import { Component, computed, input, output } from '@angular/core';
import type { EquipmentSlot, InventoryItem } from '../../core/api/game-api.models';
import { RARITY_LABELS } from '../../shared/item-card/item-card.component';

const SLOT_LABELS: Readonly<Record<EquipmentSlot, string>> = {
  WEAPON: 'Waffe',
  HEAD: 'Kopf',
  CHEST: 'Brust',
  HANDS: 'Handschuhe',
  LEGS: 'Beine',
  FEET: 'Stiefel',
  AMULET: 'Amulett',
};

interface StatRow {
  label: string;
  value: number;
  diff: number | null;
}

type StatKey = 'weaponDamage' | 'bonusAttack' | 'bonusHp' | 'bonusArmor';
const STAT_LABELS: ReadonlyArray<{ label: string; key: StatKey }> = [
  { label: 'Waffenschaden', key: 'weaponDamage' },
  { label: 'Angriff', key: 'bonusAttack' },
  { label: 'Leben', key: 'bonusHp' },
  { label: 'Rüstung', key: 'bonusArmor' },
];

/** Selected-item details and equip comparison (spec §32–37). */
@Component({
  selector: 'app-inventory-detail-panel',
  templateUrl: './inventory-detail-panel.component.html',
  styleUrl: './inventory-detail-panel.component.scss',
})
export class InventoryDetailPanelComponent {
  readonly item = input<InventoryItem | null>(null);
  readonly equippedItemInSlot = input<InventoryItem | null>(null);
  readonly characterLevel = input(1);
  readonly busy = input(false);
  readonly equip = output<string>();

  protected readonly rarityLabel = computed(() => {
    const item = this.item();
    return item ? RARITY_LABELS[item.item.rarity] : '';
  });

  protected readonly slotLabel = computed(() => {
    const slot = this.item()?.item.equipmentSlot;
    return slot ? SLOT_LABELS[slot] : null;
  });

  protected readonly statRows = computed<StatRow[]>(() => {
    const item = this.item();
    if (!item) {
      return [];
    }
    const compareTo = this.equippedItemInSlot();
    const comparable = compareTo && compareTo.id !== item.id ? compareTo.item : null;

    return STAT_LABELS.map(({ label, key }) => ({
      label,
      value: item.item[key],
      diff: comparable ? item.item[key] - comparable[key] : null,
    })).filter((row) => row.value > 0 || (row.diff ?? 0) !== 0);
  });

  protected readonly isEquippable = computed(() => !!this.item()?.item.equipmentSlot);

  protected readonly meetsLevelRequirement = computed(() => {
    const item = this.item();
    return item ? item.item.requiredLevel <= this.characterLevel() : true;
  });

  protected onEquip(): void {
    const item = this.item();
    if (item) {
      this.equip.emit(item.id);
    }
  }
}