# Copyright (c) 2006 Carnegie Mellon University
#
# You may copy and modify this freely under the same terms as
# Sphinx-III

"""Read/write Sphinx-III transition matrix files.

This module reads and writes the HMM transition matrix files used by
SphinxTrain, Sphinx-III, and PocketSphinx.
"""

__author__ = "David Huggins-Daines <dhdaines@gmail.com>"
__version__ = "$Revision$"

from .s3file import S3File, S3File_write
from numpy import shape


def open(filename, mode="rb"):
    if mode in ("r", "rb"):
        return S3TmatFile(filename)
    elif mode in ("w", "wb"):
        return S3TmatFile_write(filename)
    else:
        raise Exception("mode must be 'r', 'rb', 'w', or 'wb'")


class S3TmatFile(S3File):
    "Read Sphinx-III format transition matrix files"
    def __init__(self, filename, mode="rb"):
        super().__init__(filename=filename, mode=mode)
        self._params = self._load()

    def readgauheader(self):
        if self.fileattr["version"] != "1.0":
            raise Exception("Version mismatch: must be 1.0 but is "
                            + self.fileattr["version"])
    
    def _load(self):
        self.readgauheader()
        self.fh.seek(self.data_start, 0)
        return self.read3d()


class S3TmatFile_write(S3File_write):
    "Write Sphinx-III format transition matrix files"

    def writeall(self, stuff):
        n_tmat, n_state, spam = shape(stuff)
        if n_state + 1 != spam:
            raise Exception("n_state rows %d != n_state columns %d - 1"
                            % (n_state, spam))
        self.fh.seek(self.data_start, 0)
        self.write3d(stuff)