from flask import Blueprint, request, jsonify, g, url_for
from sqlalchemy import select, and_, func, distinct, or_
from sqlalchemy.exc import IntegrityError
from werkzeug.datastructures import MultiDict
import os
import uuid
import math
from config import DEFAULT_COURSE_COVER
from db.model import db, Course, Category, User, Chat, Enrollment
from utils.utils import random_string_generator, split_pdf_into_pages_with_text
from utils.auth import auth_required, requires_role
from constants import *
from config import *
from constants import PublishedStatus
from typing import Union
from db.model import UserRole

course = Blueprint('course', __name__)

@course.route('/listAll')
def list_all_courses():
    limit: int = int(request.args.get('limit', 10))
    offset: int = int(request.args.get('offset', 0))
    category_uuid: str = request.args.get('category_uuid')
    search_q: str = request.args.get('search_q', '').strip()
    sort_by: str = request.args.get('sort_by', '').strip()
    show_pending: bool = bool(int(request.args.get('show_pending', 0)))
    available_sorts = ['date_asc', 'date_desc', 'name_asc', 'name_desc', 'students_desc', 'students_asc']
    if category_uuid is not None:
        category_uuid: uuid.UUID = uuid.UUID(request.args.get('category_uuid'))
    # Build the query as required
    query: select = select(Course)
    if search_q != '':
        query = query.where(or_(Course.name.like(f'%{search_q}%'), Course.description.like(f'%{search_q}%'),
                                User.firstName.like(f'%{search_q}%')))
    if category_uuid is not None:
        query = query.where(Course.categoryID == category_uuid)
    if g.get('is_authed'):
        if show_pending and g.current_user.role == int(UserRole.ADMIN):
            query = query.where(Course.publishedStatus == int(PublishedStatus.PENDING))
    else:
        query = query.where(Course.publishedStatus == int(PublishedStatus.APPROVED))
    #total_pages_for_offset: int = db.session.execute(func.count(Course.id).select_from(Course)).scalar()/limit
    total_pages_for_offset: int = db.session.execute(
            select(func.count()).select_from(query.subquery())
        ).scalar() / limit

    query = query.limit(limit).offset(offset)
    total_pages: int = math.ceil(total_pages_for_offset)
    if sort_by in available_sorts:
        if sort_by == 'date_asc':
            query = query.order_by(Course.creationDate.asc())
        elif sort_by == 'date_desc':
            query = query.order_by(Course.creationDate.desc())
        elif sort_by == 'name_asc':
            query = query.order_by(Course.name.asc())
        elif sort_by == 'name_desc':
            query = query.order_by(Course.name.desc())
        elif sort_by == 'students_desc':
            query = query.order_by(Course.totalEnrolled.desc())
        elif sort_by == 'students_asc':
            query = query.order_by(Course.totalEnrolled.asc())
    courses: list[Course] = db.session.execute(query).scalars()
    course_list: list[dict] = []
    for item in courses:
        course_list.append(
            {
                'id': item.id,
                'name': item.name,
                'description': item.description,
                'isActive': item.isActive,
                'creationDate': item.creationDate,
                'coverImage': url_for('send_file', filename=item.coverImage),
                'totalEnrolled': item.totalEnrolled,
                'author': {
                    'id': item.author.id,
                    'firstName': item.author.firstName,
                    'lastName': item.author.lastName,
                    'username': item.author.username,
                    'bio': item.author.bio,
                    'lastOnline': item.author.lastOnline,
                    'pfpFilename': url_for('send_file', filename=item.author.pfpFilename)
                },
                'category': {
                    'id': item.categoryID,
                    'name': item.category.name,
                    'description': item.category.description
                }
            })
    return jsonify({
        'total_pages': total_pages,
        'current_offset': offset,
        'limit': limit,
        'data': course_list,
    })

@course.route('/enroll')
@auth_required()
def enroll_user():
    if not request.form.get('course_uuid'):
        return jsonify({'message': 'Missing required parameter "course_uuid" '}), 400
    course_uuid: uuid.UUID = uuid.UUID(request.form.get('course_uuid'))
    selected_course: Course = db.session.execute(select(Course).where(Course.id == course_uuid)).scalar()
    if not selected_course:
        return jsonify({'message': 'Course not found'}), 404
    new_enroll: Enrollment = Enrollment(
        userID=g.current_user.id,
        courseID=course_uuid
    )
    try:
        selected_course.totalEnrolled = selected_course.totalEnrolled + 1
        db.session.add(new_enroll)
        db.session.commit()
    except IntegrityError:
        return jsonify({'message': 'Already enrolled to this course'})
    return jsonify({'message': 'Enrollment successful'}), 200

@course.route('/createCourse', methods=['POST'])
@auth_required()
def create_course():
    form_data: dict  = request.form
    course_uploaded_cover_image: MultiDict|None = request.files.get('cover_image', None)
    course_uploaded_pdf: MultiDict|None = request.files.get('course_pdf', None)
    cover_file_name: str = DEFAULT_COURSE_COVER
    pdf_file_name: str = ''
    pdf_total_pages: int = 1
    if course_uploaded_cover_image is not None:
        cover_file_name: str = random_string_generator(32)+"."+course_uploaded_cover_image.filename.split('.')[-1]
        course_uploaded_cover_image.save(os.path.join(USER_UPLOADS_DIR, cover_file_name))
    if course_uploaded_pdf is not None:
        pdf_file_name: str = random_string_generator(32) +"."+ course_uploaded_pdf.filename.split('.')[-1]
        course_uploaded_pdf.save(os.path.join(USER_UPLOADS_DIR, pdf_file_name))

        pdf_parts_root_dir = os.path.join(USER_UPLOADS_DIR, pdf_file_name + "_parts")
        os.makedirs(pdf_parts_root_dir, exist_ok=True)
        pdf_total_pages = split_pdf_into_pages_with_text(
            pdf_path=os.path.join(USER_UPLOADS_DIR, pdf_file_name),
            output_directory=pdf_parts_root_dir
        )

    published_status: PublishedStatus = PublishedStatus.PENDING
    try:
        course_name: str = form_data['course_name']
    except KeyError:
        return jsonify({'message': 'Course name cannot be empty'}), 401
    course_description: str = form_data.get('course_description', '')
    category_id: uuid.UUID = uuid.UUID(form_data['category_uuid'])
    page_for_community: int = int(form_data.get('page_for_community', 1))  # TODO: Add this field to model
    category: Category = db.session.execute(select(Category).where(Category.id == category_id)).scalar()
    # author: User = db.session.execute(select(User).where(User.id == g.current_user.id)).scalar()
    new_course: Course = Course(
        name=course_name,
        categoryID=category_id,
        authorID=g.current_user.id,
        category=category,
        author=g.current_user,
        description=course_description,
        isActive=True,
        pageForCommunity=page_for_community,
        publishedStatus=int(published_status),
        coverImage=cover_file_name,
        serverFilename=pdf_file_name,
        totalPages=pdf_total_pages,
        enrollments=[],
        quizzes=[],
        chats=[]
    )

    # chat: Chat = Chat(courseID=new_course.id) TODO: Add a welcome chat for this course
    db.session.add(new_course)
    db.session.commit()
    return jsonify({'message': 'Course was created successfully.'}), 200

@course.route('/update', methods=['UPDATE', 'DELETE'])
@auth_required()
def update_course():
    form_data = request.form
    course_id: uuid.UUID = uuid.UUID(form_data['course_id'])
    selected_course: Course|None = None
    if g.current_user.role == int(UserRole.ADMIN):
        selected_course: Course = db.session.execute(select(Course).where(and_(
            Course.id == course_id
        ))).scalar()
    else:
        selected_course: Course = db.session.execute(select(Course).where(and_(
            Course.id == course_id, Course.publishedStatus != int(PublishedStatus.BANNED)
        ))).scalar()
    if not selected_course:
        return jsonify({'message': 'The course could not be found'}), 404
    if request.method == 'DELETE':
        if selected_course.authorID == g.current_user.id or g.current_user.role == int(UserRole.ADMIN):
            db.session.delete(selected_course)
            db.session.commit()
            return jsonify({'message': 'Course was deleted successfully'}), 200
        else:
            return jsonify({'message': 'Unauthorized for this change'}), 401
    else:
        # Update the data
        if selected_course.authorID == g.current_user.id or g.current_user.role == int(UserRole.ADMIN):
            if form_data.get('course_name'):
                selected_course.name = form_data.get('course_name')
            if form_data.get('course_description'):
                selected_course.description = form_data.get('course_description')
            if form_data.get('category_uuid'):
                selected_course.categoryID = uuid.UUID(form_data.get('category_uuid'))
            if form_data.get('isActive'):
                selected_course.isActive = bool(int(form_data.get('active')))

            # Admin Guarded
            if form_data.get('published_status'):
                if g.current_user.role != int(UserRole.ADMIN):
                    return jsonify({'message': 'Unauthorized'}), 401
                valid_states: list[int] = [
                    int(e) for e in
                    [PublishedStatus.APPROVED,
                     PublishedStatus.PENDING,
                     PublishedStatus.DECLINED,
                     PublishedStatus.REVOKED,
                     PublishedStatus.BANNED,
                     PublishedStatus.DRAFT]
                ]
                if int(form_data.get('published_status')) not in valid_states:
                    return jsonify({'message': 'Invalid state to update'}), 401
                selected_course.publishedStatus = int(form_data.get('published_status'))
            if request.files.get('cover_image'):
                cover_file_name: str = random_string_generator(32) + request.files.get('cover_image').filename.split('.')[-1]
                request.files.get('cover_image').save(os.path.join(USER_UPLOADS_DIR, cover_file_name))
                selected_course.coverImage = cover_file_name
            if request.files.get('course_pdf'):
                pdf_file_name: str = random_string_generator(32) + request.files.get('course_pdf').filename.split('.')[1]
                request.files.get('course_pdf').save(os.path.join(USER_UPLOADS_DIR, pdf_file_name))
                selected_course.serverFilename = pdf_file_name
            if g.current_user.role != int(UserRole.ADMIN):
                selected_course.publishedStatus = int(PublishedStatus.PENDING)
            db.session.commit()
            return jsonify({'message': 'Course info updated'}), 200
        else:
            return jsonify({'message': 'Unauthorized for this change'}), 401

@course.route('/info/<string:course_uuid>')
def course_info(course_uuid):
    course_uuid: uuid.UUID = uuid.UUID(course_uuid)
    selected_course: Course = db.session.execute(select(Course).where(and_(Course.id == course_uuid))).scalar()
    if not selected_course:
        return jsonify({'message': 'The course does not exist'}), 404
    # Only allow owner or admin to query info for course that is not published or is pending
    if not selected_course.isActive or selected_course.publishedStatus != int(PublishedStatus.APPROVED):
        if g.get("is_authed"):
            if g.current_user.role == int(UserRole.ADMIN) or g.current_user.id == selected_course.authorID:
                pass
            else:
                return jsonify({'message': 'The course does not exist.'}), 404
    self_enrollment_record: Union[None, Enrollment] = None
    self_enrollment_data: dict = {}
    if g.get("is_authed"):
        self_enrollment_record: Enrollment = db.session.execute(
            select(Enrollment).where(
                and_(
                    Enrollment.courseID == selected_course.id, Enrollment.userID == g.current_user.id
                )
            )
        )
        if self_enrollment_record:
            self_enrollment_data = {
                'lastActivity': self_enrollment_record.lastActivity,
                'currentPage': self_enrollment_record.currentPage,
                'maxPage': self_enrollment_record.maxPage,
                'joinedDate': self_enrollment_record.joinedDate,
                'userID': self_enrollment_record.userID
            }
    # Get total enrolled user and total unique user chatting about the course and put it in dict
    summary_user: dict = {
        'totalEnrolled': db.session.execute(
            select(func.count(Enrollment.id)).where(Enrollment.courseID == course_uuid)
        ).scalar(),

        'usersInChat': db.session.execute(
            select(func.count(distinct(Chat.userID))).select_from(Chat).where(Chat.courseID == course_uuid)
        ).scalar(),

        'totalChats': db.session.execute(
            select(func.count()).select_from(Chat).where(Chat.courseID == course_uuid)
        ).scalar()
    }
    pages: list = []
    if self_enrollment_record:
        for i in range(selected_course.totalPages):
            pages.append(
                url_for('get_pdf_file_as_pages',
                        filename=selected_course.serverFilename,
                        page=i + 1,
                        dtype='pdf')
            )
    else:
        if selected_course.totalPages < 3:
            pages.append(
                url_for('get_pdf_file_as_pages',
                        filename=selected_course.serverFilename,
                        page=1,
                        dtype='pdf')
            )
        else:
            for i in range(3):
                pages.append(
                    url_for('get_pdf_file_as_pages',
                            filename=selected_course.serverFilename,
                            page=i+1,
                            dtype='pdf')
                )
    return jsonify({
        'message': 'successful',
        'data': {
            'id':  selected_course.id,
            'courseName': selected_course.name,
            'courseDescription': selected_course.description,
            'isActive':  selected_course.isActive,
            'publishedStatus': selected_course.publishedStatus,
            'creationDate': selected_course.creationDate, # TODO: Format to particular structure
            'coverImage': url_for('send_file', filename=selected_course.coverImage),
            'serverFilename': url_for('send_file', filename=selected_course.serverFilename),
            'totalPages': 100,
            'author': {
                'id': selected_course.authorID,
                'username': selected_course.author.username,
                'firstName': selected_course.author.firstName,
                'lastName': selected_course.author.lastName,
                'pfpFilename': url_for('send_file', filename=selected_course.author.pfpFilename),
                'bio':  selected_course.author.bio
            },
            'selfEnrollment': {
                'isEnrolled': self_enrollment_record is not None,
                'data': self_enrollment_data
            },
            'enrollmentSummary':  summary_user
        }
    }), 200

@course.route('/getCategories', methods=['GET'])
def get_categories():
    categories: list[Category] = db.session.execute(select(Category)).scalars()
    cat_list: list[dict] = []
    for category in categories:
        cat_list.append(
            {
                'id': category.id,
                'name': category.name,
                'description': category.description,
                'isActive': category.isActive,
                'creationDate': category.creationDate
            }
        )
    return jsonify(cat_list), 200

@course.route('/createCategory', methods=['Post'])
@auth_required()
@requires_role([UserRole.ADMIN])
def create_category():
    try:
        new_cat: Category = Category(
        name=request.form['name'],
        description=request.form.get('description'),
        isActive=bool(int(request.form.get('isActive'))),
        courses=[]
        )
    except KeyError:
        return jsonify({'message': 'Missing required parameter "name" '}), 400
    db.session.add(new_cat)
    db.session.commit()
    return jsonify({'message': 'Category created'}), 201

@course.route('/updateCategory', methods=['POST', 'DELETE'])
@auth_required()
@requires_role([UserRole.ADMIN])
def update_category():
    form_data: dict = request.form
    try:
        category_id: uuid.UUID = uuid.UUID(form_data['category_id'])
    except KeyError:
        return jsonify({'message': 'Missing required parameter "category_id" '}), 400
    selected_category: Category = db.session.execute(select(Category).where(Category.id == category_id)).scalar()
    if not selected_category:
        return jsonify({'message': 'Category not found'}), 404
    if request.method == 'DELETE':
        db.session.delete(selected_category)
        db.session.commit()
        return jsonify({'message': 'Category deleted'}), 200
    else:
        if form_data.get('name'):
            selected_category.name = form_data.get('name')
        if form_data.get('description'):
            selected_category.description = form_data.get('description')
        if form_data.get('isActive'):
            selected_category.isActive = bool(int(form_data.get('isActive')))
        db.session.commit()
        return jsonify({'message': 'Category updated'}), 200

@course.route('/enrolled')
@auth_required()
def enrolled_courses():
    enrollments: Course = db.session.execute(
        select(Enrollment).where(
            and_(Enrollment.userID == g.current_user.id, Course.publishedStatus == int(PublishedStatus.APPROVED))
        )
    ).scalars()
    enrolled_list: list[dict] = []
    for enroll_row in enrollments:
        item = enroll_row.course
        enrolled_list.append(
            {
                'id': enroll_row.id,
                'course_id': enroll_row.courseID,
                'lastActivity': enroll_row.lastActivity,
                'currentPage': enroll_row.currentPage,
                'maxPage': enroll_row.maxPage,
                'joinedDate': enroll_row.joinedDate,
                'userID': enroll_row.userID,
                'name': item.name,
                'description': item.description,
                'isActive': item.isActive,
                'creationDate': item.creationDate,
                'coverImage': url_for('send_file', filename=item.coverImage),
                'totalEnrolled': item.totalEnrolled,
                'author': {
                    'id': item.author.id,
                    'firstName': item.author.firstName,
                    'lastName': item.author.lastName,
                    'username': item.author.username,
                    'bio': item.author.bio,
                    'lastOnline': item.author.lastOnline,
                    'pfpFilename': url_for('send_file', filename=item.author.pfpFilename)
                },
                'category': {
                    'id': item.categoryID,
                    'name': item.category.name,
                    'description': item.category.description
                }
            })

    return jsonify(enrolled_list), 200

@course.route('/myCourses')
@auth_required()
def my_courses():
    courses: Course = db.session.execute(select(Course).where(Course.authorID == g.current_user.id)
    ).scalars()
    course_list: list[dict] = []
    for item in courses:
        course_list.append(
            {
                'id': item.id,
                'name': item.name,
                'description': item.description,
                'isActive': item.isActive,
                'publishedStatus': item.publishedStatus,
                'creationDate': item.creationDate,
                'coverImage': url_for('send_file', filename=item.coverImage),
                'totalEnrolled': item.totalEnrolled,
                'author': {
                    'id': item.author.id,
                    'firstName': item.author.firstName,
                    'lastName': item.author.lastName,
                    'username': item.author.username,
                    'bio': item.author.bio,
                    'lastOnline': item.author.lastOnline,
                    'pfpFilename': url_for('send_file', filename=item.author.pfpFilename)
                },
                'category': {
                    'id': item.categoryID,
                    'name': item.category.name,
                    'description': item.category.description
                }
            })
    return jsonify(course_list), 200