import { useEffect, useState } from 'react'
import type { RecallSignals, VideoMatchEnrichedVO } from '../api/types'

/**
 * 精排参数——前后端同构的单一来源。
 *
 * 公式 (VIDEO/ARTICLE):
 *   sim_norm = clip((sim - lower) / (1 - lower), 0, 1)
 *   rov_norm = clip((rov - rovClipLow) / (rovClipHigh - rovClipLow), 0, 1)
 *   composite = boost × (alpha × sim_norm + (1 - alpha) × rov_norm)
 *   boost = deconstructBoost（仅 VIDEO 模态生效，按 modality 判定）
 *
 * 公式 (MATERIAL):
 *   sim_norm = clip((sim - simThreshold) / (1 - simThreshold), 0, 1)
 *   qualityScore = (wCtr × ctr + wViral × viral + wRoi × roi) / qualTotalW
 *   composite = alpha × sim_norm + (1 - alpha) × qualityScore
 *   质量缺失时按 materialMissingStrategy 处理："group"（分组）或 "shrink"（收缩）
 */
export interface RankingParams {
  simThreshold: number
  simThresholdsByCode: Record<string, number>
  /** ROV 归一化下界（clip 低值） */
  rovClipLow: number
  /** ROV 归一化上界（clip 高值） */
  rovClipHigh: number
  /** 相关性 VS 质量的权衡权重 [0, 1]，VIDEO/ARTICLE/MATERIAL 通用 */
  alpha: number
  /** 解构维度加权（兜底，未在 boostsByCode 中配置的维度使用此值） */
  deconstructBoost: number
  /** 按维度独立 boost —— 每个 configCode 可单独设置，覆盖 deconstructBoost */
  boostsByCode: Record<string, number>
  /** 素材质量子维度权重——打开率，默认 0.5（与 wViral/wRoi 之和为 1） */
  wCtr: number
  /** 素材质量子维度权重——裂变率，默认 0.3 */
  wViral: number
  /** 素材质量子维度权重——ROI，默认 0.2 */
  wRoi: number
  /** 素材质量缺失策略："group" | "shrink" */
  materialMissingStrategy: 'group' | 'shrink'
}

export const DEFAULT_RANKING_PARAMS: RankingParams = {
  simThreshold: 0.65,
  simThresholdsByCode: {},
  boostsByCode: {},
  rovClipLow: 0,
  rovClipHigh: 0.07,
  alpha: 0.6,
  deconstructBoost: 1.0,
  wCtr: 0.5,
  wViral: 0.3,
  wRoi: 0.2,
  materialMissingStrategy: 'group',
}

export interface ScoreBreakdown {
  composite: number
  simNorm: number
  rovNorm: number
  boost: number
  lowerBound: number
  passesThreshold: boolean
  /** 精排加权质量分：素材=(wCtr·ctr+wViral·viral+wRoi·roi)/Σw；视频=rov_norm */
  weightedQuality?: number
  /** 素材质量缺失时置 true，调用方按策略单独成组 */
  qualityMissing?: boolean
}

const clip01 = (x: number) => Math.max(0, Math.min(1, x))

/** signals.quality 缺失时，从 materialDetail.quality 构造质量信号 */
function materialQualityFromDetail(
  item: VideoMatchEnrichedVO,
): RecallSignals['quality'] | undefined {
  const q = item.materialDetail?.quality
  if (!q) return undefined
  const ctr = q.conversionEfficiencyScore
  const viral = q.viralScore
  const roi = q.revenueScore
  const hasData = [ctr, viral, roi].some((v) => v != null && Number.isFinite(v))
  if (!hasData) return undefined
  return {
    hasData: true,
    ctr: ctr ?? null,
    viral: viral ?? null,
    roi: roi ?? null,
  }
}

export function effectiveSimThreshold(
  configCode: string | null | undefined,
  params: RankingParams,
): number {
  if (configCode && configCode in params.simThresholdsByCode) {
    return params.simThresholdsByCode[configCode]
  }
  return params.simThreshold
}

/**
 * 计算单条召回结果的综合得分——WP2 前后端同构版本。
 *
 * 关键修正：
 * - 读 signals 而非散落字段（sim/rov/quality）
 * - deconstructBoost 按 modality===VIDEO 判定，不按 configCode.startsWith("VIDEO_")
 * - ARTICLE 无 rov 时退化为纯 sim 排序
 * - MATERIAL 质量缺失按 signals.quality.hasData 统一判定，不再回退 0.5
 */
export function computeCompositeScore(
  item: VideoMatchEnrichedVO,
  params: RankingParams,
): ScoreBreakdown | null {
  // WP2: 读 signals.sim，兼容旧 score 字段
  const sim = item.signals?.sim ?? item.score
  if (sim == null || !Number.isFinite(sim)) return null

  const lowerBound = effectiveSimThreshold(item.configCode, params)
  const denom = 1 - lowerBound
  const simNorm = denom > 0 ? clip01((sim - lowerBound) / denom) : 0
  const passesThreshold = sim >= lowerBound

  // 素材模态：多维质量加权
  if (item.modality === 'MATERIAL') {
    const quality = item.signals?.quality ?? materialQualityFromDetail(item)
    return rankMaterial(simNorm, lowerBound, passesThreshold, quality, params)
  }

  // VIDEO / ARTICLE 模态：ROV 公式
  return rankVideoArticle(simNorm, lowerBound, passesThreshold, item, params)
}

function rankMaterial(
  simNorm: number,
  lowerBound: number,
  passesThreshold: boolean,
  quality: RecallSignals['quality'] | undefined,
  params: RankingParams,
): ScoreBreakdown {
  const alpha = params.alpha

  if (quality == null || !quality.hasData) {
    // group（默认）：无质量数据，仅依赖相关性
    if (params.materialMissingStrategy === 'group') {
      return {
        composite: alpha * simNorm,
        simNorm,
        rovNorm: 0,
        boost: 1,
        lowerBound,
        passesThreshold,
        qualityMissing: true,
      }
    }
    // shrink: 无先验均值时退化为 alpha × simNorm
    return {
      composite: alpha * simNorm,
      simNorm,
      rovNorm: 0,
      boost: 1,
      lowerBound,
      passesThreshold,
    }
  }

  const ctr = quality.ctr ?? 0
  const viral = quality.viral ?? 0
  const roi = quality.roi ?? 0
  const qualTotalW = params.wCtr + params.wViral + params.wRoi || 1
  const weightedQuality = (params.wCtr * ctr + params.wViral * viral + params.wRoi * roi) / qualTotalW
  const composite = alpha * simNorm + (1 - alpha) * weightedQuality
  return {
    composite,
    simNorm,
    rovNorm: 0,
    boost: 1,
    lowerBound,
    passesThreshold,
    weightedQuality,
  }
}

function rankVideoArticle(
  simNorm: number,
  lowerBound: number,
  passesThreshold: boolean,
  item: VideoMatchEnrichedVO,
  params: RankingParams,
): ScoreBreakdown {
  // WP2: 读 signals.rov，兼容旧 videoDetail.rov
  const rov = item.signals?.rov ?? undefined

  // 按维度独立 boost：优先取 boostsByCode[configCode]，回退 deconstructBoost
  const codeBoost = item.configCode ? (params.boostsByCode?.[item.configCode] ?? params.deconstructBoost) : params.deconstructBoost
  const hasRov = rov != null && Number.isFinite(rov)
  const boost = (item.modality === 'VIDEO' && hasRov) ? codeBoost : 1

  if (!hasRov) {
    const composite = boost * simNorm
    return { composite, simNorm, rovNorm: 0, boost, lowerBound, passesThreshold }
  }

  const rovDenom = params.rovClipHigh - params.rovClipLow
  const rovNorm = rovDenom > 0 ? clip01((rov - params.rovClipLow) / rovDenom) : 0
  const composite = boost * (params.alpha * simNorm + (1 - params.alpha) * rovNorm)
  return { composite, simNorm, rovNorm, boost, lowerBound, passesThreshold, weightedQuality: rovNorm }
}

const STORAGE_KEY = 'vector_recall_ranking_params'

function loadFromStorage(): RankingParams {
  try {
    const raw = localStorage.getItem(STORAGE_KEY)
    if (!raw) return DEFAULT_RANKING_PARAMS
    const parsed = JSON.parse(raw) as Record<string, unknown>

    // WP2 迁移：rovP5/rovP95 → rovClipLow/rovClipHigh
    if (parsed.rovClipLow === undefined && typeof parsed.rovP5 === 'number') {
      parsed.rovClipLow = parsed.rovP5
    }
    if (parsed.rovClipHigh === undefined && typeof parsed.rovP95 === 'number') {
      parsed.rovClipHigh = parsed.rovP95
    }
    // 清理已迁移/废弃的字段，避免脏数据残留
    delete parsed.rovP5
    delete parsed.rovP95
    delete parsed.wSim

    return {
      ...DEFAULT_RANKING_PARAMS,
      ...parsed,
      simThresholdsByCode:
        (parsed.simThresholdsByCode as Record<string, number>) ?? {},
    } as RankingParams
  } catch {
    return DEFAULT_RANKING_PARAMS
  }
}

function saveToStorage(p: RankingParams) {
  try {
    localStorage.setItem(STORAGE_KEY, JSON.stringify(p))
  } catch {
    // localStorage 失败时静默，当次会话仍可用
  }
}

/** 展开 boostsByCode：未单独配置的 configCode 使用 deconstructBoost */
export function expandRankingBoosts(r: RankingParams, codes: string[]): RankingParams {
  const expanded: Record<string, number> = { ...r.boostsByCode }
  for (const code of codes) {
    if (!(code in expanded)) expanded[code] = r.deconstructBoost
  }
  return { ...r, boostsByCode: expanded }
}

/** 召回请求用精排参数：展开维度 boost + 完整字段 */
export function rankingForRequest(r: RankingParams, codes: string[]): RankingParams {
  return toRankingPayload(expandRankingBoosts(r, codes))
}

/** 随召回请求提交的精排参数（字段与后端 RankingSpec 对齐） */
export function toRankingPayload(params: RankingParams): RankingParams {
  return {
    simThreshold: params.simThreshold,
    simThresholdsByCode: params.simThresholdsByCode ?? {},
    rovClipLow: params.rovClipLow,
    rovClipHigh: params.rovClipHigh,
    alpha: params.alpha,
    deconstructBoost: params.deconstructBoost,
    boostsByCode: params.boostsByCode ?? {},
    wCtr: params.wCtr,
    wViral: params.wViral,
    wRoi: params.wRoi,
    materialMissingStrategy: params.materialMissingStrategy,
  }
}

export function useRankingParams(): [RankingParams, (next: RankingParams) => void] {
  const [params, setParams] = useState<RankingParams>(() => loadFromStorage())
  useEffect(() => {
    saveToStorage(params)
  }, [params])
  return [params, setParams]
}