty? && options[:programs].empty?

warn "Loading state #{options[:persistence_filename]}." if options[:verbosity] == :debug && !options[:persistence_filename].nil?

# Instantiate interpreter
interpreter = Rpl.new( persistence_filename: options[:persistence_filename],
                       live_persistence: options[:live_persistence] )

# first run provided files if any
options[:files].each do |filename|
  interpreter.run!( "\"#{File.expand_path( 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]

interpreter.persist_state if options[:persistence]

puts interpreter.export_stack