#!/usr/bin/env ruby

require 'pp'
require 'digest/md5'

module Obj
  class Header
    SIZE = 5*4 # 5x 32-bit little-endian integers

    attr_reader(
      :num_sprites, # Number of entries in the directory. Always dir_size/8?
      :dir_offset,  # Offset of the sprite directory. Also the size of the main header
      :dir_size,    # Number of bytes allocated to the sprite directory. Always num_sprites*8?
      :data_offset, # Number of bytes allocated to the sprites themselves
      :data_size    # Total size of the sprite data
      # JUNGTIL.obj has 0x0000 0x0000 0x0000 following. Probably just padding to
      # allow the sprite directory to start at a word boundary.
    )

    def self.parse(data)
      hdr = new(*data[0..SIZE - 1].unpack("V*"))
      pp hdr
      hdr.validate!(data.bytes.size)
      hdr
    end

    def initialize(*entries)
      @num_sprites, @dir_offset, @dir_size, @data_offset, @data_size = *entries
    end

    def validate!(overall_size)
      raise "Directory overlaps EOF" if overall_size < dir_size + dir_offset
      raise "Data overlaps EOF" if overall_size < data_offset + data_size
      raise "Bad dir_size or num_sprites" if num_sprites * DirEntry::SIZE != dir_size
      raise "Directory overlaps data" if data_range.cover?(dir_offset+1)
      raise "Data overlaps directory" if dir_range.cover?(data_offset+1)

      true
    end

    def dir_range
      dir_offset...(dir_offset+dir_size)
    end

    def data_range
      data_offset...(data_offset+data_size)
    end
  end

  class DirEntry
    SIZE = 8

    attr_reader :rel_offset # Relative to the main header's data_offset
    attr_reader :sprite_size

    def self.parse(rel_data)
      new(*rel_data.unpack("VV"))
    end

    def initialize(rel_offset, sprite_size)
      @rel_offset = rel_offset
      @sprite_size = sprite_size
    end

    def sprite_range
      rel_offset...(rel_offset+sprite_size)
    end
  end

  class SpriteDir
    attr_reader :entries

    def self.parse(rel_data)
      count = rel_data.bytes.size
      num_entries = count / DirEntry::SIZE
      trailing = count%DirEntry::SIZE

      raise "SpriteDir block has #{trailing} trailing bytes" unless trailing == 0

      entries = 0.upto(num_entries-1).map do |n|
        rel_offset = n * DirEntry::SIZE
        DirEntry.parse(rel_data.byteslice(rel_offset, DirEntry::SIZE))
      end

      pp entries

      new(entries)
    end
    
    def initialize(entries)
      @entries = entries
    end

    # Convert the directory into an Array of bytes. Until we work out how to
    # parse sprites, anyway...
    def realize(rel_data)
      entries.map { |entry| rel_data[entry.sprite_range] }
    end
  end

=begin
  SpriteHeader = Struct.new(
    :unknown0,        # Possibly magic data? It's the same for every sprite in jungtil.obj
    :maybe_dimension, # Low nibble comes to 63 in jungtil.obj which would work for a 64x64 tile
    :size,            # Number of bytes of pixel data following this header
  ) do
    SIZE = 4*6        # Seems to be, anyway. Based on 

    def self.parse(rel_data)
      new(*sprite_data[0..SIZE-1]).unpack("V*")
    end

    def pixel_range
      SIZE...size # maybe,anyway
    end
  end

  Sprite = Struct.new(
    :header, :data
  ) do
    def self.parse(rel_data)
      hdr = SpriteHeader.parse(rel_data)
      sprite_pixels = rel_data[hdr.pixel_range]

      Sprite.new(hdr, sprite_pixels)
    end
  end
=end

  class Parsed
    attr_reader :header
    attr_reader :directory
    attr_reader :sprites
    attr_accessor :filename

    def initialize(header, directory, sprites)
      @header = header
      @directory = directory
      @sprites = sprites
    end
  end

  def self.parse(data)
    hdr = Header.parse(data)
    dir = SpriteDir.parse(data[hdr.dir_range])
    sprites = dir.realize(data[hdr.data_range])

    Parsed.new(hdr, dir, sprites)
  end
end

def hex(num, leading=0)
  return " "*(leading) if num.nil?

  "%0#{leading}x"%num
end

VISIBLE_CHARS = ("0".ord)..("z".ord)
def text(num)
  return " " if num.nil?
  if VISIBLE_CHARS.cover?(num)
    num.chr
  else
    " "
  end
end

def ascii(num)
  return "   " if num.nil?

  "%3d"%num
end

def header!(blocksize=8)
  nums = (0...blocksize).to_a
  hdr = "        #{nums.join("  ")}       #{nums.join("")}"

  puts "-" * (hdr.size + 1)
  puts hdr
  puts "-" * (hdr.size + 1)
end

def display(data, blocksize=8, skip=0, header: false)
  bytes = data.bytes[skip..-1]
  nrows = (bytes.count / blocksize)

  0.upto(nrows) do |i|
    header!(blocksize) if i%16==0 || i == skip
    block = bytes[(i*blocksize)...(i*blocksize+blocksize)]

    block.concat([nil]*(blocksize-block.size)) if block.size < blocksize

    out = [
      "0x#{hex(i*blocksize, 4)}",
      block.map { |b| hex(b, 2) },                          # hex
      "    | " + block.map { |b| text(b) }.join("") + " |",   # ascii
      block.map { |b| ascii(b) } ,# decimal bytes
      "",# decimal 2-bytes
      # decimal 4-bytes
    ]

    puts out.flatten.join(' ')
    # puts Digest::MD5.hexdigest(data[skip..-1])
  end
end

def load_obj(filename)
  Obj.parse(File.read(filename).force_encoding("BINARY"))
end

def dump(filename, spriteno = -1)
  obj = load_obj(filename)

  if spriteno == -1
    puts "Dumping all sprites for #{filename}"
    obj.sprites.each { |sprite| display(sprite, header: true) }
  else
    puts "Dumping sprite #{spriteno} for #{filename}"
    display(obj.sprites[spriteno])
  end
end

# The per-sprite data in jungtil.obj is too small to represent a 64x64 block,
# even at 1bpp, so try some decompression algorithms to see what comes out.
#
# Tried so far, with no success:
#   * DEFLATE / ZLIB
#   * LZO
#   * LZOP

def decompress(filename)
  puts "\nAttempting decompression of #{filename}..."

  require 'zlib'

  obj = load_obj(filename)

  obj.sprites.each_with_index do |sprite, i|
    print "Sprite %02d..."%i

    # Step through the start of each sprite so we aren't stopped by a hypothetical header
    (0...64).each do |offset|
      block = sprite.byteslice(offset, sprite.size-offset)

      begin
        inflater = Zlib::Inflate.new(-32)
        decompressed = ""
        decompressed << inflater.inflate(block)
        raise "0 bytes" if decompressed.size == 0

        puts "succeeded! sprite=#{i} offset=#{offset} decompressed_size=#{decompressed.size}"
        puts "data:"
        puts decompressed.inspect
        exit 0
      rescue => err
        puts "failed: #{err}"
      end
    end

    #puts "failed"
  end
end

# Print the first 128 bytes of sprites in a friendly format. Permits into-obj comparisons
def compare(filenames)
  objs = filenames.map { |filename| load_obj(filename).tap { |obj| obj.filename = filename } }

  objs.each do |obj|

  end

  sprites = 
    if spriteno == -1
    else
    

    end
end

case command = ARGV.shift
when "dump" then
  ARGV.each { |filename| dump(filename) } 
when "compare" then
  compare(filenames)
when "decompress" then
  ARGV.each { |filename| decompress(filename) }
else
  puts "Unrecognized command #{command}"
  exit(1)
end