import { CHARACTERS, type CharacterCode } from './characters'
import { classify, type Complete } from './classify'
import type { Config } from './config'
import { formatExamples } from './examples'
import { retrieve, type IndexEntry } from './retrieval'

export type InjectDeps = {
  config: Config
  indexes: Readonly<Record<CharacterCode, readonly IndexEntry[]>>
  complete: Complete
  append: (text: string) => Promise<unknown>
  now: () => number
  turn: number
}

// 回傳 null 表示這一輪不注入（沒選角色、強度 0、索引為空、分類失敗或沒有同標籤的對白）。
// 索引為空時不呼叫模型，省下一次無用的分類。
export async function buildInjection(
  { config, indexes, complete, now, turn }: Omit<InjectDeps, 'append'>,
  userText: string,
): Promise<{ text: string | null; fn: string | null; ms: number } | null> {
  const character = config.character
  if (character === null || config.intensity === 0) return null
  const index = indexes[character]
  if (index.length === 0) return null
  const started = now()
  const fn = await classify(complete, userText)
  const ms = now() - started
  if (fn === null) return { text: null, fn: null, ms }
  return { text: formatExamples(CHARACTERS[character].name, retrieve(index, fn, { turn })), fn, ms }
}