#! /usr/bin/python

import sys
import os.path
import re

macros = {}

token = None
line = ""
idRe = "[a-zA-Z_][a-zA-Z_0-9]*"
tokenRe = "#?" + idRe + "|[0-9]+|."
inComment = False
inDirective = False
def getToken():
    global token
    global line
    global inComment
    global inDirective
    while True:
        line = line.lstrip()
        if line != "":
            if line.startswith("/*"):
                inComment = True
                line = line[2:]
            elif inComment:
                commentEnd = line.find("*/")
                if commentEnd < 0:
                    line = ""
                else:
                    inComment = False
                    line = line[commentEnd + 2:]
            else:
                match = re.match(tokenRe, line)
                token = match.group(0)
                line = line[len(token):]
                if token.startswith('#'):
                    inDirective = True
                elif token in macros and not inDirective:
                    line = macros[token] + line
                    continue
                return True
        elif inDirective:
            token = "$"
            inDirective = False
            return True
        else:
            global lineNumber
            line = inputFile.readline()
            lineNumber += 1
            while line.endswith("\\\n"):
                line = line[:-2] + inputFile.readline()
                lineNumber += 1
            if line == "":
                if token == None:
                    fatal("unexpected end of input")
                token = None
                return False

def fatal(msg):
    sys.stderr.write("%s:%d: error at \"%s\": %s\n" % (fileName, lineNumber, token, msg))
    sys.exit(1)

def skipDirective():
    getToken()
    while token != '$':
        getToken()

def isId(s):
    return re.match(idRe + "$", s) != None

def forceId():
    if not isId(token):
        fatal("identifier expected")

def forceInteger():
    if not re.match('[0-9]+$', token):
        fatal("integer expected")

def match(t):
    if token == t:
        getToken()
        return True
    else:
        return False

def forceMatch(t):
    if not match(t):
        fatal("%s expected" % t)

def parseTaggedName():
    assert token in ('struct', 'union')
    name = token
    getToken()
    forceId()
    name = "%s %s" % (name, token)
    getToken()
    return name

def print_enum(tag, constants, storage_class):
    print """
%(storage_class)sconst char *
%(tag)s_to_string(uint16_t value)
{
    switch (value) {\
""" % {"tag": tag,
       "bufferlen": len(tag) + 32,
       "storage_class": storage_class}
    for constant in constants:
        print "    case %s: return \"%s\";" % (constant, constant)
    print """\
    }
    return NULL;
}\
""" % {"tag": tag}

def usage():
    argv0 = os.path.basename(sys.argv[0])
    print '''\
%(argv0)s, for extracting OpenFlow error codes from header files
usage: %(argv0)s FILE [FILE...]

This program reads the header files specified on the command line and
outputs a C source file for translating OpenFlow error codes into
strings, for use as lib/ofp-errors.c in the Open vSwitch source tree.

This program is specialized for reading include/openflow/openflow.h
and include/openflow/nicira-ext.h.  It will not work on arbitrary
header files without extensions.''' % {"argv0": argv0}
    sys.exit(0)

def extract_ofp_errors(filenames):
    error_types = {}

    global fileName
    for fileName in filenames:
        global inputFile
        global lineNumber
        inputFile = open(fileName)
        lineNumber = 0
        while getToken():
            if token in ("#ifdef", "#ifndef", "#include",
                         "#endif", "#elif", "#else", '#define'):
                skipDirective()
            elif match('enum'):
                forceId()
                enum_tag = token
                getToken()

                forceMatch("{")

                constants = []
                while isId(token):
                    constants.append(token)
                    getToken()
                    if match('='):
                        while token != ',' and token != '}':
                            getToken()
                    match(',')

                forceMatch('}')

                if enum_tag == "ofp_error_type":
                    error_types = {}
                    for error_type in constants:
                        error_types[error_type] = []
                elif enum_tag == 'nx_vendor_code':
                    pass
                elif enum_tag.endswith('_code'):
                    error_type = 'OFPET_%s' % '_'.join(enum_tag.split('_')[1:-1]).upper()
                    if error_type not in error_types:
                        fatal("enum %s looks like an error code enumeration but %s is unknown" % (enum_tag, error_type))
                    error_types[error_type] += constants
            elif token in ('struct', 'union'):
                getToken()
                forceId()
                getToken()
                forceMatch('{')
                while not match('}'):
                    getToken()
            elif match('OFP_ASSERT') or match('BOOST_STATIC_ASSERT'):
                while token != ';':
                    getToken()
            else:
                fatal("parse error")
        inputFile.close()

    print "/* -*- buffer-read-only: t -*- */"
    print "#include <config.h>"
    print '#include "ofp-errors.h"'
    print "#include <inttypes.h>"
    print "#include <stdio.h>"
    for fileName in sys.argv[1:]:
        print '#include "%s"' % fileName
    print '#include "type-props.h"'

    for error_type, constants in sorted(error_types.items()):
        tag = 'ofp_%s_code' % re.sub('^OFPET_', '', error_type).lower()
        print_enum(tag, constants, "static ")
    print_enum("ofp_error_type", error_types.keys(), "")
    print """
const char *
ofp_error_code_to_string(uint16_t type, uint16_t code)
{
    switch (type) {\
"""
    for error_type in error_types:
        tag = 'ofp_%s_code' % re.sub('^OFPET_', '', error_type).lower()
        print "    case %s:" % error_type
        print "        return %s_to_string(code);" % tag
    print """\
    }
    return NULL;
}\
"""

if __name__ == '__main__':
    if '--help' in sys.argv:
        usage()
    elif len(sys.argv) < 2:
        sys.stderr.write("at least one non-option argument required; "
                         "use --help for help\n")
        sys.exit(1)
    else:
        extract_ofp_errors(sys.argv[1:])