class Writer
  def initialize(out)
    @out = out
    @level = 0
    @indent = ' ' * 2
  end

  def indent(&b)
    @level += 1
    if b
      yield
      dedent
    end
  end

  def dedent
    @level -= 1
  end

  def puts(s)
    @out.puts (@indent * @level) + s
  end

  def block(start, finish)
    puts start if start
    indent
    yield
    dedent
    puts finish if finish
  end

  def finish_if_block(rtn)
    if rtn.is_a?(Hash) && rtn.key?(:type)
      if rtn[:type] == :else_if
        puts "elif #{rtn[:cond]}\nthen"
        indent
        new_rtn = rtn[:block].call
        dedent
        finish_if_block new_rtn
      elsif rtn[:type] == :else
        puts "else"
        indent
        rtn[:block].call
        dedent
        puts 'fi'
      end
    else
      puts 'fi'
    end
  end

  def else_if_block(cond, &b)
    {:type => :else_if, :cond => cond, :block => b}
  end

  def else_block(&b)
    {:type => :else, :block => b}
  end

  def if_block(cond, &b)
    puts "if #{cond}\nthen"
    indent
    rtn = yield
    dedent
    finish_if_block rtn
  end
end

w = Writer.new($stdout)
w.if_block 'x=1' do
  w.puts 'blah'
end

w.puts ''

# works, but kinda sucks to read
w.if_block 'x == 1' do
  w.puts 'x is 1'
  w.else_if_block 'x == 2' do
    w.puts 'x is 2'
    w.else_if_block 'x == 3' do
      w.puts 'x is 3'
      w.else_block do
        w.puts 'fuck knows.'
      end
    end
  end
end

# this would be better
# if false
#   w.if_block 'x == 1' {
#     w.puts 'x is 1'
#   }.elsif_block 'x == 2' {
#     w.puts 'x is 2'
#   }.else_block {
#     w.puts 'fuck knows.'
#   }
# end

# but this would require either delaying the output somehow until we
# figured out if there was a subsquent call or having a terminator,
# which is an easy solution, but kinda leaky:
# if false
#   w.if_block 'x == 1' {
#     w.puts 'x is 1'
#   }.elsif_block 'x == 2' {
#     w.puts 'x is 2'
#   }.else_block {
#     w.puts 'fuck knows.'
#   }.fi
# end

# hmmm, some sort of invoking call might fix it
# def test(x)
#   puts x.inspect
# end
# w.if_block w.if_clause('x == 1') {
#   w.puts 'x is 1'
# }.else_clause {
#   w.puts 'who knows.'
# }

class Writer

  class IfBlock
    attr_accessor :if_b, :else_if_bs, :else_b

    def initialize
      @if_b = nil
      @else_if_bs = []
      @else_b = nil
    end

    def if(cond, &b)
      @if_b = [cond, b]
      self
    end

    def else_if(cond, &b)
      @else_if_bs << [cond, b]
      self
    end

    def else(&b)
      @else_b = b
      self
    end
  end

  def if_block_2
    block = IfBlock.new
    yield block
    puts "if #{block.if_b[0]}\nthen"
    indent do
      block.if_b[1].call
    end
    block.else_if_bs.each do |else_if_b|
      puts "elif #{else_if_b[0]}\nthen"
      indent do
        else_if_b[1].call
      end
    end
    if block.else_b
      puts "else"
      indent do
        block.else_b.call
      end
    end
    puts "fi"
  end
end

# maybe this:
puts "\n\nhere:\n"
w.if_block_2 do |block|
  block.if 'x == 1' do
    w.puts 'x is 1'
  end
  block.else_if 'x == 2' do
    w.puts 'x is 2'
  end
  block.else_if 'x == 3' do
    w.puts 'x is 3'
  end
  block.else do
    w.puts 'fuck knows'
  end
end

# or this:
puts "\n\nthere:\n"
w.if_block_2 do |block|
  block.if('x == 1') {
    w.puts 'x is 1'
  }.else_if('x == 2') {
    w.puts 'x is 2'
  }.else_if('x == 3') {
    w.puts 'x is 3'
  }.else {
    w.puts 'fuck knows'
  }
end

w.if_block_2 do
  if_ 'x == 1' do
    w.puts 'x is 1'
  end
  elsif_ 'x == 2' do
    w.puts 'x is 2'
  end
  elsif_ 'x == 3' do
    w.puts 'x is 3'
  end
  else_ do
    w.puts 'fuck knows'
  end
end

class Writer
  def function(name)
    puts "#{ name } ()\n{"
    indent do
      yield
    end
    puts "}"
  end
end

w.function "f" do
  w.puts "echo 'BLAH'"
end