r"""Utility functions that are used across modules for colors.

Public utility functions should be added to documentation in the '/docs/_templates/overrides/tropycal.utils.rst' file."""

import numpy as np
import matplotlib.colors as mcolors
import matplotlib as mlib
import warnings

from .generic_utils import *
from .._compat import get_cmap as _get_cmap

# ===========================================================================================================
# Public utilities
# These are used internally and have use externally. Add these to documentation.
# ===========================================================================================================


def get_colors_sshws(wind_speed):
    r"""
    Retrieve the default colors for the Saffir-Simpson Hurricane Wind Scale (SSHWS).

    Parameters
    ----------
    wind_speed : int or list
        Sustained wind speed in knots.

    Returns
    -------
    str
        Hex string for the corresponding color.
    """

    # If category string passed, convert to wind
    if isinstance(wind_speed, str):
        wind_speed = category_label_to_wind(wind_speed)

    # Return default SSHWS category color scale
    if wind_speed < 5:
        return '#FFFFFF'
    elif wind_speed < 34:
        return '#8FC2F2'  # '#7DB7ED'
    elif wind_speed < 64:
        return '#3185D3'
    elif wind_speed < 83:
        return '#FFFF00'
    elif wind_speed < 96:
        return '#FF9E00'
    elif wind_speed < 113:
        return '#DD0000'
    elif wind_speed < 137:
        return '#FF00FC'
    else:
        return '#8B0088'


def get_colors_sshws_recon(wind_speed):
    r"""
    Retrieve modified colors for the Saffir-Simpson Hurricane Wind Scale (SSHWS).

    Parameters
    ----------
    wind_speed : int or list
        Sustained wind speed in knots.

    Returns
    -------
    str
        Hex string for the corresponding color.

    Notes
    -----
    These are the same colors as the default SSHWS colors, but include a special 50-64 knot category.
    """

    # If category string passed, convert to wind
    if isinstance(wind_speed, str):
        wind_speed = category_label_to_wind(wind_speed)

    # Return default SSHWS category color scale
    if wind_speed < 5:
        return '#FFFFFF'
    elif wind_speed < 34:
        return '#8FC2F2'
    elif wind_speed < 50:
        return '#3185D3'
    elif wind_speed < 64:
        return '#05539b'
    elif wind_speed < 83:
        return '#FFFF00'
    elif wind_speed < 96:
        return '#FF9E00'
    elif wind_speed < 113:
        return '#DD0000'
    elif wind_speed < 137:
        return '#FF00FC'
    else:
        return '#8B0088'


def make_colormap(colors, whiten=0):

    z = np.array(sorted(colors.keys()))
    n = len(z)
    z1 = min(z)
    zn = max(z)
    x0 = (z - z1) / (zn - z1)

    CC = mcolors.ColorConverter()
    R = []
    G = []
    B = []
    for i in range(n):
        Ci = colors[z[i]]
        if type(Ci) == str:
            RGB = CC.to_rgb(Ci)
        else:
            RGB = Ci
        R.append(RGB[0] + (1-RGB[0])*whiten)
        G.append(RGB[1] + (1-RGB[1])*whiten)
        B.append(RGB[2] + (1-RGB[2])*whiten)

    cmap_dict = {}
    cmap_dict['red'] = [(x0[i], R[i], R[i]) for i in range(len(R))]
    cmap_dict['green'] = [(x0[i], G[i], G[i]) for i in range(len(G))]
    cmap_dict['blue'] = [(x0[i], B[i], B[i]) for i in range(len(B))]
    mymap = mcolors.LinearSegmentedColormap('mymap', cmap_dict)

    return mymap


def get_colors_ef(colormap='default'):
    r"""
    Retrieve a list of colors for the Enhanced Fujita (EF) tornado scale.

    Parameters
    ----------
    colormap : str or list
        Matplotlib colormap to use. Default is 'default', which uses Tropycal's default colors for the EF scale. If a list, this list must have 6 colors in order from EF0 to EF5.

    Returns
    -------
    list or cmap
        If used a matplotlib colormap, a cmap is returned, otherwise a list of colors is returned.
    """

    # Matplotlib colormap
    if isinstance(colormap, str) and colormap != 'default':
        try:
            cmap = _get_cmap(colormap)
            norm = mlib.colors.Normalize(vmin=0, vmax=5)
            colors = cmap(norm([0, 1, 2, 3, 4, 5]))
        except:
            # colors = [colormap]*6
            raise ValueError('Colormap not found.')

    # User-passed list of colors
    elif isinstance(colormap, list):
        if len(colormap) == 6:
            colors = colormap
        else:
            raise ValueError(
                'Must pass a list of 6 colors to correspond from EF0 to EF5.')

    # Otherwise, return default colors
    else:
        colors = ['lightsalmon', 'tomato', 'red',
                  'firebrick', 'darkred', 'purple']

    # Return list of colors, or colormap
    return colors


def get_colors_pph(plot_type, colormap, levels=None):
    r"""
    Retrieve a list of colors for Practically Perfect Hindcast (PPH) for tornadoes.

    Parameters
    ----------
    plot_type : str
        Plot type for PPH. Can be "daily" for single-day PPH, or "total" for multi-day PPH.
    colormap : str or list
        Matplotlib colormap to use. Default is 'spc', which uses Tropycal's default colors for the EF scale. If a list, this list must have 6 colors in order from EF0 to EF5.
    levels : list
        List of contour levels. Default is SPC intervals.

    Returns
    -------
    colors : list or cmap
        If used a matplotlib colormap, a cmap is returned, otherwise a list of colors is returned.
    levels : list
        List of contour levels.
    """

    # Insert default levels if none specified
    if levels is None:
        levels = [2, 5, 10, 15, 30, 45, 60, 100]

    # Default SPC colormap
    if colormap == 'spc':

        # Daily plot type
        if plot_type == 'daily':
            levels = [2, 5, 10, 15, 30, 45, 60, 100]
            colors = ['#008B00', '#8B4726', '#FFC800',
                      '#FF0000', '#FF00FF', '#912CEE', '#104E8B']

        # Multi-day plot type
        else:
            warnings.warn('SPC colors only allowed for daily PPH.\n' +
                          'Defaulting to plasma colormap.')
            colormap = 'plasma'

    # User-defined colormap
    if colormap != 'spc':

        # Matplotlib colormap
        if isinstance(colormap, str):
            cmap = _get_cmap(colormap)
            norm = mlib.colors.Normalize(vmin=0, vmax=len(levels)-2)
            colors = cmap(norm(np.arange(len(levels))))

        # User defined list of colors
        elif isinstance(colormap, list):
            colors = colormap

        # If a cmap is passed
        else:
            norm = mlib.colors.Normalize(vmin=0, vmax=len(levels)-2)
            colors = colormap(norm(np.arange(len(levels))))

    # Return colormap and values
    return colors, levels

# ===========================================================================================================
# Private utilities
# These are primarily intended to be used internally. Do not add these to documentation.
# ===========================================================================================================


def rgb_tuple_to_str(rgb_tuple):
    r"""
    Convert an RGB tuple to hex string.

    Parameters
    ----------
    rgb_tuple : tuple
        Tuple ordered in (r,g,b) containing integers from 0 to 255.

    Returns
    -------
    str
        Hex string for RGB value.
    """

    r, g, b = rgb_tuple
    r = int(r)
    g = int(g)
    b = int(b)
    return '#%02x%02x%02x' % (r, g, b)


def get_cmap_levels(varname, colormap, levels, linear=False):
    r"""
    Retrieve a list of colors for Practically Perfect Hindcast (PPH) for tornadoes.

    Parameters
    ----------
    varname : str
        if 'vmax', 'sfmr', or 'fl_to_sfc', then SSHWS category colors can be used.
    colormap : str or list
        Matplotlib colormap to use. Default is 'category', which uses Tropycal's default colors for the SSHWS scale. If a list, a colormap is generated from this list.
    levels : list
        List of contour levels. Default is SPC intervals.
    linear : bool
        If colormap is 'category', determine whether to generate a colorbar using linear category increments (True) or wind increments (False).

    Returns
    -------
    colors : cmap
        Matplotlib colormap object.
    levels : list
        List of contour levels.
    """

    # Default SSHWS colormap
    if colormap in ['category', 'category_recon']:

        # Ensure variable contains some element of surface wind
        if varname in ['vmax', 'sfmr', 'wspd', 'pkwnd', 'fl_to_sfc']:

            # Generate contour levels
            levels = [category_to_wind(c) for c in range(-1, 6)]+[200]

            # Linear category increments
            if linear:
                colors = [mcolors.to_rgba(get_colors_sshws(lev))
                          for c, lev in enumerate(levels[:-1]) for _ in range(levels[c+1]-levels[c])]

            # Linear wind increments
            else:
                if colormap == 'category':
                    levels = [category_to_wind(c) for c in range(-1, 6)]+[200]
                    colors = [get_colors_sshws(lev) for lev in levels[:-1]]
                else:
                    levels = [category_to_wind(
                        c) for c in range(-1, 1)]+[50]+[category_to_wind(c) for c in range(1, 6)]+[200]
                    colors = [get_colors_sshws_recon(lev) for lev in levels[:-1]]
                cmap = mcolors.ListedColormap(colors)

        # Otherwise, default to plasma colormap
        else:
            warnings.warn(
                'Saffir Simpson category colors are not allowed for this variable.')
            colormap = 'plasma'

    # Other colormap options
    if colormap not in ['category', 'category_recon']:

        # Matplotlib colormap name
        if isinstance(colormap, str):
            cmap = _get_cmap(colormap)

        # User defined list of colors
        elif isinstance(colormap, list):
            cmap = mcolors.ListedColormap(colormap)

        # Dictionary
        elif isinstance(colormap, dict):
            cmap = make_colormap(colormap)

        # ListedColormap
        elif isinstance(colormap, mlib.colors.ListedColormap):
            cmap = colormap

        # Default to plasma
        else:
            cmap = _get_cmap('plasma')

        # Normalize colors relative to levels
        norm = mlib.colors.Normalize(vmin=0, vmax=len(levels)-1)

        # If more than 2 levels were passed, use those for the contour levels
        if len(levels) > 2:
            colors = cmap(norm(np.arange(len(levels)-1)))
            cmap = mcolors.ListedColormap(colors)

        # Otherwise, create a list of colors based on levels
        else:
            colors = cmap(norm(np.linspace(0, 1, 256)))
            cmap = mcolors.LinearSegmentedColormap.from_list(
                'my_colormap', colors)

            y0 = min(levels)
            y1 = max(levels)
            dy = (y1-y0)/8
            scalemag = int(np.log(dy)/np.log(10))
            dy_scaled = dy*10**-scalemag
            dc = min([1, 2, 5, 10], key=lambda x: abs(x-dy_scaled))
            dc = dc*10**scalemag
            c0 = np.ceil(y0/dc)*dc
            c1 = np.floor(y1/dc)*dc
            levels = np.arange(c0, c1+dc, dc)

            if scalemag > 0:
                levels = levels.astype(int)

    # Return colormap and levels
    return cmap, levels
