# Example of embedding CEF Python browser using Tkinter toolkit.
# This example has two widgets: a navigation bar and a browser.
#
# Tested configurations:
# - Tk 8.6 and CEF Python v55.3+ on Linux
# - Tk 8.5 and CEF Python v55.4+ on Windows
#
# Known issue on Linux: When typing url, mouse must be over url
# entry widget otherwise keyboard focus is lost (Issue #255
# and Issue #284).

from cefpython3 import cefpython as cef
try:
    import tkinter as tk
except ImportError:
    import Tkinter as tk
import sys
import os
import platform
import logging as _logging

# Fix for PyCharm hints warnings
WindowUtils = cef.WindowUtils()

# Platforms
WINDOWS = (platform.system() == "Windows")
LINUX = (platform.system() == "Linux")
MAC = (platform.system() == "Darwin")

# Globals
logger = _logging.getLogger("tkinter_.py")
# Python 2.7 on Windows comes with Tk 8.5 which doesn't support PNG images
IMAGE_EXT = ".gif" if WINDOWS else ".png"


def main():
    logger.setLevel(_logging.INFO)
    stream_handler = _logging.StreamHandler()
    formatter = _logging.Formatter("[%(filename)s] %(message)s")
    stream_handler.setFormatter(formatter)
    logger.addHandler(stream_handler)
    logger.info("CEF Python {ver}".format(ver=cef.__version__))
    logger.info("Python {ver}".format(ver=sys.version[:6]))
    logger.info("Tk {ver}".format(ver=tk.TkVersion))
    assert cef.__version__ >= "55.3", "CEF Python v55.3+ required to run this"
    sys.excepthook = cef.ExceptHook  # To shutdown all CEF processes on error
    cef.Initialize()
    app = MainFrame(tk.Tk())
    app.mainloop()
    cef.Shutdown()


class MainFrame(tk.Frame):

    def __init__(self, master):
        self.browser_frame = None
        self.navigation_bar = None

        # Root
        master.geometry("800x600")
        tk.Grid.rowconfigure(master, 0, weight=1)
        tk.Grid.columnconfigure(master, 0, weight=1)

        # MainFrame
        tk.Frame.__init__(self, master)
        self.master.title("Tkinter example")
        self.master.protocol("WM_DELETE_WINDOW", self.on_close)
        self.master.bind("", self.on_root_configure)
        self.setup_icon()
        self.bind("", self.on_configure)
        self.bind("", self.on_focus_in)
        self.bind("", self.on_focus_out)

        # NavigationBar
        self.navigation_bar = NavigationBar(self)
        self.navigation_bar.grid(row=0, column=0,
                                 sticky=(tk.N + tk.S + tk.E + tk.W))
        tk.Grid.rowconfigure(self, 0, weight=0)
        tk.Grid.columnconfigure(self, 0, weight=0)

        # BrowserFrame
        self.browser_frame = BrowserFrame(self, self.navigation_bar)
        self.browser_frame.grid(row=1, column=0,
                                sticky=(tk.N + tk.S + tk.E + tk.W))
        tk.Grid.rowconfigure(self, 1, weight=1)
        tk.Grid.columnconfigure(self, 0, weight=1)

        # Pack MainFrame
        self.pack(fill=tk.BOTH, expand=tk.YES)

    def on_root_configure(self, _):
        logger.debug("MainFrame.on_root_configure")
        if self.browser_frame:
            self.browser_frame.on_root_configure()

    def on_configure(self, event):
        logger.debug("MainFrame.on_configure")
        if self.browser_frame:
            width = event.width
            height = event.height
            if self.navigation_bar:
                height = height - self.navigation_bar.winfo_height()
            self.browser_frame.on_mainframe_configure(width, height)

    def on_focus_in(self, _):
        logger.debug("MainFrame.on_focus_in")

    def on_focus_out(self, _):
        logger.debug("MainFrame.on_focus_out")

    def on_close(self):
        if self.browser_frame:
            self.browser_frame.on_root_close()
        self.master.destroy()

    def get_browser(self):
        if self.browser_frame:
            return self.browser_frame.browser
        return None

    def get_browser_frame(self):
        if self.browser_frame:
            return self.browser_frame
        return None

    def setup_icon(self):
        resources = os.path.join(os.path.dirname(__file__), "resources")
        icon_path = os.path.join(resources, "tkinter"+IMAGE_EXT)
        if os.path.exists(icon_path):
            self.icon = tk.PhotoImage(file=icon_path)
            # noinspection PyProtectedMember
            self.master.call("wm", "iconphoto", self.master._w, self.icon)


class NavigationBar(tk.Frame):

    def __init__(self, master):
        self.back_state = tk.NONE
        self.forward_state = tk.NONE
        self.back_image = None
        self.forward_image = None
        self.reload_image = None

        tk.Frame.__init__(self, master)
        resources = os.path.join(os.path.dirname(__file__), "resources")

        # Back button
        back_png = os.path.join(resources, "back"+IMAGE_EXT)
        if os.path.exists(back_png):
            self.back_image = tk.PhotoImage(file=back_png)
        self.back_button = tk.Button(self, image=self.back_image,
                                     command=self.go_back)
        self.back_button.grid(row=0, column=0)

        # Forward button
        forward_png = os.path.join(resources, "forward"+IMAGE_EXT)
        if os.path.exists(forward_png):
            self.forward_image = tk.PhotoImage(file=forward_png)
        self.forward_button = tk.Button(self, image=self.forward_image,
                                        command=self.go_forward)
        self.forward_button.grid(row=0, column=1)

        # Reload button
        reload_png = os.path.join(resources, "reload"+IMAGE_EXT)
        if os.path.exists(reload_png):
            self.reload_image = tk.PhotoImage(file=reload_png)
        self.reload_button = tk.Button(self, image=self.reload_image,
                                       command=self.reload)
        self.reload_button.grid(row=0, column=2)

        # Url entry
        self.url_entry = tk.Entry(self)
        self.url_entry.bind("", self.on_url_focus_in)
        self.url_entry.bind("", self.on_url_focus_out)
        self.url_entry.bind("", self.on_load_url)
        self.url_entry.bind("", self.on_button1)
        self.url_entry.grid(row=0, column=3,
                            sticky=(tk.N + tk.S + tk.E + tk.W))
        tk.Grid.rowconfigure(self, 0, weight=100)
        tk.Grid.columnconfigure(self, 3, weight=100)

        # Update state of buttons
        self.update_state()

    def go_back(self):
        if self.master.get_browser():
            self.master.get_browser().GoBack()

    def go_forward(self):
        if self.master.get_browser():
            self.master.get_browser().GoForward()

    def reload(self):
        if self.master.get_browser():
            self.master.get_browser().Reload()

    def set_url(self, url):
        self.url_entry.delete(0, tk.END)
        self.url_entry.insert(0, url)

    def on_url_focus_in(self, _):
        logger.debug("NavigationBar.on_url_focus_in")

    def on_url_focus_out(self, _):
        logger.debug("NavigationBar.on_url_focus_out")

    def on_load_url(self, _):
        if self.master.get_browser():
            self.master.get_browser().StopLoad()
            self.master.get_browser().LoadUrl(self.url_entry.get())

    def on_button1(self, _):
        """Fix CEF focus issues (#255). See also FocusHandler.OnGotFocus."""
        logger.debug("NavigationBar.on_button1")
        self.master.master.focus_force()

    def update_state(self):
        browser = self.master.get_browser()
        if not browser:
            if self.back_state != tk.DISABLED:
                self.back_button.config(state=tk.DISABLED)
                self.back_state = tk.DISABLED
            if self.forward_state != tk.DISABLED:
                self.forward_button.config(state=tk.DISABLED)
                self.forward_state = tk.DISABLED
            self.after(100, self.update_state)
            return
        if browser.CanGoBack():
            if self.back_state != tk.NORMAL:
                self.back_button.config(state=tk.NORMAL)
                self.back_state = tk.NORMAL
        else:
            if self.back_state != tk.DISABLED:
                self.back_button.config(state=tk.DISABLED)
                self.back_state = tk.DISABLED
        if browser.CanGoForward():
            if self.forward_state != tk.NORMAL:
                self.forward_button.config(state=tk.NORMAL)
                self.forward_state = tk.NORMAL
        else:
            if self.forward_state != tk.DISABLED:
                self.forward_button.config(state=tk.DISABLED)
                self.forward_state = tk.DISABLED
        self.after(100, self.update_state)


class Tabs(tk.Frame):

    def __init__(self):
        tk.Frame.__init__(self)
        # TODO: implement tabs


class BrowserFrame(tk.Frame):

    def __init__(self, master, navigation_bar=None):
        self.navigation_bar = navigation_bar
        self.closing = False
        self.browser = None
        tk.Frame.__init__(self, master)
        self.bind("", self.on_focus_in)
        self.bind("", self.on_focus_out)
        self.bind("", self.on_configure)
        self.focus_set()

    def embed_browser(self):
        window_info = cef.WindowInfo()
        window_info.SetAsChild(self.winfo_id())
        self.browser = cef.CreateBrowserSync(window_info,
                                             url="https://www.google.com/")
        assert self.browser
        self.browser.SetClientHandler(LoadHandler(self))
        self.browser.SetClientHandler(FocusHandler(self))
        self.message_loop_work()

    def message_loop_work(self):
        cef.MessageLoopWork()
        self.after(10, self.message_loop_work)

    def on_configure(self, _):
        if not self.browser:
            self.embed_browser()

    def on_root_configure(self):
        # Root  event will be called when top window is moved
        if self.browser:
            self.browser.NotifyMoveOrResizeStarted()

    def on_mainframe_configure(self, width, height):
        if self.browser:
            if WINDOWS:
                WindowUtils.OnSize(self.winfo_id(), 0, 0, 0)
            elif LINUX:
                self.browser.SetBounds(0, 0, width, height)
            self.browser.NotifyMoveOrResizeStarted()

    def on_focus_in(self, _):
        logger.debug("BrowserFrame.on_focus_in")
        if self.browser:
            self.browser.SetFocus(True)

    def on_focus_out(self, _):
        logger.debug("BrowserFrame.on_focus_out")
        if self.browser:
            self.browser.SetFocus(False)

    def on_root_close(self):
        if self.browser:
            # Close browser and free reference by setting to None
            self.browser.CloseBrowser(True)
            self.browser = None
        self.destroy()


class LoadHandler(object):

    def __init__(self, browser_frame):
        self.browser_frame = browser_frame

    def OnLoadStart(self, browser, **_):
        if self.browser_frame.master.navigation_bar:
            self.browser_frame.master.navigation_bar.set_url(browser.GetUrl())


class FocusHandler(object):

    def __init__(self, browser_frame):
        self.browser_frame = browser_frame

    def OnTakeFocus(self, next_component, **_):
        logger.debug("FocusHandler.OnTakeFocus, next={next}"
                     .format(next=next_component))

    def OnSetFocus(self, source, **_):
        logger.debug("FocusHandler.OnSetFocus, source={source}"
                     .format(source=source))
        return False

    def OnGotFocus(self, **_):
        """Fix CEF focus issues (#255). Call browser frame's focus_set
           to get rid of type cursor in url entry widget."""
        logger.debug("FocusHandler.OnGotFocus")
        self.browser_frame.focus_set()


if __name__ == '__main__':
    main()