/**
 * Calculates percentage of savings target met
 * Formula: savings ÷ (savings_target_months × monthly burn)
 */
export const useReserveProgress = () => {
  const calculateReserveProgress = (
    currentSavings: number,
    savingsTargetMonths: number,
    monthlyBurn: number
  ): number => {
    const targetAmount = savingsTargetMonths * monthlyBurn
    if (targetAmount <= 0) return 100
    return Math.min((currentSavings / targetAmount) * 100, 100)
  }
  
  const getReserveProgressStatus = (progressPct: number): 'green' | 'yellow' | 'red' => {
    if (progressPct >= 80) return 'green'
    if (progressPct >= 50) return 'yellow'
    return 'red'
  }
  
  const getReserveProgressMessage = (status: 'green' | 'yellow' | 'red'): string => {
    switch (status) {
      case 'red':
        return 'Build savings to your target before increasing paid hours.'
      case 'yellow':
        return 'Savings progress is moderate. Continue building reserves.'
      case 'green':
        return 'Savings target nearly reached or exceeded.'
    }
  }
  
  const calculateTargetAmount = (savingsTargetMonths: number, monthlyBurn: number): number => {
    return savingsTargetMonths * monthlyBurn
  }
  
  const calculateShortfall = (
    currentSavings: number,
    savingsTargetMonths: number,
    monthlyBurn: number
  ): number => {
    const targetAmount = calculateTargetAmount(savingsTargetMonths, monthlyBurn)
    return Math.max(0, targetAmount - currentSavings)
  }
  
  const analyzeReserveProgress = (
    currentSavings: number,
    savingsTargetMonths: number,
    monthlyBurn: number
  ) => {
    const progressPct = calculateReserveProgress(currentSavings, savingsTargetMonths, monthlyBurn)
    const status = getReserveProgressStatus(progressPct)
    const targetAmount = calculateTargetAmount(savingsTargetMonths, monthlyBurn)
    const shortfall = calculateShortfall(currentSavings, savingsTargetMonths, monthlyBurn)
    
    return {
      progressPct: Math.round(progressPct),
      status,
      message: getReserveProgressMessage(status),
      currentSavings,
      targetAmount,
      shortfall
    }
  }
  
  return {
    calculateReserveProgress,
    getReserveProgressStatus,
    getReserveProgressMessage,
    calculateTargetAmount,
    calculateShortfall,
    analyzeReserveProgress
  }
}