import os
from datetime import datetime as dt, timezone as tz
from flask import request, redirect, url_for, flash, render_template, Blueprint, session, current_app
from flask_security import roles_accepted, current_user
from sqlalchemy import desc
from sqlalchemy.orm import joinedload
from werkzeug.datastructures import FileStorage
from werkzeug.utils import secure_filename
from sqlalchemy.exc import SQLAlchemyError
import requests
from requests.exceptions import SSLError
from urllib.parse import urlparse
import io

from common.models.document import Document, DocumentLanguage, DocumentVersion
from common.extensions import db
from .document_forms import AddDocumentForm, AddURLForm
from common.utils.middleware import mw_before_request
from common.utils.celery_utils import current_celery

document_bp = Blueprint('document_bp', __name__, url_prefix='/document')


@document_bp.before_request
def before_request():
    mw_before_request()


@document_bp.route('/add_document', methods=['GET', 'POST'])
@roles_accepted('Super User', 'Tenant Admin')
def add_document():
    form = AddDocumentForm()

    # If the form is submitted
    if request.method == 'POST' and form.validate_on_submit():
        current_app.logger.info(f'Adding document for tenant {session["tenant"]["id"]}')
        file = form.file.data
        filename = secure_filename(file.filename)
        extension = filename.rsplit('.', 1)[1].lower()

        new_doc, new_doc_lang, new_doc_vers = create_document_stack(form, file, filename, extension)

        task = current_celery.send_task('create_embeddings', queue='embeddings', args=[
            session['tenant']['id'],
            new_doc_vers.id,
        ])
        current_app.logger.info(f'Embedding creation started for tenant {session["tenant"]["id"]}, '
                                f'Document Version {new_doc_vers.id}. '
                                f'Embedding creation task: {task.id}')

        return redirect(url_for('document_bp.documents'))

    return render_template('document/add_document.html', form=form)


@document_bp.route('/add_url', methods=['GET', 'POST'])
@roles_accepted('Super User', 'Tenant Admin')
def add_url():
    form = AddURLForm()

    # If the form is submitted
    if request.method == 'POST' and form.validate_on_submit():
        current_app.logger.info(f'Adding document for tenant {session["tenant"]["id"]}')
        url = form.url.data

        html = fetch_html(url)
        file = io.StringIO(html)

        parsed_url = urlparse(url)
        path_parts = parsed_url.path.split('/')
        filename = path_parts[-1]
        if filename == '':
            filename = 'index'
        if not filename.endswith('.html'):
            filename += '.html'
        extension = 'html'

        new_doc, new_doc_lang, new_doc_vers = create_document_stack(form, file, filename, extension)

        task = current_celery.send_task('create_embeddings', queue='embeddings', args=[
            session['tenant']['id'],
            new_doc_vers.id,
        ])
        current_app.logger.info(f'Embedding creation started for tenant {session["tenant"]["id"]}, '
                                f'Document Version {new_doc_vers.id}. '
                                f'Embedding creation task: {task.id}')

        return redirect(url_for('document_bp.documents'))

    return render_template('document/add_url.html', form=form)


@document_bp.route('/documents', methods=['GET', 'POST'])
@roles_accepted('Super User', 'Tenant Admin')
def documents():
    page = request.args.get('page', 1, type=int)
    per_page = request.args.get('per_page', 10, type=int)

    query = Document.query.order_by(desc(Document.created_at)).options(
        joinedload(Document.languages).joinedload(DocumentLanguage.versions))

    pagination = query.paginate(page=page, per_page=per_page, error_out=False)
    docs = pagination.items

    rows = prepare_document_data(docs)

    return render_template('document/documents.html', rows=rows, pagination=pagination)


@document_bp.route('/process_version/<int:version_id>', methods=['POST'])
@roles_accepted('Super User', 'Tenant Admin')
def process_version(version_id):
    version = DocumentVersion.query.get_or_404(version_id)
    if not version.processing:
        print(f'Placeholder for processing version: {version_id}')

    return redirect(url_for('documents'))


def set_logging_information(obj, timestamp):
    obj.created_at = timestamp
    obj.updated_at = timestamp
    obj.created_by = current_user.id
    obj.updated_by = current_user.id


def create_document_stack(form, file, filename, extension):
    # Create the Document
    new_doc = create_document(form, filename)

    # Create the DocumentLanguage
    new_doc_lang = create_language_for_document(new_doc, form.language.data, form.user_context.data)

    # Create the DocumentVersion
    new_doc_vers = DocumentVersion()
    new_doc_vers.document_language = new_doc_lang
    set_logging_information(new_doc_vers, dt.now(tz.utc))

    try:
        db.session.add(new_doc)
        db.session.add(new_doc_lang)
        db.session.add(new_doc_vers)
        db.session.commit()
    except SQLAlchemyError as e:
        current_app.logger.error(f'Error adding document for tenant {session["tenant"]["id"]}: {e}')
        flash('Error adding document.', 'error')
        db.session.rollback()
        error = e.args
        raise
    except Exception as e:
        current_app.logger.error('Unknown error')
        raise

    try:
        new_doc_lang = db.session.merge(new_doc_lang)
        new_doc_vers = db.session.merge(new_doc_vers)
        new_doc_lang.latest_version_id = new_doc_vers.id
        db.session.commit()
    except SQLAlchemyError as e:
        current_app.logger.error(f'Error adding document for tenant {session["tenant"]["id"]}: {e}')
        flash('Error adding document.', 'error')
        db.session.rollback()
        error = e.args
        raise
    except Exception as e:
        current_app.logger.error(f'Error adding document for tenant {session["tenant"]["id"]}: {e}')
        flash('Error adding document.', 'error')
        db.session.rollback()
        error = e.args
        raise

    current_app.logger.info(f'Document added successfully for tenant {session["tenant"]["id"]}, '
                            f'Document Version {new_doc.id}')

    upload_file_for_version(new_doc_vers, file, extension)

    return new_doc, new_doc_lang, new_doc_vers


def log_session_state(session, msg=""):
    current_app.logger.debug(f"{msg} - Session dirty: {session.dirty}")
    current_app.logger.debug(f"{msg} - Session new: {session.new}")


def create_document(form, filename):
    new_doc = Document()
    if form.name.data == '':
        new_doc.name = filename.rsplit('.', 1)[0]
    else:
        new_doc.name = form.name.data

    if form.valid_from.data or form.valid_from.data != '':
        new_doc.valid_from = form.valid_from.data
    else:
        new_doc.valid_from = dt.now(tz.utc)
    new_doc.tenant_id = session['tenant']['id']
    set_logging_information(new_doc, dt.now(tz.utc))

    return new_doc


def create_language_for_document(document, language, user_context):
    new_doc_lang = DocumentLanguage()
    if language == '':
        new_doc_lang.language = session['default_language']
    else:
        new_doc_lang.language = language

    if user_context != '':
        new_doc_lang.user_context = user_context

    new_doc_lang.document = document

    set_logging_information(new_doc_lang, dt.now(tz.utc))

    return new_doc_lang


def upload_file_for_version(doc_vers, file, extension):
    doc_vers.file_type = extension
    doc_vers.file_name = doc_vers.calc_file_name()
    doc_vers.file_location = doc_vers.calc_file_location()

    upload_path = os.path.join(current_app.config['UPLOAD_FOLDER'], doc_vers.file_location)
    if not os.path.exists(upload_path):
        os.makedirs(upload_path, exist_ok=True)
    if isinstance(file, FileStorage):
        file.save(os.path.join(upload_path, doc_vers.file_name))
    elif isinstance(file, io.StringIO):
        # It's a StringIO object, handle accordingly
        # Example: write content to a file manually
        content = file.getvalue()
        with open(os.path.join(upload_path, doc_vers.file_name), 'w', encoding='utf-8') as file:
            file.write(content)
    else:
        raise TypeError('Unsupported file type.')

    try:
        db.session.commit()
    except SQLAlchemyError as e:
        db.session.rollback()
        flash('Error saving document.', 'error')
        current_app.logger.error(
            f'Error saving document for tenant {session["tenant"]["id"]} while uploading file: {error}')

    current_app.logger.info(f'Succesfully saved document for tenant {session['tenant']['id']} for '
                            f'document version {doc_vers.id} while uploading file.')


def fetch_html(url):
    # Fetches HTML content from a URL
    try:
        response = requests.get(url)
    except SSLError as e:
        current_app.logger.error(f"Error fetching HTML from {url} for tenant {session['tenant']['id']}. "
                                 f"Error Encountered: {e}")
        if current_app.config.get('DEBUG'):  # only allow when in a development environment
            current_app.logger.info(f"Skipping SSL verification for {url} for tenant {session['tenant']['id']}. "
                                    f"Only while in development environment.")
            response = requests.get(url, verify=False)  # Disable SSL verification
        else:
            response = None

    response.raise_for_status()  # Will raise an exception for bad requests
    return response.text


# Sample code for adding or updating versions and ensuring latest_version is set in DocumentLanguage
# def add_or_update_version(language_id, version_data):
#     new_version = Version(language_id=language_id, **version_data)
#     db.session.add(new_version)
#     db.session.flush()  # Ensures new_version gets an ID assigned if it's new
#
#     # Assuming we always call this when we know it's the latest
#     language = Language.query.get(language_id)
#     language.latest_version_id = new_version.id
#     db.session.commit()

# sample code for using latest_version in the application
# @app.route('/language/<int:language_id>')
# def show_language(language_id):
#     language = Language.query.get_or_404(language_id)
#     latest_version = language.latest_version  # This is now a direct, efficient database access
#     return render_template('language_details.html', language=language, latest_version=latest_version)


def prepare_document_data(docs):
    rows = []
    for doc in docs:
        doc_row = [{'value': doc.name, 'class': '', 'type': 'text'},
                   {'value': doc.created_at.strftime("%Y-%m-%d %H:%M:%S"), 'class': '', 'type': 'text'}]
        # Document basic details
        if doc.valid_from:
            doc_row.append({'value': doc.valid_from.strftime("%Y-%m-%d"), 'class': '', 'type': 'text'})
        else:
            doc_row.append({'value': '', 'class': '', 'type': 'text'})

        # Nested languages and versions
        languages_rows = []
        for lang in doc.languages:
            lang_row = [{'value': lang.language, 'class': '', 'type': 'text'}]

            # Latest version details if available (should be available ;-) )
            if lang.latest_version:
                lang_row.append({'value': lang.latest_version.created_at.strftime("%Y-%m-%d %H:%M:%S"),
                                 'class': '', 'type': 'text'})
                if lang.latest_version.url:
                    lang_row.append({'value': lang.latest_version.url,
                                     'class': '', 'type': 'link', 'href': lang.latest_version.url})
                else:
                    lang_row.append({'value': '', 'class': '', 'type': 'text'})

                if lang.latest_version.file_name:
                    lang_row.append({'value': lang.latest_version.file_name, 'class': '', 'type': 'text'})
                else:
                    lang_row.append({'value': '', 'class': '', 'type': 'text'})

                if lang.latest_version.file_type:
                    lang_row.append({'value': lang.latest_version.file_type, 'class': '', 'type': 'text'})
                else:
                    lang_row.append({'value': '', 'class': '', 'type': 'text'})
                    # Include other details as necessary

            languages_rows.append(lang_row)

        doc_row.append({'is_group': True, 'colspan': '5',
                        'headers': ['Language', 'Latest Version', 'URL', 'File Name', 'Type'],
                        'sub_rows': languages_rows})
        rows.append(doc_row)
    return rows