<?php

declare(strict_types=1);

namespace BattleForge\Tests\Unit\Domain;

use BattleForge\Domain\Battlefield;
use BattleForge\Domain\CombatEngine;
use BattleForge\Domain\CombatException;
use BattleForge\Domain\MatchState;
use BattleForge\Domain\Position;
use BattleForge\Domain\UnitState;
use PHPUnit\Framework\TestCase;

final class CombatEngineTest extends TestCase
{
    public function testMatchAndUnitStateAreImmutable(): void
    {
        $unit = $this->unit('unit-1', 'alpha', new Position(0, 0));
        $match = new MatchState(new Battlefield(8, 8), [$unit], 'alpha');

        $moved = $unit->moveTo(new Position(1, 0))->spendAction();
        $next = $match->withUnit($moved);

        self::assertSame('0:0', $match->unit('unit-1')->position->key());
        self::assertSame('1:0', $next->unit('unit-1')->position->key());
        self::assertSame(1, $next->unit('unit-1')->actionsRemaining);
    }

    public function testMoveUpdatesUnitAndAppendsActionLogWithoutMutatingMatch(): void
    {
        $match = new MatchState(
            new Battlefield(8, 8),
            [
                $this->unit('alpha-1', 'alpha', new Position(0, 0)),
                $this->unit('bravo-1', 'bravo', new Position(7, 7)),
            ],
            'alpha',
        );

        $next = (new CombatEngine())->move($match, 'alpha-1', new Position(2, 0));

        self::assertSame('0:0', $match->unit('alpha-1')->position->key());
        self::assertSame('2:0', $next->unit('alpha-1')->position->key());
        self::assertSame(1, $next->unit('alpha-1')->actionsRemaining);
        self::assertSame(['alpha-1 moved to 2:0'], $next->actionLog);
    }

    public function testMoveRejectsUnitFromInactiveTeam(): void
    {
        $match = new MatchState(
            new Battlefield(8, 8),
            [
                $this->unit('alpha-1', 'alpha', new Position(0, 0)),
                $this->unit('bravo-1', 'bravo', new Position(7, 7)),
            ],
            'alpha',
        );

        $this->expectException(CombatException::class);
        $this->expectExceptionMessage("It is not this unit's turn.");

        (new CombatEngine())->move($match, 'bravo-1', new Position(6, 7));
    }

    public function testMoveRejectsOccupiedDestination(): void
    {
        $match = new MatchState(
            new Battlefield(8, 8),
            [
                $this->unit('alpha-1', 'alpha', new Position(0, 0)),
                $this->unit('alpha-2', 'alpha', new Position(1, 0)),
                $this->unit('bravo-1', 'bravo', new Position(7, 7)),
            ],
            'alpha',
        );

        $this->expectException(CombatException::class);
        $this->expectExceptionMessage('Destination is not reachable.');

        (new CombatEngine())->move($match, 'alpha-1', new Position(1, 0));
    }

    private function unit(string $id, string $team, Position $position): UnitState
    {
        return new UnitState($id, $team, $position, 10, 10, 4, 2, 4, 2);
    }
}