''' Pprint rewrite

* Needs to work with AST, pyclbr, json, xml, and existing pprint
* Incorporates features of reprlib and textwrap
* Would be nice to be able to print general document outlines
* ? Possible to create nicely formatted YAML and/or pickletools.dis()
* Easy to add custom formatters 

# ??? Lower initial goal or replacing pprint._format with drop in substitute
#     and slightly expand the API
# ??? check for overlap with formatter.py

'''

__all__ = 'Separator', 'Format', 'Indent', 'guard', 'pprint'

from collections import namedtuple

#------------- Formatting Controls ----------------------------------------

Separator = namedtuple('Separator', 'sep')
Format = namedtuple('Format', 'value')
Indent = 'Indent'
NL = 'NL'                   # force a newline, even if will fit on curr row

#------------- Default Handlers ------------------------------------------

def guard(predicate=None, *, hasattr=None, classname=None, isinstance=None):
    'Attaches a match() function attribute to a generator or function'
    import builtins
    def match(obj):
        return (
            (predicate is None or predicate(obj)) and
            (hasattr is None or builtins.hasattr(obj, hasattr)) and
            (isinstance is None or builtins.isinstance(obj, isinstance)) and
            (classname is None or getattr(type(obj), '__name__', '') == classname)
        )    
    def decorating_function(user_function):
        user_function.match = match
        return user_function
    return decorating_function

@guard()
def universal_handler(obj):
    yield repr(obj)

@guard(isinstance=dict)
def dict_handler(d):
    yield "{"
    for k in sorted(d):
        v = d[k]
        yield Indent, Format(k), ': '                   # rstrip() is automatic
        yield Indent, Indent, Format(v), Separator(',') # separators go between elements
    yield '}'

@guard(isinstance=list)
def list_handler(s):
    yield '['
    for elem in s:
        yield Format(elem), Separator(',')
    yield ']'

@guard(isinstance=tuple, hasattr='_fields')
def general_named_tuple_handler(obj):
    yield obj.__name__, '('
    for field, value in zip(obj._fields, obj):
        yield Format(field), '= ', Format(value)
    yield ')'

default_handlers = [
    universal_handler,
    dict_handler,
]

#-------------- Controller -----------------------------------------------

# runner responsibilites
#    test the guard
#    decide whether consecutive yields and fit on one line or should be newlined
#    NL is a forced newline
#    rstrip the line
#    handle width / textwrap issues

def pprint(obj, handlers=[], indent=1, level=0):
    for handler in reversed(default_handlers + handlers):
        if handler.match(obj):
            break
    prefix = [Indent] * level
    for row in handler(obj):
        row = prefix + list(row)
        print(row)
    
#-------------- Test call -----------------------------------------------        

if __name__ == '__main__':

    from collections import namedtuple

    Point3D = namedtuple('Point3D', 'x y z')

    @guard(classname='Point3D')
    def point3d_handler(obj):
        yield '<3D: %O9.2f | %09.2f | %09.2f >' % obj  

    obj = [
        dict(item='Wand of Fireballs', location=Point3D(21,18.2,17.5)),
        dict(item='Ring of Invisibility', location=Point3D(12,8.75,3.14)),
    ]
    obj = dict(a=1, b=2)

    pprint(obj, handlers=[point3d_handler], level=2)