@extends('layouts.side_bar')

@section('content')
<div class="container-fluid py-4">
    <div class="row justify-content-center">
        <div class="col-12 col-xl-10">
            <div class="card border-0 shadow-sm mb-4 bg-warning-subtle">
                <div class="card-body d-flex flex-wrap justify-content-between align-items-center gap-2 p-4">
                    <div>
                        <h2 class="h4 mb-1">Edit Course</h2>
                        <p class="text-secondary mb-0">Update course details, subjects, and lecturer mappings.</p>
                    </div>
                    <a href="{{ route('courses.show', $course) }}" class="btn btn-outline-secondary rounded-pill">View Course</a>
                </div>
            </div>

            <div class="card border-0 shadow-sm">
                <div class="card-body p-4 p-lg-5">
                    <form method="POST" action="{{ route('courses.update', $course) }}" class="row g-3 js-confirm-submit" data-swal-title="Save changes?" data-swal-text="Course details will be updated." data-swal-confirm="Yes, update" data-swal-icon="question">
                        @csrf
                        @method('PUT')

                        <div class="col-md-6">
                            <label for="title" class="form-label">Course Title</label>
                            <input id="title" type="text" name="title" value="{{ old('title', $course->title) }}" class="form-control border-2 border-secondary-subtle @error('title') is-invalid @enderror" required>
                            @error('title')
                                <div class="invalid-feedback">{{ $message }}</div>
                            @enderror
                        </div>

                        <div class="col-md-6">
                            <label for="course_code_preview" class="form-label">Course Code</label>
                            <input id="course_code_preview" type="text" class="form-control border-2 border-secondary-subtle" value="{{ $course->course_code }}" readonly>
                            <small class="text-secondary">Auto-updates when course title changes.</small>
                        </div>

                        <div class="col-md-6">
                            <label for="price" class="form-label">Price</label>
                            <input id="price" type="number" step="0.01" min="0" name="price" value="{{ old('price', $course->price) }}" class="form-control border-2 border-secondary-subtle @error('price') is-invalid @enderror" required>
                            @error('price')
                                <div class="invalid-feedback">{{ $message }}</div>
                            @enderror
                        </div>

                        <div class="col-md-6">
                            <label for="status" class="form-label">Status</label>
                            <select id="status" name="status" class="form-select border-2 border-secondary-subtle @error('status') is-invalid @enderror" required>
                                <option value="active" {{ old('status', $course->status) === 'active' ? 'selected' : '' }}>Active</option>
                                <option value="inactive" {{ old('status', $course->status) === 'inactive' ? 'selected' : '' }}>Inactive</option>
                            </select>
                            @error('status')
                                <div class="invalid-feedback">{{ $message }}</div>
                            @enderror
                        </div>

                        <div class="col-12">
                            <label for="description" class="form-label">Description</label>
                            <textarea id="description" name="description" rows="3" class="form-control border-2 border-secondary-subtle @error('description') is-invalid @enderror">{{ old('description', $course->description) }}</textarea>
                            @error('description')
                                <div class="invalid-feedback">{{ $message }}</div>
                            @enderror
                        </div>

                        <div class="col-12">
                            <div class="d-flex justify-content-between align-items-center mb-2">
                                <label class="form-label mb-0">Subjects and Lecturers</label>
                                <button type="button" id="add-subject-row" class="btn btn-outline-primary btn-sm">Add Subject</button>
                            </div>
                            @error('subjects')
                                <div class="text-danger small mb-2">{{ $message }}</div>
                            @enderror
                            <div id="subject-rows" class="d-flex flex-column gap-2"></div>
                        </div>

                        <div class="col-12 d-flex gap-2 pt-2">
                            <button type="submit" class="btn btn-primary rounded-pill px-4">Update</button>
                            <a href="{{ route('courses.index') }}" class="btn btn-outline-secondary">Cancel</a>
                        </div>
                    </form>
                </div>
            </div>
        </div>
    </div>
</div>
@endsection

@push('scripts')
<script>
    document.addEventListener('DOMContentLoaded', function () {
        const titleInput = document.getElementById('title');
        const codeInput = document.getElementById('course_code_preview');
        const currentNumber = Number(@json($course->id));
        const subjects = @json($subjects);
        const lecturersBySubject = @json($lecturersBySubject);
        const initialRows = @json(old('subjects', $selectedSubjects));
        const rowsContainer = document.getElementById('subject-rows');
        const addButton = document.getElementById('add-subject-row');

        function buildCode(title, number) {
            let letters = String(title || '').replace(/[^a-zA-Z]/g, '').toUpperCase();
            if (!letters) letters = 'CRS';
            let noVowels = letters.replace(/[AEIOU]/g, '');
            let prefix = (noVowels || letters).slice(0, 3);
            if (prefix.length < 3) prefix = prefix.padEnd(3, 'X');
            return prefix + String(number).padStart(3, '0');
        }

        function subjectOptions(selectedValue) {
            return ['<option value="">Select subject</option>'].concat(subjects.map(function (subject) {
                const selected = String(subject.id) === String(selectedValue) ? 'selected' : '';
                return '<option value="' + subject.id + '" ' + selected + '>' + (subject.subject_code || '') + ' - ' + subject.name + '</option>';
            })).join('');
        }

        function lecturerOptions(subjectId, selectedValue) {
            const lecturers = lecturersBySubject[String(subjectId)] || [];
            const items = ['<option value="">Select lecturer</option>'];

            lecturers.forEach(function (lecturer) {
                const selected = String(lecturer.id) === String(selectedValue) ? 'selected' : '';
                items.push('<option value="' + lecturer.id + '" ' + selected + '>' + lecturer.name + '</option>');
            });

            return items.join('');
        }

        function addRow(rowData) {
            const index = rowsContainer.children.length;
            const wrapper = document.createElement('div');
            wrapper.className = 'row g-2 align-items-end border rounded p-2';

            wrapper.innerHTML = '' +
                '<div class="col-md-5">' +
                    '<label class="form-label">Subject</label>' +
                    '<select name="subjects[' + index + '][subject_id]" class="form-select border-2 border-secondary-subtle js-subject-select" required>' +
                        subjectOptions(rowData.subject_id || '') +
                    '</select>' +
                '</div>' +
                '<div class="col-md-5">' +
                    '<label class="form-label">Lecturer</label>' +
                    '<select name="subjects[' + index + '][lecturer_id]" class="form-select border-2 border-secondary-subtle js-lecturer-select" required></select>' +
                '</div>' +
                '<div class="col-md-2 d-grid">' +
                    '<button type="button" class="btn btn-outline-danger js-remove-row">Remove</button>' +
                '</div>';

            rowsContainer.appendChild(wrapper);

            const subjectSelect = wrapper.querySelector('.js-subject-select');
            const lecturerSelect = wrapper.querySelector('.js-lecturer-select');

            function refreshLecturers() {
                if (subjectSelect.value) {
                    lecturerSelect.innerHTML = lecturerOptions(subjectSelect.value, rowData.lecturer_id || '');
                    rowData.lecturer_id = '';
                } else {
                    lecturerSelect.innerHTML = '<option value="">Select subject first</option>';
                }
            }

            refreshLecturers();

            subjectSelect.addEventListener('change', function () {
                rowData.lecturer_id = '';
                lecturerSelect.innerHTML = lecturerOptions(subjectSelect.value, '');
            });

            wrapper.querySelector('.js-remove-row').addEventListener('click', function () {
                wrapper.remove();
            });
        }

        function renderInitialRows() {
            if (!initialRows.length) {
                addRow({subject_id: '', lecturer_id: ''});
                return;
            }

            initialRows.forEach(function (row) {
                addRow(row || {subject_id: '', lecturer_id: ''});
            });
        }

        function updatePreview() {
            codeInput.value = buildCode(titleInput.value, currentNumber);
        }

        updatePreview();
        titleInput.addEventListener('input', updatePreview);
        addButton.addEventListener('click', function () {
            addRow({subject_id: '', lecturer_id: ''});
        });

        renderInitialRows();
    });
</script>
@endpush