package service

// Legacy IANA timezone aliases → canonical names.
//
// Browsers report Intl.DateTimeFormat().resolvedOptions().timeZone, and the
// ICU/CLDR data they ship still uses several LEGACY ids as its canonical
// form — Safari and Chrome genuinely say "Asia/Calcutta", not "Asia/Kolkata".
// Go's time.LoadLocation resolves these aliases, so they pass validation and
// get stored; but a Postgres built against tzdata without the "backward"
// links (Debian/Alpine images with the tzdata-legacy split) rejects them in
// AT TIME ZONE with SQLSTATE 22023. Everything we store or hand to SQL goes
// through canonicalTZ first.
var legacyTZ = map[string]string{
	// Ids ICU/CLDR still reports as canonical (the ones browsers send).
	"Asia/Calcutta":        "Asia/Kolkata",
	"Asia/Katmandu":        "Asia/Kathmandu",
	"Asia/Rangoon":         "Asia/Yangon",
	"Asia/Saigon":          "Asia/Ho_Chi_Minh",
	"America/Buenos_Aires": "America/Argentina/Buenos_Aires",
	"America/Catamarca":    "America/Argentina/Catamarca",
	"America/Cordoba":      "America/Argentina/Cordoba",
	"America/Jujuy":        "America/Argentina/Jujuy",
	"America/Mendoza":      "America/Argentina/Mendoza",
	"America/Indianapolis": "America/Indiana/Indianapolis",
	"America/Louisville":   "America/Kentucky/Louisville",
	"America/Godthab":      "America/Nuuk",
	"Atlantic/Faeroe":      "Atlantic/Faroe",
	"Pacific/Ponape":       "Pacific/Pohnpei",
	"Pacific/Truk":         "Pacific/Chuuk",
	"Europe/Kiev":          "Europe/Kyiv",

	// Other common backward links, in case a zone arrives from an older
	// client or was set by hand.
	"Asia/Ashkhabad":        "Asia/Ashgabat",
	"Asia/Chongqing":        "Asia/Shanghai",
	"Asia/Chungking":        "Asia/Shanghai",
	"Asia/Dacca":            "Asia/Dhaka",
	"Asia/Harbin":           "Asia/Shanghai",
	"Asia/Istanbul":         "Europe/Istanbul",
	"Asia/Kashgar":          "Asia/Urumqi",
	"Asia/Macao":            "Asia/Macau",
	"Asia/Tel_Aviv":         "Asia/Jerusalem",
	"Asia/Thimbu":           "Asia/Thimphu",
	"Asia/Ujung_Pandang":    "Asia/Makassar",
	"Asia/Ulan_Bator":       "Asia/Ulaanbaatar",
	"Africa/Asmera":         "Africa/Asmara",
	"America/Coral_Harbour": "America/Atikokan",
	"Australia/ACT":         "Australia/Sydney",
	"Australia/Canberra":    "Australia/Sydney",
	"Australia/NSW":         "Australia/Sydney",
	"Australia/North":       "Australia/Darwin",
	"Australia/Queensland":  "Australia/Brisbane",
	"Australia/South":       "Australia/Adelaide",
	"Australia/Tasmania":    "Australia/Hobart",
	"Australia/Victoria":    "Australia/Melbourne",
	"Australia/West":        "Australia/Perth",
	"US/Alaska":             "America/Anchorage",
	"US/Arizona":            "America/Phoenix",
	"US/Central":            "America/Chicago",
	"US/Eastern":            "America/New_York",
	"US/Hawaii":             "Pacific/Honolulu",
	"US/Mountain":           "America/Denver",
	"US/Pacific":            "America/Los_Angeles",
	"GB":                    "Europe/London",
	"GB-Eire":               "Europe/London",
	"Eire":                  "Europe/Dublin",
	"Egypt":                 "Africa/Cairo",
	"Hongkong":              "Asia/Hong_Kong",
	"Iceland":               "Atlantic/Reykjavik",
	"Israel":                "Asia/Jerusalem",
	"Japan":                 "Asia/Tokyo",
	"NZ":                    "Pacific/Auckland",
	"Poland":                "Europe/Warsaw",
	"Portugal":              "Europe/Lisbon",
	"PRC":                   "Asia/Shanghai",
	"ROC":                   "Asia/Taipei",
	"ROK":                   "Asia/Seoul",
	"Singapore":             "Asia/Singapore",
	"Turkey":                "Europe/Istanbul",
}

// canonicalTZ returns the canonical IANA name for tz, resolving legacy
// aliases; unknown values pass through unchanged.
func canonicalTZ(tz string) string {
	if c, ok := legacyTZ[tz]; ok {
		return c
	}
	return tz
}