import crypto from 'crypto';

export const KNOWLEDGE_MODULE_ID = 'HL-MOD-KNOWLEDGE-001';

export interface ModuleManifest {
  id: string;
  name: string;
  version: string;
  kind: 'native-application';
  state: 'LIVE';
  description: string;
  capabilities: string[];
  dataPolicy: string;
}

export interface ChannelModuleState {
  id: string;
  installed: boolean;
  mounted: boolean;
  order: number;
}

export interface ChannelState {
  schema: 'hololake.personal-channel-state/v1';
  channelId: string;
  revision: number;
  updatedAt: string;
  modules: ChannelModuleState[];
}

export interface ChannelPatch {
  operation: 'set_module_state';
  moduleId: string;
  installed?: boolean;
  mounted?: boolean;
}

export interface ChannelReceipt {
  schema: 'hololake.channel-receipt/v1';
  id: string;
  operation: ChannelPatch;
  before: ChannelState;
  after: ChannelState;
  createdAt: string;
  reversible: true;
}

export const MODULE_REGISTRY: ModuleManifest[] = [{
  id: KNOWLEDGE_MODULE_ID,
  name: '知识库',
  version: '0.8.0',
  kind: 'native-application',
  state: 'LIVE',
  description: 'Git 驱动的个人知识空间，支持导入、编辑、检索、历史与 HoloLake 语言操作。',
  capabilities: [
    'knowledge.import',
    'knowledge.read',
    'knowledge.search',
    'knowledge.edit',
    'knowledge.history',
  ],
  dataPolicy: '移除模块只卸载频道入口，不删除用户文档、历史或服务器绑定。',
}];

export function defaultChannelState(now = new Date().toISOString()): ChannelState {
  return {
    schema: 'hololake.personal-channel-state/v1',
    channelId: 'CHANNEL-PERSONAL-DEFAULT',
    revision: 0,
    updatedAt: now,
    modules: [{ id: KNOWLEDGE_MODULE_ID, installed: true, mounted: true, order: 0 }],
  };
}

export function normalizeChannelState(input: unknown): ChannelState {
  const fallback = defaultChannelState();
  if (!input || typeof input !== 'object') return fallback;
  const candidate = input as Partial<ChannelState>;
  const known = new Set(MODULE_REGISTRY.map(module => module.id));
  const modules = Array.isArray(candidate.modules)
    ? candidate.modules
      .filter(module => module && known.has(module.id))
      .map((module, index) => ({
        id: module.id,
        installed: module.installed !== false,
        mounted: module.installed !== false && module.mounted !== false,
        order: Number.isFinite(module.order) ? Number(module.order) : index,
      }))
    : fallback.modules;
  for (const manifest of MODULE_REGISTRY) {
    if (!modules.some(module => module.id === manifest.id)) {
      modules.push({ id: manifest.id, installed: false, mounted: false, order: modules.length });
    }
  }
  return {
    schema: 'hololake.personal-channel-state/v1',
    channelId: typeof candidate.channelId === 'string' && candidate.channelId ? candidate.channelId : fallback.channelId,
    revision: Number.isInteger(candidate.revision) && Number(candidate.revision) >= 0 ? Number(candidate.revision) : 0,
    updatedAt: typeof candidate.updatedAt === 'string' ? candidate.updatedAt : fallback.updatedAt,
    modules: modules.sort((a, b) => a.order - b.order),
  };
}

export function applyChannelPatch(currentInput: ChannelState, patch: ChannelPatch, now = new Date().toISOString()): ChannelReceipt {
  const before = normalizeChannelState(currentInput);
  if (patch.operation !== 'set_module_state') throw new Error('不支持的频道动作');
  if (!MODULE_REGISTRY.some(module => module.id === patch.moduleId)) throw new Error('模块未在光湖注册表登记');
  if (typeof patch.installed !== 'boolean' && typeof patch.mounted !== 'boolean') throw new Error('频道动作没有状态变化');

  const modules = before.modules.map(module => {
    if (module.id !== patch.moduleId) return module;
    const installed = typeof patch.installed === 'boolean' ? patch.installed : module.installed;
    const mounted = installed && (typeof patch.mounted === 'boolean' ? patch.mounted : module.mounted);
    return { ...module, installed, mounted };
  });
  const after = { ...before, revision: before.revision + 1, updatedAt: now, modules };
  return {
    schema: 'hololake.channel-receipt/v1',
    id: `HL-CHANNEL-RCPT-${crypto.randomUUID()}`,
    operation: patch,
    before,
    after,
    createdAt: now,
    reversible: true,
  };
}