#!/usr/bin/env python

import sys, math

# must match <linux/nl80211.h> enum nl80211_reg_rule_flags

flag_definitions = {
    'NO-OFDM':		1<<0,
    'NO-CCK':		1<<1,
    'NO-INDOOR':	1<<2,
    'NO-OUTDOOR':	1<<3,
    'DFS':		1<<4,
    'PTP-ONLY':		1<<5,
    'PTMP-ONLY':	1<<6,
    'PASSIVE-SCAN':	1<<7,
    'NO-IBSS':		1<<8,
    # hole at bit 9. FIXME: Where is NO-HT40 defined?
    'NO-HT40':		1<<10,
}

class FreqBand(object):
    def __init__(self, start, end, bw, comments=None):
        self.start = start
        self.end = end
        self.maxbw = bw
        self.comments = comments or []

    def __cmp__(self, other):
        s = self
        o = other
        if not isinstance(o, FreqBand):
            return False
        return cmp((s.start, s.end, s.maxbw), (o.start, o.end, o.maxbw))

    def __hash__(self):
        s = self
        return hash((s.start, s.end, s.maxbw))

    def __str__(self):
        return '<FreqBand %.3f - %.3f @ %.3f>' % (
                  self.start, self.end, self.maxbw)

class PowerRestriction(object):
    def __init__(self, max_ant_gain, max_eirp, comments = None):
        self.max_ant_gain = max_ant_gain
        self.max_eirp = max_eirp
        self.comments = comments or []

    def __cmp__(self, other):
        s = self
        o = other
        if not isinstance(o, PowerRestriction):
            return False
        return cmp((s.max_ant_gain, s.max_eirp),
                   (o.max_ant_gain, o.max_eirp))

    def __str__(self):
        return '<PowerRestriction ...>'

    def __hash__(self):
        s = self
        return hash((s.max_ant_gain, s.max_eirp))

class FlagError(Exception):
    def __init__(self, flag):
        self.flag = flag

class Permission(object):
    def __init__(self, freqband, power, flags):
        assert isinstance(freqband, FreqBand)
        assert isinstance(power, PowerRestriction)
        self.freqband = freqband
        self.power = power
        self.flags = 0
        for flag in flags:
            if not flag in flag_definitions:
                raise FlagError(flag)
            self.flags |= flag_definitions[flag]
        self.textflags = flags

    def _as_tuple(self):
        return (self.freqband, self.power, self.flags)

    def __cmp__(self, other):
        if not isinstance(other, Permission):
            return False
        return cmp(self._as_tuple(), other._as_tuple())

    def __hash__(self):
        return hash(self._as_tuple())

class Country(object):
    def __init__(self, permissions=None, comments=None):
        self._permissions = permissions or []
        self.comments = comments or []

    def add(self, perm):
        assert isinstance(perm, Permission)
        self._permissions.append(perm)
        self._permissions.sort()

    def __contains__(self, perm):
        assert isinstance(perm, Permission)
        return perm in self._permissions

    def __str__(self):
        r = ['(%s, %s)' % (str(b), str(p)) for b, p in self._permissions]
        return '<Country (%s)>' % (', '.join(r))

    def _get_permissions_tuple(self):
        return tuple(self._permissions)
    permissions = property(_get_permissions_tuple)

class SyntaxError(Exception):
    pass

class DBParser(object):
    def __init__(self, warn=None):
        self._warn_callout = warn or sys.stderr.write

    def _syntax_error(self, txt=None):
        txt = txt and ' (%s)' % txt or ''
        raise SyntaxError("Syntax error in line %d%s" % (self._lineno, txt))

    def _warn(self, txt):
        self._warn_callout("Warning (line %d): %s\n" % (self._lineno, txt))

    def _parse_band_def(self, bname, banddef, dupwarn=True):
        try:
            freqs, bw = banddef.split('@')
            bw = float(bw)
        except ValueError:
            bw = 20.0

        try:
            start, end = freqs.split('-')
            start = float(start)
            end = float(end)
        except ValueError:
            self._syntax_error("band must have frequency range")

        b = FreqBand(start, end, bw, comments=self._comments)
        self._comments = []
        self._banddup[bname] = bname
        if b in self._bandrev:
            if dupwarn:
                self._warn('Duplicate band definition ("%s" and "%s")' % (
                              bname, self._bandrev[b]))
            self._banddup[bname] = self._bandrev[b]
        self._bands[bname] = b
        self._bandrev[b] = bname
        self._bandline[bname] = self._lineno

    def _parse_band(self, line):
        try:
            bname, line = line.split(':', 1)
            if not bname:
                self._syntax_error("'band' keyword must be followed by name")
        except ValueError:
            self._syntax_error("band name must be followed by colon")

        if bname in flag_definitions:
            self._syntax_error("Invalid band name")

        self._parse_band_def(bname, line)

    def _parse_power(self, line):
        try:
            pname, line = line.split(':', 1)
            if not pname:
                self._syntax_error("'power' keyword must be followed by name")
        except ValueError:
            self._syntax_error("power name must be followed by colon")

        if pname in flag_definitions:
            self._syntax_error("Invalid power name")

        self._parse_power_def(pname, line)

    def _parse_power_def(self, pname, line, dupwarn=True):
        try:
            (max_ant_gain,
             max_eirp) = line.split(',')
            if max_ant_gain == 'N/A':
                max_ant_gain = '0'
            if max_eirp == 'N/A':
                max_eirp = '0'
            max_ant_gain = float(max_ant_gain)
            def conv_pwr(pwr):
                if pwr.endswith('mW'):
                    pwr = float(pwr[:-2])
                    return 10.0 * math.log10(pwr)
                else:
                    return float(pwr)
            max_eirp = conv_pwr(max_eirp)
        except ValueError:
            self._syntax_error("invalid power data")

        p = PowerRestriction(max_ant_gain, max_eirp,
                             comments=self._comments)
        self._comments = []
        self._powerdup[pname] = pname
        if p in self._powerrev:
            if dupwarn:
                self._warn('Duplicate power definition ("%s" and "%s")' % (
                              pname, self._powerrev[p]))
            self._powerdup[pname] = self._powerrev[p]
        self._power[pname] = p
        self._powerrev[p] = pname
        self._powerline[pname] = self._lineno

    def _parse_country(self, line):
        try:
            cname, line = line.split(':', 1)
            if not cname:
                self._syntax_error("'country' keyword must be followed by name")
            if line:
                self._syntax_error("extra data at end of country line")
        except ValueError:
            self._syntax_error("country name must be followed by colon")

        cnames = cname.split(',')

        self._current_countries = {}
        for cname in cnames:
            if len(cname) != 2:
                self._warn("country '%s' not alpha2" % cname)
            if not cname in self._countries:
                self._countries[cname] = Country(comments=self._comments)
            self._current_countries[cname] = self._countries[cname]
        self._comments = []

    def _parse_country_item(self, line):
        if line[0] == '(':
            try:
                band, line = line[1:].split('),', 1)
                bname = 'UNNAMED %d' % self._lineno
                self._parse_band_def(bname, band, dupwarn=False)
            except:
                self._syntax_error("Badly parenthesised band definition")
        else:
            try:
                bname, line = line.split(',', 1)
                if not bname:
                    self._syntax_error("country definition must have band")
                if not line:
                    self._syntax_error("country definition must have power")
            except ValueError:
                self._syntax_error("country definition must have band and power")

        if line[0] == '(':
            items = line.split('),', 1)
            if len(items) == 1:
                pname = items[0]
                line = ''
                if not pname[-1] == ')':
                    self._syntax_error("Badly parenthesised power definition")
                pname = pname[:-1]
                flags = []
            else:
                pname = items[0]
                flags = items[1].split(',')
            power = pname[1:]
            pname = 'UNNAMED %d' % self._lineno
            self._parse_power_def(pname, power, dupwarn=False)
        else:
            line = line.split(',')
            pname = line[0]
            flags = line[1:]

        if not bname in self._bands:
            self._syntax_error("band does not exist")
        if not pname in self._power:
            self._syntax_error("power does not exist")
        self._bands_used[bname] = True
        self._power_used[pname] = True
        # de-duplicate so binary database is more compact
        bname = self._banddup[bname]
        pname = self._powerdup[pname]
        b = self._bands[bname]
        p = self._power[pname]
        try:
            perm = Permission(b, p, flags)
        except FlagError, e:
            self._syntax_error("Invalid flag '%s'" % e.flag)
        for cname, c in self._current_countries.iteritems():
            if perm in c:
                self._warn('Rule "%s, %s" added to "%s" twice' % (
                              bname, pname, cname))
            else:
                c.add(perm)

    def parse(self, f):
        self._current_countries = None
        self._bands = {}
        self._power = {}
        self._countries = {}
        self._bands_used = {}
        self._power_used = {}
        self._bandrev = {}
        self._powerrev = {}
        self._banddup = {}
        self._powerdup = {}
        self._bandline = {}
        self._powerline = {}

        self._comments = []

        self._lineno = 0
        for line in f:
            self._lineno += 1
            line = line.strip()
            if line[0:1] == '#':
                self._comments.append(line[1:].strip())
            line = line.replace(' ', '').replace('\t', '')
            if not line:
                self._comments = []
            line = line.split('#')[0]
            if not line:
                continue
            if line[0:4] == 'band':
                self._parse_band(line[4:])
                self._current_countries = None
                self._comments = []
            elif line[0:5] == 'power':
                self._parse_power(line[5:])
                self._current_countries = None
                self._comments = []
            elif line[0:7] == 'country':
                self._parse_country(line[7:])
                self._comments = []
            elif self._current_countries is not None:
                self._parse_country_item(line)
                self._comments = []
            else:
                self._syntax_error("Expected band, power or country definition")

        countries = self._countries
        bands = {}
        for k, v in self._bands.iteritems():
            if k in self._bands_used:
                bands[self._banddup[k]] = v
                continue
            # we de-duplicated, but don't warn again about the dupes
            if self._banddup[k] == k:
                self._lineno = self._bandline[k]
                self._warn('Unused band definition "%s"' % k)
        power = {}
        for k, v in self._power.iteritems():
            if k in self._power_used:
                power[self._powerdup[k]] = v
                continue
            # we de-duplicated, but don't warn again about the dupes
            if self._powerdup[k] == k:
                self._lineno = self._powerline[k]
                self._warn('Unused power definition "%s"' % k)
        return countries
