// ═══ inventory.js ═══
// ============================================================
//  INVENTORY — weapon picker state and equip helpers
// ============================================================

const MAX_WEAPON_SLOTS = 8;

let _pickerSlot      = -1;
let _pickerScrollY   = 0;
let _pickerScrollMax = 0;

function weaponUpgradeCount(w) {
  return (G.weaponUpgradesBought[w.instanceId] || []).length;
}

function weaponElementLabel(w) {
  return getWeaponElements(w)
    .map(el => ELEMENTS[el]?.icon || '')
    .join('');
}

function weaponStatRows(w) {
  return [
    ['DMG', w.damage],
    ['RATE', w.fireRate + 'f'],
    w.aoeRadius ? ['AOE', w.aoeRadius] : null,
    w.targets && w.targets > 1 ? ['TARGETS', w.targets] : null,
    w.pierce ? ['PIERCE', w.pierce] : null,
    w.chains ? ['CHAINS', w.chains] : null,
    ['TARGET', (w.targeting || 'nearest').toUpperCase()],
  ].filter(Boolean);
}

function weaponUpgradeLabels(w) {
  const bought = G.weaponUpgradesBought[w.instanceId] || [];
  const tree = WEAPON_UPGRADE_TREES[w.defId] || [];
  return bought.map(id => tree.find(u => u.id === id)?.label || id);
}

function openWeaponPicker(slotIndex) {
  if (slotIndex >= G.tower.weaponSlots) return;
  _pickerSlot    = slotIndex;
  _pickerScrollY = 0;
  setPaused(true, false);
  document.body.classList.add('inventory-open');
  G.weaponInventory = G.weaponInventory || [];
}

function closeWeaponPicker() {
  document.body.classList.remove('inventory-open');
  _pickerSlot    = -1;
  _pickerScrollY = 0;
  if (!G.shopOpen) setPaused(false);
}

function equipWeaponInstanceToSlot(slotIndex, instanceId) {
  if (slotIndex >= G.tower.weaponSlots) return;
  G.weaponInventory = G.weaponInventory || [];

  const sourceSlot = G.weapons.slice(0, G.tower.weaponSlots).findIndex(w => w && w.instanceId === instanceId);
  if (sourceSlot === slotIndex) return;

  const displaced = G.weapons[slotIndex];
  if (sourceSlot >= 0) {
    G.weapons[slotIndex] = G.weapons[sourceSlot];
    G.weapons[sourceSlot] = displaced || null;
  } else {
    const invIdx = G.weaponInventory.findIndex(w => w.instanceId === instanceId);
    if (invIdx === -1) return;
    const invWeapon = G.weaponInventory.splice(invIdx, 1)[0];
    G.weapons[slotIndex] = invWeapon;
    if (displaced) G.weaponInventory.push(displaced);
  }

  addLog(getWeaponDef(G.weapons[slotIndex]).name + ' equipped.', 'info');
  updateHUD();
}

function removeWeaponFromSlot(slotIndex) {
  if (slotIndex >= G.tower.weaponSlots) return;
  const activeCount = G.weapons.slice(0, G.tower.weaponSlots).filter(w => w != null).length;
  if (activeCount <= 1) { addLog('Cannot remove last weapon!', 'lose'); return; }
  const w = G.weapons[slotIndex];
  if (!w) return;
  G.weaponInventory = G.weaponInventory || [];
  G.weaponInventory.push(w);
  G.weapons[slotIndex] = null;
  addLog(getWeaponDef(w).name + ' moved to inventory.', 'info');
  updateHUD();
}

function buyAndEquipWeapon(slotIndex, defId) {
  const def = WEAPON_DEFS.find(w => w.id === defId);
  if (!def || slotIndex >= G.tower.weaponSlots || spendableCredits() < def.cost) return;
  if (!canBuyWeaponType(defId)) {
    addLog(`${def.name} limit reached (${MAX_WEAPONS_PER_TYPE}/${MAX_WEAPONS_PER_TYPE}).`, 'lose');
    return;
  }
  G.credits -= def.cost;
  const instance = makeWeaponInstance(defId);
  G.weaponUpgradesBought[instance.instanceId] = [];

  const displaced = G.weapons[slotIndex];
  G.weapons[slotIndex] = instance;
  if (displaced) {
    G.weaponInventory = G.weaponInventory || [];
    G.weaponInventory.push(displaced);
    addLog(`Purchased ${def.name}! Swapped previous weapon to inventory.`, 'win');
  } else {
    addLog(`Purchased ${def.name}!`, 'win');
  }
  updateHUD();
}