# Copyright (c) 2015 Ultimaker B.V.
# Uranium is released under the terms of the LGPLv3 or higher.

from PyQt5.QtCore import QObject, pyqtProperty, pyqtSignal, QCoreApplication, QUrl, QSizeF
from PyQt5.QtGui import QColor, QFont, QFontMetrics, QFontDatabase, QFontInfo
from PyQt5.QtQml import QQmlComponent, QQmlContext
from UM.FlameProfiler import pyqtSlot
import json
import os
import os.path
import sys

from UM.Logger import Logger
from UM.Resources import Resources
from UM.Preferences import Preferences
from UM.Application import Application
from UM.Decorators import deprecated

class Theme(QObject):
    def __init__(self, engine, parent = None):
        super().__init__(parent)

        self._engine = engine
        self._styles = None
        self._path = ""
        self._icons = {}
        self._images = {}

        # Workaround for incorrect default font on Windows
        if sys.platform == "win32":
            default_font = QFont()
            default_font.setPointSize(9)
            QCoreApplication.instance().setFont(default_font)

        self._em_height = int(QFontMetrics(QCoreApplication.instance().font()).ascent())
        self._em_width = self._em_height

        self._initializeDefaults()

        Preferences.getInstance().addPreference("general/theme", Application.getInstance().default_theme)
        try:
            theme_path = Resources.getPath(Resources.Themes, Preferences.getInstance().getValue("general/theme"))
            self.load(theme_path)
        except FileNotFoundError:
            Logger.log("e", "Could not find theme file, resetting to the default theme.")

            # cannot the current theme, so go back to the default
            Preferences.getInstance().setValue("general/theme", Application.getInstance().default_theme)
            theme_path = Resources.getPath(Resources.Themes, Preferences.getInstance().getValue("general/theme"))
            self.load(theme_path)

    themeLoaded = pyqtSignal()

    @pyqtSlot(result = "QVariantList")
    def getThemes(self):
        themes = []
        for path in Resources.getAllPathsForType(Resources.Themes):
            try:
                for file in os.listdir(path):
                    folder = os.path.join(path, file)
                    theme_file = os.path.join(folder, "theme.json")
                    if os.path.isdir(folder) and os.path.isfile(theme_file):
                        theme_id = os.path.basename(folder)

                        with open(theme_file) as f:
                            try:
                                data = json.load(f)
                            except json.decoder.JSONDecodeError:
                                Logger.log("w", "Could not parse theme %s", theme_id)
                                continue # do not add this theme to the list, but continue looking for other themes

                            try:
                                theme_name = data["metadata"]["name"]
                            except KeyError:
                                Logger.log("w", "Theme %s does not have a name; using its id instead", theme_id)
                                theme_name = theme_id # fallback if no name is specified in json

                        themes.append({
                            "id": theme_id,
                            "name": theme_name
                        })
            except FileNotFoundError:
                pass
        themes.sort(key = lambda k: k["name"])

        return themes

    @pyqtSlot(str, result = "QColor")
    def getColor(self, color):
        if color in self._colors:
            return self._colors[color]

        Logger.log("w", "No color %s defined in Theme", color)
        return QColor()

    @pyqtSlot(str, result = "QSizeF")
    def getSize(self, size):
        if size in self._sizes:
            return self._sizes[size]

        Logger.log("w", "No size %s defined in Theme", size)
        return QSizeF()

    @pyqtSlot(str, result = "QUrl")
    def getIcon(self, icon_name):
        if icon_name in self._icons:
            return self._icons[icon_name]

        Logger.log("w", "No icon %s defined in Theme", icon_name)
        return QUrl()

    @pyqtSlot(str, result = "QUrl")
    def getImage(self, image_name):
        if image_name in self._images:
            return self._images[image_name]

        Logger.log("w", "No image %s defined in Theme", image_name)
        return QUrl()

    @pyqtSlot(str, result = "QFont")
    def getFont(self, font_name):
        if font_name in self._fonts:
            return self._fonts[font_name]

        Logger.log("w", "No font %s defined in Theme", font_name)
        return QFont()

    @pyqtProperty(QObject, notify = themeLoaded)
    def styles(self):
        return self._styles

    @pyqtProperty("QVariantMap", notify = themeLoaded)
    @deprecated("Use getIcon for performance reasons", "2.1")
    def icons(self):
        return self._icons

    @pyqtProperty("QVariantMap", notify = themeLoaded)
    @deprecated("Use getImage for performance reasons", "2.1")
    def images(self):
        return self._images

    @pyqtProperty("QVariantMap", notify = themeLoaded)
    @deprecated("Use getColor for performance reasons", "2.1")
    def colors(self):
        return self._colors

    @pyqtProperty("QVariantMap", notify = themeLoaded)
    @deprecated("Use getFont for performance reasons", "2.1")
    def fonts(self):
        return self._fonts

    @pyqtProperty("QVariantMap", notify = themeLoaded)
    @deprecated("Use getSize for performance reasons", "2.1")
    def sizes(self):
        return self._sizes

    @pyqtSlot(str)
    def load(self, path, is_first_call = True):
        if path == self._path:
            return

        with open(os.path.join(path, "theme.json")) as f:
            Logger.log("d", "Loading theme file: %s", os.path.join(path, "theme.json"))
            data = json.load(f)

        # Iteratively load inherited themes
        try:
            theme_id = data["metadata"]["inherits"]
            self.load(Resources.getPath(Resources.Themes, theme_id), is_first_call = False)
        except FileNotFoundError:
            Logger.log("e", "Could not find inherited theme %s", theme_id)
        except KeyError:
            pass # No metadata or no inherits keyword in the theme.json file

        if "colors" in data:
            for name, color in data["colors"].items():
                c = QColor(color[0], color[1], color[2], color[3])
                self._colors[name] = c

        fontsdir = os.path.join(path, "fonts")
        if os.path.isdir(fontsdir):
            for file in os.listdir(fontsdir):
                if "ttf" in file:
                    QFontDatabase.addApplicationFont(os.path.join(fontsdir, file))

        if "fonts" in data:
            system_font_size = QCoreApplication.instance().font().pointSize()
            for name, font in data["fonts"].items():
                f = QFont()
                f.setFamily(font.get("family", QCoreApplication.instance().font().family()))

                f.setBold(font.get("bold", False))
                f.setLetterSpacing(QFont.AbsoluteSpacing, font.get("letterSpacing", 0))
                f.setItalic(font.get("italic", False))
                f.setPointSize(int(font.get("size", 1) * system_font_size))
                f.setCapitalization(QFont.AllUppercase if font.get("capitalize", False) else QFont.MixedCase)

                self._fonts[name] = f

        if "sizes" in data:
            for name, size in data["sizes"].items():
                s = QSizeF()
                s.setWidth(round(size[0] * self._em_width))
                s.setHeight(round(size[1] * self._em_height))

                self._sizes[name] = s

        iconsdir = os.path.join(path, "icons")
        if os.path.isdir(iconsdir):
            for icon in os.listdir(iconsdir):
                name = os.path.splitext(icon)[0]
                self._icons[name] = QUrl.fromLocalFile(os.path.join(iconsdir, icon))

        imagesdir = os.path.join(path, "images")
        if os.path.isdir(imagesdir):
            for image in os.listdir(imagesdir):
                name = os.path.splitext(image)[0]
                self._images[name] = QUrl.fromLocalFile(os.path.join(imagesdir, image))

        styles = os.path.join(path, "styles.qml")
        if os.path.isfile(styles):
            c = QQmlComponent(self._engine, styles)
            context = QQmlContext(self._engine, self._engine)
            context.setContextProperty("Theme", self)
            self._styles = c.create(context)

            if c.isError():
                for error in c.errors():
                    Logger.log("e", error.toString())

        Logger.log("d", "Loaded theme %s", path)
        self._path = path

        # only emit the theme loaded signal once after all the themes in the inheritance chain have been loaded
        if is_first_call:
            self.themeLoaded.emit()

    def _initializeDefaults(self):
        self._fonts = {
            "system": QCoreApplication.instance().font(),
            "fixed": QFontDatabase.systemFont(QFontDatabase.FixedFont)
        }

        palette = QCoreApplication.instance().palette()
        self._colors = {
            "system_window": palette.window(),
            "system_text": palette.text()
        }

        self._sizes = {
            "line": QSizeF(self._em_width, self._em_height)
        }

    ##  Get the singleton instance for this class.
    @classmethod
    def getInstance(cls, engine = None):
        # Note: Explicit use of class name to prevent issues with inheritance.
        if Theme.__instance is None:
            Theme.__instance = cls(engine)
        return Theme.__instance

    __instance = None   # type: 'Theme'

def createTheme(engine, script_engine = None):
    return Theme.getInstance(engine)

