import ast
import os
from datetime import datetime as dt, timezone as tz

import chardet
from flask import request, redirect, 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 minio.error import S3Error

from common.models.document import Document, DocumentVersion
from common.extensions import db, minio_client
from .document_forms import AddDocumentForm, AddURLForm, EditDocumentForm, EditDocumentVersionForm, AddYoutubeForm, \
    AddURLsForm
from common.utils.middleware import mw_before_request
from common.utils.celery_utils import current_celery
from common.utils.nginx_utils import prefixed_url_for
from common.utils.view_assistants import form_validation_failed, prepare_table_for_macro, form_to_dict

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


@document_bp.before_request
def log_before_request():
    current_app.logger.debug(f"Before request (document_bp): {request.method} {request.url}")


@document_bp.after_request
def log_after_request(response):
    current_app.logger.debug(
        f"After request  (document_bp): {request.method} {request.url} - Status: {response.status}")
    return response


@document_bp.before_request
def before_request():
    try:
        mw_before_request()
    except Exception as e:
        current_app.logger.error(f'Error switching schema in Document Blueprint: {e}')
        for role in current_user.roles:
            current_app.logger.debug(f'User {current_user.email} has role {role.name}')
        raise


@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 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()
        form_dict = form_to_dict(form)

        new_doc, new_doc_vers = create_document_stack(form_dict, 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}')
        flash(f'Processing on document {new_doc.name}, version {new_doc_vers.id} started. Task ID: {task.id}.',
              'success')

        return redirect(prefixed_url_for('document_bp.documents'))
    else:
        form_validation_failed(request, form)

    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 form.validate_on_submit():
        current_app.logger.info(f'Adding url for tenant {session["tenant"]["id"]}')
        url = form.url.data

        doc_vers = DocumentVersion.query.filter_by(url=url).all()
        if doc_vers:
            current_app.logger.info(f'A document with url {url} already exists. No new document created.')
            flash(f'A document with url {url} already exists. No new document created.', 'info')
            return redirect(prefixed_url_for('document_bp.documents'))
        # Only when no document with URL exists
        html = fetch_html(url)
        file = io.BytesIO(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'
        form_dict = form_to_dict(form)

        new_doc, new_doc_vers = create_document_stack(form_dict, 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}')
        flash(f'Processing on document {new_doc.name}, version {new_doc_vers.id} started. Task ID: {task.id}.',
              'success')

        return redirect(prefixed_url_for('document_bp.documents'))
    else:
        form_validation_failed(request, form)

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


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

    if form.validate_on_submit():
        urls = form.urls.data.split('\n')
        urls = [url.strip() for url in urls if url.strip()]

        for i, url in enumerate(urls):
            try:
                doc_vers = DocumentVersion.query.filter_by(url=url).all()
                if doc_vers:
                    current_app.logger.info(f'A document with url {url} already exists. No new document created.')
                    flash(f'A document with url {url} already exists. No new document created.', 'info')
                    continue

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

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

                # Use the name prefix if provided, otherwise use the filename
                doc_name = f"{form.name.data}-{filename}" if form.name.data else filename

                new_doc, new_doc_vers = create_document_stack({
                    'name': doc_name,
                    'url': url,
                    'language': form.language.data,
                    'user_context': form.user_context.data,
                    'valid_from': form.valid_from.data
                }, file, filename, 'html')

                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}')
                flash(f'Processing on document {new_doc.name}, version {new_doc_vers.id} started. Task ID: {task.id}.',
                      'success')

            except Exception as e:
                current_app.logger.error(f"Error processing URL {url}: {str(e)}")
                flash(f'Error processing URL {url}: {str(e)}', 'danger')

        return redirect(prefixed_url_for('document_bp.documents'))
    else:
        form_validation_failed(request, form)

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

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

    if form.validate_on_submit():
        current_app.logger.info(f'Adding Youtube document for tenant {session["tenant"]["id"]}')
        url = form.url.data
        current_app.logger.debug(f'Value of language field: {form.language.data}')

        doc_vers = DocumentVersion.query.filter_by(url=url).all()
        if doc_vers:
            current_app.logger.info(f'A document with url {url} already exists. No new document created.')
            flash(f'A document with url {url} already exists. No new document created.', 'info')
            return redirect(prefixed_url_for('document_bp.documents'))
        # As downloading a Youtube document can take quite some time, we offload this downloading to the worker
        # We just pass a simple file to get things conform
        file = "Youtube placeholder file"

        filename = 'placeholder.youtube'
        extension = 'youtube'
        form_dict = form_to_dict(form)
        current_app.logger.debug(f'Form data: {form_dict}')

        new_doc, new_doc_vers = create_document_stack(form_dict, 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'Processing and Embedding on Youtube document started for tenant '
                                f'{session["tenant"]["id"]}, '
                                f'Document Version {new_doc_vers.id}. '
                                f'Processing and Embedding Youtube task: {task.id}')
        flash(f'Processing on Youtube document {new_doc.name}, version {new_doc_vers.id} started. Task ID: {task.id}.',
              'success')

        return redirect(prefixed_url_for('document_bp.documents'))
    else:
        form_validation_failed(request, form)

    return render_template('document/add_youtube.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))

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

    rows = prepare_table_for_macro(docs, [('id', ''), ('name', ''), ('valid_from', ''), ('valid_to', '')])

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


@document_bp.route('/handle_document_selection', methods=['POST'])
@roles_accepted('Super User', 'Tenant Admin')
def handle_document_selection():
    document_identification = request.form['selected_row']
    doc_id = ast.literal_eval(document_identification).get('value')

    action = request.form['action']

    match action:
        case 'edit_document':
            return redirect(prefixed_url_for('document_bp.edit_document', document_id=doc_id))
        case 'document_versions':
            return redirect(prefixed_url_for('document_bp.document_versions', document_id=doc_id))
        case 'refresh_document':
            refresh_document(doc_id)
            return redirect(prefixed_url_for('document_bp.document_versions', document_id=doc_id))
        case 're_embed_latest_versions':
            re_embed_latest_versions()

    # Add more conditions for other actions
    return redirect(prefixed_url_for('document_bp.documents'))


@document_bp.route('/edit_document/<int:document_id>', methods=['GET', 'POST'])
@roles_accepted('Super User', 'Tenant Admin')
def edit_document(document_id):
    doc = Document.query.get_or_404(document_id)
    form = EditDocumentForm(obj=doc)

    if form.validate_on_submit():
        doc.name = form.name.data
        doc.valid_from = form.valid_from.data
        doc.valid_to = form.valid_to.data

        update_logging_information(doc, dt.now(tz.utc))

        try:
            db.session.add(doc)
            db.session.commit()
            flash(f'Document {doc.id} updated successfully', 'success')
        except SQLAlchemyError as e:
            db.session.rollback()
            flash(f'Error updating document: {e}', 'danger')
            current_app.logger.error(f'Error updating document: {e}')
    else:
        form_validation_failed(request, form)

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


@document_bp.route('/edit_document_version/<int:document_version_id>', methods=['GET', 'POST'])
@roles_accepted('Super User', 'Tenant Admin')
def edit_document_version(document_version_id):
    doc_vers = DocumentVersion.query.get_or_404(document_version_id)
    form = EditDocumentVersionForm(obj=doc_vers)

    if form.validate_on_submit():
        doc_vers.user_context = form.user_context.data

        update_logging_information(doc_vers, dt.now(tz.utc))

        try:
            db.session.add(doc_vers)
            db.session.commit()
            flash(f'Document Version {doc_vers.id} updated successfully', 'success')
        except SQLAlchemyError as e:
            db.session.rollback()
            flash(f'Error updating document version: {e}', 'danger')
            current_app.logger.error(f'Error updating document version {doc_vers.id} '
                                     f'for tenant {session['tenant']['id']}: {e}')
    else:
        form_validation_failed(request, form)

    return render_template('document/edit_document_version.html', form=form, document_version_id=document_version_id,
                           doc_details=f'Document {doc_vers.document.name}')


@document_bp.route('/document_versions/<int:document_id>', methods=['GET', 'POST'])
@roles_accepted('Super User', 'Tenant Admin')
def document_versions(document_id):
    doc_vers = DocumentVersion.query.get_or_404(document_id)
    doc_desc = f'Document {doc_vers.document.name}, Language {doc_vers.language}'

    page = request.args.get('page', 1, type=int)
    per_page = request.args.get('per_page', 10, type=int)

    query = (DocumentVersion.query.filter_by(doc_id=document_id)
             .order_by(DocumentVersion.language)
             .order_by(desc(DocumentVersion.id)))

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

    rows = prepare_table_for_macro(doc_langs, [('id', ''), ('url', ''), ('file_location', ''),
                                               ('file_name', ''), ('file_type', ''),
                                               ('processing', ''), ('processing_started_at', ''),
                                               ('processing_finished_at', ''), ('processing_error', '')])

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


@document_bp.route('/handle_document_version_selection', methods=['POST'])
@roles_accepted('Super User', 'Tenant Admin')
def handle_document_version_selection():
    document_version_identification = request.form['selected_row']
    doc_vers_id = ast.literal_eval(document_version_identification).get('value')

    action = request.form['action']

    match action:
        case 'edit_document_version':
            return redirect(prefixed_url_for('document_bp.edit_document_version', document_version_id=doc_vers_id))
        case 'process_document_version':
            process_version(doc_vers_id)
            # Add more conditions for other actions

    doc_vers = DocumentVersion.query.get_or_404(doc_vers_id)
    return redirect(prefixed_url_for('document_bp.document_versions', document_id=doc_vers.doc_id))


@document_bp.route('/library_operations', methods=['GET', 'POST'])
@roles_accepted('Super User', 'Tenant Admin')
def library_operations():
    return render_template('document/library_operations.html')


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

    match action:
        case 're_embed_latest_versions':
            re_embed_latest_versions()
        case 'refresh_all_documents':
            refresh_all_documents()

    return redirect(prefixed_url_for('document_bp.library_operations'))


def refresh_all_documents():
    for doc in Document.query.all():
        refresh_document(doc.id)


def refresh_document(doc_id):
    doc = Document.query.get_or_404(doc_id)
    doc_vers = DocumentVersion.query.filter_by(doc_id=doc_id).order_by(desc(DocumentVersion.id)).first()
    if not doc_vers.url:
        current_app.logger.info(f'Document {doc_id} has no URL, skipping refresh')
        flash(f'This document has no URL. I can only refresh documents with a URL. skipping refresh', 'alert')
        return

    new_doc_vers = create_version_for_document(doc, doc_vers.url, doc_vers.language, doc_vers.user_context)

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

    html = fetch_html(new_doc_vers.url)
    file = io.BytesIO(html)

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

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

    upload_file_for_version(new_doc_vers, file, 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}')
    flash(f'Processing on document {doc.name}, version {new_doc_vers.id} started. Task ID: {task.id}.',
          'success')


def re_embed_latest_versions():
    docs = Document.query.all()
    for doc in docs:
        latest_doc_version = DocumentVersion.query.filter_by(doc_id=doc.id).order_by(desc(DocumentVersion.id)).first()
        if latest_doc_version:
            process_version(latest_doc_version.id)


def process_version(version_id):
    task = current_celery.send_task('create_embeddings', queue='embeddings', args=[
        session['tenant']['id'],
        version_id,
    ])
    current_app.logger.info(f'Embedding creation retriggered by user {current_user.id}, {current_user.email} '
                            f'for tenant {session["tenant"]["id"]}, '
                            f'Document Version {version_id}. '
                            f'Embedding creation task: {task.id}')

    flash(f'Processing for document version {version_id} retriggered successfully...', 'success')

    return redirect(prefixed_url_for('document_bp.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 update_logging_information(obj, timestamp):
    obj.updated_at = timestamp
    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 DocumentVersion
    new_doc_vers = create_version_for_document(new_doc,
                                               form.get('url', ''),
                                               form.get('language', 'en'),
                                               form.get('user_context', '')
                                               )

    try:
        db.session.add(new_doc)
        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.', 'alert')
        db.session.rollback()
        error = e.args
        raise
    except Exception as e:
        current_app.logger.error('Unknown error')
        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_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'] == '':
        new_doc.name = filename.rsplit('.', 1)[0]
    else:
        new_doc.name = form['name']

    if form['valid_from'] and form['valid_from'] != '':
        new_doc.valid_from = form['valid_from']
    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_version_for_document(document, url, language, user_context):
    new_doc_vers = DocumentVersion()
    if url != '':
        new_doc_vers.url = url

    if language == '':
        new_doc_vers.language = session['default_language']
    else:
        new_doc_vers.language = language

    if user_context != '':
        new_doc_vers.user_context = user_context

    new_doc_vers.document = document

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

    return new_doc_vers


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()

    # Normally, the tenant bucket should exist. But let's be on the safe side if a migration took place.
    tenant_id = session['tenant']['id']
    minio_client.create_tenant_bucket(tenant_id)

    try:
        minio_client.upload_document_file(
            tenant_id,
            doc_vers.doc_id,
            doc_vers.language,
            doc_vers.id,
            doc_vers.file_name,
            file
        )
        db.session.commit()
        current_app.logger.info(f'Successfully saved document to MinIO for tenant {tenant_id} for '
                                f'document version {doc_vers.id} while uploading file.')
    except S3Error as e:
        db.session.rollback()
        flash('Error saving document to MinIO.', 'error')
        current_app.logger.error(
            f'Error saving document to MinIO for tenant {tenant_id}: {e}')
        raise
    except SQLAlchemyError as e:
        db.session.rollback()
        flash('Error saving document metadata.', 'error')
        current_app.logger.error(
            f'Error saving document metadata for tenant {tenant_id}: {e}')
        raise


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.content


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