"""
mtbtn module. Contains the Mt3dBtn class. Note that the user can access
the Mt3dBtn class as `flopy.mt3d.Mt3dBtn`.

Additional information for this MT3DMS package can be found in the MT3DMS
User's Manual.

"""

import warnings

import numpy as np

from ..pakbase import Package
from ..utils import Util2d, Util3d


class Mt3dBtn(Package):
    """
    Basic Transport Package Class.

    Parameters
    ----------
    model : model object
        The model object (of type :class:`flopy.mt3dms.mt.Mt3dms`) to which
        this package will be added.
    MFStyleArr : str
        Specifies whether or not to read arrays using the MODFLOW array reader
        format or the original MT3DMS array reader
    DRYCell : str
        Specifies whether or not to route mass through dry cells.  When MF-NWT
        is used to generate the flow-transport link file, this is a distinct
        possibility.
    Legacy99Stor : str
        Specifies whether or not to use the storage formulation used in MT3DMS
    FTLPrint : str
        Specifies if flow-transport link terms (cell-by-cell flows) should be
        echoed to the MT3D-USGS listing file.
    NoWetDryPrint : str
        Specifies whether or not to suppress wet/dry messaging in the MT3D-USGS
        listing file.
    OmitDryBudg : str
        Specifies whether or not to include the mass flux terms through dry
        cells in the mass budget written to the listing file.
    AltWTSorb : str
        Specifies whether or not to use the MT3DMS formulation (this keyword
        omitted) for the solid phase, whereby the entire cell thickness is
        available for interacting with the aqueous phase, even though the
        aqueous phase may only occupy a portion of the cell's thickness.  When
        used, only the saturated portion of the cell is available for sorbing
    ncomp : int
        The total number of chemical species in the simulation. (default is
        None, will be changed to 1 if sconc is single value)
    mcomp : int
        The total number of 'mobile' species (default is 1). mcomp must be
        equal or less than ncomp.
    tunit : str
        The name of unit for time (default is 'D', for 'days'). Used for
        identification purposes only.
    lunit : str
        The name of unit for length (default is 'M', for 'meters'). Used for
        identification purposes only.
    munit : str
        The name of unit for mass (default is 'KG', for 'kilograms'). Used for
        identification purposes only.
    prsity : float or array of floats (nlay, nrow, ncol)
        The effective porosity of the porous medium in a single porosity
        system, or the mobile porosity in a dual-porosity medium (the immobile
        porosity is defined through the Chemical Reaction Package. (default is
        0.25).
    icbund : int or array of ints (nlay, nrow, ncol)
        The icbund array specifies the boundary condition type for solute
        species (shared by all species). If icbund = 0, the cell is an inactive
        concentration cell; If icbund < 0, the cell is a constant-concentration
        cell; If icbund > 0, the cell is an active concentration cell where the
        concentration value will be calculated. (default is 1).
    sconc : float, array of (nlay, nrow, ncol), or filename
        sconc is the starting concentration for the first species.  To specify
        starting concentrations for other species in a multi-species
        simulation, include additional keywords, such as sconc2, sconc3, and
        so forth.
    cinact : float
        The value for indicating an inactive concentration cell. (default is
        1e30).
    thkmin : float
        The minimum saturated thickness in a cell, expressed as the decimal
        fraction of its thickness, below which the cell is considered inactive.
        (default is 0.01).
    ifmtcn : int
        A flag/format code indicating how the calculated concentration should
        be printed to the standard output text file. Format codes for printing
        are listed in Table 3 of the MT3DMS manual. If ifmtcn > 0 printing is
        in wrap form; ifmtcn < 0 printing is in strip form; if ifmtcn = 0
        concentrations are not printed. (default is 0).
    ifmtnp : int
        A flag/format code indicating how the number of particles should
        be printed to the standard output text file. The convention is
        the same as for ifmtcn. (default is 0).
    ifmtrf : int
        A flag/format code indicating how the calculated retardation factor
        should be printed to the standard output text file. The convention is
        the same as for ifmtcn. (default is 0).
    ifmtdp : int
        A flag/format code indicating how the distance-weighted dispersion
        coefficient should be printed to the standard output text file. The
        convention is the same as for ifmtcn. (default is 0).
    savucn : bool
        A logical flag indicating whether the concentration solution should be
        saved in an unformatted file. (default is True).
    nprs : int
        A flag indicating (i) the frequency of the output and
        (ii) whether the output frequency is specified in terms
        of total elapsed simulation time or the transport step number. If
        nprs > 0 results will be saved at the times as specified in timprs;
        if nprs = 0, results will not be saved except at the end of simulation;
        if NPRS < 0, simulation results will be saved whenever the number of
        transport steps is an even multiple of nprs. (default is 0).
    timprs : list of floats
        The total elapsed time at which the simulation results are saved. The
        number of entries in timprs must equal nprs. (default is None).
    obs: array of int
        An array with the cell indices (layer, row, column) for which the
        concentration is to be printed at every transport step. (default is
        None).  obs indices must be entered as zero-based numbers as a 1 is
        added to them before writing to the btn file.
    nprobs: int
        An integer indicating how frequently the concentration at the specified
        observation points should be saved. (default is 1).
    chkmas: bool
        A logical flag indicating whether a one-line summary of mass balance
        information should be printed. (default is True).
    nprmas: int
        An integer indicating how frequently the mass budget information
        should be saved. (default is 1).
    dt0: float
        The user-specified initial transport step size within each time-step
        of the flow solution. (default is 0).
    mxstrn: int
        The maximum number of transport steps allowed within one time step
        of the flow solution. (default is 50000).
    ttsmult: float
        The multiplier for successive transport steps within a flow time-step
        if the GCG solver is used and the solution option for the advection
        term is the standard finite-difference method. (default is 1.0).
    ttsmax: float
        The maximum transport step size allowed when transport step size
        multiplier TTSMULT > 1.0. (default is 0).
    species_names: list of str
        A list of names for every species in the simulation.
    extension : string
        Filename extension (default is 'btn')
    unitnumber : int
        File unit number (default is None).
    filenames : str or list of str
        Filenames to use for the package. If filenames=None the package name
        will be created using the model name and package extension. If a
        single string is passed the package will be set to the string.
        Default is None.

    Attributes
    ----------

    Methods
    -------

    See Also
    --------

    Notes
    -----

    Examples
    --------

    >>> import flopy
    >>> mt = flopy.mt3dms.Mt3dms()
    >>> btn = flopy.mt3dms.Mt3dBtn(mt)

    """

    def __init__(
        self,
        model,
        MFStyleArr=False,
        DRYCell=False,
        Legacy99Stor=False,
        FTLPrint=False,
        NoWetDryPrint=False,
        OmitDryBud=False,
        AltWTSorb=False,
        nlay=None,
        nrow=None,
        ncol=None,
        nper=None,
        ncomp=1,
        mcomp=1,
        tunit="D",
        lunit="M",
        munit="KG",
        laycon=None,
        delr=None,
        delc=None,
        htop=None,
        dz=None,
        prsity=0.30,
        icbund=1,
        sconc=0.0,
        cinact=1e30,
        thkmin=0.01,
        ifmtcn=0,
        ifmtnp=0,
        ifmtrf=0,
        ifmtdp=0,
        savucn=True,
        nprs=0,
        timprs=None,
        obs=None,
        nprobs=1,
        chkmas=True,
        nprmas=1,
        perlen=None,
        nstp=None,
        tsmult=None,
        ssflag=None,
        dt0=0,
        mxstrn=50000,
        ttsmult=1.0,
        ttsmax=0,
        species_names=None,
        extension="btn",
        unitnumber=None,
        filenames=None,
        **kwargs,
    ):

        if unitnumber is None:
            unitnumber = Mt3dBtn._defaultunit()
        elif unitnumber == 0:
            unitnumber = Mt3dBtn._reservedunit()

        # call base package constructor
        super().__init__(
            model,
            extension=extension,
            name=self._ftype(),
            unit_number=unitnumber,
            filenames=self._prepare_filenames(filenames),
        )

        # Set these variables from the Modflow model (self.parent.mf) unless
        # they are specified in the constructor.
        self.setmodflowvars(
            nlay,
            nrow,
            ncol,
            nper,
            laycon,
            delr,
            delc,
            htop,
            dz,
            perlen,
            nstp,
            tsmult,
        )

        # Make the rest of the assignments
        self.heading1 = "# BTN for MT3DMS, generated by Flopy."
        self.heading2 = "#"
        self.MFStyleArr = MFStyleArr
        if self.MFStyleArr:
            model.free_format = True
            model.array_format = None
        self.DRYCell = DRYCell
        self.Legacy99Stor = Legacy99Stor
        self.FTLPrint = FTLPrint
        self.NoWetDryPrint = NoWetDryPrint
        self.OmitDryBud = OmitDryBud
        self.AltWTSorb = AltWTSorb
        self.ncomp = ncomp
        self.mcomp = mcomp
        self.tunit = tunit
        self.lunit = lunit
        self.munit = munit
        self.cinact = cinact
        self.thkmin = thkmin
        self.ifmtcn = ifmtcn
        self.ifmtnp = ifmtnp
        self.ifmtrf = ifmtrf
        self.ifmtdp = ifmtdp
        self.savucn = savucn
        self.nprs = nprs
        self.timprs = timprs
        if obs is not None:
            if isinstance(obs, list):
                obs = np.array(obs)
            if obs.ndim != 2:
                raise Exception(
                    "obs must be (or be convertible to) a 2d array"
                )
        self.obs = obs
        self.nprobs = nprobs
        self.chkmas = chkmas
        self.nprmas = nprmas
        if species_names is None:
            species_names = []
        self.species_names = species_names
        self.prsity = Util3d(
            model,
            (self.nlay, self.nrow, self.ncol),
            np.float32,
            prsity,
            name="prsity",
            locat=self.unit_number[0],
            array_free_format=False,
        )
        self.icbund = Util3d(
            model,
            (self.nlay, self.nrow, self.ncol),
            np.int32,
            icbund,
            name="icbund",
            locat=self.unit_number[0],
            array_free_format=False,
        )
        self.ssflag = ssflag
        self.dt0 = Util2d(
            model,
            (self.nper,),
            np.float32,
            dt0,
            name="dt0",
            array_free_format=False,
        )
        self.mxstrn = Util2d(
            model, (self.nper,), np.int32, mxstrn, name="mxstrn"
        )
        self.ttsmult = Util2d(
            model, (self.nper,), np.float32, ttsmult, name="ttmult"
        )
        self.ttsmax = Util2d(
            model, (self.nper,), np.float32, ttsmax, name="ttsmax"
        )

        # Do some fancy stuff for multi-species concentrations
        self.sconc = []
        u3d = Util3d(
            model,
            (self.nlay, self.nrow, self.ncol),
            np.float32,
            sconc,
            name="sconc1",
            locat=self.unit_number[0],
            array_free_format=False,
        )
        self.sconc.append(u3d)
        if ncomp > 1:
            for icomp in range(2, ncomp + 1):
                name = f"sconc{icomp}"
                val = 0.0
                if name in kwargs:
                    val = kwargs.pop(name)
                else:
                    print(
                        f"BTN: setting sconc for component {icomp} "
                        f"to zero, kwarg name {name}"
                    )
                u3d = Util3d(
                    model,
                    (self.nlay, self.nrow, self.ncol),
                    np.float32,
                    val,
                    name=name,
                    locat=self.unit_number[0],
                    array_free_format=False,
                )
                self.sconc.append(u3d)

        # Check to make sure that all kwargs have been consumed
        if len(list(kwargs.keys())) > 0:
            raise Exception(
                f"BTN error: unrecognized kwargs: {' '.join(list(kwargs.keys()))}"
            )

        # Finally add self to parent's package list and return
        self.parent.add_package(self)
        return

    def setmodflowvars(
        self,
        nlay,
        nrow,
        ncol,
        nper,
        laycon,
        delr,
        delc,
        htop,
        dz,
        perlen,
        nstp,
        tsmult,
    ):
        """
        Set these variables from the MODFLOW model, if it exists

        """
        # Members that may come from a modflow model (model.mf)
        validmfdis = True
        try:
            dum = self.parent.mf.dis.nlay
            mf = self.parent.mf
        except:
            validmfdis = False

        mfvarlist = [
            nlay,
            nrow,
            ncol,
            nper,
            laycon,
            delr,
            delc,
            htop,
            dz,
            perlen,
            nstp,
            tsmult,
        ]
        if not validmfdis:
            for v in mfvarlist:
                s = "BTN error. Required input is None, but no modflow model."
                s += " If no modflow model is passed to Mt3dms, then values "
                s += "must be specified in the BTN constructor for: "
                s += "nlay, nrow, ncol, nper, laycon, delr, delc, htop, dz, "
                s += "perlen, nstp, and tsmult."
                if v is None:
                    raise Exception(s)

        if nlay is not None:
            self.nlay = nlay
        else:
            self.nlay = mf.dis.nlay

        if nrow is not None:
            self.nrow = nrow
        else:
            self.nrow = mf.dis.nrow

        if ncol is not None:
            self.ncol = ncol
        else:
            self.ncol = mf.dis.ncol

        if nper is not None:
            self.nper = nper
        else:
            self.nper = mf.dis.nper

        nlay = self.nlay
        nrow = self.nrow
        ncol = self.ncol
        nper = self.nper

        if delr is not None:
            self.delr = Util2d(
                self.parent,
                (ncol,),
                np.float32,
                delr,
                name="delr",
                locat=self.unit_number[0],
                array_free_format=False,
            )
        else:
            self.delr = Util2d(
                self.parent,
                (ncol,),
                np.float32,
                mf.dis.delr.get_value(),
                name="delr",
                locat=self.unit_number[0],
                array_free_format=False,
            )

        if delc is not None:
            self.delc = Util2d(
                self.parent,
                (nrow,),
                np.float32,
                delc,
                name="delc",
                locat=self.unit_number[0],
            )
        else:
            self.delc = Util2d(
                self.parent,
                (nrow,),
                np.float32,
                mf.dis.delc.get_value(),
                name="delc",
                locat=self.unit_number[0],
                array_free_format=False,
            )

        if htop is not None:
            self.htop = Util2d(
                self.parent,
                (nrow, ncol),
                np.float32,
                htop,
                name="htop",
                locat=self.unit_number[0],
                array_free_format=False,
            )
        else:
            self.htop = Util2d(
                self.parent,
                (nrow, ncol),
                np.float32,
                mf.dis.top.get_value(),
                name="htop",
                locat=self.unit_number[0],
                array_free_format=False,
            )

        if dz is not None:
            self.dz = Util3d(
                self.parent,
                (nlay, nrow, ncol),
                np.float32,
                dz,
                name="dz",
                locat=self.unit_number[0],
                array_free_format=False,
            )
        else:
            thickness = mf.modelgrid.thick
            self.dz = Util3d(
                self.parent,
                (nlay, nrow, ncol),
                np.float32,
                thickness,
                name="dz",
                locat=self.unit_number[0],
                array_free_format=False,
            )

        if perlen is not None:
            self.perlen = Util2d(
                self.parent,
                (nper,),
                np.float32,
                perlen,
                name="perlen",
                locat=self.unit_number[0],
            )
        else:
            self.perlen = Util2d(
                self.parent,
                (nper,),
                np.float32,
                mf.dis.perlen.get_value(),
                name="perlen",
                locat=self.unit_number[0],
            )

        if nstp is not None:
            self.nstp = Util2d(
                self.parent,
                (nper,),
                np.int32,
                nstp,
                name="nstp",
                locat=self.unit_number[0],
            )
        else:
            self.nstp = Util2d(
                self.parent,
                (nper,),
                np.int32,
                mf.dis.nstp.get_value(),
                name="nstp",
                locat=self.unit_number[0],
            )

        if tsmult is not None:
            self.tsmult = Util2d(
                self.parent,
                (nper,),
                np.float32,
                tsmult,
                name="tsmult",
                locat=self.unit_number[0],
            )
        else:
            self.tsmult = Util2d(
                self.parent,
                (nper,),
                np.float32,
                mf.dis.tsmult.get_value(),
                name="tsmult",
                locat=self.unit_number[0],
            )

        self.laycon = None
        if laycon is not None:
            self.laycon = Util2d(
                self.parent,
                (nlay,),
                np.int32,
                laycon,
                name="laycon",
                locat=self.unit_number[0],
            )
        else:
            flow_package = mf.get_package("BCF6")
            if flow_package is not None:
                self.laycon = Util2d(
                    self.parent,
                    (nlay,),
                    np.int32,
                    flow_package.laycon.get_value(),
                    name="laycon",
                    locat=self.unit_number[0],
                )
            else:
                flow_package = mf.get_package("LPF")
                if flow_package is not None:
                    self.laycon = Util2d(
                        self.parent,
                        (nlay,),
                        np.int32,
                        flow_package.laytyp.get_value(),
                        name="laycon",
                        locat=self.unit_number[0],
                    )
                flow_package = mf.get_package("UPW")
                if flow_package is not None:
                    self.laycon = Util2d(
                        self.parent,
                        (nlay,),
                        np.int32,
                        flow_package.laytyp.get_value(),
                        name="laycon",
                        locat=self.unit_number[0],
                    )

        s = "BTN warning. Laycon has not been set.  A modflow model with a "
        s += " BCF or LPF package does not exist and laycon was not passed "
        s += " to the BTN constructor.  Setting laycon to 1 (convertible)."
        if self.laycon is None:
            warnings.warn(s)
            self.laycon = Util2d(
                self.parent,
                (nlay,),
                np.int32,
                1,
                name="laycon",
                locat=self.unit_number[0],
            )
        return

    def write_file(self):
        """
        Write the package file

        Returns
        -------
        None

        """
        # Open file for writing
        f_btn = open(self.fn_path, "w")

        # A1,2
        f_btn.write(f"#{self.heading1}\n#{self.heading2}\n")

        # A3; Keywords
        # Build a string of the active keywords
        str1 = ""
        if self.MFStyleArr:
            str1 += " MODFLOWSTYLEARRAYS"
        if self.DRYCell:
            str1 += " DRYCELL"
        if self.Legacy99Stor:
            str1 += " LEGACY99STORAGE"
        if self.FTLPrint:
            str1 += " FTLPRINT"
        if self.NoWetDryPrint:
            str1 += " NOWETDRYPRINT"
        if self.OmitDryBud:
            str1 += " OMITDRYCELLBUDGET"
        if self.AltWTSorb:
            str1 += " ALTWTSORB"

        if str1 != "":
            f_btn.write(str1 + "\n")

        # A3
        f_btn.write(
            "{0:10d}{1:10d}{2:10d}{3:10d}{4:10d}{5:10d}\n".format(
                self.nlay,
                self.nrow,
                self.ncol,
                self.nper,
                self.ncomp,
                self.mcomp,
            )
        )

        # A4
        f_btn.write(f"{self.tunit:4s}{self.lunit:4s}{self.munit:4s}\n")

        # A5
        if self.parent.adv != None:
            f_btn.write("{0:2s}".format("T"))
        else:
            f_btn.write("{0:2s}".format("F"))
        if self.parent.dsp != None:
            f_btn.write("{0:2s}".format("T"))
        else:
            f_btn.write("{0:2s}".format("F"))
        if self.parent.ssm != None:
            f_btn.write("{0:2s}".format("T"))
        else:
            f_btn.write("{0:2s}".format("F"))
        if self.parent.rct != None:
            f_btn.write("{0:2s}".format("T"))
        else:
            f_btn.write("{0:2s}".format("F"))
        if self.parent.gcg != None:
            f_btn.write("{0:2s}".format("T"))
        else:
            f_btn.write("{0:2s}".format("F"))
        f_btn.write("\n")

        # A6
        self.laycon.set_fmtin("(40I2)")
        f_btn.write(self.laycon.string)

        # A7
        f_btn.write(self.delr.get_file_entry())

        # A8
        f_btn.write(self.delc.get_file_entry())

        # A9
        f_btn.write(self.htop.get_file_entry())

        # A10
        f_btn.write(self.dz.get_file_entry())

        # A11
        f_btn.write(self.prsity.get_file_entry())

        # A12
        f_btn.write(self.icbund.get_file_entry())

        # A13
        # Starting concentrations
        for s in range(len(self.sconc)):
            f_btn.write(self.sconc[s].get_file_entry())

        # A14
        f_btn.write(f"{self.cinact:10.0E}{self.thkmin:10.2E}\n")

        # A15
        f_btn.write(
            f"{self.ifmtcn:10d}{self.ifmtnp:10d}{self.ifmtrf:10d}{self.ifmtdp:10d}"
        )
        if self.savucn == True:
            ss = "T"
        else:
            ss = "F"
        f_btn.write(f"{ss:>10s}\n")

        # A16, A17
        if self.timprs is None:
            f_btn.write(f"{self.nprs:10d}\n")
        else:
            f_btn.write(f"{len(self.timprs):10d}\n")
            timprs = Util2d(
                self.parent,
                (len(self.timprs),),
                np.float32,
                self.timprs,
                name="timprs",
                fmtin="(8G10.4)",
            )
            timprs.format.fortran = "(8G10.4)"
            f_btn.write(timprs.string)

        # A18, A19
        if self.obs is None:
            f_btn.write(f"{0:10d}{self.nprobs:10d}\n")
        else:
            nobs = self.obs.shape[0]
            f_btn.write(f"{nobs:10d}{self.nprobs:10d}\n")
            for i in range(nobs):
                f_btn.write(
                    "{0:10d}{1:10d}{2:10d}\n".format(
                        self.obs[i, 0] + 1,
                        self.obs[i, 1] + 1,
                        self.obs[i, 2] + 1,
                    )
                )

        # A20 CHKMAS, NPRMAS
        if self.chkmas == True:
            ss = "T"
        else:
            ss = "F"
        f_btn.write(f"{ss:>10s}{self.nprmas:10d}\n")

        # A21, 22, 23 PERLEN, NSTP, TSMULT
        for t in range(self.nper):
            s = f"{self.perlen[t]:10G}{self.nstp[t]:10d}{self.tsmult[t]:10G}"
            if self.ssflag is not None:
                s += " " + self.ssflag[t]
            s += "\n"
            f_btn.write(s)
            f_btn.write(
                "{0:10.4G}{1:10d}{2:10.4G}{3:10.4G}\n".format(
                    self.dt0[t],
                    self.mxstrn[t],
                    self.ttsmult[t],
                    self.ttsmax[t],
                )
            )
        f_btn.close()
        return

    @classmethod
    def load(cls, f, model, ext_unit_dict=None):
        """
        Load an existing package.

        Parameters
        ----------
        f : filename or file handle
            File to load.
        model : model object
            The model object (of type :class:`flopy.mt3d.mt.Mt3dms`) to
            which this package will be added.
        ext_unit_dict : dictionary, optional
            If the arrays in the file are specified using EXTERNAL,
            or older style array control records, then `f` should be a file
            handle.  In this case ext_unit_dict is required, which can be
            constructed using the function
            :class:`flopy.utils.mfreadnam.parsenamefile`.

        Returns
        -------
        btn :  Mt3dBtn object
            Mt3dBtn object.

        Examples
        --------

        >>> import flopy
        >>> mt = flopy.mt3d.Mt3dms()
        >>> btn = flopy.mt3d.Mt3dBtn.load('test.btn', mt)

        """
        openfile = not hasattr(f, "read")
        if openfile:
            filename = f
            f = open(filename, "r")

        # A1
        if model.verbose:
            print("   loading COMMENT LINES A1 AND A2...")
        line = f.readline()
        if model.verbose:
            print("A1: ".format(line.strip()))

        # A2
        line = f.readline()
        if model.verbose:
            print("A2: ".format(line.strip()))

        # New keyword options in MT3D-USGS are found here
        line = f.readline()
        m_arr = line.strip().split()

        # Set default values for the keywords
        MFStyleArr = False
        DRYCell = False
        Legacy99Stor = False
        FTLPrint = False
        NoWetDryPrint = False
        OmitDryBud = False
        AltWTSorb = False
        if (
            m_arr[0].strip().isdigit() is not True
        ):  # If m_arr[0] is not a digit, it is a keyword
            if model.verbose:
                print(f"   loading optional keywords: {line.strip()}")
            for i in range(0, len(m_arr)):
                if m_arr[i].upper() == "MODFLOWSTYLEARRAYS":
                    MFStyleArr = True
                    model.array_format = None
                    model.free_format = True
                if m_arr[i].upper() == "DRYCELL":
                    DRYCell = True
                if m_arr[i].upper() == "LEGACY99STORAGE":
                    Legacy99Stor = True
                if m_arr[i].upper() == "FTLPRINT":
                    FTLPrint = True
                if m_arr[i].upper() == "NOWETDRYPRINT":
                    NoWetDryPrint = True
                if m_arr[i].upper() == "OMITDRYCELLBUDGET":
                    OmitDryBud = True
                if m_arr[i].upper() == "ALTWTSORB":
                    AltWTSorb = True
        elif model.verbose:
            print("   optional keywords not identifed/loaded")

        # A3
        if model.verbose:
            print("   loading NLAY, NROW, NCOL, NPER, NCOMP, MCOMP...")
        if m_arr[0].isdigit() is False:
            line = f.readline()
        nlay = int(line[0:10])
        nrow = int(line[10:20])
        ncol = int(line[20:30])
        nper = int(line[30:40])
        try:
            ncomp = int(line[40:50])
        except:
            ncomp = 1
        try:
            mcomp = int(line[50:60])
        except:
            mcomp = 1
        if model.verbose:
            print(f"   NLAY {nlay}")
            print(f"   NROW {nrow}")
            print(f"   NCOL {ncol}")
            print(f"   NPER {nper}")
            print(f"   NCOMP {ncomp}")
            print(f"   MCOMP {mcomp}")

        if model.verbose:
            print("   loading TUNIT, LUNIT, MUNIT...")
        line = f.readline()
        tunit = line[0:4]
        lunit = line[4:8]
        munit = line[8:12]
        if model.verbose:
            print(f"   TUNIT {tunit}")
            print(f"   LUNIT {lunit}")
            print(f"   MUNIT {munit}")

        if model.verbose:
            print("   loading TRNOP...")
        trnop = f.readline()[:20].strip().split()
        if model.verbose:
            print(f"   TRNOP {trnop}")

        if model.verbose:
            print("   loading LAYCON...")
        laycon = Util2d.load_txt((nlay,), f, np.int32, "(40I2)")
        if model.verbose:
            print(f"   LAYCON {laycon}")

        if model.verbose:
            print("   loading DELR...")
        delr = Util2d.load(
            f,
            model,
            (ncol,),
            np.float32,
            "delr",
            ext_unit_dict,
            array_format="mt3d",
        )
        if model.verbose:
            print(f"   DELR {delr}")

        if model.verbose:
            print("   loading DELC...")
        delc = Util2d.load(
            f,
            model,
            (nrow,),
            np.float32,
            "delc",
            ext_unit_dict,
            array_format="mt3d",
        )
        if model.verbose:
            print(f"   DELC {delc}")

        if model.verbose:
            print("   loading HTOP...")
        htop = Util2d.load(
            f,
            model,
            (nrow, ncol),
            np.float32,
            "htop",
            ext_unit_dict,
            array_format="mt3d",
        )
        if model.verbose:
            print(f"   HTOP {htop}")

        if model.verbose:
            print("   loading DZ...")
        dz = Util3d.load(
            f,
            model,
            (nlay, nrow, ncol),
            np.float32,
            "dz",
            ext_unit_dict,
            array_format="mt3d",
        )
        if model.verbose:
            print(f"   DZ {dz}")

        if model.verbose:
            print("   loading PRSITY...")
        prsity = Util3d.load(
            f,
            model,
            (nlay, nrow, ncol),
            np.float32,
            "prsity",
            ext_unit_dict,
            array_format="mt3d",
        )
        if model.verbose:
            print(f"   PRSITY {prsity}")

        if model.verbose:
            print("   loading ICBUND...")
        icbund = Util3d.load(
            f,
            model,
            (nlay, nrow, ncol),
            np.int32,
            "icbund",
            ext_unit_dict,
            array_format="mt3d",
        )
        if model.verbose:
            print(f"   ICBUND {icbund}")

        if model.verbose:
            print("   loading SCONC...")
        kwargs = {}
        sconc = Util3d.load(
            f,
            model,
            (nlay, nrow, ncol),
            np.float32,
            "sconc1",
            ext_unit_dict,
            array_format="mt3d",
        )
        if ncomp > 1:
            for icomp in range(2, ncomp + 1):
                name = f"sconc{icomp}"
                if model.verbose:
                    print(f"   loading {name}...")
                u3d = Util3d.load(
                    f,
                    model,
                    (nlay, nrow, ncol),
                    np.float32,
                    name,
                    ext_unit_dict,
                    array_format="mt3d",
                )
                kwargs[name] = u3d
        if model.verbose:
            print(f"   SCONC {sconc}")

        if model.verbose:
            print("   loading CINACT, THCKMIN...")
        line = f.readline()
        cinact = float(line[0:10])
        try:
            thkmin = float(line[10:20])
        except:
            thkmin = 0.01
        if model.verbose:
            print(f"   CINACT {cinact}")
            print(f"   THKMIN {thkmin}")

        if model.verbose:
            print("   loading IFMTCN, IFMTNP, IFMTRF, IFMTDP, SAVUCN...")
        line = f.readline()
        ifmtcn = int(line[0:10])
        ifmtnp = int(line[10:20])
        ifmtrf = int(line[20:30])
        ifmtdp = int(line[30:40])
        savucn = False
        if "t" in line[40:50].lower():
            savucn = True
        if model.verbose:
            print(f"   IFMTCN {ifmtcn}")
            print(f"   IFMTNP {ifmtnp}")
            print(f"   IFMTRF {ifmtrf}")
            print(f"   IFMTDP {ifmtdp}")
            print(f"   SAVUCN {savucn}")

        if model.verbose:
            print("   loading NPRS...")
        line = f.readline()
        nprs = int(line[0:10])
        if model.verbose:
            print(f"   NPRS {nprs}")

        timprs = None
        if nprs > 0:
            if model.verbose:
                print("   loading TIMPRS...")
            timprs = Util2d.load_txt((nprs,), f, np.float32, "(8F10.0)")
            if model.verbose:
                print(f"   TIMPRS {timprs}")

        if model.verbose:
            print("   loading NOBS, NPROBS...")
        line = f.readline()
        nobs = int(line[0:10])
        try:
            nprobs = int(line[10:20])
        except:
            nprobs = 1
        if model.verbose:
            print(f"   NOBS {nobs}")
            print(f"   NPROBS {nprobs}")

        obs = None
        if nobs > 0:
            if model.verbose:
                print("   loading KOBS, IOBS, JOBS...")
            obs = []
            for l in range(nobs):
                line = f.readline()
                k = int(line[0:10])
                i = int(line[10:20])
                j = int(line[20:30])
                obs.append([k, i, j])
            obs = np.array(obs) - 1
            if model.verbose:
                print(f"   OBS {obs}")

        if model.verbose:
            print("   loading CHKMAS, NPRMAS...")
        line = f.readline()
        chkmas = False
        if "t" in line[0:10].lower():
            chkmas = True
        try:
            nprmas = int(line[10:20])
        except:
            nprmas = 1
        if model.verbose:
            print(f"   CHKMAS {chkmas}")
            print(f"   NPRMAS {nprmas}")

        if model.verbose:
            print(
                "   loading PERLEN, NSTP, TSMULT, TSLNGH, DT0, MXSTRN, TTSMULT, TTSMAX..."
            )
        dt0, mxstrn, ttsmult, ttsmax = [], [], [], []
        perlen = []
        nstp = []
        tsmult = []
        tslngh = []
        ssflag = []
        for kper in range(nper):
            line = f.readline()
            perlen.append(float(line[0:10]))
            nstp.append(int(line[10:20]))
            tsmult.append(float(line[20:30]))
            sf = " "
            ll = line[30:].strip().split()
            if len(ll) > 0:
                if "sstate" in ll[0].lower():
                    sf = "SState"
            ssflag.append(sf)

            if tsmult[-1] <= 0:
                t = Util2d.load_txt((nstp[-1],), f, np.float32, "(8F10.0)")
                tslngh.append(t)
                raise Exception("tsmult <= 0 not supported")

            line = f.readline()
            dt0.append(float(line[0:10]))
            mxstrn.append(int(line[10:20]))
            ttsmult.append(float(line[20:30]))
            ttsmax.append(float(line[30:40]))

        if model.verbose:
            print(f"   PERLEN {perlen}")
            print(f"   NSTP {nstp}")
            print(f"   TSMULT {tsmult}")
            print(f"   SSFLAG {ssflag}")
            print(f"   TSLNGH {tslngh}")
            print(f"   DT0 {dt0}")
            print(f"   MXSTRN {mxstrn}")
            print(f"   TTSMULT {ttsmult}")
            print(f"   TTSMAX {ttsmax}")

        if openfile:
            f.close()

        # set package unit number
        unitnumber = None
        filenames = [None]
        if ext_unit_dict is not None:
            unitnumber, filenames[0] = model.get_ext_dict_attr(
                ext_unit_dict, filetype=Mt3dBtn._ftype()
            )

        return cls(
            model,
            MFStyleArr=MFStyleArr,
            DRYCell=DRYCell,
            Legacy99Stor=Legacy99Stor,
            FTLPrint=FTLPrint,
            NoWetDryPrint=NoWetDryPrint,
            OmitDryBud=OmitDryBud,
            AltWTSorb=AltWTSorb,
            nlay=nlay,
            nrow=nrow,
            ncol=ncol,
            nper=nper,
            ncomp=ncomp,
            mcomp=mcomp,
            tunit=tunit,
            laycon=laycon,
            delr=delr,
            delc=delc,
            htop=htop,
            dz=dz,
            lunit=lunit,
            munit=munit,
            prsity=prsity,
            icbund=icbund,
            sconc=sconc,
            cinact=cinact,
            thkmin=thkmin,
            ifmtcn=ifmtcn,
            ifmtnp=ifmtnp,
            ifmtrf=ifmtrf,
            ifmtdp=ifmtdp,
            savucn=savucn,
            nprs=nprs,
            timprs=timprs,
            obs=obs,
            nprobs=nprobs,
            chkmas=chkmas,
            nprmas=nprmas,
            perlen=perlen,
            nstp=nstp,
            tsmult=tsmult,
            ssflag=ssflag,
            dt0=dt0,
            mxstrn=mxstrn,
            ttsmult=ttsmult,
            ttsmax=ttsmax,
            unitnumber=unitnumber,
            filenames=filenames,
            **kwargs,
        )

    @staticmethod
    def _ftype():
        return "BTN"

    @staticmethod
    def _defaultunit():
        return 31

    @staticmethod
    def _reservedunit():
        return 1
