#!/usr/bin/env python
#
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"""
This is a utility for converting JavaScript source code into uint16_t[],
that are used for embedding JavaScript code into the Node.js binary.
"""
import argparse
import os
import re
import functools
import codecs

def ReadFile(filename):
  if is_verbose:
    print(filename)
  with codecs.open(filename, "r", "utf-8") as f:
    lines = f.read()
    return lines


def ReadMacroFiles(filenames):
  """

  :rtype: List(str)
  """
  result = []
  for filename in filenames:
    with open(filename, "rt") as f:
      # strip python-like comments and whitespace padding
      lines = [line.split('#')[0].strip() for line in f]
      # filter empty lines
      result.extend(filter(bool, lines))
  return result


def ExpandConstants(lines, constants):
  for key, value in constants.items():
    lines = lines.replace(key, str(value))
  return lines


def ExpandMacros(lines, macros):
  def expander(s):
    return ExpandMacros(s, macros)

  for name, macro in macros.items():
    name_pattern = re.compile("\\b%s\\(" % name)
    pattern_match = name_pattern.search(lines, 0)
    while pattern_match is not None:
      # Scan over the arguments
      height = 1
      start = pattern_match.start()
      end = pattern_match.end()
      assert lines[end - 1] == '('
      last_match = end
      arg_index = [0]  # Wrap state into array, to work around Python "scoping"
      mapping = {}

      def add_arg(s):
        # Remember to expand recursively in the arguments
        if arg_index[0] >= len(macro.args):
          return
        replacement = expander(s.strip())
        mapping[macro.args[arg_index[0]]] = replacement
        arg_index[0] += 1

      while end < len(lines) and height > 0:
        # We don't count commas at higher nesting levels.
        if lines[end] == ',' and height == 1:
          add_arg(lines[last_match:end])
          last_match = end + 1
        elif lines[end] in ['(', '{', '[']:
          height = height + 1
        elif lines[end] in [')', '}', ']']:
          height = height - 1
        end = end + 1
      # Remember to add the last match.
      add_arg(lines[last_match:end - 1])
      if arg_index[0] < len(macro.args) - 1:
        lineno = lines.count(os.linesep, 0, start) + 1
        raise Exception(
          'line %s: Too few arguments for macro "%s"' % (lineno, name))
      result = macro.expand(mapping)
      # Replace the occurrence of the macro with the expansion
      lines = lines[:start] + result + lines[end:]
      pattern_match = name_pattern.search(lines, start + len(result))
  return lines


class TextMacro:
  def __init__(self, args, body):
    self.args = args
    self.body = body

  def expand(self, mapping):
    result = self.body
    for key, value in mapping.items():
      result = result.replace(key, value)
    return result


class PythonMacro:
  def __init__(self, args, fun):
    self.args = args
    self.fun = fun

  def expand(self, mapping):
    args = []
    for arg in self.args:
      args.append(mapping[arg])
    return str(self.fun(*args))


CONST_PATTERN = re.compile('^const\s+([a-zA-Z0-9_]+)\s*=\s*([^;]*);$')
MACRO_PATTERN = re.compile('^macro\s+([a-zA-Z0-9_]+)\s*\(([^)]*)\)\s*=\s*([^;]*);$')
PYTHON_MACRO_PATTERN = re.compile('^python\s+macro\s+([a-zA-Z0-9_]+)\s*\(([^)]*)\)\s*=\s*([^;]*);$')


def ReadMacros(macro_files):
  lines = ReadMacroFiles(macro_files)
  constants = {}
  macros = {}
  for line in lines:
    line = line.split('#')[0].strip()
    if len(line) == 0:
      continue
    const_match = CONST_PATTERN.match(line)
    if const_match:
      name = const_match.group(1)
      value = const_match.group(2).strip()
      constants[name] = value
    else:
      macro_match = MACRO_PATTERN.match(line)
      if macro_match:
        name = macro_match.group(1)
        args = [p.strip() for p in macro_match.group(2).split(',')]
        body = macro_match.group(3).strip()
        macros[name] = TextMacro(args, body)
      else:
        python_match = PYTHON_MACRO_PATTERN.match(line)
        if python_match:
          name = python_match.group(1)
          args = [p.strip() for p in macro_match.group(2).split(',')]
          body = python_match.group(3).strip()
          fun = eval("lambda " + ",".join(args) + ': ' + body)
          macros[name] = PythonMacro(args, fun)
        else:
          raise Exception("Illegal line: " + line)
  return constants, macros


TEMPLATE = """
#include "env-inl.h"
#include "node_native_module.h"
#include "node_internals.h"

namespace node {{

namespace native_module {{

{0}

void NativeModuleLoader::LoadJavaScriptSource() {{
  {1}
}}

UnionBytes NativeModuleLoader::GetConfig() {{
  return UnionBytes(config_raw, {2});  // config.gypi
}}

}}  // namespace native_module

}}  // namespace node
"""

ONE_BYTE_STRING = """
static const uint8_t {0}[] = {{
{1}
}};
"""

TWO_BYTE_STRING = """
static const uint16_t {0}[] = {{
{1}
}};
"""

INITIALIZER = 'source_.emplace("{0}", UnionBytes{{{1}, {2}}});'

CONFIG_GYPI_ID = 'config_raw'

SLUGGER_RE =re.compile('[.\-/]')

is_verbose = False

def GetDefinition(var, source, step=30):
  template = ONE_BYTE_STRING
  code_points = [ord(c) for c in source]
  if any(c > 127 for c in code_points):
    template = TWO_BYTE_STRING
    # Treat non-ASCII as UTF-8 and encode as UTF-16 Little Endian.
    encoded_source = bytearray(source, 'utf-16le')
    code_points = [
      encoded_source[i] + (encoded_source[i + 1] * 256)
      for i in range(0, len(encoded_source), 2)
    ]

  # For easier debugging, align to the common 3 char for code-points.
  elements_s = ['%3s' % x for x in code_points]
  # Put no more then `step` code-points in a line.
  slices = [elements_s[i:i + step] for i in range(0, len(elements_s), step)]
  lines = [','.join(s) for s in slices]
  array_content = ',\n'.join(lines)
  definition = template.format(var, array_content)

  return definition, len(code_points)


def AddModule(filename, consts, macros, definitions, initializers):
  code = ReadFile(filename)
  code = ExpandConstants(code, consts)
  code = ExpandMacros(code, macros)
  name = NormalizeFileName(filename)
  slug = SLUGGER_RE.sub('_', name)
  var = slug + '_raw'
  definition, size = GetDefinition(var, code)
  initializer = INITIALIZER.format(name, var, size)
  definitions.append(definition)
  initializers.append(initializer)

def NormalizeFileName(filename):
  split = filename.split(os.path.sep)
  if split[0] == 'deps':
    split = ['internal'] + split
  else:  # `lib/**/*.js` so drop the 'lib' part
    split = split[1:]
  if len(split):
    filename = '/'.join(split)
  return os.path.splitext(filename)[0]


def JS2C(source_files, target):
  # Process input from all *macro.py files
  consts, macros = ReadMacros(source_files['.py'])

  # Build source code lines
  definitions = []
  initializers = []

  for filename in source_files['.js']:
    AddModule(filename, consts, macros, definitions, initializers)

  config_def, config_size = handle_config_gypi(source_files['config.gypi'])
  definitions.append(config_def)

  # Emit result
  definitions = ''.join(definitions)
  initializers = '\n  '.join(initializers)
  out = TEMPLATE.format(definitions, initializers, config_size)
  write_if_chaged(out, target)


def handle_config_gypi(config_filename):
  # if its a gypi file we're going to want it as json
  # later on anyway, so get it out of the way now
  config = ReadFile(config_filename)
  config = jsonify(config)
  config_def, config_size = GetDefinition(CONFIG_GYPI_ID, config)
  return config_def, config_size


def jsonify(config):
  # 1. string comments
  config = re.sub(r'#.*?\n', '', config)
  # 3. normalize string literals from ' into "
  config = re.sub('\'', '"', config)
  # 2. turn pseudo-booleans strings into Booleans
  config = re.sub('"true"', 'true', config)
  config = re.sub('"false"', 'false', config)
  return config


def write_if_chaged(content, target):
  if os.path.exists(target):
    with open(target, 'rt') as existing:
      old_content = existing.read()
  else:
    old_content = ''
  if old_content == content:
    return
  with open(target, "wt") as output:
    output.write(content)


def SourceFileByExt(files_by_ext, filename):
  """
  :type files_by_ext: dict
  :type filename: str
  :rtype: dict
  """
  ext = os.path.splitext(filename)[-1]
  files_by_ext.setdefault(ext, []).append(filename)
  return files_by_ext

def main():
  parser = argparse.ArgumentParser(
    description='Convert code files into `uint16_t[]`s',
    fromfile_prefix_chars='@'
  )
  parser.add_argument('--target', help='output file')
  parser.add_argument('--verbose', action='store_true', help='output file')
  parser.add_argument('sources', nargs='*', help='input files')
  options = parser.parse_args()
  global is_verbose
  is_verbose = options.verbose
  source_files = functools.reduce(SourceFileByExt, options.sources, {})
  # Should have exactly 3 types: `.js`, `.py`, and `.gypi`
  assert len(source_files) == 3
  # Currently config.gypi is the only `.gypi` file allowed
  assert source_files['.gypi'] == ['config.gypi']
  source_files['config.gypi'] = source_files.pop('.gypi')[0]
  JS2C(source_files, options.target)


if __name__ == "__main__":
  main()