"""Tests für layout.first_fit (BUG-04).

Behauptung: Add-Item darf bestehende Items NICHT verschieben.
- Leeres Layout → Add 2×2 hello → Position (0,0), kein Pack
- Layout mit Lücke → Add 1×1 hello → landet in erster Lücke, andere bleiben
- Layout voll → Add → None, kein anderes Item verändert
"""
import os, sys
sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

import unittest
from layout import Item, first_fit, GRID_COLS, GRID_ROWS


class TestFirstFit(unittest.TestCase):
    def test_first_fit_empty_grid(self):
        """Auf leerem Grid wird Item bei (0,0) platziert — kein Pack nötig."""
        new_item = Item("new1", "hello", 0, 0, 1, 1)
        placed = first_fit(new_item, [])
        self.assertIsNotNone(placed)
        self.assertEqual((placed.x, placed.y), (0, 0))

    def test_first_fit_does_not_move_existing(self):
        """Items mit Lücke: hello wird in Lücke gesetzt, andere bleiben."""
        existing = [
            Item("a", "clock",   0, 0, 2, 2),
            Item("b", "weather", 2, 0, 2, 2),
            Item("c", "system",  0, 2, 2, 2),
            Item("d", "spotify", 2, 2, 2, 1),
        ]
        before = {(it.id, it.x, it.y) for it in existing}
        new_item = Item("new", "hello", 0, 0, 1, 1)
        placed = first_fit(new_item, existing)
        self.assertIsNotNone(placed)
        after = {(it.id, it.x, it.y) for it in existing}
        self.assertEqual(before, after, f"EXISTING MOVED! before={before} after={after}")
        self.assertEqual((placed.x, placed.y), (2, 3))

    def test_first_fit_full_grid_returns_none(self):
        """Wenn kein Platz: None zurück, keine Mutation."""
        existing = [
            Item("a", "x", 0, 0, 2, 2),
            Item("b", "y", 2, 0, 2, 2),
            Item("c", "z", 0, 2, 2, 2),
            Item("d", "w", 2, 2, 2, 2),
        ]
        before = {(it.id, it.x, it.y, it.w, it.h) for it in existing}
        new_item = Item("new", "hello", 0, 0, 1, 1)
        placed = first_fit(new_item, existing)
        self.assertIsNone(placed)
        after = {(it.id, it.x, it.y, it.w, it.h) for it in existing}
        self.assertEqual(before, after)


if __name__ == "__main__":
    unittest.main(verbosity=2)