// SLA 服务可用性档位定义
// 参考：mail_monitor_wechat/README.md 服务可用性档位说明

export interface SlaTier {
  name: string
  availability: number
  penalty: number
  ratio: number | null // 当月总秒数占比，第五档 ratio 为 null（无上限）
}

export const SLA_TIERS: SlaTier[] = [
  { name: '第一档', availability: 0.99, penalty: 0, ratio: 0.01 },
  { name: '第二档', availability: 0.97, penalty: 0.10, ratio: 0.03 },
  { name: '第三档', availability: 0.95, penalty: 0.25, ratio: 0.05 },
  { name: '第四档', availability: 0.90, penalty: 0.50, ratio: 0.10 },
  { name: '第五档', availability: 0, penalty: 1.00, ratio: null },
]

export interface SlaStatus {
  level: 'safe' | 'warning' | 'over-tier1' | 'critical' | 'excluded'
  color: string
  text: string
}

/**
 * 返回指定年月的总秒数
 */
export function getMonthSeconds(year: number, month: number): number {
  const daysInMonth = new Date(year, month, 0).getDate()
  return daysInMonth * 24 * 3600
}

/**
 * 返回第一档 SLA 截止时间
 * 截止 = assign_time + 当月总秒数 × 1%
 */
export function getTier1Deadline(assignTime: string): Date {
  const at = new Date(assignTime)
  const monthSec = getMonthSeconds(at.getFullYear(), at.getMonth() + 1)
  const tier1Window = monthSec * 0.01 // 1%
  return new Date(at.getTime() + tier1Window * 1000)
}

/**
 * 返回第二档 SLA 截止时间（用于"严重"判定）
 */
export function getTier2Deadline(assignTime: string): Date {
  const at = new Date(assignTime)
  const monthSec = getMonthSeconds(at.getFullYear(), at.getMonth() + 1)
  const tier2Window = monthSec * 0.03 // 3%
  return new Date(at.getTime() + tier2Window * 1000)
}

/**
 * 根据 assign_time 和 counted_in_sla 返回 SLA 状态
 */
export function getSlaStatus(assignTime: string, countedInSla: number): SlaStatus {
  if (countedInSla === 0) {
    return { level: 'excluded', color: '#94a3b8', text: '不计入SLA' }
  }

  const now = new Date()
  const tier1Deadline = getTier1Deadline(assignTime)
  const tier1Window = tier1Deadline.getTime() - new Date(assignTime).getTime()

  // 剩余时间（毫秒），正数表示还没超，负数表示已超
  const remaining = tier1Deadline.getTime() - now.getTime()

  if (remaining > 0) {
    const remainingRatio = remaining / tier1Window
    if (remainingRatio > 0.5) {
      const h = Math.floor(remaining / 3600000)
      const m = Math.floor((remaining % 3600000) / 60000)
      return { level: 'safe', color: '#22c55e', text: `还剩 ${h}h ${m}m` }
    } else {
      const h = Math.floor(remaining / 3600000)
      const m = Math.floor((remaining % 3600000) / 60000)
      return { level: 'warning', color: '#eab308', text: `还剩 ${h}h ${m}m` }
    }
  }

  // 已超第一档
  const exceeded = Math.abs(remaining)
  const tier2Deadline = getTier2Deadline(assignTime)

  if (now < tier2Deadline) {
    const h = Math.floor(exceeded / 3600000)
    const m = Math.floor((exceeded % 3600000) / 60000)
    return { level: 'over-tier1', color: '#f97316', text: `超时 ${h}h ${m}m` }
  }

  // 已超第二档（严重）
  const h = Math.floor(exceeded / 3600000)
  const m = Math.floor((exceeded % 3600000) / 60000)
  return { level: 'critical', color: '#ef4444', text: `超时 ${h}h ${m}m` }
}