from django.shortcuts import render, get_object_or_404, redirect
from django.db.models import Q
from django.contrib.auth.decorators import login_required, user_passes_test
from django.utils.html import strip_tags
from .models import Assignment, Submission, Answer
import json
from .forms import AnswersForm, StudentRegistrationForm
from django.contrib.auth import login
def register(request):
    if request.user.is_authenticated:
        return redirect('lms:dashboard')
    if request.method == 'POST':
        form = StudentRegistrationForm(request.POST)
        if form.is_valid():
            user = form.save(commit=False)
            user.role = 'STUDENT'
            user.save()
            login(request, user)
            return redirect('lms:dashboard')
    else:
        form = StudentRegistrationForm()
    return render(request, 'lms/register.html', {'form': form})

def is_student(user):
    return user.is_authenticated and user.role == 'STUDENT'

def home(request):
    if request.user.is_authenticated:
        if getattr(request.user, 'role', None) == 'STUDENT':
            return redirect('lms:dashboard')
        else:
            return redirect('/admin/')
    return render(request, 'lms/home.html')

@login_required
@user_passes_test(is_student, login_url='/login/')
def dashboard(request):
    assignments = Assignment.objects.filter(
        Q(assign_to_all=True) | Q(assigned_students=request.user),
        is_published=True
    ).distinct().order_by('-created_at')
    
    # Check which ones the student has submitted
    submissions = Submission.objects.filter(student=request.user)
    submitted_assignment_ids = submissions.values_list('assignment_id', flat=True)

    from django.utils import timezone
    return render(request, 'lms/dashboard.html', {
        'assignments': assignments,
        'submitted_assignment_ids': submitted_assignment_ids,
        'submissions': {sub.assignment_id: sub for sub in submissions},
        'now': timezone.now()
    })

@login_required
@user_passes_test(is_student, login_url='/login/')
def assignment_detail(request, pk):
    assignment = get_object_or_404(Assignment, pk=pk, is_published=True)
    questions = assignment.questions.all()
    
    # Try to get existing submission
    submission = Submission.objects.filter(assignment=assignment, student=request.user).first()
    
    from django.utils import timezone
    can_submit = True
    if assignment.is_closed:
        can_submit = False
    if assignment.deadline and timezone.now() > assignment.deadline:
        can_submit = False

    if submission:
        if request.method == 'POST':
            # Do not allow updating
            return redirect('lms:dashboard')
        form = None
    else:
        if not can_submit:
            form = None
        elif request.method == 'POST':
            form = AnswersForm(request.POST, request.FILES, questions=questions)
            if form.is_valid():
                submission = Submission.objects.create(assignment=assignment, student=request.user)
                
                all_auto = True
                total_points = 0
                max_points = 0
                
                for q in questions:
                    answer_obj = Answer(submission=submission, question=q)
                    if q.question_type == 'TEXT_AUTO':
                        val = form.cleaned_data.get(f'answer_{q.id}', '')
                        answer_obj.text_answer = val
                        if q.correct_answer:
                            correct = strip_tags(q.correct_answer).strip().lower()
                            answer_obj.is_correct = (val.strip().lower() == correct)
                            answer_obj.points = 1 if answer_obj.is_correct else 0
                            total_points += answer_obj.points
                        else:
                            all_auto = False
                        max_points += 1
                    elif q.question_type == 'TABLE_AUTO':
                        rows = getattr(q, 'table_rows', 2) or 2
                        table_data = []
                        for i in range(1, rows + 1):
                            val1 = form.cleaned_data.get(f'answer_{q.id}_r{i}_c1', '')
                            val2 = form.cleaned_data.get(f'answer_{q.id}_r{i}_c2', '')
                            table_data.append([val1, val2])
                        answer_obj.text_answer = json.dumps(table_data)
                        if q.correct_answer:
                            correct_rows = q.correct_answer.split(';')
                            is_correct = True
                            if len(correct_rows) != rows:
                                is_correct = False
                            else:
                                for i, row in enumerate(correct_rows):
                                    cols = row.split('|')
                                    if len(cols) == 2:
                                        if cols[0].strip().lower() != table_data[i][0].strip().lower() or cols[1].strip().lower() != table_data[i][1].strip().lower():
                                            is_correct = False
                                            break
                                    else:
                                        is_correct = False
                                        break
                            answer_obj.is_correct = is_correct
                            answer_obj.points = 1 if is_correct else 0
                            total_points += answer_obj.points
                        else:
                            all_auto = False
                        max_points += 1
                    else:
                        all_auto = False
                        val = form.cleaned_data.get(f'file_{q.id}')
                        if val:
                            answer_obj.file_answer = val
                    answer_obj.save()
                    
                if all_auto and max_points > 0:
                    submission.status = 'GRADED'
                    submission.grade = f"{total_points}/{max_points}"
                else:
                    submission.status = 'PENDING'
                submission.save()
                return redirect('lms:dashboard')
        else:
            form = AnswersForm(questions=questions)
        
    question_fields = []
    if form:
        for q in questions:
            if q.question_type == 'TEXT_AUTO':
                question_fields.append((q, 'text', form[f'answer_{q.id}']))
            elif q.question_type == 'TABLE_AUTO':
                rows = getattr(q, 'table_rows', 2) or 2
                table_fields = []
                for i in range(1, rows + 1):
                    table_fields.append([form[f'answer_{q.id}_r{i}_c1'], form[f'answer_{q.id}_r{i}_c2']])
                question_fields.append((q, 'table', table_fields))
            else:
                question_fields.append((q, 'file', form[f'file_{q.id}']))

    return render(request, 'lms/assignment_detail.html', {
        'assignment': assignment,
        'form': form,
        'submission': submission,
        'questions': questions,
        'question_fields': question_fields,
        'can_submit': can_submit,
    })