#!/usr/bin/env python

import re
import sys
from xml.dom.minidom import parse, Node

#
# DOM traversal utility functions
#

def findChildren(node, path):
    result = []
    if len(path)==1:
        for i in node.childNodes:
            if i.nodeType==Node.ELEMENT_NODE:
                if i.tagName==path[0]:
                    result.append(i)
    else:
        for i in node.childNodes:
            if i.nodeType==Node.ELEMENT_NODE:
                if i.tagName==path[0]:
                    result.extend(findChildren(i, path[1:]))
    return result

def findData(node, path):
    return [ i.firstChild.data for i in findChildren(node, path) ]

isPointer = re.compile('(.*)([ ]+)([*]+)')

def findParams(node):
    n = findData(node, ['name'])[0]
    t = ''
    for i in node.childNodes:
        if i.nodeType==Node.TEXT_NODE:
            t += i.data
        if i.nodeType==Node.ELEMENT_NODE and i.tagName=='ptype':
            t += i.firstChild.data

    t.strip()
    m = isPointer.match(t)
    if m:
        t = ('%s%s'%(m.group(1), m.group(3))).strip()
    return ( t, n.strip())

def findEnums(dom):
    return {i.getAttribute('name'): i.getAttribute('value') for i in findChildren(dom, [ 'registry', 'enums', 'enum' ])}

def findCommands(dom):
    ret = {}
    for i in findChildren(dom, [ 'registry', 'commands', 'command' ]):
      r,n = findParams(findChildren(i, ['proto'])[0])
      p = [ findParams(j) for j in findChildren(i, ['param'])]
      ret[n] = (r, p)
    return ret

def findFeatures(dom):
    ret = {}
    for i in findChildren(dom, [ 'registry', 'feature' ]):
        n = i.getAttribute('name')
        e = [j.getAttribute("name") for j in findChildren(i, [ 'require', 'enum' ])]
        c = [j.getAttribute("name") for j in findChildren(i, [ 'require', 'command' ])]
        ret[n] = (e,c)
    return ret

def findExtensions(dom):
    ret = {}
    for i in findChildren(dom, [ 'registry', 'extensions', 'extension' ]):
        n = i.getAttribute('name')
        e = [j.getAttribute("name") for j in findChildren(i, [ 'require', 'enum' ])]
        c = [j.getAttribute("name") for j in findChildren(i, [ 'require', 'command' ])]
        ret[n] = (e,c)
    return ret

def findApi(dom, name):
    enums      = findEnums(dom)
    commands   = findCommands(dom)
    features   = findFeatures(dom)
    extensions = findExtensions(dom)
    return (enums, commands, features, extensions)

#
#
#

isWGL = re.compile('WGL_([A-Z0-9]+)_.*')

def writeExtension(f, name, extension, enums, commands):
    f.write(('%s\n'%name).encode())

    url = 'https://www.khronos.org/registry/egl/specs/eglspec.1.5.pdf'

    m = isWGL.match(name)
    if m:
        url = 'https://www.khronos.org/registry/OpenGL/extensions/%s/%s.txt'%(m.group(1), name)

    f.write(('%s\n'%(url)).encode())

    if name.find('_VERSION_')==-1:
        f.write(('%s\n'%name).encode())
    else:
        f.write('\n'.encode())
    f.write('\n'.encode())

    enums = [ (j, enums[j]) for j in extension[0] ]
    for e in sorted(enums, key=lambda i: i[1]):
        f.write(('\t%s %s\n'%(e[0], e[1])).encode())

    commands = [ (j, commands[j]) for j in extension[1] ]
    for c in sorted(commands):
        params = ', '.join( [ '%s %s'%(j[0].strip(), j[1].strip()) for j in c[1][1] ] )
        if len(params)==0:
            params = 'void'
        f.write(('\t%s %s (%s)\n'%(c[1][0].strip(), c[0].strip(), params)).encode())

if __name__ == '__main__':

  from argparse import ArgumentParser
  import os

  parser = ArgumentParser(description='usage: %prog [options] [XML specs...]')
  parser.add_argument("--core", dest="core", help="location for core outputs", default='')
  parser.add_argument("--api", dest="name", help="API name: egl, wgl, glx, etc", default='')
  parser.add_argument("--extensions", dest="extensions", help="location for extensions outputs", default='')

  (options, args) = parser.parse_known_args()
  options = vars(options)

  for i in args:

    dom = parse(i)
    api = findApi(dom, options['name'])

    print('Found {} enums, {} commands, {} features and {} extensions.'.format(
        len(api[0]), len(api[1]), len(api[2]), len(api[3])))

    if len(options['core']):
        for i in api[2].keys():
            with open('%s/%s'%(options['core'], i), 'wb') as f:
                writeExtension(f, i, api[2][i], api[0], api[1])

    if len(options['extensions']):
        for i in api[3].keys():
            with open('%s/%s'%(options['extensions'], i), 'wb') as f:
                writeExtension(f, i, api[3][i], api[0], api[1])