#!/usr/bin/env python3

import os
import tkinter
import tkinter.filedialog
import tkinter.messagebox
##
import requests
from lxml import etree
##
from . import subsections


class Configurator(tkinter.Tk):
    def __init__(self, version = '0.2.0', *args, **kwargs):
        super().__init__(*args, **kwargs)
        maxwidth, maxheight = self.winfo_screenwidth(), self.winfo_screenheight()
        self.geometry('{0}x{1}+0+0'.format(maxwidth, maxheight))
        self.title('AIF-NG Configuration Generator')
        self.xml_attrib = {('{http://www.w3.org/2001/XMLSchema-instance}'
                            'schemaLocation'): ('http://aif-ng.io/ '
                                                'http://aif-ng.io/aif.xsd'),
                           'version': version}
        self.xml_nsmap = {'xsi': 'http://www.w3.org/2001/XMLSchema-instance',
                          None: 'http://aif-ng.io/'}
        self.xml = etree.Element('aif', attrib = self.xml_attrib, nsmap = self.xml_nsmap)
        self.xsd = None
        self.savefilename = None
        self.saveelems = []
        self._initMenuBar()
        self._initXSD()
        self.build()

    def _initMenuBar(self):
        menubar = tkinter.Menu(self)
        # File
        filemenu = tkinter.Menu(menubar, tearoff = 0)
        filemenu.add_command(label = 'New', command = self.file_new)
        filemenu.add_command(label = 'Clear', command = self.file_clear)
        filemenu.add_command(label = 'Save', command = self.file_save)
        filemenu.add_command(label = 'Save as...', command = self.file_saveas)
        filemenu.add_command(label = 'Load...', command = self.file_load)
        filemenu.add_separator()
        filemenu.add_command(label="Exit", command = self.exit)
        menubar.add_cascade(label = 'File', menu = filemenu)
        # Help
        helpmenu = tkinter.Menu(menubar, tearoff = 0)
        helpmenu.add_command(label = 'About')
        menubar.add_cascade(label = 'Help', menu = helpmenu)
        ##
        self.config(menu = menubar)
        return()

    def _initXSD(self, xsdpath = None):
        # TODO: locally-cache XSD file?
        if xsdpath:
            xsdpath = os.path.abspath(os.path.expanduser(xsdpath))
            if not os.path.isfile(xsdpath):
                raise ValueError(('An explicit XSD path was specified but '
                                  'does not exist on the local filesystem'))
            with open(xsdpath, 'rb') as fh:
                raw_xsd = fh.read()
        else:
            xsi = self.xml.nsmap.get('xsi', 'http://www.w3.org/2001/XMLSchema-instance')
            schemaLocation = '{{{0}}}schemaLocation'.format(xsi)
            schemaURL = self.xml.attrib.get(schemaLocation,
                                            'https://aif-ng.io/aif.xsd?ref={0}'.format(self.xml.attrib['version']))
            split_url = schemaURL.split()
            if len(split_url) == 2:  # a properly defined schemaLocation
                schemaURL = split_url[1]
            else:
                schemaURL = split_url[0]  # a LAZY schemaLocation
            req = requests.get(schemaURL)
            if not req.ok:
                raise RuntimeError('Could not download XSD')
            raw_xsd = req.content
        self.xsd = etree.XMLSchema(etree.XML(raw_xsd))
        return()

    def build(self):
        self.saveelems.append(subsections.meta.Obj(self.xml, self))
        self.saveelems.append(subsections.storage.Obj(self.xml, self))
        # self.update()
        return()

    def check(self):
        if not self.xsd:
            self._initXSD()
        return(self.xsd.validate(self.xml))

    def clearinput(self):
        # ???
        # maybe https://stackoverflow.com/a/2260355/733214
        # or maybe https://stackoverflow.com/a/19477781/733214 ?
        self.xml = etree.Element('aif', attrib = self.xml_attrib, nsmap = self.xml_nsmap)
        for i in self.saveelems:
            i.new()
        return()

    def exit(self):
        if not self.check():
            tkinter.messagebox.showwarning('Incompatible Configuration',
                                           ('The configuration state as currently defined is not a valid '
                                            'configuration file for AIF-NG. It will not work properly until '
                                            'completed.'))
        # Check for unsaved changes here?
        self.destroy()
        return()

    def file_load(self):
        fname = tkinter.filedialog.askopenfilename(defaultextension = '.xml')
        with open(fname, 'rb') as fh:
            try:
                self.xml = etree.fromstring(fh.read())
            except etree.XMLSyntaxError as e:
                tkinter.messagebox.showerror('Invalid XML',
                                             ('The imported configuration ({0}) is invalid XML: {1}').format(fname,
                                                                                                             e))
                return()
        if not self.check():
            tkinter.messagebox.showwarning('Incompatible Configuration',
                                           ('The imported configuration ({0}) is not a valid configuration file '
                                            'for AIF-NG. It will not work properly until completed.').format(fname))
        return()

    def file_clear(self):
        self.clearinput()
        return()

    def file_new(self):
        self.clearinput()
        self.savefilename = None
        return()

    def file_save(self):
        self.savefile()
        return()

    def file_saveas(self):
        self.savefile(forcefile = True)

    def savefile(self, forcefile = False):
        if not self.check():
            # TODO: make this persistently configurable?
            tkinter.messagebox.showwarning('Incompatible Configuration',
                                           ('The configuration state as currently defined is not a valid '
                                            'configuration file for AIF-NG. It will not work properly until '
                                            'completed.'))
        if not self.savefilename or forcefile:
            savefilename = tkinter.filedialog.asksaveasfilename(defaultextension = '.xml')
            if savefilename is None:  # "Cancel" button
                return()
            self.savefilename = savefilename
        for i in self.saveelems:
            i.save()
        with open(self.savefilename, 'wb') as fh:
            fh.write(etree.tostring(self.xml,
                                    encoding = 'utf-8',
                                    xml_declaration = True,
                                    pretty_print = True,
                                    with_tail = True,
                                    inclusive_ns_prefixes = True))
        return()


# if __name__ == '__main__':
#     app = Configurator()
#     app.mainloop()