"""
This module provides routines to adjust subplot params so that subplots are
nicely fit in the figure. In doing so, only axis labels, tick labels, axes
titles and offsetboxes that are anchored to axes are currently considered.

Internally, it assumes that the margins (left_margin, etc.) which are
differences between ax.get_tightbbox and ax.bbox are independent of axes
position. This may fail if Axes.adjustable is datalim. Also, This will fail
for some cases (for example, left or right margin is affected by xlabel).
"""

from matplotlib import cbook, rcParams
from matplotlib.font_manager import FontProperties
from matplotlib.transforms import TransformedBbox, Bbox


def _get_left(tight_bbox, axes_bbox):
    return axes_bbox.xmin - tight_bbox.xmin


def _get_right(tight_bbox, axes_bbox):
    return tight_bbox.xmax - axes_bbox.xmax


def _get_bottom(tight_bbox, axes_bbox):
    return axes_bbox.ymin - tight_bbox.ymin


def _get_top(tight_bbox, axes_bbox):
    return tight_bbox.ymax - axes_bbox.ymax


def auto_adjust_subplotpars(
        fig, renderer, nrows_ncols, num1num2_list, subplot_list,
        ax_bbox_list=None, pad=1.08, h_pad=None, w_pad=None, rect=None):
    """
    Return a dict of subplot parameters to adjust spacing between subplots
    or ``None`` if resulting axes would have zero height or width.

    Note that this function ignores geometry information of subplot
    itself, but uses what is given by the *nrows_ncols* and *num1num2_list*
    parameters.  Also, the results could be incorrect if some subplots have
    ``adjustable=datalim``.

    Parameters
    ----------
    nrows_ncols : Tuple[int, int]
        Number of rows and number of columns of the grid.
    num1num2_list : List[int]
        List of numbers specifying the area occupied by the subplot
    subplot_list : list of subplots
        List of subplots that will be used to calculate optimal subplot_params.
    pad : float
        Padding between the figure edge and the edges of subplots, as a
        fraction of the font size.
    h_pad, w_pad : float
        Padding (height/width) between edges of adjacent subplots, as a
        fraction of the font size.  Defaults to *pad*.
    rect : Tuple[float, float, float, float]
        [left, bottom, right, top] in normalized (0, 1) figure coordinates.
    """
    rows, cols = nrows_ncols

    font_size_inches = (
        FontProperties(size=rcParams["font.size"]).get_size_in_points() / 72)
    pad_inches = pad * font_size_inches
    if h_pad is not None:
        vpad_inches = h_pad * font_size_inches
    else:
        vpad_inches = pad_inches

    if w_pad is not None:
        hpad_inches = w_pad * font_size_inches
    else:
        hpad_inches = pad_inches

    if len(num1num2_list) != len(subplot_list) or len(subplot_list) == 0:
        raise ValueError

    if rect is None:
        margin_left = margin_bottom = margin_right = margin_top = None
    else:
        margin_left, margin_bottom, _right, _top = rect
        if _right:
            margin_right = 1 - _right
        else:
            margin_right = None
        if _top:
            margin_top = 1 - _top
        else:
            margin_top = None

    vspaces = [[] for i in range((rows + 1) * cols)]
    hspaces = [[] for i in range(rows * (cols + 1))]

    union = Bbox.union

    if ax_bbox_list is None:
        ax_bbox_list = [
            union([ax.get_position(original=True) for ax in subplots])
            for subplots in subplot_list]

    for subplots, ax_bbox, (num1, num2) in zip(subplot_list,
                                               ax_bbox_list,
                                               num1num2_list):
        if all(not ax.get_visible() for ax in subplots):
            continue

        tight_bbox_raw = union([ax.get_tightbbox(renderer) for ax in subplots
                                if ax.get_visible()])
        tight_bbox = TransformedBbox(tight_bbox_raw,
                                     fig.transFigure.inverted())

        row1, col1 = divmod(num1, cols)

        if num2 is None:
            # left
            hspaces[row1 * (cols + 1) + col1].append(
                                        _get_left(tight_bbox, ax_bbox))
            # right
            hspaces[row1 * (cols + 1) + (col1 + 1)].append(
                                        _get_right(tight_bbox, ax_bbox))
            # top
            vspaces[row1 * cols + col1].append(
                                        _get_top(tight_bbox, ax_bbox))
            # bottom
            vspaces[(row1 + 1) * cols + col1].append(
                                        _get_bottom(tight_bbox, ax_bbox))

        else:
            row2, col2 = divmod(num2, cols)

            for row_i in range(row1, row2 + 1):
                # left
                hspaces[row_i * (cols + 1) + col1].append(
                                    _get_left(tight_bbox, ax_bbox))
                # right
                hspaces[row_i * (cols + 1) + (col2 + 1)].append(
                                    _get_right(tight_bbox, ax_bbox))
            for col_i in range(col1, col2 + 1):
                # top
                vspaces[row1 * cols + col_i].append(
                                    _get_top(tight_bbox, ax_bbox))
                # bottom
                vspaces[(row2 + 1) * cols + col_i].append(
                                    _get_bottom(tight_bbox, ax_bbox))

    fig_width_inch, fig_height_inch = fig.get_size_inches()

    # margins can be negative for axes with aspect applied. And we
    # append + [0] to make minimum margins 0

    if not margin_left:
        margin_left = max([sum(s) for s in hspaces[::cols + 1]] + [0])
        margin_left += pad_inches / fig_width_inch

    if not margin_right:
        margin_right = max([sum(s) for s in hspaces[cols::cols + 1]] + [0])
        margin_right += pad_inches / fig_width_inch

    if not margin_top:
        margin_top = max([sum(s) for s in vspaces[:cols]] + [0])
        margin_top += pad_inches / fig_height_inch

    if not margin_bottom:
        margin_bottom = max([sum(s) for s in vspaces[-cols:]] + [0])
        margin_bottom += pad_inches / fig_height_inch

    if margin_left + margin_right >= 1:
        cbook._warn_external('Tight layout not applied. The left and right '
                             'margins cannot be made large enough to '
                             'accommodate all axes decorations. ')
        return None
    if margin_bottom + margin_top >= 1:
        cbook._warn_external('Tight layout not applied. The bottom and top '
                             'margins cannot be made large enough to '
                             'accommodate all axes decorations. ')
        return None

    kwargs = dict(left=margin_left,
                  right=1 - margin_right,
                  bottom=margin_bottom,
                  top=1 - margin_top)
    if cols > 1:
        hspace = (
            max(sum(s)
                for i in range(rows)
                for s in hspaces[i * (cols + 1) + 1:(i + 1) * (cols + 1) - 1])
            + hpad_inches / fig_width_inch)
        # axes widths:
        h_axes = (1 - margin_right - margin_left - hspace * (cols - 1)) / cols
        if h_axes < 0:
            cbook._warn_external('Tight layout not applied. tight_layout '
                                 'cannot make axes width small enough to '
                                 'accommodate all axes decorations')
            return None
        else:
            kwargs["wspace"] = hspace / h_axes

    if rows > 1:
        vspace = (max(sum(s) for s in vspaces[cols:-cols])
                  + vpad_inches / fig_height_inch)
        v_axes = (1 - margin_top - margin_bottom - vspace * (rows - 1)) / rows
        if v_axes < 0:
            cbook._warn_external('Tight layout not applied. tight_layout '
                                 'cannot make axes height small enough to '
                                 'accommodate all axes decorations')
            return None
        else:
            kwargs["hspace"] = vspace / v_axes

    return kwargs


def get_renderer(fig):
    if fig._cachedRenderer:
        renderer = fig._cachedRenderer
    else:
        canvas = fig.canvas

        if canvas and hasattr(canvas, "get_renderer"):
            renderer = canvas.get_renderer()
        else:  # Some noninteractive backends have no renderer until draw time.
            cbook._warn_external("tight_layout: falling back to Agg renderer")
            from matplotlib.backends.backend_agg import FigureCanvasAgg
            canvas = FigureCanvasAgg(fig)
            renderer = canvas.get_renderer()

    return renderer


def get_subplotspec_list(axes_list, grid_spec=None):
    """Return a list of subplotspec from the given list of axes.

    For an instance of axes that does not support subplotspec, None is inserted
    in the list.

    If grid_spec is given, None is inserted for those not from the given
    grid_spec.
    """
    subplotspec_list = []
    for ax in axes_list:
        axes_or_locator = ax.get_axes_locator()
        if axes_or_locator is None:
            axes_or_locator = ax

        if hasattr(axes_or_locator, "get_subplotspec"):
            subplotspec = axes_or_locator.get_subplotspec()
            subplotspec = subplotspec.get_topmost_subplotspec()
            gs = subplotspec.get_gridspec()
            if grid_spec is not None:
                if gs != grid_spec:
                    subplotspec = None
            elif gs.locally_modified_subplot_params():
                subplotspec = None
        else:
            subplotspec = None

        subplotspec_list.append(subplotspec)

    return subplotspec_list


def get_tight_layout_figure(fig, axes_list, subplotspec_list, renderer,
                            pad=1.08, h_pad=None, w_pad=None, rect=None):
    """
    Return subplot parameters for tight-layouted-figure with specified padding.

    Parameters
    ----------
    fig : Figure
    axes_list : list of Axes
    subplotspec_list : list of `.SubplotSpec`
        The subplotspecs of each axes.
    renderer : renderer
    pad : float
        Padding between the figure edge and the edges of subplots, as a
        fraction of the font size.
    h_pad, w_pad : float
        Padding (height/width) between edges of adjacent subplots.  Defaults to
        *pad*.
    rect : Tuple[float, float, float, float], optional
        (left, bottom, right, top) rectangle in normalized figure coordinates
        that the whole subplots area (including labels) will fit into.
        Defaults to using the entire figure.

    Returns
    -------
    subplotspec or None
        subplotspec kwargs to be passed to `.Figure.subplots_adjust` or
        None if tight_layout could not be accomplished.

    """

    subplot_list = []
    nrows_list = []
    ncols_list = []
    ax_bbox_list = []

    # Multiple axes can share same subplot_interface (e.g., axes_grid1); thus
    # we need to join them together.
    subplot_dict = {}

    subplotspec_list2 = []

    for ax, subplotspec in zip(axes_list, subplotspec_list):
        if subplotspec is None:
            continue

        subplots = subplot_dict.setdefault(subplotspec, [])

        if not subplots:
            myrows, mycols, _, _ = subplotspec.get_geometry()
            nrows_list.append(myrows)
            ncols_list.append(mycols)
            subplotspec_list2.append(subplotspec)
            subplot_list.append(subplots)
            ax_bbox_list.append(subplotspec.get_position(fig))

        subplots.append(ax)

    if len(nrows_list) == 0 or len(ncols_list) == 0:
        return {}

    max_nrows = max(nrows_list)
    max_ncols = max(ncols_list)

    num1num2_list = []
    for subplotspec in subplotspec_list2:
        rows, cols, num1, num2 = subplotspec.get_geometry()
        div_row, mod_row = divmod(max_nrows, rows)
        div_col, mod_col = divmod(max_ncols, cols)
        if mod_row != 0:
            cbook._warn_external('tight_layout not applied: number of rows '
                                 'in subplot specifications must be '
                                 'multiples of one another.')
            return {}
        if mod_col != 0:
            cbook._warn_external('tight_layout not applied: number of '
                                 'columns in subplot specifications must be '
                                 'multiples of one another.')
            return {}

        rowNum1, colNum1 = divmod(num1, cols)
        if num2 is None:
            rowNum2, colNum2 = rowNum1, colNum1
        else:
            rowNum2, colNum2 = divmod(num2, cols)

        num1num2_list.append((rowNum1 * div_row * max_ncols +
                              colNum1 * div_col,
                              ((rowNum2 + 1) * div_row - 1) * max_ncols +
                              (colNum2 + 1) * div_col - 1))

    kwargs = auto_adjust_subplotpars(fig, renderer,
                                     nrows_ncols=(max_nrows, max_ncols),
                                     num1num2_list=num1num2_list,
                                     subplot_list=subplot_list,
                                     ax_bbox_list=ax_bbox_list,
                                     pad=pad, h_pad=h_pad, w_pad=w_pad)

    # kwargs can be none if tight_layout fails...
    if rect is not None and kwargs is not None:
        # if rect is given, the whole subplots area (including
        # labels) will fit into the rect instead of the
        # figure. Note that the rect argument of
        # *auto_adjust_subplotpars* specify the area that will be
        # covered by the total area of axes.bbox. Thus we call
        # auto_adjust_subplotpars twice, where the second run
        # with adjusted rect parameters.

        left, bottom, right, top = rect
        if left is not None:
            left += kwargs["left"]
        if bottom is not None:
            bottom += kwargs["bottom"]
        if right is not None:
            right -= (1 - kwargs["right"])
        if top is not None:
            top -= (1 - kwargs["top"])

        kwargs = auto_adjust_subplotpars(fig, renderer,
                                         nrows_ncols=(max_nrows, max_ncols),
                                         num1num2_list=num1num2_list,
                                         subplot_list=subplot_list,
                                         ax_bbox_list=ax_bbox_list,
                                         pad=pad, h_pad=h_pad, w_pad=w_pad,
                                         rect=(left, bottom, right, top))

    return kwargs
