import pmt

from . import gr_python as gr

class PythonTag(object):
    " Python container for tags "
    def __init__(self):
        self.offset = None
        self.key    = None
        self.value  = None
        self.srcid  = False

def tag_to_python(tag):
    """ Convert a stream tag to a Python-readable object """
    newtag = PythonTag()
    newtag.offset = tag.offset
    newtag.key = pmt.to_python(tag.key)
    newtag.value = pmt.to_python(tag.value)
    newtag.srcid = pmt.to_python(tag.srcid)
    return newtag

def python_to_tag(tag_struct):
    """
    Convert a Python list/tuple/dictionary to a stream tag.

    When using a list or tuple format, this function expects the format:
      tag_struct[0] --> tag's offset (as an integer)
      tag_struct[1] --> tag's key (as a PMT)
      tag_struct[2] --> tag's value (as a PMT)
      tag_struct[3] --> tag's srcid (as a PMT)

    When using a dictionary, we specify the dictionary keys using:
      tag_struct['offset'] --> tag's offset (as an integer)
      tag_struct['key'] --> tag's key (as a PMT)
      tag_struct['value'] --> tag's value (as a PMT)
      tag_struct['srcid'] --> tag's srcid (as a PMT)

    If the function can take the Python object and successfully
    construct a tag, it will return the tag. Otherwise, it will return
    None.
    """
    good = False
    tag = gr.tag_t()
    if(type(tag_struct) == dict):
        if('offset' in tag_struct):
            if(isinstance(tag_struct['offset'], int)):
                tag.offset = tag_struct['offset']
                good = True

        if('key' in tag_struct):
            if(isinstance(tag_struct['key'], pmt.pmt_base)):
                tag.key = tag_struct['key']
                good = True

        if('value' in tag_struct):
            if(isinstance(tag_struct['value'], pmt.pmt_base)):
                tag.value = tag_struct['value']
                good = True

        if('srcid' in tag_struct):
            if(isinstance(tag_struct['srcid'], pmt.pmt_base)):
                tag.srcid = tag_struct['srcid']
                good = True

    elif(type(tag_struct) == list or type(tag_struct) == tuple):
        if(len(tag_struct) == 4):
            if(isinstance(tag_struct[0], int)):
                tag.offset = tag_struct[0]
                good = True

            if(isinstance(tag_struct[1], pmt.pmt_base)):
                tag.key = tag_struct[1]
                good = True

            if(isinstance(tag_struct[2], pmt.pmt_base)):
                tag.value = tag_struct[2]
                good = True

            if(isinstance(tag_struct[3], pmt.pmt_base)):
                tag.srcid = tag_struct[3]
                good = True

        elif(len(tag_struct) == 3):
            if(isinstance(tag_struct[0], int)):
                tag.offset = tag_struct[0]
                good = True

            if(isinstance(tag_struct[1], pmt.pmt_base)):
                tag.key = tag_struct[1]
                good = True

            if(isinstance(tag_struct[2], pmt.pmt_base)):
                tag.value = tag_struct[2]
                good = True

            tag.srcid = pmt.PMT_F

    if(good):
        return tag
    else:
        return None
