/**
 * Resource Interaction Tests — Phase 4.3
 *
 * Tests: resource element picking, proximity detection,
 * collection into inventory, resource depletion.
 */

import { describe, it, expect } from 'vitest';
import { createWorld, addEntity, addComponent, query } from 'bitecs';
import { Position, Resource, PlayerTag } from '../src/ecs/components';
import { Inventory } from '../src/player/inventory';
import {
  pickResourceElement,
  interactionSystem,
  type ResourceInfo,
  type InteractionResult,
  MINERAL_ELEMENTS,
  GEYSER_ELEMENTS,
} from '../src/player/interaction';

// === Helpers ===

function createTestWorld() {
  const world = createWorld();
  const resourceData = new Map<number, ResourceInfo>();
  const inventory = new Inventory();
  return { world, resourceData, inventory };
}

function addPlayer(world: ReturnType<typeof createWorld>, x: number, y: number): number {
  const eid = addEntity(world);
  addComponent(world, eid, Position);
  addComponent(world, eid, PlayerTag);
  Position.x[eid] = x;
  Position.y[eid] = y;
  return eid;
}

function addResource(
  world: ReturnType<typeof createWorld>,
  resourceData: Map<number, ResourceInfo>,
  x: number,
  y: number,
  itemId: string,
  quantity: number,
  range = 40,
): number {
  const eid = addEntity(world);
  addComponent(world, eid, Position);
  addComponent(world, eid, Resource);
  Position.x[eid] = x;
  Position.y[eid] = y;
  Resource.quantity[eid] = quantity;
  Resource.interactRange[eid] = range;
  resourceData.set(eid, { itemId, tileX: Math.floor(x / 32), tileY: Math.floor(y / 32) });
  return eid;
}

// === pickResourceElement ===

describe('pickResourceElement', () => {
  it('always returns element from provided list', () => {
    for (let x = 0; x < 20; x++) {
      for (let y = 0; y < 20; y++) {
        const el = pickResourceElement(x, y, 12345, MINERAL_ELEMENTS);
        expect(MINERAL_ELEMENTS).toContain(el);
      }
    }
  });

  it('is deterministic (same inputs → same output)', () => {
    const a = pickResourceElement(5, 10, 42, MINERAL_ELEMENTS);
    const b = pickResourceElement(5, 10, 42, MINERAL_ELEMENTS);
    expect(a).toBe(b);
  });

  it('varies with different positions', () => {
    const results = new Set<string>();
    for (let i = 0; i < 100; i++) {
      results.add(pickResourceElement(i, i * 7, 42, MINERAL_ELEMENTS));
    }
    // Should use more than one element (statistical certainty)
    expect(results.size).toBeGreaterThan(1);
  });

  it('works with geyser elements', () => {
    const el = pickResourceElement(3, 7, 42, GEYSER_ELEMENTS);
    expect(GEYSER_ELEMENTS).toContain(el);
  });
});

// === Interaction System ===

describe('interactionSystem — collection', () => {
  it('collects element when in range and pressing E', () => {
    const { world, resourceData, inventory } = createTestWorld();
    addPlayer(world, 100, 100);
    addResource(world, resourceData, 120, 100, 'Fe', 5);

    const result = interactionSystem(world, true, inventory, resourceData);

    expect(result).not.toBeNull();
    expect(result!.type).toBe('collected');
    expect(result!.itemId).toBe('Fe');
    expect(inventory.getCount('Fe')).toBe(1);
  });

  it('does nothing when E is not pressed', () => {
    const { world, resourceData, inventory } = createTestWorld();
    addPlayer(world, 100, 100);
    addResource(world, resourceData, 120, 100, 'Fe', 5);

    const result = interactionSystem(world, false, inventory, resourceData);

    expect(result).toBeNull();
    expect(inventory.getCount('Fe')).toBe(0);
  });

  it('does nothing when no resources in range', () => {
    const { world, resourceData, inventory } = createTestWorld();
    addPlayer(world, 100, 100);
    addResource(world, resourceData, 500, 500, 'Fe', 5); // far away

    const result = interactionSystem(world, true, inventory, resourceData);

    expect(result).not.toBeNull();
    expect(result!.type).toBe('nothing_nearby');
  });

  it('picks closest resource when multiple in range', () => {
    const { world, resourceData, inventory } = createTestWorld();
    addPlayer(world, 100, 100);
    addResource(world, resourceData, 130, 100, 'Cu', 3); // 30px away
    addResource(world, resourceData, 115, 100, 'Fe', 5); // 15px away (closer)

    const result = interactionSystem(world, true, inventory, resourceData);

    expect(result!.itemId).toBe('Fe'); // picked closer one
  });

  it('decrements resource quantity on collection', () => {
    const { world, resourceData, inventory } = createTestWorld();
    addPlayer(world, 100, 100);
    const resEid = addResource(world, resourceData, 120, 100, 'Fe', 3);

    interactionSystem(world, true, inventory, resourceData);

    expect(Resource.quantity[resEid]).toBe(2);
  });
});

describe('interactionSystem — depletion', () => {
  it('depletes resource when quantity reaches 0', () => {
    const { world, resourceData, inventory } = createTestWorld();
    addPlayer(world, 100, 100);
    addResource(world, resourceData, 120, 100, 'Fe', 1);

    const result = interactionSystem(world, true, inventory, resourceData);

    expect(result!.type).toBe('depleted');
    expect(result!.itemId).toBe('Fe');
    expect(resourceData.size).toBe(0);
  });

  it('removes entity from world on depletion', () => {
    const { world, resourceData, inventory } = createTestWorld();
    addPlayer(world, 100, 100);
    addResource(world, resourceData, 120, 100, 'Fe', 1);

    interactionSystem(world, true, inventory, resourceData);

    const remaining = query(world, [Resource]);
    expect(remaining.length).toBe(0);
  });
});

describe('interactionSystem — inventory full', () => {
  it('reports inventory_full when cannot add', () => {
    const { world, resourceData } = createTestWorld();
    const inventory = new Inventory(1, 1); // very small
    inventory.addItem('H', 1); // fills it up

    addPlayer(world, 100, 100);
    addResource(world, resourceData, 120, 100, 'Fe', 5);

    const result = interactionSystem(world, true, inventory, resourceData);

    expect(result!.type).toBe('inventory_full');
    expect(Resource.quantity[query(world, [Resource])[0]]).toBe(5); // not consumed
  });
});