#!/usr/bin/env python3

import re, sys, os.path

def usage():
    sys.stderr.write("Usage: $0 whitelist-config-in whitelist-header-out\n")
    sys.stderr.write("    Reads in whitelist config, sorting the contents\n")
    sys.stderr.write("    and outputs a header file\n")
    sys.exit(-1)

class Error(Exception):
    pass

class DuplicateEntry(Error):
    def __init__(self, e):
        super(Error, self).__init__(
             "Multiple entries with matching netfn/cmd found ({})".format(e))

class ParseError(Error):
    def __init__(self, d):
        super(Error, self).__init__("Parse error at: '{}'".format(d))

class entry:
    linere = re.compile(
            r'(0x[0-9a-f]{2}):(0x[0-9a-f]{2})((:(0x[0-9a-f]{4}))?)\s*((//\s*(.*))?)',
            re.I
        )
    def __init__(self, data):
        # parse data line into values:
        # type 1, two values: netfn, cmd
        # type 2, three values: netfn, cmd, channels
        try:
            m = self.linere.fullmatch(data).groups()
        except:
            raise ParseError(data)
        self.netfn = int(m[0], 16)
        self.cmd = int(m[1], 16)
        if m[4] is not None:
            self.channels = int(m[4], 16)
        else:
            # if no channel was provided, default to previous behavior, which
            # is allow all interfaces, including the system interface (ch 15)
            self.channels = 0xffff
        if m[6] is not None:
            self.comment = "// " + m[7]
        else:
            self.comment = "//"
    def __str__(self):
        return " ".join([ '{',
            "0x{0.netfn:02x},".format(self),
            "0x{0.cmd:02x},".format(self),
            "0x{0.channels:04x}".format(self),
            "},",
            "{0.comment}".format(self),
        ])
    def __lt__(self, other):
        if self.netfn == other.netfn:
            return self.cmd < other.cmd
        return self.netfn < other.netfn
    def match(self, other):
        return (self.netfn == other.netfn) and (self.cmd == other.cmd)

def parse(config):
    entries = []
    with open(config) as f:
        for line in f:
            line = line.strip()
            if len(line) == 0 or line[0] == '#':
                continue
            e = entry(line)
            if any([e.match(item) for item in entries]):
                d = DuplicateEntry(e)
                sys.stderr.write("WARNING: {}\n".format(d))
            else:
                entries.append(e)
    entries.sort()
    return entries

def output(entries, hppfile):
    lines = [
            "#pragma once",
            "",
            "// AUTOGENERATED FILE; DO NOT MODIFY",
            "",
            "#include <array>",
            "#include <tuple>",
            "",
            "using netfncmd_tuple = std::tuple<unsigned char, unsigned char, unsigned short>;",
            "",
            "constexpr const std::array<netfncmd_tuple, {}> whitelist = ".format(
                    len(entries)),
            "{{"
            ]
    lines.extend(['    {}'.format(e) for e in entries])
    lines.append("}};\n");

    with open(hppfile, "w") as hpp:
        hpp.write("\n".join(lines))


if __name__ == "__main__":
    if len(sys.argv) != 3:
        usage()
    config = sys.argv[1]
    header = sys.argv[2]
    entries = parse(config)
    output(entries, header)