import { inflateSync } from 'node:zlib'
import type { ParsedCard } from '#shared/types'

const PNG_SIGNATURE = Buffer.from([0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A])

/** 读取 PNG 中所有文本块（tEXt / zTXt / iTXt），返回 关键字 → 文本 */
export function readPngTextChunks(buf: Buffer): Record<string, string> {
  if (buf.length < 8 || !buf.subarray(0, 8).equals(PNG_SIGNATURE)) throw new Error('不是有效的 PNG 文件')
  const out: Record<string, string> = {}
  let off = 8
  while (off + 8 <= buf.length) {
    const len = buf.readUInt32BE(off)
    const type = buf.toString('ascii', off + 4, off + 8)
    const data = buf.subarray(off + 8, off + 8 + len)
    if (type === 'tEXt') {
      const sep = data.indexOf(0)
      if (sep > 0) out[data.toString('latin1', 0, sep).toLowerCase()] = data.toString('latin1', sep + 1)
    }
    else if (type === 'zTXt') {
      const sep = data.indexOf(0)
      if (sep > 0) out[data.toString('latin1', 0, sep).toLowerCase()] = inflateSync(data.subarray(sep + 2)).toString('latin1')
    }
    else if (type === 'iTXt') {
      // keyword\0 compressionFlag compressionMethod languageTag\0 translatedKeyword\0 text
      const sep = data.indexOf(0)
      if (sep > 0) {
        const keyword = data.toString('latin1', 0, sep).toLowerCase()
        const compressed = data[sep + 1] === 1
        const langEnd = data.indexOf(0, sep + 3)
        const transEnd = data.indexOf(0, langEnd + 1)
        const body = data.subarray(transEnd + 1)
        out[keyword] = (compressed ? inflateSync(body) : body).toString('utf8')
      }
    }
    if (type === 'IEND') break
    off += 12 + len
  }
  return out
}

function decodeCardText(text: string): Record<string, unknown> {
  const trimmed = text.trim()
  if (trimmed.startsWith('{')) return JSON.parse(trimmed)
  return JSON.parse(Buffer.from(trimmed, 'base64').toString('utf8'))
}

/** 从 PNG 或 JSON 中提取原始角色卡对象 */
export function extractRawCard(buf: Buffer, filename = ''): Record<string, unknown> {
  const isPng = buf.subarray(0, 8).equals(PNG_SIGNATURE)
  if (isPng) {
    const chunks = readPngTextChunks(buf)
    // V3 卡优先读 ccv3，同时兼容只写了 chara 的 V2/V1 卡
    const raw = chunks.ccv3 ?? chunks.chara
    if (!raw) throw new Error('这张 PNG 里没有角色卡数据（缺少 chara / ccv3 文本块）。如果图片经过截图、压缩或聊天软件转发，元数据会丢失，请使用原始文件。')
    return decodeCardText(raw)
  }
  const text = buf.toString('utf8').replace(/^/, '')
  try {
    return JSON.parse(text)
  }
  catch {
    throw new Error(`无法解析文件 ${filename}：既不是 PNG 角色卡也不是 JSON`)
  }
}

const str = (v: unknown) => (typeof v === 'string' ? v : v == null ? '' : String(v))
const strArr = (v: unknown) => (Array.isArray(v) ? v.map(str).filter(Boolean) : [])

/** 将 V1 / V2 / V3 角色卡统一成内部结构 */
export function normalizeCard(raw: Record<string, unknown>): ParsedCard {
  const specRaw = str(raw.spec)
  const hasData = raw.data && typeof raw.data === 'object'
  const d = (hasData ? raw.data : raw) as Record<string, unknown>
  const spec: ParsedCard['spec'] = specRaw === 'chara_card_v3' ? 'v3' : specRaw === 'chara_card_v2' || hasData ? 'v2' : 'v1'
  const ext = (d.extensions ?? {}) as Record<string, unknown>
  const book = (d.character_book ?? null) as { entries?: Record<string, unknown>[] } | null

  const lore = (book?.entries ?? []).map((e, i) => {
    const extE = (e.extensions ?? {}) as Record<string, unknown>
    return {
      title: str(e.comment) || str(e.name) || `条目 ${i + 1}`,
      keys: [...strArr(e.keys), ...strArr(e.secondary_keys)],
      content: str(e.content),
      constant: Boolean(e.constant),
      enabled: e.enabled !== false && extE.disable !== true,
      order: Number(e.insertion_order ?? e.priority ?? 100) || 100
    }
  }).filter(e => e.content.trim())

  return {
    spec,
    name: str(d.name) || str(raw.name) || '未命名角色',
    description: str(d.description),
    personality: str(d.personality),
    scenario: str(d.scenario),
    firstMes: str(d.first_mes),
    mesExample: str(d.mes_example),
    systemPrompt: str(d.system_prompt),
    postHistoryInstructions: str(d.post_history_instructions),
    creatorNotes: str(d.creator_notes) || str(raw.creatorcomment),
    alternateGreetings: strArr(d.alternate_greetings),
    tags: strArr(d.tags),
    world: typeof ext.world === 'string' ? ext.world : '',
    lore,
    raw
  }
}

/** 替换酒馆宏：{{char}} / {{user}} / <BOT> / <USER> */
export function replaceMacros(text: string, charName: string, userName: string) {
  if (!text) return text
  return text
    .replace(/\{\{\s*char\s*\}\}|<BOT>/gi, charName)
    .replace(/\{\{\s*user\s*\}\}|<USER>/gi, userName || '主角')
    .replace(/\r\n/g, '\n')
}

export function parseCardFile(buf: Buffer, filename = '') {
  return normalizeCard(extractRawCard(buf, filename))
}