import bisect, sys

"""
This file contains functions that were originally included in
Panda3D but were removed due to being obsolete. These are required
by Toontown, and probably cannot be replaced by anything else that
is still in Panda3D.
"""

class PriorityCallbacks:
    """ manage a set of prioritized callbacks, and allow them to be invoked in order of priority """
    def __init__(self):
        self._callbacks = []

    def clear(self):
        while self._callbacks:
            self._callbacks.pop()

    def add(self, callback, priority=None):
        if priority is None:
            priority = 0
        item = (priority, callback)
        bisect.insort(self._callbacks, item)
        return item

    def remove(self, item):
        self._callbacks.pop(bisect.bisect_left(self._callbacks, item))

    def __call__(self):
        for priority, callback in self._callbacks:
            callback()

def clampScalar(value, a, b):
    # calling this ought to be faster than calling both min and max
    if a < b:
        if value < a:
            return a
        elif value > b:
            return b
        else:
            return value
    else:
        if value < b:
            return b
        elif value > a:
            return a
        else:
            return value

def describeException(backTrace = 4):
    # When called in an exception handler, returns a string describing
    # the current exception.

    def byteOffsetToLineno(code, byte):
        # Returns the source line number corresponding to the given byte
        # offset into the indicated Python code module.

        import array
        lnotab = array.array('B', code.co_lnotab)

        line   = code.co_firstlineno
        for i in xrange(0, len(lnotab), 2):
            byte -= lnotab[i]
            if byte <= 0:
                return line
            line += lnotab[i+1]

        return line

    infoArr = sys.exc_info()
    exception = infoArr[0]
    exceptionName = getattr(exception, '__name__', None)
    extraInfo = infoArr[1]
    trace = infoArr[2]

    stack = []
    while trace.tb_next:
        # We need to call byteOffsetToLineno to determine the true
        # line number at which the exception occurred, even though we
        # have both trace.tb_lineno and frame.f_lineno, which return
        # the correct line number only in non-optimized mode.
        frame = trace.tb_frame
        module = frame.f_globals.get('__name__', None)
        lineno = byteOffsetToLineno(frame.f_code, frame.f_lasti)
        stack.append("%s:%s, " % (module, lineno))
        trace = trace.tb_next

    frame = trace.tb_frame
    module = frame.f_globals.get('__name__', None)
    lineno = byteOffsetToLineno(frame.f_code, frame.f_lasti)
    stack.append("%s:%s, " % (module, lineno))

    description = ""
    for i in xrange(len(stack) - 1, max(len(stack) - backTrace, 0) - 1, -1):
        description += stack[i]

    description += "%s: %s" % (exceptionName, extraInfo)
    return description