import type { World, CombatantActor, Item, ItemDropActor, Vec2 } from "../../core/types";
import { EntityAccessor } from "../../engine/EntityAccessor";
import { type ECSWorld } from "../../engine/ecs/World";
import { EntityBuilder } from "../../engine/ecs/EntityBuilder";

/**
 * Result of attempting to use an item
 */
export interface ItemUseResult {
  success: boolean;
  consumed: boolean;
  message?: string;
}

/**
 * Manages item-related operations including spawning, pickup, and usage.
 * Extracted from GameScene to centralize item logic and reduce complexity.
 */
export class ItemManager {
  private world: World;
  private entityAccessor: EntityAccessor;
  private ecsWorld?: ECSWorld;

  constructor(world: World, entityAccessor: EntityAccessor, ecsWorld?: ECSWorld) {
    this.world = world;
    this.entityAccessor = entityAccessor;
    this.ecsWorld = ecsWorld;
  }

  /**
   * Update references when world changes (e.g., new floor)
   */
  updateWorld(world: World, entityAccessor: EntityAccessor, ecsWorld?: ECSWorld): void {
    this.world = world;
    this.entityAccessor = entityAccessor;
    if (ecsWorld) this.ecsWorld = ecsWorld;
  }

  /**
   * Spawn an item drop at the specified position
   */
  spawnItem(item: Item, pos: Vec2): void {
    if (!this.world || !this.ecsWorld) return;
    
    // Deep clone item (crucial for items with mutable stats like ammo)
    const clonedItem = { ...item } as Item;
    if ('stats' in clonedItem && clonedItem.stats) {
        (clonedItem as any).stats = { ...clonedItem.stats }; 
    }

    // ECS Path: Spawn using EntityBuilder
    EntityBuilder.create(this.ecsWorld)
        .withPosition(pos.x, pos.y)
        .asGroundItem(clonedItem)
        .build();
  }

  /**
   * Try to pickup an item at the player's position
   * @returns The picked up item, or null if nothing to pick up
   */
  tryPickup(player: CombatantActor): Item | null {
    if (!player || !player.inventory) return null;

    let itemActor: ItemDropActor | null = null;
    
    // Use EntityAccessor to find item on the ground
    if (this.entityAccessor) {
        itemActor = this.entityAccessor.findItemDropAt(player.pos.x, player.pos.y);
    }

    if (itemActor) {
      const item = itemActor.item;
      const result = this.addItem(player, item);
      
      // Remove from world
      this.entityAccessor.removeActor(itemActor.id);
      
      console.log("Picked up:", item.name);
      return result;
    }

    return null;
  }

  /**
   * Add an item to player inventory, handling stacking if applicable
   * @returns The added or modified item
   */
  addItem(player: CombatantActor, item: Item): Item {
    if (!player.inventory) throw new Error("Player has no inventory");

    // Deep clone item (crucial for items with mutable stats like ammo or when picking up from ground)
    const itemToAdd = { ...item } as Item;
    if ('stats' in itemToAdd && itemToAdd.stats) {
        (itemToAdd as any).stats = { ...itemToAdd.stats }; 
    }

    // Stacking Logic
    if (itemToAdd.stackable) {
        const existingItem = player.inventory.items.find(it => it.id === itemToAdd.id);
        if (existingItem) {
            existingItem.quantity = (existingItem.quantity || 1) + (itemToAdd.quantity || 1);
            console.log(`Stacked ${itemToAdd.name}. New quantity: ${existingItem.quantity}`);
            return existingItem;
        }
    }

    // Add to inventory
    itemToAdd.quantity = itemToAdd.quantity || 1;
    player.inventory.items.push(itemToAdd);
    return itemToAdd;
  }

  /**
   * Handle using an item from inventory
   * Returns information about what happened
   */
  handleUse(itemId: string, player: CombatantActor): ItemUseResult {
    if (!player || !player.inventory) {
      return { success: false, consumed: false, message: "Invalid player state" };
    }

    const itemIdx = player.inventory.items.findIndex(it => it.id === itemId);
    if (itemIdx === -1) {
      return { success: false, consumed: false, message: "Item not found" };
    }

    const item = player.inventory.items[itemIdx];

    // Check if item is a healing consumable
    if (item.type === "Consumable" && item.stats?.hp) {
      const healAmount = item.stats.hp;
      
      if (player.stats.hp >= player.stats.maxHp) {
        return { success: false, consumed: false, message: "Already at full health" };
      }

      player.stats.hp = Math.min(player.stats.hp + healAmount, player.stats.maxHp);
      
      // Consume item (check stack)
      if (item.quantity && item.quantity > 1) {
          item.quantity--;
      } else {
          player.inventory.items.splice(itemIdx, 1);
      }
      
      return { 
        success: true, 
        consumed: true, 
        message: `Healed for ${healAmount} HP` 
      };
    }

    // Throwable items
    if (item.type === "Consumable" && item.throwable) {
      return { 
        success: true, 
        consumed: false, 
        message: "Throwable item - use targeting" 
      };
    }

    return { 
      success: false, 
      consumed: false, 
      message: "Item has no effect" 
    };
  }

  /**
   * Remove an item from player inventory by ID
   */
  removeFromInventory(player: CombatantActor, itemId: string): boolean {
    if (!player || !player.inventory) return false;

    const itemIdx = player.inventory.items.findIndex(it => it.id === itemId);
    if (itemIdx === -1) return false;

    player.inventory.items.splice(itemIdx, 1);
    return true;
  }

  /**
   * Get an item from player inventory by ID
   */
  getItem(player: CombatantActor, itemId: string): Item | null {
    if (!player || !player.inventory) return null;

    const item = player.inventory.items.find(it => it.id === itemId);
    return item || null;
  }
}