/**
 * 简化模式 - 模型加载
 * 按文件名直接加载模型，支持按需加载和自动回退
 */
import { ElMessage } from 'element-plus'
import type * as THREE from 'three'
import { DRACOLoader } from 'three/examples/jsm/loaders/DRACOLoader.js'
import { GLTFLoader } from 'three/examples/jsm/loaders/GLTFLoader.js'
import { markRaw } from 'vue'
import type { ModelModeContext } from '../types'

// ============================================================
// 配置常量
// ============================================================

/** DRACO解码器路径 */
const DRACO_DECODER_PATH = 'https://www.gstatic.com/draco/v1/decoders/'

/** 简化模式配置 */
const SIMPLIFIED_MODE_CONFIG = {
  /** 层级显示的最大深度 */
  maxHierarchyDepth: 2,
  /** 模型文件扩展名 */
  fileExtension: '.glb',
} as const

// ============================================================
// 主钩子函数
// ============================================================

/**
 * 简化模式组合式函数
 * @param context - 模型模式上下文
 */
export function useSimplifiedMode(context: ModelModeContext) {
  const {
    store,
    isLoading,
    archetypeModel,
    modelGroup,
    objectMap,
    modelCache,
    replaceWithPBRMaterial,
    generateHierarchy,
    initEnvironment,
    applyLightingMode,
    fitView,
    rebuildObjectMap,
    generateBreadcrumbs,
  } = context

  // ============================================================
  // 模型设置
  // ============================================================

  /**
   * 从缓存设置模型
   * @param model - 缓存的模型
   * @param fileName - 文件名
   */
  const setupModelFromCache = (model: THREE.Object3D, fileName: string) => {
    const clonedModel = model.clone()
    const nameWithoutExt = fileName.replace(SIMPLIFIED_MODE_CONFIG.fileExtension, '')

    // 设置模型名称
    clonedModel.name = nameWithoutExt

    // 更新原型模型
    archetypeModel.value = markRaw(clonedModel.clone())

    // 清空并添加到模型组
    modelGroup.clear()
    modelGroup.add(clonedModel)

    // 生成层级结构（只显示指定深度的节点）
    let hierarchy = []
    if (clonedModel.children.length > 0) {
      // 如果模型有子节点，将每个子节点作为一级节点
      clonedModel.children.forEach((child, index) => {
        const childPath = index === 0 ? nameWithoutExt : `${nameWithoutExt}~child${index}`
        const childHierarchy = generateHierarchy(
          child,
          childPath,
          1,
          SIMPLIFIED_MODE_CONFIG.maxHierarchyDepth
        )
        hierarchy.push(childHierarchy)
      })
    } else {
      // 如果模型没有子节点，使用模型本身作为一级节点
      const modelHierarchy = generateHierarchy(
        clonedModel,
        nameWithoutExt,
        1,
        SIMPLIFIED_MODE_CONFIG.maxHierarchyDepth
      )
      hierarchy = [modelHierarchy]
    }

    store.modelHierarchy = hierarchy

    // 生成面包屑（返回供调用者处理）
    const breadcrumbs = generateBreadcrumbs(nameWithoutExt)

    // 重建物体映射
    objectMap.clear()
    rebuildObjectMap(clonedModel)

    // 初始化环境和光照
    initEnvironment()
    applyLightingMode()

    // 适配视图
    fitView(clonedModel)
  }

  // ============================================================
  // 模型加载
  // ============================================================

  /**
   * 根据命名约定构建模型URL
   * @param fileName - 文件名
   * @returns 完整URL路径
   */
  const buildModelUrl = (fileName: string): string => {
    // 格式: Root~Parent~Child.glb -> /3DModels/Root/Root~Parent~Child.glb
    const nameWithoutExt = fileName.slice(0, -4)
    const rootFolder = nameWithoutExt.split('~')[0]
    return `/3DModels/${rootFolder}/${fileName}`
  }

  /**
   * 按文件名加载模型
   * @param fileName - 文件名（可带或不带.glb扩展名）
   * @param onLoaded - 加载完成回调
   */
  const loadModelByFileName = (fileName: string, onLoaded?: () => void) => {
    // 确保有.glb扩展名
    if (!fileName.endsWith(SIMPLIFIED_MODE_CONFIG.fileExtension)) {
      fileName += SIMPLIFIED_MODE_CONFIG.fileExtension
    }

    // 检查缓存
    if (store.modelCacheEnabled && modelCache.has(fileName)) {
      const cached = modelCache.get(fileName)!
      setupModelFromCache(cached, fileName)
      if (onLoaded) onLoaded()
      return
    }

    // 开始加载
    isLoading.value = true
    store.isModelLoading = true

    const url = buildModelUrl(fileName)
    console.log(`从 ${url} 加载模型`)

    // 创建加载器
    const loader = new GLTFLoader()
    const dracoLoader = new DRACOLoader()
    dracoLoader.setDecoderPath(DRACO_DECODER_PATH)
    loader.setDRACOLoader(dracoLoader)

    loader.load(
      url,
      gltf => {
        const rawModel = gltf.scene
        replaceWithPBRMaterial(rawModel)

        // 缓存模型
        if (store.modelCacheEnabled) {
          modelCache.set(fileName, rawModel.clone())
        }

        // 设置模型
        setupModelFromCache(rawModel, fileName)

        isLoading.value = false
        store.isModelLoading = false
        dracoLoader.dispose()

        if (onLoaded) onLoaded()
      },
      undefined,
      error => {
        console.warn('加载模型失败:', fileName, error)
        ElMessage.error(`模型加载失败: ${fileName}，请检查网络连接或模型文件是否存在`)

        // 回退逻辑：尝试加载父级模型
        const nameWithoutExt = fileName.slice(0, -4)
        const parts = nameWithoutExt.split('~')

        if (parts.length > 1) {
          // 移除最后一级，尝试加载父级
          parts.pop()
          const parentName = parts.join('~')
          console.log('回退到父级:', parentName)
          loadModelByFileName(parentName, onLoaded)
        } else {
          // 没有父级可回退
          console.error('没有父级可以回退，或根节点加载失败。')
          isLoading.value = false
          store.isModelLoading = false
          dracoLoader.dispose()
        }
      }
    )
  }

  // ============================================================
  // 导出接口
  // ============================================================

  return {
    /** 按文件名加载模型 */
    loadModelByFileName,
  }
}