package engine

import (
	"fmt"
	"math"
	"time"
)

// FormatRelativeDate returns a human-readable relative date string.
// Within 14 days: "today", "tomorrow", "yesterday", "in 3d", "2d ago"
// Beyond 14 days: "Feb 28", "Mar 15"
// Cross-year: "Feb 28 2027"
func FormatRelativeDate(t time.Time) string {
	now := timeNow()
	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, now.Location())
	target := time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, t.Location())

	days := int(math.Round(target.Sub(today).Hours() / 24))

	switch {
	case days == 0:
		return "today"
	case days == 1:
		return "tomorrow"
	case days == -1:
		return "yesterday"
	case days > 1 && days <= 14:
		return fmt.Sprintf("in %dd", days)
	case days < -1 && days >= -14:
		return fmt.Sprintf("%dd ago", -days)
	default:
		if t.Year() != now.Year() {
			return t.Format("Jan 2 2006")
		}
		return t.Format("Jan 2")
	}
}

// FormatDateWithRelative returns "2026-02-20 (in 2 days)" style.
// Used in info/detail views where both absolute and relative are useful.
func FormatDateWithRelative(t time.Time) string {
	absolute := t.Format("2006-01-02 15:04")
	relative := FormatRelativeDate(t)
	return fmt.Sprintf("%s (%s)", absolute, relative)
}