import { redactSecrets } from './secrets.ts'
import type { Fs } from './types.ts'

export type Turn = { role: 'user' | 'assistant'; text: string; at: number }
export type InteractionMemory = {
  recent: Turn[]
  /** 壓縮後的摘要行與累計關係變化 */
  summary: string[]
  relationDelta: number
}

export const RECENT_MAX = 30
export const COMPRESS_COUNT = 20
const SUMMARY_MAX = 40
const LINE_MAX = 60

export const empty = (): InteractionMemory => ({ recent: [], summary: [], relationDelta: 0 })

// 互動記憶不存大段程式碼；只留對話文字
export function dialogueOnly(text: string): string {
  return text
    .replace(/```[\s\S]*?(?:```|$)/g, ' ')
    .replace(/`[^`\n]{40,}`/g, ' ')
    .replace(/[ \t]+/g, ' ')
    .trim()
}

export function clean(text: string): string {
  return redactSecrets(dialogueOnly(text))
}

export function add(m: InteractionMemory, turn: Turn, relationDelta: number): InteractionMemory {
  const text = clean(turn.text)
  if (!text) return { ...m, relationDelta: m.relationDelta + relationDelta }
  let next: InteractionMemory = {
    ...m,
    recent: [...m.recent, { ...turn, text }],
    relationDelta: m.relationDelta + relationDelta,
  }
  if (next.recent.length > RECENT_MAX) next = compress(next)
  return next
}

/** 把最舊的逐字紀錄壓縮成摘要行 */
export function compress(m: InteractionMemory): InteractionMemory {
  const old = m.recent.slice(0, COMPRESS_COUNT)
  const lines = old
    .filter(t => t.role === 'user')
    .map(t => (t.text.length > LINE_MAX ? t.text.slice(0, LINE_MAX) + '…' : t.text))
  return { ...m, recent: m.recent.slice(COMPRESS_COUNT), summary: [...m.summary, ...lines].slice(-SUMMARY_MAX) }
}

export async function load(fs: Fs, path: string): Promise<InteractionMemory> {
  const raw = await fs.read(path)
  if (!raw) return empty()
  try {
    return { ...empty(), ...JSON.parse(raw) }
  } catch {
    return empty()
  }
}

export const save = (fs: Fs, path: string, m: InteractionMemory) => fs.write(path, JSON.stringify(m))