import type { Asset, Collection, Entity } from './api'
export interface Presentation {
  name: string
  handle?: string
  avatar?: Asset
  body: string
  kind: string
}
type Presenter = (a: Collection, root?: Entity) => Presentation
const generic: Presenter = (a) => ({
  name: a.author_name || '已保存的内容',
  body: a.text || a.summary || '暂无正文',
  kind: '收藏',
})
const x: Presenter = (a, root) => {
  const key = a.graph?.relations.find(
    (r) => r.source === a.graph?.root && r.type === 'authored_by',
  )?.target
  const profile =
    root?.type === 'x.profile'
      ? root
      : a.graph?.entities.find((e) => e.key === key && e.type === 'x.profile')
  return {
    ...generic(a),
    kind: root?.type === 'x.profile' ? '资料' : '帖子',
    handle:
      typeof profile?.data.username === 'string'
        ? profile.data.username
        : undefined,
    avatar: profile?.assets?.find(
      (v) => v.purpose === 'avatar' && v.state === 'ready',
    ),
  }
}
const registry: Record<string, Presenter> = { 'x.post': x, 'x.profile': x }
export function present(a: Collection) {
  const root = a.graph?.entities.find((e) => e.key === a.graph?.root)
  return (registry[root?.type || ''] || generic)(a, root)
}

function parseDate(value?: string) {
  if (!value) return
  const d = new Date(value)
  return Number.isFinite(d.getTime()) ? d : undefined
}
export function date(value?: string) {
  const d = parseDate(value)
  if (!d) return ''
  return new Intl.DateTimeFormat('zh-CN', {
    dateStyle: 'medium',
    timeStyle: 'short',
  }).format(d)
}
const day = (d: Date) => new Date(d.getFullYear(), d.getMonth(), d.getDate())
function daysAgo(d: Date, now: Date) {
  return Math.round((+day(now) - +day(d)) / 86400000)
}
/** List timestamps read like the chat list: time today, date before that. */
export function shortDate(value?: string, now = new Date()) {
  const d = parseDate(value)
  if (!d) return ''
  const distance = daysAgo(d, now)
  if (distance === 0)
    return `${d.getHours()}:${String(d.getMinutes()).padStart(2, '0')}`
  if (distance === 1) return '昨天'
  const date = `${d.getMonth() + 1}月${d.getDate()}日`
  return d.getFullYear() === now.getFullYear()
    ? date
    : `${d.getFullYear()}年${date}`
}
/** Buckets the collection by when it was saved, newest bucket first. */
export function groupLabel(value?: string, now = new Date()) {
  const d = parseDate(value)
  if (!d) return '已保存'
  const distance = daysAgo(d, now)
  if (distance === 0) return '今天'
  if (distance === 1) return '昨天'
  const month = `${d.getMonth() + 1}月`
  return d.getFullYear() === now.getFullYear()
    ? month
    : `${d.getFullYear()}年${month}`
}
export interface CollectionGroup {
  label: string
  items: Collection[]
}
export function groupCollections(items: Collection[], now = new Date()) {
  const groups: CollectionGroup[] = []
  for (const item of items) {
    const label = groupLabel(item.saved_at || item.observed_at, now)
    const last = groups.at(-1)
    if (last?.label === label) last.items.push(item)
    else groups.push({ label, items: [item] })
  }
  return groups
}

const isImage = (a: Asset) => !!a.mime?.startsWith('image/')
const isVideo = (a: Asset) => !!a.mime?.startsWith('video/')
/** Media that finished saving, in the order the source published it. */
export function readyMedia(assets: Asset[] = []) {
  return assets.filter((a) => a.state === 'ready')
}
export function mediaSummary(assets: Asset[] = []) {
  const ready = readyMedia(assets)
  const images = ready.filter(isImage).length
  const videos = ready.filter(isVideo).length
  const others = ready.length - images - videos
  return [
    images && `${images} 张图片`,
    videos && `${videos} 段视频`,
    others && `${others} 个文件`,
  ]
    .filter(Boolean)
    .join(' · ')
}
/** Media state in words. Storage states never reach the reader. */
export function mediaNotice(asset: Asset) {
  if (asset.state === 'pending') return '媒体还在保存中'
  if (asset.state === 'failed') return '这个媒体没能保存下来'
  return '这个媒体暂时无法打开'
}
const warnings: Record<string, string> = {
  'resource omitted: unsupported type or resource limit':
    '部分媒体超出限制，没有保存。',
}
/** Adapter warnings are diagnostic strings; readers get plain wording. */
export function warningText(warning: string) {
  return warnings[warning] || '部分内容没有完整保存。'
}
export function warningList(list?: string[] | null) {
  return [...new Set((list ?? []).map(warningText))]
}
/** One-paragraph preview for a list row. */
export function excerpt(text: string, limit = 120) {
  const flat = text.replaceAll(/\s+/g, ' ').trim()
  return flat.length > limit ? `${flat.slice(0, limit)}…` : flat
}