# XML "function" nodes that evaluate their contents to text

import datetime

import exc

import xml_dom

class SyntaxException(Exception):

    def __init__(self, cause=None):

        Exception.__init__(self, 'Invalid syntax in XML function: '+str(cause))

def map_items(func, items):

    return [(name, func(value)) for name, value in items]

def conv_items(type_, items):

    try: return map_items(type_, items)

    except ValueError, e: raise SyntaxException(e)

def alt(items):

    items = list(items)

    items.sort()

    return items[0][1] # value of lowest-numbered item

def range_(items):

    items = dict(conv_items(float, items))

    try:

        to = items['to']

        from_ = items['from']

    except KeyError, e: raise SyntaxException(e)

    return str(to - from_)

def avg(items):

    count = 0

    sum_ = 0.

    for name, value in conv_items(float, items):

        count += 1

        sum_ += value

    return str(sum_/count)

def date(items):

    items = dict(items)

    if 'date' in items:

        str_ = items['date']

        try: year = float(str_)

        except ValueError:

            try: import dateutil.parser

            except ImportError: return str_

            try: date = dateutil.parser.parse(str_)

            except ValueError, e: raise SyntaxException(e)

        else: date = (datetime.date(int(year), 1, 1) +

            datetime.timedelta(round((year % 1.)*365)))

    else:

        try: year = items['year']

        except KeyError, e: raise SyntaxException(e)

        month = items.get('month', '1')

        day = items.get('day', '1')

        try:

            year = int(year)

            month = int(month)

            day = int(day)

        except ValueError, e: raise SyntaxException(e)

        date = datetime.date(year, month, day)

    return date.strftime('%Y-%m-%d')

def name(items):

    items = dict(items)

    return ' '.join([items['first'], items['last']])

def namePart(items):

    items = dict(items)

    def to_parts(name): return items[name].split(' ')

    parts = []

    if 'first' in items: parts += to_parts('first')[:1]

    if 'last' in items: parts += to_parts('last')[-1:]

    if 'middle' in items: parts += to_parts('middle')[1:-1]

    return ' '.join(parts)

# Function names must start with _ to avoid collisions with real tags

# Functions take arguments (items)

funcs = {'_alt': alt, '_range': range_, '_avg': avg, '_date': date,

    '_name': name, '_namePart': namePart}

def process(node):

    name = node.tagName

    if name.startswith('_') and name in funcs:

        try: value = funcs[name](xml_dom.NodeTextEntryIter(node))

        except SyntaxException, e:

            exc.add_msg(e, 'function: '+str(node))

            raise

        else: xml_dom.replace_with_text(node, value)

    else:

        for child in xml_dom.NodeElemIter(node): process(child)