package utils

import (
	"math"
	"time"
)

// RoundToTwoDecimals rounds a float64 to two decimal places
func RoundToTwoDecimals(value float64) float64 {
	return math.Round(value*100) / 100
}

// StartOfDay returns the start of the day for a given time
func StartOfDay(t time.Time) time.Time {
	return time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())
}

// EndOfDay returns the end of the day for a given time
func EndOfDay(t time.Time) time.Time {
	return time.Date(t.Year(), t.Month(), t.Day(), 23, 59, 59, 999999999, t.Location())
}

// StartOfMonth returns the first day of the month for a given time
func StartOfMonth(t time.Time) time.Time {
	return time.Date(t.Year(), t.Month(), 1, 0, 0, 0, 0, t.Location())
}

// EndOfMonth returns the last day of the month for a given time
func EndOfMonth(t time.Time) time.Time {
	return StartOfMonth(t).AddDate(0, 1, 0).Add(-time.Nanosecond)
}

// StartOfYear returns the first day of the year for a given time
func StartOfYear(t time.Time) time.Time {
	return time.Date(t.Year(), 1, 1, 0, 0, 0, 0, t.Location())
}

// EndOfYear returns the last day of the year for a given time
func EndOfYear(t time.Time) time.Time {
	return time.Date(t.Year(), 12, 31, 23, 59, 59, 999999999, t.Location())
}

// StartOfWeek returns the start of the week (Monday) for a given time
func StartOfWeek(t time.Time) time.Time {
	weekday := int(t.Weekday())
	if weekday == 0 {
		weekday = 7 // Sunday is 7
	}
	return StartOfDay(t.AddDate(0, 0, -(weekday - 1)))
}

// EndOfWeek returns the end of the week (Sunday) for a given time
func EndOfWeek(t time.Time) time.Time {
	return EndOfDay(StartOfWeek(t).AddDate(0, 0, 6))
}

// ParseDate parses a date string in YYYY-MM-DD format
func ParseDate(dateStr string) (time.Time, error) {
	return time.Parse("2006-01-02", dateStr)
}

// FormatDate formats a time to YYYY-MM-DD string
func FormatDate(t time.Time) string {
	return t.Format("2006-01-02")
}

// Min returns the minimum of two integers
func Min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

// Max returns the maximum of two integers
func Max(a, b int) int {
	if a > b {
		return a
	}
	return b
}

// Abs returns the absolute value of a float64
func Abs(value float64) float64 {
	return math.Abs(value)
}

// CalculatePercentage calculates the percentage of part relative to total
func CalculatePercentage(part, total float64) float64 {
	if total == 0 {
		return 0
	}
	return RoundToTwoDecimals((part / total) * 100)
}