package tools

import (
	"fmt"
	"math"
)

// MoneyCalculator 金额计算工具（以分为单位）
type MoneyCalculator struct{}

// NewMoneyCalculator 创建金额计算器
func NewMoneyCalculator() *MoneyCalculator {
	return &MoneyCalculator{}
}

// YuanToCents 元转分
func (m *MoneyCalculator) YuanToCents(yuan float64) int64 {
	return int64(math.Round(yuan * 100))
}

// CentsToYuan 分转元
func (m *MoneyCalculator) CentsToYuan(cents int64) float64 {
	return float64(cents) / 100
}

// FormatYuan 格式化显示金额（分转元，保留2位小数）
func (m *MoneyCalculator) FormatYuan(cents int64) string {
	return fmt.Sprintf("%.2f", m.CentsToYuan(cents))
}

// Add 金额相加
func (m *MoneyCalculator) Add(amount1, amount2 int64) int64 {
	return amount1 + amount2
}

// Subtract 金额相减
func (m *MoneyCalculator) Subtract(amount1, amount2 int64) int64 {
	return amount1 - amount2
}

// Multiply 金额乘法（金额 * 数量）
func (m *MoneyCalculator) Multiply(amount int64, quantity int) int64 {
	return amount * int64(quantity)
}

// MultiplyFloat 金额乘法（金额 * 浮点数，如折扣）
func (m *MoneyCalculator) MultiplyFloat(amount int64, rate float64) int64 {
	return int64(math.Round(float64(amount) * rate))
}

// Divide 金额除法（平均分配）
func (m *MoneyCalculator) Divide(amount int64, count int) int64 {
	if count <= 0 {
		return 0
	}
	return amount / int64(count)
}

// CalculateDiscount 计算折扣金额
func (m *MoneyCalculator) CalculateDiscount(originalAmount int64, discountRate float64) int64 {
	if discountRate <= 0 || discountRate >= 1 {
		return 0
	}
	return int64(math.Round(float64(originalAmount) * discountRate))
}

// CalculatePercentage 计算百分比金额
func (m *MoneyCalculator) CalculatePercentage(amount int64, percentage float64) int64 {
	return int64(math.Round(float64(amount) * percentage / 100))
}

// Max 取最大金额
func (m *MoneyCalculator) Max(amounts ...int64) int64 {
	if len(amounts) == 0 {
		return 0
	}
	max := amounts[0]
	for _, amount := range amounts[1:] {
		if amount > max {
			max = amount
		}
	}
	return max
}

// Min 取最小金额
func (m *MoneyCalculator) Min(amounts ...int64) int64 {
	if len(amounts) == 0 {
		return 0
	}
	min := amounts[0]
	for _, amount := range amounts[1:] {
		if amount < min {
			min = amount
		}
	}
	return min
}

// IsPositive 判断是否为正数
func (m *MoneyCalculator) IsPositive(amount int64) bool {
	return amount > 0
}

// IsZero 判断是否为零
func (m *MoneyCalculator) IsZero(amount int64) bool {
	return amount == 0
}

// IsNegative 判断是否为负数
func (m *MoneyCalculator) IsNegative(amount int64) bool {
	return amount < 0
}

// Equal 判断金额是否相等
func (m *MoneyCalculator) Equal(amount1, amount2 int64) bool {
	return amount1 == amount2
}

// Greater 判断第一个金额是否大于第二个
func (m *MoneyCalculator) Greater(amount1, amount2 int64) bool {
	return amount1 > amount2
}

// Less 判断第一个金额是否小于第二个
func (m *MoneyCalculator) Less(amount1, amount2 int64) bool {
	return amount1 < amount2
}

// Sum 计算金额总和
func (m *MoneyCalculator) Sum(amounts ...int64) int64 {
	var total int64
	for _, amount := range amounts {
		total += amount
	}
	return total
}

// SplitAmount 金额分摊（处理分摊不均的情况）
func (m *MoneyCalculator) SplitAmount(totalAmount int64, count int) []int64 {
	if count <= 0 {
		return []int64{}
	}

	baseAmount := totalAmount / int64(count)
	remainder := totalAmount % int64(count)

	amounts := make([]int64, count)
	for i := 0; i < count; i++ {
		amounts[i] = baseAmount
		if int64(i) < remainder {
			amounts[i]++
		}
	}

	return amounts
}

// 全局金额计算器实例
var Money = NewMoneyCalculator()

// 便捷函数
func YuanToCents(yuan float64) int64 {
	return Money.YuanToCents(yuan)
}

func CentsToYuan(cents int64) float64 {
	return Money.CentsToYuan(cents)
}

func FormatYuan(cents int64) string {
	return Money.FormatYuan(cents)
}