package matching

import (
	"fmt"
	"strings"
	"time"
)

var sheetsEpoch = time.Date(1899, 12, 30, 0, 0, 0, 0, time.UTC)

// FormatDate normalizes a date value from Google Sheets.
//
// Accepts nil, empty string, int/float64 Sheets serial days since 1899-12-30,
// a pre-formatted "YYYY-MM-DD" string (returned as-is), or any other value
// (returned as fmt.Sprint(v).TrimSpace). Never returns an error.
//
// Ports scripts/match_payments.py format_date.
func FormatDate(val any) string {
	if val == nil {
		return ""
	}
	switch v := val.(type) {
	case int:
		return sheetsEpoch.Add(time.Duration(float64(v) * 24 * float64(time.Hour))).Format("2006-01-02")
	case int64:
		return sheetsEpoch.Add(time.Duration(float64(v) * 24 * float64(time.Hour))).Format("2006-01-02")
	case float64:
		return sheetsEpoch.Add(time.Duration(v * 24 * float64(time.Hour))).Format("2006-01-02")
	case string:
		s := strings.TrimSpace(v)
		if s == "" {
			return ""
		}
		if len(s) == 10 && s[4] == '-' && s[7] == '-' {
			return s
		}
		return s
	default:
		return strings.TrimSpace(fmt.Sprint(v))
	}
}