# (C) Copyright 2004-2021 Enthought, Inc., Austin, TX
# All rights reserved.
#
# This software is provided without warranty under the terms of the BSD
# license included in LICENSE.txt and may be redistributed only under
# the conditions described in the aforementioned license. The license
# is also available online at http://www.enthought.com/licenses/BSD.txt
#
# Thanks for using Enthought open source!

""" Creates a wxPython user interface for a specified UI object.
"""


import wx

from pyface.api import SystemMetrics

from .helper import save_window, TraitsUIScrolledPanel

from .ui_base import BaseDialog

from .ui_panel import panel

from .constants import DefaultTitle, WindowColor, scrollbar_dx

from traitsui.menu import (
    ApplyButton,
    RevertButton,
    OKButton,
    CancelButton,
    HelpButton,
)


def ui_modal(ui, parent):
    """ Creates a modal wxPython user interface for a specified UI object.
    """
    _ui_dialog(ui, parent, BaseDialog.MODAL)


def ui_nonmodal(ui, parent):
    """ Creates a non-modal wxPython user interface for a specified UI object.
    """
    _ui_dialog(ui, parent, BaseDialog.NONMODAL)


def _ui_dialog(ui, parent, style):
    """ Creates a wxPython dialog box for a specified UI object.

    Changes are not immediately applied to the underlying object. The user must
    click **Apply** or **OK** to apply changes. The user can revert changes by
    clicking **Revert** or **Cancel**.
    """
    if ui.owner is None:
        ui.owner = ModalDialog()

    BaseDialog.display_ui(ui, parent, style)


class ModalDialog(BaseDialog):
    """ Modal dialog box for Traits-based user interfaces.
    """

    def init(self, ui, parent, style):
        self.is_modal = style == self.MODAL
        style = 0
        view = ui.view
        if view.resizable:
            style |= wx.RESIZE_BORDER

        title = view.title
        if title == "":
            title = DefaultTitle

        revert = apply = False
        window = ui.control
        if window is not None:
            window.SetSizer(None)
            ui.reset()
            if hasattr(self, "revert"):
                revert = self.revert.IsEnabled()
            if hasattr(self, "apply"):
                apply = self.apply.IsEnabled()
        else:
            self.ui = ui
            if self.is_modal:
                window = wx.Dialog(
                    parent, -1, title, style=style | wx.DEFAULT_DIALOG_STYLE
                )
            else:
                window = wx.Frame(
                    parent,
                    -1,
                    title,
                    style=style
                    | (wx.DEFAULT_FRAME_STYLE & (~wx.RESIZE_BORDER)),
                )

            window.SetBackgroundColour(WindowColor)
            self.control = window
            self.set_icon(view.icon)
            window.Bind(wx.EVT_CLOSE, self._on_close_page)
            window.Bind(wx.EVT_CHAR, self._on_key)

            # Create the 'context' copies we will need while editing:
            context = ui.context
            ui._context = context
            ui.context = self._copy_context(context)
            ui._revert = self._copy_context(context)

        # Create the actual trait sheet panel and imbed it in a scrollable
        # window (if requested):
        sw_sizer = wx.BoxSizer(wx.VERTICAL)
        if ui.scrollable:
            sizer = wx.BoxSizer(wx.VERTICAL)
            sw = TraitsUIScrolledPanel(window)
            trait_sheet = panel(ui, sw)
            sizer.Add(trait_sheet, 1, wx.EXPAND | wx.ALL, 4)
            tsdx, tsdy = trait_sheet.GetSize()
            tsdx += 8
            tsdy += 8
            sw.SetScrollRate(16, 16)
            max_dy = (2 * SystemMetrics().screen_height) // 3
            sw.SetSizer(sizer)
            sw.SetSize(
                wx.Size(
                    tsdx + ((tsdy > max_dy) * scrollbar_dx), min(tsdy, max_dy)
                )
            )
        else:
            sw = panel(ui, window)

        sw_sizer.Add(sw, 1, wx.EXPAND)

        buttons = [self.coerce_button(button) for button in view.buttons]
        nbuttons = len(buttons)
        if (nbuttons != 1) or (not self.is_button(buttons[0], "")):

            # Create the necessary special function buttons:
            sw_sizer.Add(wx.StaticLine(window, -1), 0, wx.EXPAND)
            b_sizer = wx.BoxSizer(wx.HORIZONTAL)

            if nbuttons == 0:
                if view.apply:
                    self.check_button(buttons, ApplyButton)
                    if view.revert:
                        self.check_button(buttons, RevertButton)

                if view.ok:
                    self.check_button(buttons, OKButton)

                if view.cancel:
                    self.check_button(buttons, CancelButton)

                if view.help:
                    self.check_button(buttons, HelpButton)

            for raw_button, button in zip(view.buttons, buttons):
                default = raw_button == view.default_button

                if self.is_button(button, "Apply"):
                    self.apply = self.add_button(
                        button, b_sizer, self._on_apply, apply, default=default
                    )
                    ui.observe(
                        self._on_applyable, "modified", dispatch="ui"
                    )

                elif self.is_button(button, "Revert"):
                    self.revert = self.add_button(
                        button,
                        b_sizer,
                        self._on_revert,
                        revert,
                        default=default,
                    )

                elif self.is_button(button, "OK"):
                    self.ok = self.add_button(
                        button, b_sizer, self._on_ok, default=default
                    )
                    ui.observe(self._on_error, "errors", dispatch="ui")

                elif self.is_button(button, "Cancel"):
                    self.add_button(
                        button, b_sizer, self._on_cancel, default=default
                    )

                elif self.is_button(button, "Help"):
                    self.add_button(
                        button, b_sizer, self._on_help, default=default
                    )

                elif not self.is_button(button, ""):
                    self.add_button(button, b_sizer, default=default)

            sw_sizer.Add(b_sizer, 0, wx.ALIGN_RIGHT | wx.ALL, 5)

        # Add the menu bar, tool bar and status bar (if any):
        self.add_menubar()
        self.add_toolbar()
        self.add_statusbar()

        # Lay all of the dialog contents out:
        window.SetSizerAndFit(sw_sizer)

    def close(self, rc=wx.ID_OK):
        """ Closes the dialog window.
        """
        ui = self.ui
        ui.result = rc == wx.ID_OK
        save_window(ui)
        if self.is_modal:
            self.control.EndModal(rc)

        self.control.Unbind(wx.EVT_CLOSE)
        self.control.Unbind(wx.EVT_CHAR)

        ui.finish()
        self.ui = self.apply = self.revert = self.help = self.control = None

    def _copy_context(self, context):
        """ Creates a copy of a *context* dictionary.
        """
        result = {}
        for name, value in context.items():
            if value is not None:
                result[name] = value.clone_traits()
            else:
                result[name] = None

        return result

    def _apply_context(self, from_context, to_context):
        """ Applies the traits in the *from_context* to the *to_context*.
        """
        for name, value in from_context.items():
            if value is not None:
                to_context[name].copy_traits(value)
            else:
                to_context[name] = None

        if to_context is self.ui._context:
            on_apply = self.ui.view.on_apply
            if on_apply is not None:
                on_apply()

    def _on_close_page(self, event):
        """ Handles the user clicking the window/dialog "close" button/icon.
        """
        if self.ui.view.close_result:
            self._on_ok(event)
        else:
            self._on_cancel(event)

    def _on_ok(self, event=None):
        """ Closes the window and saves changes (if allowed by the handler).
        """
        if self.ui.handler.close(self.ui.info, True):
            self._apply_context(self.ui.context, self.ui._context)
            self.close(wx.ID_OK)

    def _on_cancel(self, event=None):
        """ Closes the window and discards changes (if allowed by the handler).
        """
        if self.ui.handler.close(self.ui.info, False):
            self._apply_context(self.ui._revert, self.ui._context)
            self.close(wx.ID_CANCEL)

    def _on_key(self, event):
        """ Handles the user pressing the Escape key.
        """
        if event.GetKeyCode() == 0x1B:
            self._on_close_page(event)

    def _on_apply(self, event):
        """ Handles a request to apply changes.
        """
        ui = self.ui
        self._apply_context(ui.context, ui._context)
        if hasattr(self, "revert"):
            self.revert.Enable(True)
        ui.handler.apply(ui.info)
        ui.modified = False

    def _on_revert(self, event):
        """ Handles a request to revert changes.
        """
        ui = self.ui
        self._apply_context(ui._revert, ui.context)
        self._apply_context(ui._revert, ui._context)
        self.revert.Enable(False)
        ui.handler.revert(ui.info)
        ui.modified = False

    def _on_applyable(self, event):
        """ Handles a change to the "modified" state of the user interface .
        """
        state = event.new
        self.apply.Enable(state)

    def _on_error(self, event):
        """ Handles editing errors.
        """
        errors = event.new
        self.ok.Enable(errors == 0)