# third-party
import werkzeug
import flask
import peewee
import playhouse.postgres_ext

# internals
from application import app

import database
import markdown
import form
import admin

@app.expose('/tag/')
class Tag(admin.Named):

    title = markdown.SafeMarkdownCharField(null=False, verbose_name='Title')
    text = markdown.MarkdownTextField()

    @werkzeug.utils.cached_property
    def items(self):

        return [item.tag_collection.parent for item in self.collection_items]

class TagCollectionForm(admin.AutoForm):

    def __init__(self, administerable, mode, **kwargs):

        super().__init__(administerable, mode, **kwargs)

        if mode == 'edit':

            for idx, item in enumerate(administerable.items):

                fieldset = form.Fieldset(name=f'item-{idx}')
                fieldset.intro = f'{item.tag.title} ({item.tag.name})'
                fieldset['item'] = form.ValueField(value=item)
                fieldset.buttons['delete'] = form.Button(label='Remove')

                self[fieldset.name] = fieldset

            fieldset = form.Fieldset(name='item-new')
            fieldset['tag_collection_id'] = form.ValueField(value=administerable.id)
            fieldset[TagCollectionItem.tag.name] = form.ForeignKeySelect(TagCollectionItem.tag)

            self[fieldset.name] = fieldset

    def handle(self, skip_bind=False):

        if 'submit' not in flask.request.form:
            self.errors.append(ValidationError("Missing submit information."))
            return

        submit = flask.request.form.get('submit')

        if not skip_bind:
            self.bind(flask.request.form, flask.request.files)

        # fieldsets have no .process behavior, we'll handle that in this class
        submit_relative = self.submit_relative(submit)
        self.validate(submit_relative)
        return self.process(submit_relative)

    def process(self, submit):

        if submit == 'edit':
            if self['item-new']['tag'].value: # a new tag for the collection was selected

                try:
                    tag = Tag.select().where(Tag.id == self['item-new']['tag'].value).get()
                except Tag.DoesNotExist:
                    flask.flash("Tried to add unknown tag.", 'error')
                else:

                    if tag in [item.tag for item in self.administerable.items]:
                        flask.flash(f"Tag '{tag.title}' is already in this collection.", 'warning')

                    else:

                        item = TagCollectionItem(tag_collection=self.administerable, tag=tag)
                        item.save(force_insert=True)
                        flask.flash(f"Added tag '{tag.title}'.", 'success')

                    return flask.redirect('')
        else:

            fieldset = self.submitted_fieldset(flask.request.form['submit'])

            if fieldset is not None:

                fieldset_submit = fieldset.submit_relative(flask.request.form['submit'])

                if fieldset_submit == 'delete':

                    item = fieldset['item'].value

                    try:

                        item.delete_instance()

                    except Exception as e:

                        if app.debug:
                            raise

                        app.logger.error(f"Error when deleting TagCollectionItem: {str(e)}")
                        flask.flash("Error deleting item.", 'error')

                    else:
                        flask.flash(f"Removed tag '{item.tag.title}'.", 'success')
                        return flask.redirect('')

            else: # submitted by create / delete button
                return super().process(submit)


class TagCollection(admin.Administerable):

    autoform_class = TagCollectionForm

    @werkzeug.utils.cached_property
    def parent(self):

        # find (and return) the Taggable instance using this TagCollection, if any
        # TODO: It should be possible to do this with one big JOINed statement
        for cls in Taggable.__class_descendants__.values():

            try:
                return cls.select().where(cls.tag_collection == self).get()
            except cls.DoesNotExist:
                pass # continue to next loop iteration

        return None

class TagCollectionItem(database.Model):

    class Meta:
        indexes = (
            (('tag_collection', 'tag'), True),
        )

    tag_collection = peewee.ForeignKeyField(TagCollection, null=False, backref='items', on_delete='CASCADE')
    tag = peewee.ForeignKeyField(Tag, null=False, verbose_name='Tag', backref='collection_items', on_delete='CASCADE')

class TaggableForm(admin.AutoForm):

    def __init__(self, administerable, mode, **kwargs):

        super().__init__(administerable, mode, **kwargs)

        if mode == 'create':

            del self['tag_collection_id'] # remove ForeignKeySelect

        if mode == 'edit':

            # replace tag_collection select with invisible value
            self['tag_collection_id'] = form.ValueField(value=administerable.tag_collection_id)

            if administerable.tag_collection_id:
                fs = form.ProxyFieldset(self.administerable.tag_collection.form('edit'))
                self[fs.name] = fs
            else:
                fs = form.ProxyFieldset(TagCollection().form('create'))
                self[fs.name] = fs

    def handle(self, skip_bind=False):

        if 'submit' not in flask.request.form:
            self.errors.append(ValidationError("Missing submit information."))
            return

        submit = flask.request.form.get('submit')

        if not skip_bind:
            self.bind(flask.request.form, flask.request.files)

        # find submitting element, either self or a child fieldset
        fieldset = self.submitted_fieldset(submit)

        if fieldset is not None:

            r = fieldset.handle(skip_bind=True)

            if fieldset is self['tagcollectionform'] and fieldset.form.mode == 'create':
                self.administerable.tag_collection = fieldset.form.administerable
                self.administerable.save()
                r = flask.redirect('') # reload instead of redirecting to TagCollection edit form

            return r

        else: # normal processing when a button on the form itself (i.e. not on a fieldset) submitted
            submit_relative = self.submit_relative(submit)
            self.validate(submit_relative)
            return self.process(submit_relative)

@app.abstract
class Taggable(admin.Named):

    # everything that's taggable should have its own single view,
    # so we're going with Named as parent because those should all
    # derive from it so we get pretty URLs.

    tag_collection = peewee.ForeignKeyField(TagCollection, null=True, on_delete='SET NULL')
    #autoform_blacklist = ('id', 'tag_collection_id')
    autoform_class = TaggableForm