#!/usr/bin/env python
#
# Copyright 2009, 2012, 2013 by Jeffrey M. Laughlin
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as
# published by the Free Software Foundation, either version 3 of the
# License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

"""
Python API for reading the Amateur Data Interchange Format, aka ADIF.

ADIF version 1.0 is supported.
"""

from collections import namedtuple, OrderedDict
from decimal import Decimal
from datetime import datetime


BLOCKSIZE = 1024


class ParseError(Exception):
    pass


class Field(object):
    __slots__ = ['name', 'type', 'body']
    def __init__(self, name='', type='', body=''):
        self.name = name
        self.type = type
        self.body = body

    def __repr__(self):
        return ' '.join(('<Field', self.name, self.type, self.body, '>'))

    def __eq__(self, s2):
        if self.name == s2.name and self.type == s2.type and s2.body == self.body:
            return True
        return False

    def __ne__(self, s2):
        if self.name == s2.name or self.type == s2.type or s2.body == self.body:
            return False
        return True


class Reader(object):
    def __init__(self, flo):
        self.adif_ver = None
        self.flo = flo
        # read header
        flo.seek(0)
        c = flo.read(1)
        if c == '<':
            self.header_present = False
            flo.seek(0)
        else:
            self.header_present = True
            for field in self._lex(blocksize=1):
                if field.name == 'adif_ver':
                    self.adif_ver = Decimal(field.body)
                elif field.name == 'eoh':
                    break
        self.bookmark = flo.tell()

    def _lex(self, blocksize=BLOCKSIZE):
        """Given a file like object, yield named tuple for each record."""
        flo = self.flo
        state = 'comment'
        pos = 0
        field = Field()
        while True:
            buf = flo.read(blocksize)
            #print buf
            for c in buf:
                #print "c = '%s'" % c
                if state == 'comment':
                    if c == '<':
                        state = 'name'
                        field = Field()
                elif state == 'name':
                    if c == ':':
                        state = 'len'
                        field_len = ''
                    elif c == '>':
                        state = 'comment'
                        field.name = field.name.lower()
                        field.type = field.type.lower()
                        #print field
                        yield field
                    else:
                        field.name = field.name + c
                elif state == 'len':
                    if c == ':':
                        state = 'type'
                        field_len = int(field_len)
                    elif c == '>':
                        state = 'body'
                        field_len = int(field_len)
                    else:
                        field_len = field_len + c
                elif state == 'type':
                    if c == ':':
                        raise ParseError()
                    elif c == '>':
                        state = 'body'
                    else:
                        field.type = field.type + c
                elif state == 'body':
                    if field_len > 0:
                        field.body = field.body + c
                        field_len -= 1
                    if field_len == 0:
                        state = 'comment'
                        field.name = field.name.lower()
                        field.type = field.type.lower()
                        #print field
                        yield field
                else:
                    raise Exception("Invalid state at %d" % pos)
                pos += 1
                #print field
                #print pos
            if len(buf) < blocksize:
                #print 'EOF'
                break

    def __iter__(self):
        """Iterate over records in file"""
        self.flo.seek(self.bookmark)
        rec = OrderedDict()
        for field in self._lex():
            #print field
            if field.name == 'eor':
                #print 'yield rec'
                if 'qso_date' in rec and 'time_on' in rec:
                    rec['app_datetime_on'] = datetime(int(rec['qso_date'][:4]),
                                          int(rec['qso_date'][4:6]),
                                          int(rec['qso_date'][6:8]),
                                          int(rec['time_on'][:2]),
                                          int(rec['time_on'][2:4]))
                if 'qso_date' in rec and 'time_off' in rec:
                    rec['app_datetime_off'] = datetime(int(rec['qso_date'][:4]),
                                          int(rec['qso_date'][4:6]),
                                          int(rec['qso_date'][6:8]),
                                          int(rec['time_off'][:2]),
                                          int(rec['time_off'][2:4]))
                yield rec
                rec = OrderedDict()
            else:
                # TODO: type conversion and validation
                rec[field.name] = field.body
            #print rec

def format_header(header_text=' ', adif_ver=None):
    assert header_text != ''
    if adif_ver is None:
        return "%s<eoh>" % header_text
    return "%s<adif_ver:%d>%s<eoh>" % (
            header_text, len(adif_ver), adif_ver)

def format_record(record):
    fields = []
    for k,v in record.iteritems():
        if k == 'app_datetime_on':
            continue
        fields.append("<%s:%d>%s" % (k, len(v), v))
    fields.append('<eor>')
    return ''.join(fields)