# Authors: The MNE-Python contributors.
# License: BSD-3-Clause
# Copyright the MNE-Python contributors.

import csv
import os.path as op
from collections import OrderedDict
from functools import partial

import numpy as np

from .._freesurfer import get_mni_fiducials
from ..transforms import _sph_to_cart
from ..utils import _pl, _soft_import, warn
from . import __file__ as _CHANNELS_INIT_FILE
from .montage import make_dig_montage

MONTAGE_PATH = op.join(op.dirname(_CHANNELS_INIT_FILE), "data", "montages")

_str = "U100"


# In standard_1020, T9=LPA, T10=RPA, Nasion is the same as Iz with a
# sign-flipped Y value


def _egi_256(head_size):
    fname = op.join(MONTAGE_PATH, "EGI_256.csd")
    montage = _read_csd(fname, head_size)
    ch_pos = montage._get_ch_pos()

    # For this cap, the Nasion is the frontmost electrode,
    # LPA/RPA we approximate by putting 75% of the way (toward the front)
    # between the two electrodes that are halfway down the ear holes
    nasion = ch_pos["E31"]
    lpa = 0.75 * ch_pos["E67"] + 0.25 * ch_pos["E94"]
    rpa = 0.75 * ch_pos["E219"] + 0.25 * ch_pos["E190"]

    fids_montage = make_dig_montage(
        coord_frame="unknown",
        nasion=nasion,
        lpa=lpa,
        rpa=rpa,
    )

    montage += fids_montage  # add fiducials to montage

    return montage


def _easycap(basename, head_size):
    fname = op.join(MONTAGE_PATH, basename)
    montage = _read_theta_phi_in_degrees(fname, head_size, add_fiducials=True)
    return montage


def _hydrocel(basename, head_size):
    fname = op.join(MONTAGE_PATH, basename)
    return _read_sfp(fname, head_size)


def _str_names(ch_names):
    return [str(ch_name) for ch_name in ch_names]


def _safe_np_loadtxt(fname, **kwargs):
    out = np.genfromtxt(fname, **kwargs)
    ch_names = _str_names(out["f0"])
    others = tuple(out[f"f{ii}"] for ii in range(1, len(out.dtype.fields)))
    return (ch_names,) + others


def _biosemi(basename, head_size):
    fname = op.join(MONTAGE_PATH, basename)
    fid_names = ("Nz", "LPA", "RPA")
    return _read_theta_phi_in_degrees(fname, head_size, fid_names)


def _mgh_or_standard(basename, head_size, coord_frame="unknown"):
    fid_names = ("Nz", "LPA", "RPA")
    fname = op.join(MONTAGE_PATH, basename)

    ch_names_, pos = [], []
    with open(fname) as fid:
        # Ignore units as we will scale later using the norms anyway
        for line in fid:
            if "Positions\n" in line:
                break
        pos = []
        for line in fid:
            if "Labels\n" in line:
                break
            pos.append(list(map(float, line.split())))
        for line in fid:
            if not line or not set(line) - {" "}:
                break
            ch_names_.append(line.strip(" ").strip("\n"))

    pos = np.array(pos) / 1000.0
    ch_pos = _check_dupes_odict(ch_names_, pos)
    nasion, lpa, rpa = (ch_pos.pop(n) for n in fid_names)
    if head_size is None:
        scale = 1.0
    else:
        scale = head_size / np.median(np.linalg.norm(pos, axis=1))
    for value in ch_pos.values():
        value *= scale
    # if we are in MRI/MNI coordinates, we need to replace nasion, LPA, and RPA
    # with those of fsaverage for ``trans='fsaverage'`` to work
    if coord_frame == "mri":
        lpa, nasion, rpa = (x["r"].copy() for x in get_mni_fiducials("fsaverage"))
    nasion *= scale
    lpa *= scale
    rpa *= scale

    return make_dig_montage(
        ch_pos=ch_pos, coord_frame=coord_frame, nasion=nasion, lpa=lpa, rpa=rpa
    )


standard_montage_look_up_table = {
    "EGI_256": _egi_256,
    "easycap-M1": partial(_easycap, basename="easycap-M1.txt"),
    "easycap-M10": partial(_easycap, basename="easycap-M10.txt"),
    "easycap-M43": partial(_easycap, basename="easycap-M43.txt"),
    "GSN-HydroCel-128": partial(_hydrocel, basename="GSN-HydroCel-128.sfp"),
    "GSN-HydroCel-129": partial(_hydrocel, basename="GSN-HydroCel-129.sfp"),
    "GSN-HydroCel-256": partial(_hydrocel, basename="GSN-HydroCel-256.sfp"),
    "GSN-HydroCel-257": partial(_hydrocel, basename="GSN-HydroCel-257.sfp"),
    "GSN-HydroCel-32": partial(_hydrocel, basename="GSN-HydroCel-32.sfp"),
    "GSN-HydroCel-64_1.0": partial(_hydrocel, basename="GSN-HydroCel-64_1.0.sfp"),
    "GSN-HydroCel-65_1.0": partial(_hydrocel, basename="GSN-HydroCel-65_1.0.sfp"),
    "biosemi128": partial(_biosemi, basename="biosemi128.txt"),
    "biosemi16": partial(_biosemi, basename="biosemi16.txt"),
    "biosemi160": partial(_biosemi, basename="biosemi160.txt"),
    "biosemi256": partial(_biosemi, basename="biosemi256.txt"),
    "biosemi32": partial(_biosemi, basename="biosemi32.txt"),
    "biosemi64": partial(_biosemi, basename="biosemi64.txt"),
    "mgh60": partial(_mgh_or_standard, basename="mgh60.elc", coord_frame="mri"),
    "mgh70": partial(_mgh_or_standard, basename="mgh70.elc", coord_frame="mri"),
    "standard_1005": partial(
        _mgh_or_standard, basename="standard_1005.elc", coord_frame="mri"
    ),
    "standard_1020": partial(
        _mgh_or_standard, basename="standard_1020.elc", coord_frame="mri"
    ),
    "standard_alphabetic": partial(
        _mgh_or_standard, basename="standard_alphabetic.elc", coord_frame="mri"
    ),
    "standard_postfixed": partial(
        _mgh_or_standard, basename="standard_postfixed.elc", coord_frame="mri"
    ),
    "standard_prefixed": partial(
        _mgh_or_standard, basename="standard_prefixed.elc", coord_frame="mri"
    ),
    "standard_primed": partial(
        _mgh_or_standard, basename="standard_primed.elc", coord_frame="mri"
    ),
    "artinis-octamon": partial(
        _mgh_or_standard, coord_frame="mri", basename="artinis-octamon.elc"
    ),
    "artinis-brite23": partial(
        _mgh_or_standard, coord_frame="mri", basename="artinis-brite23.elc"
    ),
    "brainproducts-RNP-BA-128": partial(
        _easycap, basename="brainproducts-RNP-BA-128.txt"
    ),
}


def _read_sfp(fname, head_size):
    """Read .sfp BESA/EGI files."""
    # fname has been already checked
    fid_names = ("FidNz", "FidT9", "FidT10")
    options = dict(dtype=(_str, "f4", "f4", "f4"))
    ch_names, xs, ys, zs = _safe_np_loadtxt(fname, **options)
    # deal with "headshape"
    mask = np.array([ch_name == "headshape" for ch_name in ch_names], bool)
    hsp = np.stack([xs[mask], ys[mask], zs[mask]], axis=-1)
    mask = ~mask
    pos = np.stack([xs[mask], ys[mask], zs[mask]], axis=-1)
    ch_names = [ch_name for ch_name, m in zip(ch_names, mask) if m]
    ch_pos = _check_dupes_odict(ch_names, pos)
    del xs, ys, zs, ch_names
    # no one grants that fid names are there.
    nasion, lpa, rpa = (ch_pos.pop(n, None) for n in fid_names)

    if head_size is not None:
        scale = head_size / np.median(np.linalg.norm(pos, axis=-1))
        for value in ch_pos.values():
            value *= scale
        nasion = nasion * scale if nasion is not None else None
        lpa = lpa * scale if lpa is not None else None
        rpa = rpa * scale if rpa is not None else None

    return make_dig_montage(
        ch_pos=ch_pos, coord_frame="unknown", nasion=nasion, rpa=rpa, lpa=lpa, hsp=hsp
    )


def _read_csd(fname, head_size):
    # Label, Theta, Phi, Radius, X, Y, Z, off sphere surface
    options = dict(
        comments="//", dtype=(_str, "f4", "f4", "f4", "f4", "f4", "f4", "f4")
    )
    ch_names, _, _, _, xs, ys, zs, _ = _safe_np_loadtxt(fname, **options)
    pos = np.stack([xs, ys, zs], axis=-1)

    if head_size is not None:
        pos *= head_size / np.median(np.linalg.norm(pos, axis=1))

    return make_dig_montage(ch_pos=_check_dupes_odict(ch_names, pos))


def _check_dupes_odict(ch_names, pos):
    """Warn if there are duplicates, then turn to ordered dict."""
    ch_names = list(ch_names)
    dups = OrderedDict((ch_name, ch_names.count(ch_name)) for ch_name in ch_names)
    dups = OrderedDict((ch_name, count) for ch_name, count in dups.items() if count > 1)
    n = len(dups)
    if n:
        dups = ", ".join(f"{ch_name} ({count})" for ch_name, count in dups.items())
        warn(
            f"Duplicate channel position{_pl(n)} found, the last will be "
            f"used for {dups}"
        )
    return OrderedDict(zip(ch_names, pos))


def _read_elc(fname, head_size):
    """Read .elc files.

    Parameters
    ----------
    fname : str
        File extension is expected to be '.elc'.
    head_size : float | None
        The size of the head in [m]. If none, returns the values read from the
        file with no modification.

    Returns
    -------
    montage : instance of DigMontage
        The montage in [m].
    """
    fid_names = ("Nz", "LPA", "RPA")

    ch_names_, pos = [], []
    with open(fname) as fid:
        # _read_elc does require to detect the units. (see _mgh_or_standard)
        for line in fid:
            if "UnitPosition" in line:
                units = line.split()[1]
                scale = dict(m=1.0, mm=1e-3)[units]
                break
        else:
            raise RuntimeError(f"Could not detect units in file {fname}")
        for line in fid:
            if "Positions\n" in line:
                break
        pos = []
        for line in fid:
            if "Labels\n" in line:
                break
            pos.append(list(map(float, line.split())))
        for line in fid:
            if not line or not set(line) - {" "}:
                break
            ch_names_.append(line.strip(" ").strip("\n"))

    pos = np.array(pos) * scale
    if head_size is not None:
        pos *= head_size / np.median(np.linalg.norm(pos, axis=1))

    ch_pos = _check_dupes_odict(ch_names_, pos)
    nasion, lpa, rpa = (ch_pos.pop(n, None) for n in fid_names)

    return make_dig_montage(
        ch_pos=ch_pos, coord_frame="unknown", nasion=nasion, lpa=lpa, rpa=rpa
    )


def _read_theta_phi_in_degrees(fname, head_size, fid_names=None, add_fiducials=False):
    ch_names, theta, phi = _safe_np_loadtxt(
        fname, skip_header=1, dtype=(_str, "i4", "i4")
    )
    if add_fiducials:
        # Add fiducials based on 10/20 spherical coordinate definitions
        # http://chgd.umich.edu/wp-content/uploads/2014/06/
        # 10-20_system_positioning.pdf
        # extrapolated from other sensor coordinates in the Easycap layouts
        # https://www.easycap.de/wp-content/uploads/2018/02/
        # Easycap-Equidistant-Layouts.pdf
        assert fid_names is None
        fid_names = ["Nasion", "LPA", "RPA"]
        ch_names.extend(fid_names)
        theta = np.append(theta, [115, -115, 115])
        phi = np.append(phi, [90, 0, 0])

    radii = np.full(len(phi), head_size)
    pos = _sph_to_cart(np.array([radii, np.deg2rad(phi), np.deg2rad(theta)]).T)
    ch_pos = _check_dupes_odict(ch_names, pos)

    nasion, lpa, rpa = None, None, None
    if fid_names is not None:
        nasion, lpa, rpa = (ch_pos.pop(n, None) for n in fid_names)

    return make_dig_montage(
        ch_pos=ch_pos, coord_frame="unknown", nasion=nasion, lpa=lpa, rpa=rpa
    )


def _read_elp_besa(fname, head_size):
    # This .elp is not the same as polhemus elp. see _read_isotrak_elp_points
    dtype = np.dtype("S8, S8, f8, f8, f8")
    data = np.loadtxt(fname, dtype=dtype)

    ch_names = data["f1"].astype(str).tolist()
    az = data["f2"]
    horiz = data["f3"]
    radius = np.abs(az / 180.0)
    az = np.deg2rad(np.array([h if a >= 0.0 else 180 + h for h, a in zip(horiz, az)]))
    pol = radius * np.pi
    rad = data["f4"] / 100
    pos = _sph_to_cart(np.array([rad, az, pol]).T)

    if head_size is not None:
        pos *= head_size / np.median(np.linalg.norm(pos, axis=1))

    ch_pos = _check_dupes_odict(ch_names, pos)

    fid_names = ("Nz", "LPA", "RPA")
    # No one grants that the fid names actually exist.
    nasion, lpa, rpa = (ch_pos.pop(n, None) for n in fid_names)

    return make_dig_montage(ch_pos=ch_pos, nasion=nasion, lpa=lpa, rpa=rpa)


def _read_brainvision(fname, head_size):
    # 'BrainVision Electrodes File' format
    # Based on BrainVision Analyzer coordinate system: Defined between
    # standard electrode positions: X-axis from T7 to T8, Y-axis from Oz to
    # Fpz, Z-axis orthogonal from XY-plane through Cz, fit to a sphere if
    # idealized (when radius=1), specified in millimeters
    defusedxml = _soft_import("defusedxml", "reading BrainVision montages")
    root = defusedxml.ElementTree.parse(fname).getroot()
    ch_names = [s.text for s in root.findall("./Electrode/Name")]
    theta = [float(s.text) for s in root.findall("./Electrode/Theta")]
    pol = np.deg2rad(np.array(theta))
    phi = [float(s.text) for s in root.findall("./Electrode/Phi")]
    az = np.deg2rad(np.array(phi))
    rad = [float(s.text) for s in root.findall("./Electrode/Radius")]
    rad = np.array(rad)  # specified in mm
    pos = _sph_to_cart(np.array([rad, az, pol]).T)

    if head_size is not None:
        pos *= head_size / np.median(np.linalg.norm(pos, axis=1))

    return make_dig_montage(ch_pos=_check_dupes_odict(ch_names, pos))


def _read_xyz(fname):
    """Import EEG channel locations from CSV, TSV, or XYZ files.

    CSV and TSV files should have columns 4 columns containing
    ch_name, x, y, and z. Each row represents one channel.
    XYZ files should have 5 columns containing
    count, x, y, z, and ch_name. Each row represents one channel
    CSV files should be separated by commas, TSV and XYZ files should be
    separated by tabs.

    Parameters
    ----------
    fname : str
        Name of the file to read channel locations from.

    Returns
    -------
    montage : instance of DigMontage
        The montage.
    """
    ch_names = []
    pos = []
    file_format = op.splitext(fname)[1].lower()
    with open(fname) as f:
        if file_format != ".xyz":
            f.readline()  # skip header
        delimiter = "," if file_format == ".csv" else "\t"
        for row in csv.reader(f, delimiter=delimiter):
            if file_format == ".xyz":
                _, x, y, z, ch_name, *_ = row
                ch_name = ch_name.strip()  # deals with variable tab size
            else:
                ch_name, x, y, z, *_ = row
            ch_names.append(ch_name)
            pos.append((x, y, z))
    d = _check_dupes_odict(ch_names, np.array(pos, dtype=float))
    return make_dig_montage(ch_pos=d)
