#!/usr/bin/env python3
# coding=utf-8
# Copyright 2013 The Emscripten Authors.  All rights reserved.
# Emscripten is available under two separate licenses, the MIT license and the
# University of Illinois/NCSA Open Source License.  Both these licenses can be
# found in the LICENSE file.

"""This tool extracts information about structs and defines from the C headers.

The JSON input format is as follows:
[
  {
    'file': 'some/header.h',
    'structs': {
      'struct_name': [
        'field1',
        'field2',
        'field3',
        {
          'field4': [
            'nested1',
            'nested2',
            {
              'nested3': [
                'deep_nested1',
                ...
              ]
            }
            ...
          ]
        },
        'field5'
      ],
      'other_struct': [
        'field1',
        'field2',
        ...
      ]
    },
    'defines': [
      'DEFINE_1',
      'DEFINE_2',
      ['f', 'FLOAT_DEFINE'],
      'DEFINE_3',
      ...
    ]
  },
  {
    'file': 'some/other/header.h',
    ...
  }
]

Please note that the 'f' for 'FLOAT_DEFINE' is just the format passed to printf(), you can put
anything printf() understands.
"""

import sys
import os
import re
import json
import argparse
import tempfile
import subprocess

__scriptdir__ = os.path.dirname(os.path.abspath(__file__))
__rootdir__ = os.path.dirname(os.path.dirname(__scriptdir__))
sys.path.insert(0, __rootdir__)

from tools import building
from tools import config
from tools import shared
from tools import system_libs
from tools import utils

QUIET = (__name__ != '__main__')
DEBUG = False

CFLAGS = [
    # Avoid parsing problems due to gcc specific syntax.
    '-D_GNU_SOURCE',
]

INTERNAL_CFLAGS = [
    '-I' + utils.path_from_root('system/lib/libc/musl/src/internal'),
    '-I' + utils.path_from_root('system/lib/libc/musl/src/include'),
    '-I' + utils.path_from_root('system/lib/pthread/'),
]

CXXFLAGS = [
    '-I' + utils.path_from_root('system/lib/libcxxabi/src'),
    '-D__EMSCRIPTEN_EXCEPTIONS__',
    '-I' + utils.path_from_root('system/lib/wasmfs/'),
    '-std=c++17',
]

DEFAULT_JSON_FILES = [
    utils.path_from_root('src/struct_info.json'),
    utils.path_from_root('src/struct_info_internal.json'),
    utils.path_from_root('src/struct_info_cxx.json'),
    utils.path_from_root('src/struct_info_webgpu.json'),
]


def show(msg):
  if shared.DEBUG or not QUIET:
    sys.stderr.write('gen_struct_info: %s\n' % msg)


# The following three functions generate C code. The output of the compiled code will be
# parsed later on and then put back together into a dict structure by parse_c_output().
#
# Example:
#   c_descent('test1', code)
#   c_set('item', 'i%i', '111', code)
#   c_set('item2', 'i%i', '9', code)
#   c_set('item3', 's%s', '"Hello"', code)
#   c_ascent(code)
#   c_set('outer', 'f%f', '0.999', code)
#
# Will result in:
#   {
#     'test1': {
#       'item': 111,
#       'item2': 9,
#       'item3': 'Hello',
#     },
#     'outer': 0.999
#   }
def c_set(name, type_, value, code):
  code.append('printf("K' + name + '\\n");')
  code.append('printf("V' + type_ + '\\n", ' + value + ');')


def c_descent(name, code):
  code.append('printf("D' + name + '\\n");')


def c_ascent(code):
  code.append('printf("A\\n");')


def parse_c_output(lines):
  result = {}
  cur_level = result
  parent = []
  key = None

  for line in lines:
    arg = line[1:].strip()
    if '::' in arg:
      arg = arg.split('::', 1)[1]
    if line[0] == 'K':
      # This is a key
      key = arg
    elif line[0] == 'V':
      # A value
      if arg[0] == 'i':
        arg = int(arg[1:])
      elif arg[0] == 'f':
        arg = float(arg[1:])
      elif arg[0] == 's':
        arg = arg[1:]

      cur_level[key] = arg
    elif line[0] == 'D':
      # Remember the current level as the last parent.
      parent.append(cur_level)

      # We descend one level.
      cur_level[arg] = {}
      cur_level = cur_level[arg]
    elif line[0] == 'A':
      # We return to the parent dict. (One level up.)
      cur_level = parent.pop()

  return result


def gen_inspect_code(path, struct, code):
  if path[0][-1] == '#':
    path[0] = path[0].rstrip('#')
    prefix = ''
  else:
    prefix = 'struct '

  c_descent(path[-1], code)

  if len(path) == 1:
    c_set('__size__', 'i%zu', 'sizeof (' + prefix + path[0] + ')', code)
  else:
    c_set('__size__', 'i%zu', 'sizeof ((' + prefix + path[0] + ' *)0)->' + '.'.join(path[1:]), code)
    # c_set('__offset__', 'i%zu', 'offsetof(' + prefix + path[0] + ', ' + '.'.join(path[1:]) + ')', code)

  for field in struct:
    if isinstance(field, dict):
      # We have to recurse to inspect the nested dict.
      fname = list(field.keys())[0]
      gen_inspect_code(path + [fname], field[fname], code)
    else:
      c_set(field, 'i%zu', 'offsetof(' + prefix + path[0] + ', ' + '.'.join(path[1:] + [field]) + ')', code)

  c_ascent(code)


def generate_c_code(headers):
  code = ['#include <stdio.h>', '#include <stddef.h>']
  for header in headers:
    code.append('#include "' + header['name'] + '"')

  code.append('int main() {')
  c_descent('structs', code)
  for header in headers:
    for name, struct in header['structs'].items():
      gen_inspect_code([name], struct, code)

  c_ascent(code)
  c_descent('defines', code)
  for header in headers:
    for name, type_ in header['defines'].items():
      # Add the necessary python type, if missing.
      if '%' not in type_:
        if type_[-1] in ('d', 'i', 'u'):
          # integer
          type_ = 'i%' + type_
        elif type_[-1] in ('f', 'F', 'e', 'E', 'g', 'G'):
          # float
          type_ = 'f%' + type_
        elif type_[-1] in ('x', 'X', 'a', 'A', 'c', 's'):
          # hexadecimal or string
          type_ = 's%' + type_

      c_set(name, type_, name, code)

  code.append('return 0;')
  code.append('}')

  return code


def generate_cmd(js_file_path, src_file_path, cflags):
  # Compile the program.
  show('Compiling generated code...')

  if any('libcxxabi' in f for f in cflags):
    compiler = shared.EMXX
  else:
    compiler = shared.EMCC

  node_flags = building.get_emcc_node_flags(shared.check_node_version())

  # -O1+ produces calls to iprintf, which libcompiler_rt doesn't support
  cmd = [compiler] + cflags + ['-o', js_file_path, src_file_path,
                               '-O0',
                               '-Werror',
                               '-Wno-format',
                               '-nolibc',
                               '-sBOOTSTRAPPING_STRUCT_INFO',
                               '-sINCOMING_MODULE_JS_API=',
                               '-sSTRICT',
                               '-sSUPPORT_LONGJMP=0',
                               '-sASSERTIONS=0'] + node_flags

  # Default behavior for emcc is to warn for binaryen version check mismatches
  # so we should try to match that behavior.
  cmd += ['-Wno-error=version-check']

  # TODO(sbc): Remove this one we remove the test_em_config_env_var test
  cmd += ['-Wno-deprecated']

  show(shared.shlex_join(cmd))
  return cmd


def inspect_headers(headers, cflags):
  # Write the source code to a temporary file.
  src_file_fd, src_file_path = tempfile.mkstemp('.c', text=True)
  show('Generating C code... ' + src_file_path)
  code = generate_c_code(headers)
  os.write(src_file_fd, '\n'.join(code).encode())
  os.close(src_file_fd)

  js_file_fd, js_file_path = tempfile.mkstemp('.js')
  # Close the unneeded FD.
  os.close(js_file_fd)

  cmd = generate_cmd(js_file_path, src_file_path, cflags)

  try:
    subprocess.check_call(cmd, env=system_libs.clean_env())
  except subprocess.CalledProcessError as e:
    sys.stderr.write('FAIL: Compilation failed!: %s\n' % e.cmd)
    sys.exit(1)

  # Run the compiled program.
  show('Calling generated program... ' + js_file_path)
  node_args = shared.node_bigint_flags(config.NODE_JS)
  info = shared.run_js_tool(js_file_path, node_args=node_args, stdout=shared.PIPE).splitlines()

  if not DEBUG:
    # Remove all temporary files.
    os.unlink(src_file_path)

    if os.path.exists(js_file_path):
      os.unlink(js_file_path)
      wasm_file_path = shared.replace_suffix(js_file_path, '.wasm')
      os.unlink(wasm_file_path)

  # Parse the output of the program into a dict.
  return parse_c_output(info)


def merge_info(target, src):
  for key, value in src['defines'].items():
    if key in target['defines']:
      raise Exception('duplicate define: %s' % key)
    target['defines'][key] = value

  for key, value in src['structs'].items():
    if key in target['structs']:
      raise Exception('duplicate struct: %s' % key)
    target['structs'][key] = value


def inspect_code(headers, cflags):
  if not DEBUG:
    info = inspect_headers(headers, cflags)
  else:
    info = {'defines': {}, 'structs': {}}
    for header in headers:
      merge_info(info, inspect_headers([header], cflags))
  return info


def parse_json(path):
  header_files = []

  with open(path, 'r') as stream:
    # Remove comments before loading the JSON.
    data = json.loads(re.sub(r'//.*\n', '', stream.read()))

  if not isinstance(data, list):
    data = [data]

  for item in data:
    for key in item.keys():
      if key not in ['file', 'defines', 'structs']:
        raise 'Unexpected key in json file: %s' % key

    header = {'name': item['file'], 'structs': {}, 'defines': {}}
    for name, data in item.get('structs', {}).items():
      if name in header['structs']:
        show('WARN: Description of struct "' + name + '" in file "' + item['file'] + '" replaces an existing description!')

      header['structs'][name] = data

    for part in item.get('defines', []):
      if not isinstance(part, list):
        # If no type is specified, assume integer.
        part = ['i', part]

      if part[1] in header['defines']:
        show('WARN: Description of define "' + part[1] + '" in file "' + item['file'] + '" replaces an existing description!')

      header['defines'][part[1]] = part[0]

    header_files.append(header)

  return header_files


def output_json(obj, stream):
  json.dump(obj, stream, indent=4, sort_keys=True)
  stream.write('\n')
  stream.close()


def main(args):
  global QUIET

  parser = argparse.ArgumentParser(description='Generate JSON infos for structs.')
  parser.add_argument('json', nargs='*',
                      help='JSON file with a list of structs and their fields (defaults to src/struct_info.json)',
                      default=DEFAULT_JSON_FILES)
  parser.add_argument('-q', dest='quiet', action='store_true', default=False,
                      help='Don\'t output anything besides error messages.')
  parser.add_argument('-o', dest='output', metavar='path', default=None,
                      help='Path to the JSON file that will be written. If omitted, the default location under `src` will be used.')
  parser.add_argument('-I', dest='includes', metavar='dir', action='append', default=[],
                      help='Add directory to include search path')
  parser.add_argument('-D', dest='defines', metavar='define', action='append', default=[],
                      help='Pass a define to the preprocessor')
  parser.add_argument('-U', dest='undefines', metavar='undefine', action='append', default=[],
                      help='Pass an undefine to the preprocessor')
  parser.add_argument('--wasm64', action='store_true',
                      help='use wasm64 architecture')
  args = parser.parse_args(args)

  QUIET = args.quiet

  extra_cflags = []

  if args.wasm64:
    # Always use =2 here so that we don't generate a binary that actually requires
    # memory64 to run.  All we care about is that the output is correct.
    extra_cflags += ['-sMEMORY64=2', '-Wno-experimental']

  # Add the user options to the list as well.
  for path in args.includes:
    extra_cflags.append('-I' + path)

  for arg in args.defines:
    extra_cflags.append('-D' + arg)

  for arg in args.undefines:
    extra_cflags.append('-U' + arg)

  # Look for structs in all passed headers.
  info = {'defines': {}, 'structs': {}}

  for f in args.json:
    # This is a JSON file, parse it.
    header_files = parse_json(f)
    # Inspect all collected structs.
    if 'internal' in f:
      use_cflags = CFLAGS + extra_cflags + INTERNAL_CFLAGS
    elif 'cxx' in f:
      use_cflags = CFLAGS + extra_cflags + CXXFLAGS
    else:
      use_cflags = CFLAGS + extra_cflags
    info_fragment = inspect_code(header_files, use_cflags)
    merge_info(info, info_fragment)

  if args.output:
    output_file = args.output
  elif args.wasm64:
    output_file = utils.path_from_root('src/struct_info_generated_wasm64.json')
  else:
    output_file = utils.path_from_root('src/struct_info_generated.json')

  with open(output_file, 'w') as f:
    output_json(info, f)

  return 0


if __name__ == '__main__':
  sys.exit(main(sys.argv[1:]))