import type { InfraMonitoringResponse } from '@/data/analytics/infra-monitoring-query'

type NumericValue = string | number | undefined

/**
 * Parses a numeric value that can be a number, string, or undefined.
 * Returns 0 for invalid or missing values.
 */
export function parseNumericValue(val: NumericValue): number {
  if (typeof val === 'number') return val
  if (typeof val === 'string') return parseFloat(val) || 0
  return 0
}

type MetricData = {
  current: number
  max: number
}

type InfrastructureMetrics = {
  cpu: MetricData
  ram: MetricData
  disk: MetricData
  diskIo: MetricData
}

export function parseInfrastructureMetrics(
  infraData: InfraMonitoringResponse | undefined
): InfrastructureMetrics | null {
  if (!infraData) {
    return null
  }

  const series = 'series' in infraData ? infraData.series : {}

  const cpuValue = parseNumericValue(series.avg_cpu_usage?.totalAverage)
  const ramValue = parseNumericValue(series.ram_usage?.totalAverage)
  const diskSystemValue = parseNumericValue(series.disk_fs_used_system?.totalAverage)
  const diskWalValue = parseNumericValue(series.disk_fs_used_wal?.totalAverage)
  const diskDatabaseValue = parseNumericValue(series.pg_database_size?.totalAverage)
  const diskSizeValue = parseNumericValue(series.disk_fs_size?.totalAverage)
  const diskUsedValue = diskSystemValue + diskWalValue + diskDatabaseValue
  const diskUsageValue = diskSizeValue > 0 ? (diskUsedValue / diskSizeValue) * 100 : 0
  const diskIoValue = parseNumericValue(series.disk_io_consumption?.totalAverage)

  return {
    cpu: {
      current: cpuValue,
      max: 100,
    },
    ram: {
      current: ramValue,
      max: 100,
    },
    disk: {
      current: diskUsageValue,
      max: 100,
    },
    diskIo: {
      current: diskIoValue,
      max: 100,
    },
  }
}

type ConnectionsData = {
  peak: number
  max: number
}

type MaxConnectionsData = {
  maxConnections?: number
}

export function parseConnectionsData(
  infraData: InfraMonitoringResponse | undefined,
  maxConnectionsData: MaxConnectionsData | undefined
): ConnectionsData {
  const max = maxConnectionsData?.maxConnections ?? 0

  if (!infraData || !('series' in infraData)) {
    return { peak: 0, max }
  }

  // Show the highest connection count observed in the selected window rather
  // than the window's totalAverage. The average varies with bucket granularity
  // (e.g. 1h vs 1m) and is hard to reason about; peak is interval-stable and
  // the more actionable signal for headroom against the connection limit.
  let peak = 0
  for (const point of infraData.data ?? []) {
    const n = parseNumericValue(point?.values?.pg_stat_database_num_backends)
    if (n > peak) peak = n
  }

  return { peak: Math.round(peak), max }
}