#!/usr/bin/ruby

# just replace strings in files. only shows changes unless -g was given as the first argument.
# no regexp nonsense - escapes do not have to be considered.

inplace = ARGV[0] == "-g" ? ARGV.shift : false
pat = ARGV.shift.to_s
rep = ARGV.shift.to_s
files = ARGV.empty? ? ["./"] : ARGV
paths = files.flat_map { |f| File.directory?(f) ? Dir["#{f}/**/*"] : [f] }
paths.select { |f| File.file?(f) }.each do |f|
  begin
    head = File.read(f, 1024)
    next if head && head.include?("\0")
    src = File.read(f)
    dst = src.gsub(pat, rep)
    if inplace
      File.write(f, dst) if dst != src
    else
      src.lines.each do |line|
        changed = line.gsub(pat, rep)
        unless changed == line
          puts f
          puts "#{line.chomp}"
          puts "#{changed.chomp}"
          puts
        end
      end
    end
  rescue
  end
end