restitution/tests/unit/CombatSystem.test.js

/**
 * CombatSystem.test.js — Tests for acquireTarget, canHit, applyDamage, and projectile logic.
 */

// Mock Phaser
const mockOverlap = jest.fn();
const mockVelocityFromAngle = jest.fn();

jest.mock('phaser', () => ({
  Math: {
    Distance: {
      Between: jest.fn((x1, y1, x2, y2) => Math.sqrt((x2 - x1) ** 2 + (y2 - y1) ** 2)),
    },
    Angle: {
      Between: jest.fn(() => 0),
      BetweenPoints: jest.fn(() => 0),
      Wrap: jest.fn((angle) => angle),
    },
    DegToRad: jest.fn((deg) => deg * Math.PI / 180),
    RadToDeg: jest.fn((rad) => rad * 180 / Math.PI),
  },
  Physics: {
    Arcade: {
      DYNAMIC_BODY: 0,
    },
  },
  Display: {
    Color: {
      GetColor32: jest.fn(() => 0xffff00),
    },
  },
  GameObjects: {
    Sprite: class {},
    Rectangle: class {},
    Graphics: class {},
    Container: class {},
    Zone: class {},
  },
  Geom: {
    Rectangle: class {
      constructor(x, y, w, h) {
        this.x = x;
        this.y = y;
        this.width = w;
        this.height = h;
      }
    },
  },
}));

import CombatSystem from 'Systems/CombatSystem.js';

// Helper to create a mock entity
function mockEntity(x, y, overrides = {}) {
  const entity = {
    x,
    y,
    rotation: 0,
    active: true,
    dead: false,
    body: {
      center: { x, y },
      velocity: { x: 0, y: 0 },
      allowGravity: false,
    },
    parentContainer: {
      name: overrides.containerName || 'Good Guys',
    },
    getData: jest.fn((key) => {
      if (key === 'health') return 100;
      if (key === 'armor') return 1;
      return undefined;
    }),
    setData: jest.fn(),
    emit: jest.fn(),
    select: jest.fn(),
    unSelect: jest.fn(),
    isDead: jest.fn(() => false),
    handleDeath: jest.fn(),
    handleTakeDamage: jest.fn(),
    getEnemyContainer: jest.fn(),
    ...overrides,
  };

  // Handle data store
  const dataStore = { health: 100, armor: 1, ...overrides._data };

  entity.getData.mockImplementation((key) => {
    if (key === 'health') return entity._data?.health ?? dataStore.health ?? 100;
    if (key === 'armor') return entity._data?.armor ?? dataStore.armor ?? 1;
    return entity._data?.[key] ?? dataStore[key];
  });

  entity.setData.mockImplementation((key, value) => {
    if (!entity._data) entity._data = { ...dataStore };
    entity._data[key] = value;
  });

  entity._data = { ...dataStore };

  return entity;
}

describe('CombatSystem', () => {
  let combat;
  let mockScene;

  beforeEach(() => {
    jest.clearAllMocks();

    mockScene = {
      events: { on: jest.fn(), emit: jest.fn(), off: jest.fn() },
      physics: {
        add: { group: jest.fn(() => ({ getChildren: () => [], create: jest.fn() })) },
        world: { enableBody: jest.fn() },
        overlap: jest.fn(() => false),
        velocityFromAngle: mockVelocityFromAngle,
      },
      add: { rectangle: jest.fn(() => ({ setDepth: jest.fn() })) },
      textures: { exists: jest.fn(() => false) },
      tweens: { addCounter: jest.fn(() => ({ stop: jest.fn() })) },
    };

    combat = new CombatSystem(mockScene);
  });

  // ── constructor ─────────────────────────────────────────────────
  describe('constructor', () => {
    test('initializes projectiles group and damage modifiers', () => {
      expect(combat.projectiles).toBeDefined();
      expect(combat.damageModifiers).toBeDefined();
      expect(combat.damageModifiers.default).toBeDefined();
      expect(combat.damageModifiers.rifle).toBeDefined();
      expect(combat.damageModifiers.cannon).toBeDefined();
      expect(combat.damageModifiers.tank_cannon).toBeDefined();
    });

    test('_goodGuys and _enemies start null', () => {
      expect(combat._goodGuys).toBeNull();
      expect(combat._enemies).toBeNull();
    });
  });

  // ── acquireTarget ───────────────────────────────────────────────
  describe('acquireTarget', () => {
    let friendlies, enemies;

    beforeEach(() => {
      friendlies = { name: 'Good Guys', list: [], getAll: jest.fn(() => []) };
      enemies = { name: 'Bad Guys', list: [], getAll: jest.fn(() => []) };
    });

    test('returns null when enemy container has no units', () => {
      const entity = mockEntity(100, 100, {
        getEnemyContainer: () => ({ list: [], getAll: () => [] }),
      });

      expect(combat.acquireTarget(entity)).toBeNull();
    });

    test('returns null when all enemies are dead', () => {
      const entity = mockEntity(100, 100, {
        getEnemyContainer: () => ({
          list: [{ dead: true }],
          getAll: () => [],
        }),
      });

      expect(combat.acquireTarget(entity)).toBeNull();
    });

    test('finds closest enemy within range', () => {
      const target1 = mockEntity(120, 100, { containerName: 'Bad Guys' });
      const target2 = mockEntity(200, 100, { containerName: 'Bad Guys' });

      // Mock LoS to always return true for this test
      const originalLos = combat.hasLineOfSight;
      combat.hasLineOfSight = jest.fn(() => true);

      const entity = mockEntity(100, 100, {
        getEnemyContainer: () => ({
          list: [target1, target2],
          getAll: () => [target1, target2],
        }),
      });

      const result = combat.acquireTarget(entity);
      expect(result).toBe(target1); // closest

      combat.hasLineOfSight = originalLos;
    });

    test('filters by fov cone', () => {
      const target = mockEntity(200, 100, { containerName: 'Bad Guys' });

      const entity = mockEntity(100, 100, {
        rotation: 0,
        getEnemyContainer: () => ({
          list: [target],
          getAll: () => [target],
        }),
      });

      // With narrow FOV, entity facing 0 and target straight ahead should work
      const originalLos = combat.hasLineOfSight;
      combat.hasLineOfSight = jest.fn(() => true);

      const result = combat.acquireTarget(entity, { fov: 90 });
      expect(result).toBe(target);

      combat.hasLineOfSight = originalLos;
    });

    test('prioritizes weakest when specified', () => {
      const strong = mockEntity(120, 100, { containerName: 'Bad Guys' });
      const weak = mockEntity(115, 100, { containerName: 'Bad Guys' });

      strong._data = { health: 80 };
      weak._data = { health: 20 };

      const entity = mockEntity(100, 100, {
        getEnemyContainer: () => ({
          list: [strong, weak],
          getAll: () => [strong, weak],
        }),
      });

      const originalLos = combat.hasLineOfSight;
      combat.hasLineOfSight = jest.fn(() => true);

      const result = combat.acquireTarget(entity, { priority: 'weakest' });
      expect(result).toBe(weak);

      combat.hasLineOfSight = originalLos;
    });

    test('returns null for null enemy container', () => {
      const entity = mockEntity(100, 100, { getEnemyContainer: () => null });
      expect(combat.acquireTarget(entity)).toBeNull();
    });
  });

  // ── canHit ──────────────────────────────────────────────────────
  describe('canHit', () => {
    test('returns false for null entities', () => {
      expect(combat.canHit(null, mockEntity(0, 0))).toEqual({ canHit: false, reason: 'invalid_entities' });
    });

    test('returns false for friendly fire (same container)', () => {
      const attacker = mockEntity(0, 0, { containerName: 'Good Guys' });
      const target = mockEntity(10, 10, { containerName: 'Good Guys' });
      expect(combat.canHit(attacker, target)).toEqual({ canHit: false, reason: 'friendly_fire' });
    });

    test('returns false for dead target', () => {
      const attacker = mockEntity(0, 0, { containerName: 'Good Guys' });
      const target = mockEntity(10, 10, {
        containerName: 'Bad Guys',
        dead: true,
      });
      expect(combat.canHit(attacker, target)).toEqual({ canHit: false, reason: 'target_dead' });
    });

    test('returns false when target is out of range', () => {
      const attacker = mockEntity(0, 0, { containerName: 'Good Guys' });
      const target = mockEntity(2000, 2000, { containerName: 'Bad Guys' });
      // distance ~2828, default range 150

      const originalLos = combat.hasLineOfSight;
      combat.hasLineOfSight = jest.fn(() => false);

      const result = combat.canHit(attacker, target);
      expect(result.canHit).toBe(false);
      expect(result.reason).toBe('out_of_range');

      combat.hasLineOfSight = originalLos;
    });
  });

  // ── applyDamage ─────────────────────────────────────────────────
  describe('applyDamage', () => {
    test('deals damage reducing health', () => {
      const entity = mockEntity(0, 0);
      entity._data = { health: 100, armor: 1 };

      const dealt = combat.applyDamage(entity, 20);
      expect(dealt).toBeGreaterThan(0);
      expect(entity.emit).toHaveBeenCalledWith('combat:damaged', expect.any(Object));
    });

    test('returns 0 for dead entity', () => {
      const entity = mockEntity(0, 0);
      entity.dead = true;

      expect(combat.applyDamage(entity, 20)).toBe(0);
    });

    test('armor reduces damage taken', () => {
      const entity = mockEntity(0, 0);
      entity._data = { health: 100, armor: 5 };

      const dealt = combat.applyDamage(entity, 20);
      // effectiveArmor = 5 * (1 - 0) = 5; damage = max(1, round(20 - 5)) = 15
      expect(dealt).toBe(15);
    });

    test('deals at least 1 damage', () => {
      const entity = mockEntity(0, 0);
      entity._data = { health: 100, armor: 1000 };

      const dealt = combat.applyDamage(entity, 1);
      expect(dealt).toBeGreaterThanOrEqual(1);
    });

    test('calls handleDeath when health drops to 0', () => {
      const entity = mockEntity(0, 0);
      entity._data = { health: 100, armor: 1 };
      entity.handleDeath = jest.fn();

      combat.applyDamage(entity, 999);
      expect(entity.handleDeath).toHaveBeenCalled();
    });

    test('emits combat:unitDamaged on scene', () => {
      const entity = mockEntity(0, 0);
      entity._data = { health: 100, armor: 1 };

      combat.applyDamage(entity, 10);
      expect(mockScene.events.emit).toHaveBeenCalledWith('combat:unitDamaged', expect.any(Object));
    });
  });

  // ── fireProjectile & projectile management ──────────────────────
  describe('fireProjectile', () => {
    test('returns null for invalid entities', () => {
      expect(combat.fireProjectile(null, mockEntity(0, 0))).toBeNull();
    });

    test('creates a fallback rectangle when no sprite texture', () => {
      const attacker = mockEntity(0, 0);
      const target = mockEntity(100, 0, { containerName: 'Bad Guys' });

      const proj = combat.fireProjectile(attacker, target);
      expect(proj).toBeDefined();
      expect(mockScene.add.rectangle).toHaveBeenCalled();
    });

    test('sets projectile data (damage, damageType, attacker, target)', () => {
      const attacker = mockEntity(0, 0);
      const target = mockEntity(100, 0, { containerName: 'Bad Guys' });

      const proj = combat.fireProjectile(attacker, target, { damageType: 'cannon' });
      expect(proj).toBeDefined();
    });
  });

  // ── registerUnitContainers ──────────────────────────────────────
  describe('registerUnitContainers', () => {
    test('stores goodGuys and enemies references', () => {
      const goodGuys = { name: 'Good Guys' };
      const enemies = { name: 'Bad Guys' };

      combat.registerUnitContainers(goodGuys, enemies);

      expect(combat._goodGuys).toBe(goodGuys);
      expect(combat._enemies).toBe(enemies);
    });
  });

  // ── update loop ─────────────────────────────────────────────────
  describe('update', () => {
    test('handles empty projectile group', () => {
      expect(() => combat.update(0, 16)).not.toThrow();
    });

    test('destroys expired projectiles', () => {
      const destroySpy = jest.fn();
      const expired = {
        active: true,
        getData: jest.fn((key) => {
          if (key === 'elapsed') return 5000;
          if (key === 'lifespan') return 4000;
          return null;
        }),
        setData: jest.fn(),
        destroy: destroySpy,
      };

      combat.projectiles = {
        getChildren: () => [expired],
      };

      combat.update(0, 16);
      expect(destroySpy).toHaveBeenCalled();
    });

    test('destroys inactive projectiles', () => {
      const destroySpy = jest.fn();
      const inactive = {
        active: false,
        getData: jest.fn(),
        setData: jest.fn(),
        destroy: destroySpy,
      };

      combat.projectiles = {
        getChildren: () => [inactive],
      };

      combat.update(0, 16);
      expect(destroySpy).toHaveBeenCalled();
    });
  });

  // ── hasLineOfSight ──────────────────────────────────────────────
  describe('hasLineOfSight', () => {
    test('returns true when no rockLayer', () => {
      combat.scene.rockLayer = undefined;
      expect(combat.hasLineOfSight({ x: 0, y: 0 }, { x: 100, y: 100 })).toBe(true);
    });

    test('returns true when worldToTileXY returns null', () => {
      combat.scene.rockLayer = {
        worldToTileXY: () => null,
      };
      expect(combat.hasLineOfSight({ x: 0, y: 0 }, { x: 100, y: 100 })).toBe(true);
    });
  });
});