feat: implement internship creation and company listing

backend/app/Http/Controllers/InternshipController.php

@@ -53,7 +53,59 @@ class InternshipController extends Controller
      */
     public function store(Request $request)
     {
-        //
+        $user = auth()->user();
+
+        $request->validate([
+            'company_id' => ['required', 'exists:companies,id'],
+            'start' => ['required', 'date'],
+            'end' => ['required', 'date', 'after:start'],
+            'year_of_study' => ['required', 'integer', 'between:1,5'],
+            'semester' => ['required', 'in:WINTER,SUMMER'],
+            'position_description' => ['required', 'string', 'min:1']
+        ]);
+
+        $request->merge([
+            'start' => date('Y-m-d H:i:s', strtotime($request->start)),
+            'end' => date('Y-m-d H:i:s', strtotime($request->end))
+        ]);
+
+        // je už nejaká prax ktorá sa časovo prekrýva?
+        $existingInternship = Internship::where('user_id', $user->id)
+            ->where(function ($query) use ($request) {
+                $query->whereBetween('start', [$request->start, $request->end])
+                    ->orWhereBetween('end', [$request->start, $request->end])
+                    ->orWhere(function ($q) use ($request) {
+                        $q->where('start', '<=', $request->start)
+                          ->where('end', '>=', $request->end);
+                    });
+            })
+            ->exists();
+        if ($existingInternship) {
+            return response()->json([
+                'message' => 'You already have an internship during this period.'
+            ], 422);
+        }
+
+        $Internship = Internship::create([
+            'user_id' => $user->id,
+            'company_id' => $request->company_id,
+            'start' => $request->start,
+            'end' => $request->end,
+            'year_of_study' => $request->year_of_study,
+            'semester' => $request->semester,
+            'position_description' => $request->position_description,
+            'agreement' => null
+        ]);
+
+        InternshipStatus::create([
+            'internship_id' => $Internship->id,
+            'status' => 'SUBMITTED',
+            'changed' => now(),
+            'note' => null,
+            'modified_by' => $user->id
+        ]);
+
+        return response()->noContent();
     }
 
     /**