from functools import wraps
from flask_login import login_required, login_user, logout_user
from app.bp import bp
from flask import jsonify, request
from app.errors import error_response
from flask_login import current_user

from app import login, db
from app.models import Course, User, Assignment


@login.user_loader
def load_user(user_id):
    return User.query.get(user_id)


def check_data(data, required_fields):
    for f in required_fields:
        if f not in data:
            return f
    return None


def instructor_required(func):
    @wraps(func)
    def dec(*args, **kwargs):
        if current_user.role != "instructor":
            return error_response(400, "User is not instructor!")
        return func(*args, **kwargs)

    return dec


@bp.route("/login", methods=["POST"])
def login_route():
    data = request.get_json()

    if current_user.is_authenticated:
        return error_response(400, "A user is already logged in!")

    if not data.get("username") or not data.get("password"):
        return error_response(400, "Must supply username and password")

    user = User.query.filter_by(username=data["username"]).first()
    if not user:
        return error_response(400, "User not found")

    if not user.check_password(data.get("password")):
        return error_response(400, "Invalid password")

    login_user(user)
    resp = jsonify(user.to_dict())
    return resp


@bp.route("/logout", methods=["POST"])
@login_required
def logout_route():
    resp = jsonify(current_user.to_dict())
    logout_user()
    return resp


@bp.route("/register", methods=["POST"])
def register():
    data = request.get_json()
    required_fields = ["role", "username", "email", "password", "password2"]
    if f := check_data(data, required_fields):
        return error_response(400, f"Must supply {f}")

    if User.query.filter_by(username=data["username"]).first():
        return error_response(409, "User with that username already exists")

    if User.query.filter_by(email=data["email"]).first():
        return error_response(409, "User with that email already exists")

    u = User()
    u.from_dict(data, new_user=True)
    db.session.add(u)
    db.session.commit()

    resp = jsonify(u.to_dict())
    return resp


@bp.route("/course", methods=["POST"])
@login_required
def create_course():
    data = request.get_json()

    required_fields = ["name", "course_code", "description", "instructor"]

    if f := check_data(data, required_fields):
        return error_response(400, f"Must supply {f}")

    u = User.query.get(data["instructor"])
    if not u:
        return error_response(400, f"User with id {data['instructor']} does not exist")

    c = Course.query.filter_by(course_code=data["course_code"]).first()
    if c:
        return error_response(
            400, f"Course with course code {data['course_code']} already exists"
        )

    if u.role != "instructor":
        return error_response(400, "User is not instructor")

    c = Course()
    c.from_dict(data)
    u.enroll(c)
    db.session.add(c)
    db.session.commit()

    return jsonify(c.to_dict())


@bp.route("/user/<int:id>/courses", methods=["GET"])
@login_required
def get_courses(id):
    u = User.query.get(id)
    d = {"courses": []}
    for c in u.enrolled_courses.all():
        d["courses"].append(c.to_dict())
    resp = jsonify(d)
    return resp


@bp.route("/course/<int:id>/students", methods=["GET"])
@login_required
def get_students_in_course(id):
    c = Course.query.get(id)
    if not c:
        return error_response(400, f"course with id {id} not found")

    students = c.students.filter_by(role="student")
    resp = {"students": []}
    for s in students:
        resp["students"].append(s.to_dict())
    return jsonify(resp)

@bp.route("/course/<int:id>/assignments", methods=["GET"])
@login_required
def get_assignments_in_course(id):
    c = Course.query.get(id)
    if not c:
        return error_response(400, f"course with id {id} not found")

    assignments = c.assignments.all()
    resp = {"assignments": []}
    for a in assignments:
        resp["assignments"].append(a.to_dict())
    return jsonify(resp)


@bp.route("/course/<int:id>", methods=["GET"])
@login_required
def get_course(id):
    c = Course.query.get(id)
    if not c:
        return error_response(400, f"course with id {id} not found")
    resp = jsonify(c.to_dict())
    return resp


@bp.route("/user/<int:uid>/enroll/<int:cid>", methods=["POST", "DELETE"])
@login_required
@instructor_required
def enroll_student(uid, cid):
    u = User.query.get(uid)
    if not u:
        return error_response(400, f"User with id {uid} does not exist")

    c = Course.query.get(cid)
    if not c:
        return error_response(400, f"Course with id {cid} does not exist")

    if request.method == "POST":
        if not u.enroll(c):
            return error_response(
                400, f"User {uid} is already enrolled in course {cid}"
            )

    elif request.method == "DELETE":
        if not u.unenroll(c):
            return error_response(400, f"User {uid} is not enrolled in course {cid}")

    resp = {"user": u.to_dict(), "course": c.to_dict()}
    return jsonify(resp)


@bp.route("/user/<string:username>/enroll/<int:cid>", methods=["POST"])
@login_required
@instructor_required
def enroll_student_by_username(username, cid):
    u = User.query.filter_by(username=username).first()
    if not u:
        return error_response(400, f"User with username {username} does not exist")

    c = Course.query.get(cid)
    if not c:
        return error_response(400, f"Course with id {cid} does not exist")

    if request.method == "POST":
        if not u.enroll(c):
            return error_response(
                400, f"User {u.id} is already enrolled in course {cid}"
            )

    elif request.method == "DELETE":
        if not u.unenroll(c):
            return error_response(400, f"User {u.id} is not enrolled in course {cid}")

    resp = {"user": u.to_dict(), "course": c.to_dict()}
    return jsonify(resp)


@bp.route("/assignment", methods=["POST"])
@login_required
@instructor_required
def create_assignment():
    data = request.get_json()
    required_fields = ["name", "description", "course_id", "due_date"]
    if f := check_data(data, required_fields):
        return error_response(400, f"Must supply {f}")

    c = Course.query.get(data["course_id"])
    if not c:
        return error_response(400, f"Course with id {data['course_id']} does not exist")

    a = Assignment()
    a.from_dict(data)
    db.session.add(a)
    db.session.commit()
    return jsonify(a.to_dict())

@bp.route("/assignment/<int:id>", methods=["GET"])
@login_required
def get_assignment(id):
    a = Assignment.query.get(id)
    if not a:
        return error_response(400, f"Assignment with id {id} does not exist")

    return jsonify(a.to_dict())