#!/usr/bin/env ruby

require "json"

class ZClass
	attr_reader :name
	attr_accessor :fields
	attr_accessor :methods

	def initialize(name)
		@name = name
		@fields = {}
		@methods = {}
	end
end

class ZField
	attr_reader :name, :type

	def initialize(name, type)
		@name = name
		@type = type
	end
end

# In the given string, replace text matching the given regexp with
# whitespace.

def blank_re(re, text)
	text.gsub(re) do |match|
		$~[0].gsub(/(\S+)/) do
			" " * $1.length
		end
	end
end

def strip_comments(text)
	text = blank_re(/\/\/.*?\n/, text)
	text = blank_re(/\/\*.*?\*\//m, text)

	# Strip preprocessor as well.

	text = blank_re(/\#[^\n]*\n/, text)

	# Also these:

	text = blank_re(/(public|protected|private):/, text)

	text
end

def scan_ignore_comments(re, text)
	text = strip_comments(text)

	text.scan(re) do |match|
		yield $~
	end
end

def find_block_end(text, start_offset)
	depth = 0

	scan_ignore_comments(/([\{\}])/, text[start_offset, text.length]) do |match|
		if match[1] == "{"
			depth += 1
		else
			depth -= 1
		end

		if depth == 0
			return start_offset + match.pre_match.length
		end
	end

	raise "Failed to find function end"
end

# Iterate over each method or function in the specified text.

def gsub_functions(text)
	last_function_end = 0

	result = text
	adjust = 0

	scan_ignore_comments(/((\w+)::)?(\w+)\s*\(([^\)]*?)\)\s*\{/m, text) do |match|
		offset = match.pre_match.length

		if offset > last_function_end
			class_name = match[2]
			name = match[3]
			end_offset = find_block_end(text, offset) + 1

			block = text[offset, end_offset - offset]

			# Get replacement text.

			replacement = yield class_name, name, block

			# Substitute old text for new text:

			before_text = result[0, offset + adjust]
			after_text = result[end_offset + adjust,
			                    result.length]
			result = before_text + replacement + after_text
			adjust += replacement.length - block.length

			# Save end position of function so that we won't
			# change anything in this block again.

			last_function_end = end_offset
		end
	end

	result
end

# Iterate over each field and method definition in the specified class
# body.

def each_field(text)
	last_field_end = 0

	scan_ignore_comments(/([\{\;])/, text) do |match|
		offset = match.pre_match.length

		#puts "#{offset} <=> #{last_field_end}"
		next if offset < last_field_end

		if match[1] == "{"
			block_end = find_block_end(text, offset)

			field_text = text[last_field_end, block_end - last_field_end]

			yield strip_comments(field_text)

			last_field_end = block_end + 1
		else
			field_text = text[last_field_end, offset-last_field_end]

			if field_text =~ /\S/m
				yield strip_comments(field_text)
			end

			last_field_end = offset + 1
		end
	end
end

# Iterate over each class in the specified text.

def each_class(text)
	scan_ignore_comments(/(struct|class)\s+(\w+)[^\{\;]*?\{/m, text) do |match|

		offset = match.pre_match.length
		block_start = offset + match[0].length

		name = match[2]
		end_offset = find_block_end(text, offset)
		body = text[block_start, end_offset - block_start]

		yield name, body
	end
end

def parse_field(text)
	# Field or method?

	if text =~ /(\w+)\s*\(/
		return [ :method, $1 ]
	elsif text !~ /\{/
		# Split into subfields and identify names.

		text = text.sub(/(\w+)/, "")
		field_type = $1

		subfields = text.split(/,/)

		result = [ :field, field_type, [] ]

		for subfield in subfields
			if subfield =~ /(\w+)/
				result[2].push($1)
			end
		end

		return result
	else
		return nil
	end
end

def parse_classes(text)

	classes = {}

	each_class(text) do |name, body|
		
		zclass = ZClass.new(name)
		classes[name] = zclass

		each_field(body) do |field_data|
			data = parse_field(field_data)

			if data == nil
				# ...
			elsif data[0] == :method
				zclass.methods[data[1]] = true
			elsif data[0] == :field
				for field_name in data[2]
					field = ZField.new(field_name, data[1])
					zclass.fields[field_name] = field
				end
			end
		end
	end
	
	classes
end

def identify_class_for_method(method_name, classes)
	result = nil

	classes.each_pair do |class_name, zclass|
		zclass.methods.each_pair do |mname, method|
			if mname != method_name
				# ...
			elsif result == nil
				result = class_name
			else
				return nil # Ambiguous.
			end
		end
	end

	result
end

def transform_method_calls(body, zclass, classes)
	body = body.gsub(/((\.|\-\>)\s*)?(\w+)(\s*)\((\s*)/) do
		deref_type = $2
		method_name = $3
		outer_space = $4
		inner_space = $5

		method_class = identify_class_for_method(method_name, classes)

		if method_class == nil
			method_class = "????"
		end

		if deref_type == "."
			# Can't transform actual method calls.
			". /* METHOD */ #{method_class}__#{method_name}" +
			"(#{inner_space}&????, "
		elsif deref_type == "->"
			# Can't transform actual method calls.
			"-> /* METHOD */ #{method_class}__#{method_name}" +
			"(#{inner_space}????, "
		elsif zclass.methods.has_key? method_name
			# Can transform implicit method calls.
			"#{zclass.name}__#{method_name}(#{inner_space}self, "
		else
			# Global function? No change.
			"#{method_name}#{outer_space}(#{inner_space}"
		end
	end
end

# Transform a method body to C.

def transform_method_body(body, zclass, name, classes)

	# Transform the method definition first.

	body = body.sub(/#{zclass.name}\s*::\s*#{name}\s*\(\s*/,
	                "#{zclass.name}__#{name}(#{zclass.name} *self, ")

	# Fields must have self-> preceding them.

	zclass.fields.each_pair do |fname, field|
		body = body.gsub(/\b#{fname}\b/, "self->#{fname}")
	end

	# Method calls

	body = transform_method_calls(body, zclass, classes)

	# Use "self" instead of "this".

	body = body.gsub(/\bthis\b/, "self")

	# Clean up left-over spurious commas.

	body = body.gsub(/self,\s*\)/, "self)")
	body = body.gsub(/\?\?\?\?,\s*\)/, "????)")

	body
end

def dump_class_info(classes)
	classes.each_pair do |name, zclass|
		puts name
		puts "\tfields:"
		zclass.fields.each_pair do |fname, field|
			puts "\t\t#{field.type} #{fname}"
		end
		puts "\tmethods:"
		zclass.methods.each_key do |mname|
			puts "\t\t#{mname}"
		end
	end
end

header = File.readlines(ARGV[1]).join

classes = parse_classes(header)

#dump_class_info(classes)

data = File.readlines(ARGV[0]).join

transformed = gsub_functions(data) do |class_name, name, body|
#	puts "#{class_name}, #{name}:"

	zclass = classes[class_name]

	if zclass != nil
		body = transform_method_body(body, zclass, name, classes)
	end

#	puts "=" * 40
#	puts body
#	puts "=" * 40

	body
end

puts transformed