# Migration from YAML to SQLite

## Overview

The Post-ERG thesis submission form has been completely overhauled to use a SQLite database instead of flat YAML files. This provides better data integrity, querying capabilities, and prepares the system for a full-featured web application.

## What Changed

### Database Implementation

**Before:** Form data was saved as individual YAML files in `data/yaml/`, with file uploads scattered in `data/content/` and `data/cover/`.

**After:** All thesis data is now stored in a relational SQLite database (`../db/posterg.db`) with proper normalization and foreign key relationships.

### New Architecture

```
Form Submission Flow:
1. User fills out enhanced form (index.php)
2. Form validates input and begins database transaction
3. Creates/links: author, thesis, supervisors, keywords, languages, formats
4. Uploads files with random names for security
5. Records file metadata in database
6. Commits transaction (all-or-nothing)
7. Redirects to confirmation page showing database data
```

### Database Schema Highlights

- **19 tables** including junction tables and views
- **Normalized structure** (3rd Normal Form)
- **Automatic timestamps** via triggers
- **Cascade deletes** for referential integrity
- **Predefined lookup tables** for orientations, AP programs, finalities, etc.
- **Views** for simplified querying (v_theses_full, v_theses_public)

## New Files

### `Database.php`
Database helper class providing:
- PDO connection with error handling
- Transaction management
- Find-or-create methods for entities
- Prepared statement helpers
- Lookup methods for all reference data

**Key Methods:**
```php
$db = new Database();
$authorId = $db->findOrCreateAuthor($name, $email);
$keywordId = $db->findOrCreateKeyword($keyword);
$orientations = $db->getAllOrientations();
$thesis = $db->getThesis($id);
```

## Modified Files

### `index.php`
**Enhancements:**
- Dynamically loads form options from database
- Added required fields per schema:
  - Subtitle (optional)
  - Synopsis (~200 words, required)
  - Finality (Approfondi/Enseignement/Spécialisé)
  - Languages (multiple selection with checkboxes)
  - Formats (multiple selection with checkboxes)
- Better form organization with sections
- Improved accessibility (proper labels, IDs)

**New Form Fields:**
| Field | Type | Required | Notes |
|-------|------|----------|-------|
| Subtitle | Text | No | New field |
| Synopsis | Textarea | Yes | ~200 words |
| Finality | Select | Yes | From finality_types table |
| Languages | Checkboxes | Yes | Multiple selection |
| Formats | Checkboxes | No | Multiple selection |

### `formulaire.php`
**Complete rewrite** with:

1. **Transaction-Based Processing:**
   - `BEGIN TRANSACTION` at start
   - All insertions in single transaction
   - `COMMIT` on success or `ROLLBACK` on error
   - Ensures data consistency

2. **Prepared Statements:**
   - All SQL queries use PDO prepared statements
   - Protection against SQL injection
   - Parameter binding for all user input

3. **Entity Creation:**
   - Finds or creates authors (by name)
   - Finds or creates supervisors (by name)
   - Finds or creates keywords (by text)
   - Links all entities via junction tables

4. **Identifier Generation:**
   - Format: `YYYY-NNN` (e.g., "2026-001")
   - Automatically increments per year
   - Unique constraint in database

5. **File Handling:**
   - Random cryptographic filenames (32 hex chars)
   - Organized by year and identifier: `data/theses/YYYY/YYYY-NNN/`
   - Cover images separate: `data/covers/`
   - Metadata stored in `thesis_files` table

6. **Validation:**
   - Year range: 2000 to current year + 1
   - Max 10 keywords enforced
   - At least one language required
   - URL format validation
   - File type and size validation

### `thanks.php`
**Complete redesign:**

- Reads from database using thesis ID
- Displays data from `v_theses_full` view
- Shows all relationships: authors, supervisors, keywords, languages, formats
- Lists uploaded files with metadata (type, size, date)
- Responsive CSS grid layout
- Publication status indicator

**Security:**
- Validates thesis ID (integer only)
- Uses prepared statements
- No path traversal vulnerability
- Error messages don't expose system details

## Database Files

### `../db/posterg.db`
Initialized SQLite database with:
- 19 tables (11 core, 5 junction, 3 reference)
- 2 views (v_theses_full, v_theses_public)
- Predefined data:
  - 15 orientations
  - 4 AP programs
  - 3 finality types
  - 2 languages (French, English)
  - 7 format types
  - 3 access types
  - 4 static pages

### Schema Documentation
See `../db/README.md` and `../db/SETUP.md` for complete documentation.

## Security Improvements Retained

All security improvements from the previous commit are preserved:

✅ CSRF protection with session tokens
✅ Input validation and sanitization
✅ Prepared statements (SQL injection protection)
✅ Random filenames for uploads
✅ File type and size validation
✅ MIME type checking
✅ Error logging without exposing paths
✅ Path traversal protection

## Data Mapping

### YAML to Database Mapping

| Old YAML Field | New Database Location | Notes |
|----------------|----------------------|-------|
| `auteurice` | `authors.name` | Normalized, reusable |
| `email` | `authors.email` | Now in authors table |
| `année` | `theses.year` | Integer field |
| `titre` | `theses.title` | Required |
| - | `theses.subtitle` | New field |
| `description` | `theses.synopsis` | Renamed for clarity |
| `problématique` | (not yet used) | Can be added to schema |
| `orientation` | `theses.orientation_id` | Foreign key to orientations |
| `ap` | `theses.ap_program_id` | Foreign key to ap_programs |
| - | `theses.finality_id` | New field (required) |
| `promoteurice` | `supervisors.name` + `thesis_supervisors` | Many-to-many |
| `tag` | `keywords.keyword` + `thesis_keywords` | Many-to-many, max 10 |
| `lien` | `theses.baiu_link` | URL validation |
| `files` | `thesis_files` table | Full metadata |
| `couverture` | (stored as file, not in DB yet) | Could add cover_path column |

## Migration Path for Existing Data

If you have existing YAML files to import:

1. **Parse YAML files:**
   ```php
   $yamlFiles = glob('data/yaml/*.yaml');
   foreach ($yamlFiles as $file) {
       $data = Yaml::parseFile($file);
       // ...
   }
   ```

2. **Insert into database:**
   ```php
   $db->beginTransaction();
   try {
       $authorId = $db->findOrCreateAuthor($data['auteurice'], $data['email']);
       // Insert thesis
       // Link relationships
       $db->commit();
   } catch (Exception $e) {
       $db->rollback();
   }
   ```

3. **Verify data:**
   ```sql
   SELECT COUNT(*) FROM theses;
   SELECT * FROM v_theses_full LIMIT 5;
   ```

## Testing Checklist

Before production deployment:

- [ ] Form loads without errors
- [ ] All dropdown options populate from database
- [ ] Form submission creates thesis record
- [ ] Author is created or found correctly
- [ ] Supervisors linked properly
- [ ] Keywords created and linked (test max 10)
- [ ] Languages required (test validation)
- [ ] Formats optional (test multiple selection)
- [ ] Files upload successfully
- [ ] File metadata recorded in database
- [ ] Thanks page displays all data correctly
- [ ] Transaction rollback works on error
- [ ] CSRF token validated
- [ ] Invalid data rejected (year, URL, etc.)

## Known Limitations

1. **No cover_path column:** Cover images uploaded but path not stored in `theses` table (can be added)
2. **No problématique field:** Old field not yet in schema (can be added to `theses.remarks` or new column)
3. **File type detection:** Basic (by extension), could be enhanced
4. **No duplicate detection:** Same thesis can be submitted multiple times
5. **No edit capability:** Once submitted, no UI to edit (admin interface needed)

## Next Steps

1. **Initialize production database:**
   ```bash
   cd /path/to/production/db
   sqlite3 posterg.db < schema.sql
   ```

2. **Set permissions:**
   ```bash
   chmod 644 posterg.db
   chown www-data:www-data posterg.db
   ```

3. **Test form submission:**
   - Submit test thesis
   - Verify all fields saved
   - Check file uploads
   - Test thanks page

4. **Import existing data:**
   - Create migration script
   - Parse old YAML files
   - Bulk insert into database
   - Verify integrity

5. **Build admin interface:**
   - CRUD operations for theses
   - User management
   - Approval workflow
   - Bulk operations

6. **Build public website:**
   - Search and filter theses
   - Respect access controls
   - Display thesis details
   - Static pages management

## Compatibility Notes

### PHP Requirements
- PHP 7.4+ (tested on PHP 8.x)
- PDO extension with SQLite support
- Composer for Symfony YAML (still used for potential migration)

### Database
- SQLite 3.8.0+
- File-based database (no server needed)
- Single file: `db/posterg.db`

### Dependencies
```json
{
    "require": {
        "symfony/yaml": "^6.2",
        "behat/transliterator": "^1.5"
    }
}
```

Note: YAML library retained for potential data migration from old files.

## Backup Strategy

SQLite database is a single file - easy to backup:

```bash
# Simple copy
cp db/posterg.db db/backups/posterg_$(date +%Y%m%d).db

# SQL dump (portable)
sqlite3 db/posterg.db .dump > backups/posterg_$(date +%Y%m%d).sql

# Compressed backup
tar -czf backups/posterg_$(date +%Y%m%d).tar.gz db/posterg.db data/
```

Set up automated daily backups via cron.

## Performance Considerations

- **Indexes:** All critical foreign keys and search fields indexed
- **Views:** Pre-computed joins for common queries
- **Transactions:** Ensure atomicity without locking issues
- **File I/O:** Random filenames prevent directory listing overhead

For large datasets (1000+ theses):
- Consider WAL mode: `PRAGMA journal_mode=WAL;`
- Optimize with `ANALYZE;` periodically
- Monitor database size and `VACUUM` if needed

## Rollback Plan

If issues arise, you can roll back to YAML-based system:

1. Use previous jj commit: `jj checkout <commit-id>`
2. Old YAML files in `data/yaml/` still intact
3. Database changes don't affect old YAML code
4. Can run both systems in parallel during transition

## Support

For questions or issues:
- Schema documentation: `db/README.md`
- Setup guide: `db/SETUP.md`
- Security details: `SECURITY.md`
- Technical specs: `db/posterg_fiche-technique.md`

---

**Migration completed:** 2026-01-27
**Database version:** 1.0
**Form version:** 2.0 (SQLite)