from .. import fileio
from ...weights.weights import W
from ...weights.util import remap_ids

__author__ = "Myunghwa Hwang <mhwang4@gmail.com>"
__all__ = ["ArcGISDbfIO"]


class ArcGISDbfIO(fileio.FileIO):
    """Opens, reads, and writes weights file objects in ArcGIS dbf format.

    Spatial weights objects in the ArcGIS ``.dbf`` format are used in ArcGIS Spatial
    Statistics tools. This format is the same as the general ``.dbf`` format,
    but the structure of the weights ``.dbf`` file is fixed unlike other ``.dbf``
    files. This ``.dbf`` format can be used with the "Generate Spatial Weights
    Matrix" tool, but not with the tools under the "Mapping Clusters" category".

    The ArcGIS ``.dbf`` file is assumed to have three or four data columns. When the
    file has four columns, the first column is meaningless and will be ignored in
    PySAL during both file reading and file writing. The next three columns hold
    origin IDs, destinations IDs, and weight values. When the file has three columns,
    it is assumed that only these data columns exist in the stated order. The name
    for the orgin IDs column should be the name of ID variable in the original
    source data table. The names for the destination IDs and weight values columns
    are NID and WEIGHT, respectively. ArcGIS Spatial Statistics tools support only
    unique integer IDs. Therefore, the values for origin and destination ID columns
    should be integer. For the case where the IDs of a weights object are not
    integers, `ArcGISDbfIO` allows users to use internal id values corresponding to
    record numbers, instead of original ids.

    An exemplary structure of an ArcGIS dbf file is as follows:
    
    ```
    [Line 1]    Field1    RECORD_ID    NID    WEIGHT
    [Line 2]    0         72           76     1
    [Line 3]    0         72           79     1
    [Line 4]    0         72           78     1
    ```

    Unlike the ArcGIS text format, this format does not seem to include self-neighbors.

    References
    ----------
    
    http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?TopicName=Convert_Spatial_Weights_Matrix_to_Table_(Spatial_Statistics)

    """

    FORMATS = ["arcgis_dbf"]
    MODES = ["r", "w"]

    def __init__(self, *args, **kwargs):
        self._varName = "Unknown"
        args = args[:2]
        fileio.FileIO.__init__(self, *args, **kwargs)
        self.file = fileio.FileIO(self.dataPath, self.mode)

    def _set_varName(self, val):
        if issubclass(type(val), str):
            self._varName = val

    def _get_varName(self):
        return self._varName

    varName = property(fget=_get_varName, fset=_set_varName)

    def read(self, n=-1):
        self._complain_ifclosed(self.closed)
        return self._read()

    def seek(self, pos):
        self.file.seek(pos)
        self.pos = self.file.pos

    def _read(self):
        """Reads ArcGIS dbf file
        
        Returns
        -------
        w : libpysal.weights.W
            A ``libpysal.weights.W`` object.
        
        Raises
        ------
        StopIteration
            Raised at the EOF.
        ValueError
            Raised when the weights data structure is incorrect.
        TypeError
            Raised when the IDs are not integers.
        
        Examples
        --------

        Type ``dir(w)`` at the interpreter to see what methods are supported.
        Open an ArcGIS ``.dbf`` file and read it into a PySAL weights object.

        >>> import libpysal
        >>> w = libpysal.io.open(
        ...     libpysal.examples.get_path('arcgis_ohio.dbf'), 'r', 'arcgis_dbf'
        ... ).read()

        Get the number of observations from the header.

        >>> w.n
        88

        Get the mean number of neighbors.

        >>> w.mean_neighbors
        5.25

        Get neighbor distances for a single observation.

        >>> w[1] == dict({2: 1.0, 11: 1.0, 6: 1.0, 7: 1.0})
        True

        """

        if self.pos > 0:
            raise StopIteration

        id_var = self.file.header[1]
        startPos = len(self.file.header)

        if startPos == 3:
            startPos = 0
        elif startPos == 4:
            startPos = 1
        else:
            msg = "Wrong structure, a weights '.dbf' "
            msg += "file requires at least three data columns."
            raise ValueError(msg)

        self.varName = id_var
        id_type = int
        id_spec = self.file.field_spec[startPos]

        if id_spec[0] != "N":
            raise TypeError("The data type for IDs should be integer.")

        self.id_var = id_var

        weights = {}
        neighbors = {}

        for row in self.file:
            i, j, w = tuple(row)[startPos:]
            i = id_type(i)
            j = id_type(j)
            w = float(w)
            if i not in weights:
                weights[i] = []
                neighbors[i] = []
            weights[i].append(w)
            neighbors[i].append(j)
            self.pos = self.file.pos

        w = W(neighbors, weights)

        return w

    def write(self, obj, useIdIndex=False):
        """Write a weights object to the opened ``.dbf`` file.

        Parameters
        ----------
        obj : libpysal.weights.W
            A ``libpysal.weights.W`` object.
        useIdIndex : bool
            Use the `W` IDs and remap (``True``). Default is ``False``.

        Raises
        ------
        TypeError
            Raised when the IDs in input ``obj`` are not integers.
        TypeError
            Raised when the input ``obj`` is not a PySAL `W`.

        Examples
        --------

        >>> import tempfile, libpysal, os
        >>> testfile = libpysal.io.open(
        ...     libpysal.examples.get_path('arcgis_ohio.dbf'), 'r', 'arcgis_dbf'
        ... )
        >>> w = testfile.read()

        Create a temporary file for this example.

        >>> f = tempfile.NamedTemporaryFile(suffix='.dbf')

        Reassign to a new variable.

        >>> fname = f.name

        Close the temporary named file.

        >>> f.close()

        Open the new file in write mode.

        >>> o = libpysal.io.open(fname, 'w', 'arcgis_dbf')

        Write the Weights object into the open file.

        >>> o.write(w)
        >>> o.close()

        Read in the newly created text file.

        >>> wnew =  libpysal.io.open(fname, 'r', 'arcgis_dbf').read()

        Compare values from old to new.

        >>> wnew.pct_nonzero == w.pct_nonzero
        True

        Clean up the temporary file created for this example.

        >>> os.remove(fname)

        """

        self._complain_ifclosed(self.closed)

        if issubclass(type(obj), W):
            self.file.header = [self.varName, "NID", "WEIGHT"]

            id_type = type(obj.id_order[0])
            if id_type is not int and not useIdIndex:
                raise TypeError("ArcGIS DBF weight files support only integer IDs.")
            if useIdIndex:
                id2i = obj.id2i
                obj = remap_ids(obj, id2i)

            id_spec = ("N", len(str(max(obj.id_order))), 0)
            self.file.field_spec = [id_spec, id_spec, ("N", 13, 6)]

            for id in obj.id_order:
                neighbors = list(zip(obj.neighbors[id], obj.weights[id]))
                for neighbor, weight in neighbors:
                    self.file.write([id, neighbor, weight])
                    self.pos = self.file.pos

        else:
            raise TypeError("Expected a PySAL weights object, got: %s." % (type(obj)))

    def flush(self):
        self._complain_ifclosed(self.closed)
        self.file.flush()

    def close(self):
        self.file.close()
