DecayDetector

import { DecayDetector } from '@pagebridge/core'

// With default rules
const detector = new DecayDetector(db)

// With custom rules
const detector = new DecayDetector(db, [
  {
    type: 'position_decay',
    threshold: 5,
    minImpressions: 200,
    comparisonWindowDays: 14,
    sustainedDays: 7
  },
  {
    type: 'low_ctr',
    threshold: 0.02,
    minImpressions: 500,
    comparisonWindowDays: 28,
    sustainedDays: 7
  }
])

// publishedDates: Map of page URL -> publish date
// Used for quiet period filtering
const publishedDates = new Map([
  ['https://example.com/blog/post-1', new Date('2025-01-15')],
  ['https://example.com/blog/post-2', new Date('2024-11-01')]
])

const signals = await detector.detectDecay(
  'sc-domain:example.com',
  publishedDates,
  { days: 45 } // quiet period config
)

// signals: DecaySignal[]

interface DecaySignal {
  page: string
  reason: 'position_decay' | 'low_ctr' | 'impressions_drop'
  severity: 'low' | 'medium' | 'high'
  metrics: {
    positionBefore: number
    positionNow: number
    positionDelta: number
    ctrBefore: number
    ctrNow: number
    impressions: number
  }
}

interface DecayRule {
  type: 'position_decay' | 'low_ctr' | 'impressions_drop'
  threshold: number
  minImpressions: number
  comparisonWindowDays: number
  sustainedDays: number
}