#
# gen_ctypes.py
#
# Parse a .h header file to generate ctypes argtype and return type definitions
#
# Copyright 2004-2016, by Paul McGuire
#
from pyparsing import *

typemap = {
    "byte" : "c_byte",
    "char" : "c_char",
    "char *" : "c_char_p",
    "double" : "c_double",
    "float" : "c_float",
    "int" : "c_int",
    "int16" : "c_int16",
    "int32" : "c_int32",
    "int64" : "c_int64",
    "int8" : "c_int8",
    "long" : "c_long",
    "longlong" : "c_longlong",
    "short" : "c_short",
    "size_t" : "c_size_t",
    "ubyte" : "c_ubyte",
    "uchar" : "c_ubyte",
    "u_char" : "c_ubyte",
    "uint" : "c_uint",
    "u_int" : "c_uint",
    "uint16" : "c_uint16",
    "uint32" : "c_uint32",
    "uint64" : "c_uint64",
    "uint8" : "c_uint8",
    "u_long" : "c_ulong",
    "ulong" : "c_ulong",
    "ulonglong" : "c_ulonglong",
    "ushort" : "c_ushort",
    "u_short" : "c_ushort",
    "void *" : "c_void_p",
    "voidp" : "c_voidp",
    "wchar" : "c_wchar",
    "wchar *" : "c_wchar_p",
    "Bool" : "c_bool",
    "void" : "None",
    }
    
LPAR,RPAR,LBRACE,RBRACE,COMMA,SEMI = map(Suppress,"(){},;")
ident = Word(alphas, alphanums + "_")
integer = Regex(r"[+-]?\d+")
hexinteger = Regex(r"0x[0-9a-fA-F]+")

const = Suppress("const")
primitiveType = oneOf(t for t in typemap if not t.endswith("*"))
structType = Suppress("struct") + ident
vartype = (Optional(const) + 
            (primitiveType | structType | ident) + 
            Optional(Word("*")("ptr")))
def normalizetype(t):
    if isinstance(t, ParseResults):
        return ' '.join(t)
        #~ ret = ParseResults([' '.join(t)])
        #~ return ret
        
vartype.setParseAction(normalizetype)

arg = Group(vartype("argtype") + Optional(ident("argname")))
func_def = (vartype("fn_type") + ident("fn_name") + 
                LPAR + Optional(delimitedList(arg|"..."))("fn_args") + RPAR + SEMI)
def derivefields(t):
    if t.fn_args and t.fn_args[-1] == "...":
        t["varargs"]=True
func_def.setParseAction(derivefields)

fn_typedef = "typedef" + func_def
var_typedef = "typedef" + primitiveType("primType") + ident("name") + SEMI

enum_def = (Keyword("enum") + LBRACE + 
            delimitedList(Group(ident("name") + '=' + (hexinteger|integer)("value")))("evalues")
            + Optional(COMMA)
            + RBRACE)

c_header = open("snmp_api.h").read()


module = "pynetsnmp"

user_defined_types = set()
typedefs = []
fn_typedefs = []
functions = []
enum_constants = []

# add structures commonly included from std lib headers
def addStdType(t,namespace=""):
    fullname = namespace+'_'+t if namespace else t
    typemap[t] = fullname
    user_defined_types.add(t)
addStdType("fd_set", "sys_select")
addStdType("timeval", "sys_time")

def getUDType(typestr):
    key = typestr.rstrip(" *")
    if key not in typemap:
        user_defined_types.add(key)
        typemap[key] = "%s_%s" % (module, key)

def typeAsCtypes(typestr):
    if typestr in typemap:
        return typemap[typestr]
    if typestr.endswith("*"):
        return "POINTER(%s)" % typeAsCtypes(typestr.rstrip(" *"))
    return typestr

# scan input header text for primitive typedefs
for td,_,_ in var_typedef.scanString(c_header):
    typedefs.append( (td.name, td.primType) )
    # add typedef type to typemap to map to itself
    typemap[td.name] = td.name

# scan input header text for function typedefs
fn_typedefs = fn_typedef.searchString(c_header)
# add each function typedef to typemap to map to itself
for fntd in fn_typedefs:
    typemap[fntd.fn_name] = fntd.fn_name

# scan input header text, and keep running list of user-defined types
for fn,_,_ in (cStyleComment.suppress() | fn_typedef.suppress() | func_def).scanString(c_header):
    if not fn: continue
    getUDType(fn.fn_type)
    for arg in fn.fn_args:
        if arg != "...":
            if arg.argtype not in typemap:
                getUDType(arg.argtype)
    functions.append(fn)                

# scan input header text for enums
enum_def.ignore(cppStyleComment)
for en_,_,_ in enum_def.scanString(c_header):
    for ev in en_.evalues:
        enum_constants.append( (ev.name, ev.value) )

print("from ctypes import *")
print("%s = CDLL('%s.dll')" % (module, module))
print()
print("# user defined types")
for tdname,tdtyp in typedefs:
    print("%s = %s" % (tdname, typemap[tdtyp]))
for fntd in fn_typedefs:
    print("%s = CFUNCTYPE(%s)" % (fntd.fn_name,
        ',\n    '.join(typeAsCtypes(a.argtype) for a in fntd.fn_args)))
for udtype in user_defined_types:
    print("class %s(Structure): pass" % typemap[udtype])

print()
print("# constant definitions")
for en,ev in enum_constants:
    print("%s = %s" % (en,ev))

print()
print("# functions")
for fn in functions:
    prefix = "%s.%s" % (module, fn.fn_name)
    
    print("%s.restype = %s" % (prefix, typeAsCtypes(fn.fn_type)))
    if fn.varargs:
        print("# warning - %s takes variable argument list" % prefix)
        del fn.fn_args[-1]

    if fn.fn_args.asList() != [['void']]:
        print("%s.argtypes = (%s,)" % (prefix, ','.join(typeAsCtypes(a.argtype) for a in fn.fn_args)))
    else:
        print("%s.argtypes = ()" % (prefix))
        

