import sys
import yaml
# Need to override internal method, so can't use C version.
# (Could use CLoader, but mumble mumble exception reporting.)
# TODO(xavid): Investiage whether the C versions would save a lot of time,
#              and if so figure out a way to use them.
from yaml import Loader, Dumper

from bazbase import translators

class BazDumper(Dumper):
    def analyze_scalar(self, scalar):
        ret = Dumper.analyze_scalar(self, scalar)
        # TODO(xavid): Are there more cases I should suppress this?
        if scalar:
            ret.allow_block = True
        return ret

class InvalidBazFile(Exception):
    pass

INCLUDE = u'!include'

class Include(str):
    pass

def expect(seq, evt):
    e = seq.next()
    if not isinstance(e, evt):
        raise InvalidBazFile("Expected %s, got %s"%(evt,e))
    return e

def default_include_name(ename, pname, value, previous=None):
    ext = translators.extension(value)
    if previous is not None and previous.endswith(ext):
        return previous
    return "%s.%s%s" % (ename, pname, ext)

def style_for_value(value):
    if '\n' in value or len(value) > 60:
        return '|'
    else:
        return None

def parse_h(curre, handler, seq):
    currp = None
    quenche = False

    if hasattr(handler, 'get_new_properties'):
        get_extra = lambda: handler.get_new_properties(curre)
    else:
        get_extra = lambda: None

    handler.start_element(curre)

    yield expect(seq, yaml.StreamStartEvent)
    e = seq.next()
    if isinstance(e, yaml.StreamEndEvent):
        # Was empty file
        extra = get_extra()
        if extra:
            # If we're adding new props, we need to make this look like
            # a proper mapping
            yield yaml.DocumentStartEvent(explicit=False)
            seq = iter([yaml.MappingStartEvent(anchor=None,
                                               tag=None,
                                               implicit=True,
                                               flow_style=False),
                        yaml.MappingEndEvent(),
                        yaml.DocumentEndEvent()])
            get_extra = lambda: extra
        else:
            yield e
            handler.end_element(curre)
            return
    elif isinstance(e, yaml.DocumentStartEvent):
        yield e
    else:
        raise InvalidBazFile("Got %s at start of document." % e)
    e = seq.next()
    if isinstance(e, yaml.ScalarEvent):
        if e.value == '':
            extra = get_extra()
            if extra:
                # If we're adding new props, we need to make this look like
                # a proper mapping
                yield yaml.MappingStartEvent(anchor=None,
                                             tag=None,
                                             implicit=True,
                                             flow_style=False)
                seq = iter([yaml.MappingEndEvent(),
                            expect(seq, yaml.DocumentEndEvent)])
                get_extra = lambda: extra
            else:
                yield e
                yield expect(seq, yaml.DocumentEndEvent)
                handler.end_element(curre)
                return
        else:
            raise InvalidBazFile("Non-empty scalar '%s' at start of mapping."
                                 % e.value)
    elif isinstance(e, yaml.MappingStartEvent):
        yield e
    else:
        raise InvalidBazFile("Got %s at start of mapping." % e)
    try:
        for e in seq:
            if isinstance(e, yaml.MappingEndEvent):
                # Write any remaining props
                extra = get_extra()
                if extra:
                    for p in extra:
                        assert isinstance(p, unicode), repr(p)
                        yield yaml.ScalarEvent(anchor=None, tag=None,
                                               implicit=(True, True),
                                               style=None,
                                               value=p)
                        if isinstance(extra[p], unicode):
                            yield yaml.ScalarEvent(
                                anchor=None, tag=None, implicit=(True, True),
                                style=style_for_value(extra[p]),
                                value=extra[p])
                        else:
                            assert isinstance(extra[p], str), repr(extra[p])
                            name = default_include_name(curre, p, extra[p])
                            name = handler.set_include(name, extra[p], new=True)
                            assert '/' not in name, name
                            yield yaml.ScalarEvent(anchor=None, tag=INCLUDE,
                                                   implicit=(False, False),
                                                   value=name)
                yield e
                break
            elif not isinstance(e, yaml.ScalarEvent):
                if (isinstance(e, yaml.SequenceStartEvent)
                    and currp is not None):
                    raise InvalidBazFile("Unexpected sequence in value for "
                                         "%s.%s; values starting with a [ "
                                         "must be quoted." % (curre, currp))
                elif (isinstance(e, yaml.MappingStartEvent)
                      and currp is not None):
                    raise InvalidBazFile("Unexpected mapping in value for "
                                         "%s.%s; values starting with a { "
                                         "must be quoted." % (curre, currp))
                else:
                    raise InvalidBazFile("Unexpected yaml event: %s"%e)
            if currp is not None:
                if e.tag == INCLUDE:
                    if '/' in e.value:
                        raise InvalidBazFile("Includes must not be in a different directory! (%s in %s.%s)" % (e.value, curre, currp))
                    if e.value.endswith('.yaml'):
                        raise InvalidBazFile("Includes must not end in .yaml! (%s in %s.%s)" % (e.value, curre, currp))
                    val = handler.get_include(e.value)
                    if val is None:
                        raise InvalidBazFile("Couldn't read include '%s' for %s.%s!" % (e.value, curre, currp))
                else:
                    assert e.tag in (None, u'!'), e.tag
                    val = e.value
                oldcurrp = currp
                currp = None
                if quenche:
                    continue
                val = val.encode('utf-8')
                ret = handler.prop(curre, oldcurrp, val)
                if ret is not None:
                    if ret != val:
                        if isinstance(ret, Include):
                            oldname = e.value if e.tag == INCLUDE else None
                            name = default_include_name(
                                curre, oldcurrp, val,
                                oldname)
                            name = handler.set_include(name, ret,
                                                       new=(name != oldname))
                            assert '/' not in name, name
                            e.tag = INCLUDE
                            e.implicit = (False, False)
                            e.style = None
                            e.value = name
                        else:
                            e.tag = None
                            e.implicit = (True, True)
                            e.style = style_for_value(ret)
                            e.value = ret
                        if e.style is None:
                            e.style = ''
                    yield currpe
                    yield e
            elif curre is not None:
                assert e.tag in (None, u'!'), e.tag
                if curre is False:
                    # Lines after the end of a .list
                    raise InvalidBazFile("Lines after end of file!")
                currp = e.value
                currpe = e
                continue
    except yaml.scanner.ScannerError, e:
        if (e.problem and e.problem.endswith("but found '*'")
            and currp is not None):
            raise InvalidBazFile("Malformed alias in value for %s.%s; values starting with a * must be quoted." % (curre, currp))
        elif (e.problem and e.problem == "mapping keys are not allowed here"
            and currp is not None):
            raise InvalidBazFile("Unexpected mapping key in value for %s.%s; values starting with a ? must be quoted." % (curre, currp))
        else:
            raise
    # TODO(xavid): Loop here for list-style files.
    yield expect(seq, yaml.DocumentEndEvent)
    yield expect(seq, yaml.StreamEndEvent)
    # Check to make sure we ended in a good state
    if currp is not None:
        raise InvalidBazFile("%s.%s unclosed!"%(curre,currp))
    # We're golden!
    handler.end_element(curre)

if False:
    def p(s):
        print >>sys.stderr,repr(s)
        return s
else:
    p = lambda s:s

# handler's methods only have a return value if outf is specified.
# Yes, I realize this is a wonky interface.
def parse(path, handler, inf=None, outf=None):
    if inf is None:
        inf = codecs.open(path,"r","utf-8")
    assert path.endswith('.yaml')
    curre = path.rsplit('/',1)[-1].rsplit('.',1)[0]
    try:
        iterator = parse_h(curre, handler, yaml.parse(inf, Loader=Loader))
        if outf:
            y = [p(s) for s in iterator]
            yaml.emit(y, outf, Dumper=BazDumper)
        else:
            for e in iterator:
                pass
    except yaml.YAMLError, exc:
        print >>sys.stderr, path
        if hasattr(exc, 'problem_mark'):
            print >>sys.stderr,exc.problem_mark,dir(exc.problem_mark)
            exc.problem_mark.name = path
        raise