// 文档驾驶舱 I2 纯逻辑层（rollout I2；契约：Dev 仓 docs/superpowers/specs
// 2026-10-16-document-visualization-read-model-contract.md @ 37b272ba，
// 四项取舍冻结见 plans/…-rollout.md §7）。只放可测判定：筛选切换、统计呈现
//（真 0 vs 不可算）、快照一致性与更新提示、上下文键与选择保留。组件只做取数编排与渲染。

// ---- 契约类型（I1 后端 DTO 的前端精简形态） ----

export interface CockpitNodeRef { kind: string; id: string; version?: string }

export interface CockpitMeta {
  schemaVersion: string
  projectId: string
  snapshotRevision: string
  asOfSeq: number
  generatedAt: string
  truncated: boolean
  truncationReasons?: string[]
}

export interface CockpitNodeState {
  content: string // complete|partial|empty|inaccessible|unavailable
  verification: string // verified|mixed|unverified|disputed|not_applicable
  sourceCount: number
  conflictCount: number
  impactCount: number
  missingChildCount: number
  structuralGap: boolean
}

export interface CockpitTreeNode {
  ref: CockpitNodeRef
  title: string
  path: string[]
  parent?: CockpitNodeRef
  childCount: number
  state: CockpitNodeState
  lastChangedAt?: string
  lastChangedBy?: string
  visibility: string // full|redacted|metadata_only
}

export interface CockpitStats {
  documentCount: number
  completion: { known: number; total: number; state: string }
  emptyNodeCount: number
  unverifiedSourceCount: number
  conflictCount: number
  pendingChangeCount: number | null
  updatedAt?: string
  statReasons: Record<string, string>
}

export interface CockpitChangeSummary {
  node: CockpitNodeRef
  title: string
  changedAt: string
  actor?: string
  kind: string
  summary: string
  version?: string
}

export interface CockpitOverview {
  meta: CockpitMeta
  project: { title: string }
  stats: CockpitStats
  documents: CockpitTreeNode[]
  recentChanges: CockpitChangeSummary[]
}

export interface CockpitTreePage {
  meta: CockpitMeta
  items: CockpitTreeNode[]
  nextCursor?: string
  hasMore: boolean
}

// ---- 统计带：点击即切换共享筛选（视图规格 §2；未知筛选由后端 400 拒绝） ----

export const STAT_FILTERS: { key: string; label: string; filter: string }[] = [
  { key: 'empty', label: '空缺节点', filter: 'state:empty' },
  { key: 'unverified', label: '未核实来源', filter: 'state:unverified' },
  { key: 'conflict', label: '冲突', filter: 'state:conflict' },
]

/** 点击统计卡：同筛选再次点击＝清除（只定位，不执行写入）。 */
export function toggleFilter(current: string, filter: string): string {
  return current === filter ? '' : filter
}

/** 统计呈现：null（不可算）显示 — 加原因；真 0 显示 0。两侧都不得互相冒充（契约 §2/§6）。 */
export function statDisplay(stats: CockpitStats, key: string): { value: string; hint?: string } {
  const reasons = stats.statReasons || {}
  if (key === 'documents') return { value: String(stats.documentCount) }
  if (key === 'completion') {
    const c = stats.completion
    if (c.state === 'unavailable') return { value: '—', hint: reasons['completion'] || '无法计算' }
    if (c.state === 'partial') return { value: `${c.known}/${c.total}`, hint: '部分计算' }
    return { value: `${c.known}/${c.total}` }
  }
  const map: Record<string, number | null | undefined> = {
    empty: stats.emptyNodeCount,
    unverified: stats.unverifiedSourceCount,
    conflict: stats.conflictCount,
    pending: stats.pendingChangeCount,
  }
  const v = map[key]
  // 原因表按后端 DTO 字段名（statReasons 键=字段名），展示键需映射。
  const reasonKey: Record<string, string> = {
    empty: 'emptyNodeCount', unverified: 'unverifiedSourceCount',
    conflict: 'conflictCount', pending: 'pendingChangeCount',
  }
  if (v === null || v === undefined) return { value: '—', hint: reasons[reasonKey[key] || key] || '暂不可计算' }
  return { value: String(v) }
}

// ---- 快照一致性（DV-R05 前端侧）：统计与树徽标同快照才同屏可信 ----

export function sameSnapshot(a?: CockpitMeta, b?: CockpitMeta): boolean {
  if (!a || !b) return false
  return a.snapshotRevision === b.snapshotRevision && a.asOfSeq === b.asOfSeq
}

/** 更新提示：展示中快照落后于最新已见快照时提示刷新（不抢占滚动，视图规格 §5）。 */
export function updateNotice(viewed: CockpitMeta | null, latest: CockpitMeta | null): string | null {
  if (!viewed || !latest) return null
  if (viewed.snapshotRevision === latest.snapshotRevision && viewed.asOfSeq === latest.asOfSeq) return null
  return `内容已更新（快照 ${latest.snapshotRevision}）——刷新查看最新状态`
}

/** 上下文键：项目+筛选标识一轮取数上下文；不匹配的旧响应直接丢弃（契约 §8）。 */
export function contextKey(projectId: string, filter: string): string {
  return `${projectId}\u0001${filter}`
}

/** 刷新不重置选择：文档仍在根清单（或选中章节的父文档仍在）则保留，否则清空。 */
export function selectionSurvives(
  selected: CockpitNodeRef | null,
  rootDocIds: string[],
  parentDocId?: string,
): CockpitNodeRef | null {
  if (!selected) return null
  if (selected.kind === 'document') return rootDocIds.includes(selected.id) ? selected : null
  if (parentDocId && rootDocIds.includes(parentDocId)) return selected
  return null
}

/** 树行徽标（诚实状态：空/部分/受限/未核实/冲突计数；不虚构成功）。 */
export function treeBadges(n: CockpitTreeNode): string[] {
  const out: string[] = []
  if (n.state.content === 'empty') out.push('空')
  else if (n.state.content === 'partial') out.push('部分')
  else if (n.state.content === 'inaccessible') out.push('受限')
  if (n.visibility === 'metadata_only') out.push('仅元数据')
  if (n.state.verification === 'unverified') out.push('未核实')
  if (n.state.conflictCount > 0) out.push(`冲突 ${n.state.conflictCount}`)
  return out
}

/** 节点状态一句话总结（全景 §4.2）。 */
export function nodeSummaryLine(n: CockpitTreeNode): string {
  const parts: string[] = []
  const content = { complete: '内容完整', partial: '内容部分', empty: '内容为空', inaccessible: '内容受限', unavailable: '暂不可读' }[n.state.content] || n.state.content
  parts.push(content)
  if (n.state.structuralGap) parts.push('层级止于章节')
  if (n.state.sourceCount > 0) parts.push(`来源 ${n.state.sourceCount}`)
  if (n.state.conflictCount > 0) parts.push(`冲突 ${n.state.conflictCount}`)
  if (n.state.impactCount > 0) parts.push(`影响 ${n.state.impactCount}`)
  return parts.join(' · ')
}