// 背包系統核心
import { apiService } from './api-service.js'
import { ITEM_TYPES, ITEM_RARITY, EQUIPMENT_SLOTS } from '../data/items.js'

export class InventorySystem {
  constructor(petSystem, eventSystem, api = apiService) {
    this.petSystem = petSystem
    this.eventSystem = eventSystem
    this.api = api
    this.items = {} // 從 API 載入的道具數據
    this.itemTypes = ITEM_TYPES
    this.itemRarity = ITEM_RARITY
    this.equipmentSlots = EQUIPMENT_SLOTS
    
    // 背包結構：{ itemId: { count: number, item: ItemData } }
    this.inventory = {}
    
    // 裝備槽位：每個槽位可以同時裝備實際套件和外觀套件
    // { slot: { equipment: itemId/object, appearance: itemId/object } }
    this.equipped = {
      weapon: { equipment: null, appearance: null },
      armor: { equipment: null, appearance: null },
      hat: { equipment: null, appearance: null },
      accessory: { equipment: null, appearance: null },
      talisman: { equipment: null, appearance: null },
      special: { equipment: null, appearance: null }
    }
    
    // 外觀設定（從外觀套件或實際裝備中提取，外觀套件優先）
    this.appearance = {}
  }

  // 初始化（從 API 載入道具數據、背包和裝備）
  async initialize() {
    try {
      // 從 API 載入道具列表
      const itemsList = await this.api.getItems()
      if (itemsList && Array.isArray(itemsList)) {
        // 將數組轉換為對象，以 itemId 為 key
        this.items = {}
        for (const item of itemsList) {
          if (item.id) {
            this.items[item.id] = item
          }
        }
        console.log(`[InventorySystem] 從 API 載入 ${Object.keys(this.items).length} 種道具`)
      } else {
        // 降級到本地數據
        const { ITEMS } = await import('../data/items.js')
        this.items = ITEMS
        console.log(`[InventorySystem] 使用本地道具數據，共 ${Object.keys(this.items).length} 種道具`)
      }
    } catch (error) {
      console.warn('[InventorySystem] 載入道具列表失敗，使用本地數據:', error)
      // 降級到本地數據
      const { ITEMS } = await import('../data/items.js')
      this.items = ITEMS
    }

    try {
      // 載入背包和裝備
      const saved = await this.api.getInventory()
      if (saved) {
        this.inventory = saved.inventory || {}
        // 兼容舊格式：如果是舊格式（單一值），轉換為新格式
        if (saved.equipped) {
          for (const [slot, equipped] of Object.entries(saved.equipped)) {
            if (this.equipped[slot]) {
              // 新格式：已有 equipment 和 appearance 結構
              if (equipped && typeof equipped === 'object' && (equipped.equipment !== undefined || equipped.appearance !== undefined)) {
                this.equipped[slot] = {
                  equipment: equipped.equipment || null,
                  appearance: equipped.appearance || null
                }
              } else if (equipped) {
                // 舊格式：單一值，判斷是裝備還是外觀
                const itemId = typeof equipped === 'string' ? equipped : equipped.itemId
                const item = this.items[itemId]
                if (item) {
                  if (item.type === 'appearance') {
                    this.equipped[slot] = { equipment: null, appearance: equipped }
                  } else {
                    this.equipped[slot] = { equipment: equipped, appearance: null }
                  }
                }
              }
            }
          }
        }
        this.appearance = saved.appearance || {}
      }
      
      // 重新應用裝備效果
      await this.reapplyEquipmentEffects()
      
      console.log(`[InventorySystem] 載入背包，共 ${Object.keys(this.inventory).length} 種道具`)
    } catch (error) {
      console.error('[InventorySystem] 載入背包失敗:', error)
      // 降級到本地載入
      const saved = localStorage.getItem('inventory')
      if (saved) {
        const data = JSON.parse(saved)
        this.inventory = data.inventory || {}
        this.equipped = { ...this.equipped, ...data.equipped }
        this.appearance = data.appearance || {}
        await this.reapplyEquipmentEffects()
      }
    }
  }

  // 添加道具到背包
  async addItem(itemId, count = 1) {
    const item = this.items[itemId]
    if (!item) {
      console.warn(`[InventorySystem] 找不到道具: ${itemId}`)
      return { success: false, message: '道具不存在' }
    }

    // 只有消耗品可以堆疊，其他道具（裝備、外觀、護身符、特殊）每件都要分開
    if (item.type === 'consumable') {
      // 消耗品可以堆疊
      if (!this.inventory[itemId]) {
        this.inventory[itemId] = {
          count: 0,
          item: { ...item }
        }
      }
      this.inventory[itemId].count += count
    } else {
      // 裝備類道具（equipment, appearance, talisman, special）每件分開
      if (!this.inventory[itemId]) {
        this.inventory[itemId] = {
          count: 0,
          items: [] // 多個相同裝備，每個有獨立耐久度
        }
      }
      
      // 添加新裝備實例（每件都是獨立的）
      for (let i = 0; i < count; i++) {
        this.inventory[itemId].items = this.inventory[itemId].items || []
        this.inventory[itemId].items.push({
          id: `${itemId}_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`,
          itemId,
          durability: item.durability !== undefined ? item.durability : Infinity,
          maxDurability: item.maxDurability !== undefined ? item.maxDurability : Infinity
        })
        this.inventory[itemId].count++
      }
    }

    // 同步到 API
    await this.saveInventory()

    console.log(`[InventorySystem] 獲得 ${count} 個 ${item.name}`)
    return { success: true, item, count }
  }

  // 移除道具（會自動卸下如果正在裝備中）
  async removeItem(itemId, count = 1) {
    // 檢查是否正在裝備中，如果是則先卸下
    for (const [slot, slotData] of Object.entries(this.equipped)) {
      if (typeof slotData === 'object' && slotData !== null) {
        if (slotData.equipment) {
          const eqItemId = typeof slotData.equipment === 'string' ? slotData.equipment : slotData.equipment.itemId
          if (eqItemId === itemId) {
            await this.unequipItem(slot, 'equipment')
          }
        }
        if (slotData.appearance) {
          const apItemId = typeof slotData.appearance === 'string' ? slotData.appearance : slotData.appearance.itemId
          if (apItemId === itemId) {
            await this.unequipItem(slot, 'appearance')
          }
        }
      }
    }
    if (!this.inventory[itemId]) {
      return { success: false, message: '道具不存在' }
    }

    const item = this.items[itemId]
    
    // 只有消耗品可以堆疊
    if (item.type === 'consumable') {
      if (this.inventory[itemId].count < count) {
        return { success: false, message: '道具數量不足' }
      }
      this.inventory[itemId].count -= count
      if (this.inventory[itemId].count <= 0) {
        delete this.inventory[itemId]
      }
    } else {
      // 裝備類道具，每件分開
      if (this.inventory[itemId].count < count) {
        return { success: false, message: '道具數量不足' }
      }
      
      // 移除指定數量的裝備實例（從未裝備的開始移除）
      this.inventory[itemId].items = this.inventory[itemId].items || []
      
      // 找出未裝備的實例
      const equippedInstances = new Set()
      for (const [slot, slotData] of Object.entries(this.equipped)) {
        if (slotData && typeof slotData === 'object') {
          if (slotData.equipment && typeof slotData.equipment === 'object' && slotData.equipment.itemId === itemId) {
            equippedInstances.add(slotData.equipment.instanceId)
          }
          if (slotData.appearance && typeof slotData.appearance === 'object' && slotData.appearance.itemId === itemId) {
            equippedInstances.add(slotData.appearance.instanceId)
          }
        }
      }
      
      // 先移除未裝備的實例
      let removed = 0
      for (let i = this.inventory[itemId].items.length - 1; i >= 0 && removed < count; i--) {
        if (!equippedInstances.has(this.inventory[itemId].items[i].id)) {
          this.inventory[itemId].items.splice(i, 1)
          removed++
        }
      }
      
      this.inventory[itemId].count -= removed
      
      if (this.inventory[itemId].count <= 0) {
        delete this.inventory[itemId]
      }
    }

    await this.saveInventory()
    console.log(`[InventorySystem] 移除道具: ${itemId} x${count}`)
    return { success: true }
  }
  
  // 重置背包（清除所有道具和裝備）
  async resetInventory() {
    this.inventory = {}
    this.equipped = {
      weapon: { equipment: null, appearance: null },
      armor: { equipment: null, appearance: null },
      hat: { equipment: null, appearance: null },
      accessory: { equipment: null, appearance: null },
      talisman: { equipment: null, appearance: null },
      special: { equipment: null, appearance: null }
    }
    this.appearance = {}
    
    // 清除裝備效果
    await this.petSystem.updateState({ equipmentBuffs: { flat: {}, percent: {} } })
    this.petSystem.calculateCombatStats()
    
    // 清除 localStorage
    localStorage.removeItem('inventory')
    
    // 同步到 API
    await this.saveInventory()
    
    console.log('[InventorySystem] 背包已重置')
    return { success: true }
  }

  // 使用消耗品
  async useItem(itemId, count = 1) {
    const item = this.items[itemId]
    if (!item) {
      return { success: false, message: '道具不存在' }
    }

    if (item.type !== 'consumable') {
      return { success: false, message: '此道具不是消耗品' }
    }

    // 檢查數量
    if (!this.inventory[itemId] || this.inventory[itemId].count < count) {
      return { success: false, message: '道具數量不足' }
    }

    const results = []

    // 執行效果
    for (let i = 0; i < count; i++) {
      const result = await this.executeItemEffects(item)
      results.push(result)
    }

    // 移除道具
    await this.removeItem(itemId, count)

    // 同步到 API
    try {
      await this.api.useItem(itemId, count)
    } catch (error) {
      console.warn('[InventorySystem] API 同步失敗:', error)
    }

    return { success: true, results }
  }

  // 執行道具效果
  async executeItemEffects(item) {
    const results = []
    const state = this.petSystem.getState()

    if (item.effects) {
      // 修改屬性
      if (item.effects.modifyStats) {
        const updates = {}
        for (const [key, value] of Object.entries(item.effects.modifyStats)) {
          if (key === 'health') {
            const maxHealth = this.petSystem.getMaxHealth()
            updates[key] = Math.min(maxHealth, (state[key] || 0) + value)
          } else if (key === 'hunger' || key === 'happiness') {
            updates[key] = Math.min(100, Math.max(0, (state[key] || 0) + value))
          } else {
            updates[key] = (state[key] || 0) + value
          }
        }
        await this.petSystem.updateState(updates)
        results.push({ type: 'modifyStats', updates })
      }

      // 治癒疾病
      if (item.effects.cureSickness && state.isSick) {
        await this.petSystem.updateState({ isSick: false })
        results.push({ type: 'cureSickness' })
      }

      // 添加 Buff
      if (item.effects.addBuff) {
        await this.eventSystem.addBuff(item.effects.addBuff)
        results.push({ type: 'addBuff', buff: item.effects.addBuff })
      }
    }

    return results
  }

  // 裝備道具
  // equipType: 'equipment' | 'appearance' | 'auto' (自動判斷)
  // instanceId: 指定要裝備的實例ID（可選，如果不指定則自動選擇第一個未裝備的）
  async equipItem(itemId, slot = null, equipType = 'auto', instanceId = null) {
    const item = this.items[itemId]
    if (!item) {
      return { success: false, message: '道具不存在' }
    }

    // 檢查是否可裝備
    if (item.type !== 'equipment' && item.type !== 'appearance' && item.type !== 'talisman' && item.type !== 'special') {
      return { success: false, message: '此道具無法裝備' }
    }

    // 確定槽位
    const targetSlot = slot || item.slot
    if (!targetSlot) {
      return { success: false, message: '道具沒有指定槽位' }
    }

    // 檢查是否有該道具
    if (!this.inventory[itemId] || this.inventory[itemId].count < 1) {
      return { success: false, message: '背包中沒有此道具' }
    }

    // 確定裝備類型
    let targetType = equipType
    if (targetType === 'auto') {
      // 自動判斷：appearance 類型裝備到 appearance 槽位，其他裝備到 equipment 槽位
      if (item.type === 'appearance') {
        targetType = 'appearance'
      } else {
        targetType = 'equipment'
      }
    }

    // 檢查槽位結構
    if (!this.equipped[targetSlot] || typeof this.equipped[targetSlot] !== 'object') {
      this.equipped[targetSlot] = { equipment: null, appearance: null }
    }

    // 如果該子槽位已有裝備，先卸下
    if (this.equipped[targetSlot][targetType]) {
      await this.unequipItem(targetSlot, targetType)
    }

    // 裝備道具
    let equippedData = null
    if (item.type === 'consumable') {
      // 消耗品不應該裝備
      return { success: false, message: '消耗品無法裝備' }
    } else {
      // 裝備類道具，使用指定的實例或選擇第一個未裝備的
      if (!instanceId) {
        // 選擇第一個未裝備的實例
        const instances = this.inventory[itemId].items || []
        if (instances.length === 0) {
          return { success: false, message: '裝備實例不存在' }
        }
        
        // 找出已裝備的實例
        const equippedInstances = new Set()
        for (const [s, slotData] of Object.entries(this.equipped)) {
          if (slotData && typeof slotData === 'object') {
            if (slotData.equipment && typeof slotData.equipment === 'object' && slotData.equipment.itemId === itemId) {
              equippedInstances.add(slotData.equipment.instanceId)
            }
            if (slotData.appearance && typeof slotData.appearance === 'object' && slotData.appearance.itemId === itemId) {
              equippedInstances.add(slotData.appearance.instanceId)
            }
          }
        }
        
        // 選擇第一個未裝備的實例
        const availableInstance = instances.find(i => !equippedInstances.has(i.id))
        if (!availableInstance) {
          return { success: false, message: '所有裝備實例都已裝備' }
        }
        instanceId = availableInstance.id
      }
      
      equippedData = {
        itemId,
        instanceId: instanceId
      }
    }

    // 裝備到對應槽位
    this.equipped[targetSlot][targetType] = equippedData

    // 更新外觀（優先使用外觀套件，如果沒有則使用實際裝備的外觀）
    await this.updateAppearance()

    // 應用裝備效果（只有實際裝備才有效果）
    await this.applyEquipmentEffects()

    // 同步到 API
    await this.saveInventory()

    const slotName = EQUIPMENT_SLOTS[targetSlot]?.name || targetSlot
    const typeName = targetType === 'appearance' ? '外觀' : '實際'
    console.log(`[InventorySystem] 裝備 ${item.name} 到 ${slotName} (${typeName})`)
    return { success: true, item, slot: targetSlot, type: targetType }
  }

  // 卸下裝備
  // type: 'equipment' | 'appearance' | null (卸下全部)
  async unequipItem(slot, type = null) {
    if (!this.equipped[slot]) {
      return { success: false, message: '該槽位沒有裝備' }
    }

    // 如果沒有指定類型，卸下全部（兼容舊代碼）
    if (type === null) {
      const results = []
      if (this.equipped[slot].equipment) {
        const result = await this.unequipItem(slot, 'equipment')
        if (result.success) results.push(result)
      }
      if (this.equipped[slot].appearance) {
        const result = await this.unequipItem(slot, 'appearance')
        if (result.success) results.push(result)
      }
      return { success: results.length > 0, results }
    }

    // 卸下指定類型的裝備
    const equipped = this.equipped[slot][type]
    if (!equipped) {
      return { success: false, message: `該槽位的${type === 'appearance' ? '外觀' : '實際'}裝備為空` }
    }

    const itemId = typeof equipped === 'string' ? equipped : equipped.itemId
    const item = this.items[itemId]

    // 清除裝備
    this.equipped[slot][type] = null

    // 更新外觀
    await this.updateAppearance()

    // 重新計算屬性（只有卸下實際裝備才需要）
    if (type === 'equipment') {
      await this.applyEquipmentEffects()
    }

    // 同步到 API
    await this.saveInventory()

    console.log(`[InventorySystem] 卸下 ${item?.name || itemId} (${type === 'appearance' ? '外觀' : '實際'})`)
    return { success: true, item, type }
  }

  // 更新外觀（優先使用外觀套件，如果沒有則使用實際裝備的外觀）
  async updateAppearance() {
    this.appearance = {}
    
    // 遍歷所有槽位
    for (const [slot, equipped] of Object.entries(this.equipped)) {
      if (!equipped) continue
      
      // 優先使用外觀套件
      if (equipped.appearance) {
        const itemId = typeof equipped.appearance === 'string' ? equipped.appearance : equipped.appearance.itemId
        const item = this.items[itemId]
        if (item && item.appearance) {
          this.appearance = { ...this.appearance, ...item.appearance }
        }
      } else if (equipped.equipment) {
        // 如果沒有外觀套件，使用實際裝備的外觀
        const itemId = typeof equipped.equipment === 'string' ? equipped.equipment : equipped.equipment.itemId
        const item = this.items[itemId]
        if (item && item.appearance) {
          this.appearance = { ...this.appearance, ...item.appearance }
        }
      }
    }
  }

  // 應用裝備效果（只應用實際裝備的效果，外觀套件不影響數值）
  async applyEquipmentEffects() {
    const state = this.petSystem.getState()
    const equipmentBuffs = {}

    // 收集所有實際裝備的加成（不包括外觀套件）
    for (const [slot, equipped] of Object.entries(this.equipped)) {
      if (!equipped || !equipped.equipment) continue

      const itemId = typeof equipped.equipment === 'string' ? equipped.equipment : equipped.equipment.itemId
      const item = this.items[itemId]
      if (!item) continue

      // 檢查耐久度（如果是裝備類且有耐久度）
      if (item.type === 'equipment' && item.durability !== Infinity) {
        const instanceId = typeof equipped.equipment === 'object' ? equipped.equipment.instanceId : null
        if (instanceId) {
          const instance = this.inventory[itemId]?.items?.find(i => i.id === instanceId)
          if (instance && instance.durability <= 0) {
            // 裝備已損壞，自動卸下
            console.log(`[InventorySystem] ${item.name} 已損壞，自動卸下`)
            this.equipped[slot].equipment = null
            continue
          }
        }
      }

      // 應用裝備效果（只有實際裝備才有效果）
      if (item.effects) {
        if (item.effects.flat) {
          for (const [key, value] of Object.entries(item.effects.flat)) {
            if (!equipmentBuffs.flat) equipmentBuffs.flat = {}
            equipmentBuffs.flat[key] = (equipmentBuffs.flat[key] || 0) + value
          }
        }
        if (item.effects.percent) {
          for (const [key, value] of Object.entries(item.effects.percent)) {
            if (!equipmentBuffs.percent) equipmentBuffs.percent = {}
            equipmentBuffs.percent[key] = (equipmentBuffs.percent[key] || 0) + value
          }
        }
      }
    }

    // 更新寵物狀態（確保結構正確）
    const finalBuffs = {
      flat: equipmentBuffs.flat || {},
      percent: equipmentBuffs.percent || {}
    }
    
    await this.petSystem.updateState({ equipmentBuffs: finalBuffs })
    
    // 重新計算戰鬥數值
    this.petSystem.calculateCombatStats()

    return finalBuffs
  }

  // 重新應用裝備效果（初始化時使用）
  async reapplyEquipmentEffects() {
    await this.applyEquipmentEffects()
  }

  // 減少裝備耐久度（只減少實際裝備的耐久度）
  async reduceDurability(slot, amount = 1) {
    const equipped = this.equipped[slot]
    if (!equipped || !equipped.equipment) return

    const itemId = typeof equipped.equipment === 'string' ? equipped.equipment : equipped.equipment.itemId
    const item = this.items[itemId]
    
    // 只有裝備類且有耐久度的才會減少
    if (item.type !== 'equipment' || item.durability === Infinity) return

    const instanceId = typeof equipped.equipment === 'object' ? equipped.equipment.instanceId : null
    if (!instanceId) return

    // 找到裝備實例
    const instance = this.inventory[itemId]?.items?.find(i => i.id === instanceId)
    if (!instance) return

    // 減少耐久度
    instance.durability = Math.max(0, instance.durability - amount)

    // 如果耐久度歸零，自動卸下
    if (instance.durability <= 0) {
      console.log(`[InventorySystem] ${item.name} 耐久度歸零，已損壞`)
      await this.unequipItem(slot, 'equipment')
    }

    await this.saveInventory()
  }

  // 修復裝備
  async repairItem(itemId, instanceId = null) {
    if (!this.inventory[itemId]) {
      return { success: false, message: '道具不存在' }
    }

    const item = this.items[itemId]
    if (item.durability === Infinity) {
      return { success: false, message: '此道具無法修復（永久裝備）' }
    }

    if (item.stackable) {
      return { success: false, message: '此道具無法修復' }
    }

    const instances = this.inventory[itemId].items || []
    let repaired = false

    if (instanceId) {
      // 修復指定實例
      const instance = instances.find(i => i.id === instanceId)
      if (instance) {
        instance.durability = instance.maxDurability || item.maxDurability
        repaired = true
      }
    } else {
      // 修復所有實例
      instances.forEach(instance => {
        instance.durability = instance.maxDurability || item.maxDurability
      })
      repaired = instances.length > 0
    }

    if (repaired) {
      await this.saveInventory()
      await this.applyEquipmentEffects() // 重新應用效果
      return { success: true, message: '裝備已修復' }
    }

    return { success: false, message: '修復失敗' }
  }

  // 獲取背包
  getInventory() {
    return { ...this.inventory }
  }

  // 獲取裝備
  getEquipped() {
    return { ...this.equipped }
  }

  // 獲取外觀
  getAppearance() {
    return { ...this.appearance }
  }

  // 檢查是否有道具
  hasItem(itemId, count = 1) {
    if (!this.inventory[itemId]) return false
    return this.inventory[itemId].count >= count
  }

  // 獲取道具數量
  getItemCount(itemId) {
    return this.inventory[itemId]?.count || 0
  }

  // 獲取裝備的道具
  // type: 'equipment' | 'appearance' | null (返回兩個)
  getEquippedItem(slot, type = null) {
    const equipped = this.equipped[slot]
    if (!equipped) return null

    if (type) {
      const equippedData = equipped[type]
      if (!equippedData) return null
      const itemId = typeof equippedData === 'string' ? equippedData : equippedData.itemId
      return this.items[itemId] || null
    } else {
      // 返回兩個
      return {
        equipment: equipped.equipment ? (() => {
          const itemId = typeof equipped.equipment === 'string' ? equipped.equipment : equipped.equipment.itemId
          return this.items[itemId] || null
        })() : null,
        appearance: equipped.appearance ? (() => {
          const itemId = typeof equipped.appearance === 'string' ? equipped.appearance : equipped.appearance.itemId
          return this.items[itemId] || null
        })() : null
      }
    }
  }

  // 保存背包（同步到 API）
  async saveInventory() {
    const data = {
      inventory: this.inventory,
      equipped: this.equipped,
      appearance: this.appearance
    }

    try {
      await this.api.saveInventory(data)
    } catch (error) {
      console.warn('[InventorySystem] API 同步失敗:', error)
      // 降級到 localStorage
      localStorage.setItem('inventory', JSON.stringify(data))
    }
  }
}