w3access agent refactor

agent.js

// Goals:
// 1. Decouple store from agent
// 2. Simplify agent creation
// 3. Agent governs data format not store
// 4. Initialization of agent, not store
// 5. DRY initialization in agent, not repeated in each store impl

/**
 * @param {AgentData} [data] Agent data
 * @param {object} [options]
 * @param {(data: AgentData) => Promise<void>} [options.save] Called when agent
 * data changes and should be persisted.
 */
Agent.create = async (data, options = {}) => {
  const agent = new Agent(data, options)
  // if data is null/undefined the agent is not initialized
  if (!agent.isInitialized) await agent.init()
  return agent
}

Agent.fromStore = async (store, options = {}) => {
  await store.open()
  const data = await store.load() // { ... } or null/undefined
  return Agent.create(data, { ...options, save: data => store.save(data) })
}

// Basically, when agent calls `this.store.save(this.#data)` it now calls
// `this.#options.save(this.#data)`.

///////////////////////////////////////////////////////////////////////////////

// In regular use:
const store = new StoreIndexedDB()
const agent = await Agent.fromStore(store)

// Then StoreMemory can be deleted, since the agent already stores all data in
// memory. It's equivalent to:
const agent = await Agent.create()
// or
const agent = new Agent()
await agent.init()