// internal/geo/tz_test.go
package geo

import (
	"strings"
	"testing"
)

func TestZonePoint(t *testing.T) {
	mapped := []string{
		"Europe/London", "Europe/Dublin", "Europe/Amsterdam",
		"Asia/Kolkata", "Asia/Calcutta",
		"America/Argentina/Buenos_Aires", "europe/london",
	}
	for _, z := range mapped {
		if _, ok := ZonePoint(z); !ok {
			t.Errorf("ZonePoint(%q) unmapped, want a point", z)
		}
	}
	a, _ := ZonePoint("Asia/Calcutta")
	b, _ := ZonePoint("Asia/Kolkata")
	if a != b {
		t.Errorf("Asia/Calcutta %v != Asia/Kolkata %v; the link must resolve to one point", a, b)
	}
	// Amsterdam is a link to Brussels in tzdata 2026b, but zone.tab gives it
	// its own row: zone.tab wins over links (spec §6.2).
	am, _ := ZonePoint("Europe/Amsterdam")
	br, _ := ZonePoint("Europe/Brussels")
	if am == br {
		t.Errorf("Europe/Amsterdam = Europe/Brussels = %v; a zone.tab row must win over a link", am)
	}
	unmapped := []string{
		"", "UTC", "Etc/UTC", "Etc/GMT+5", "GMT", "UCT", "Universal", "Zulu",
		"Factory", "Local", "localtime", "posixrules", "../etc/passwd",
		"Europe/London/Extra/Deep", strings.Repeat("A", 65), "Nowhere/Atlantis",
	}
	for _, z := range unmapped {
		if p, ok := ZonePoint(z); ok {
			t.Errorf("ZonePoint(%q) = %v, want unmappable", z, p)
		}
	}
	l, _ := ZonePoint("Europe/London")
	if l.Lat < 51 || l.Lat > 52 || l.Lon > 0.5 || l.Lon < -0.5 {
		t.Errorf("Europe/London = %v, want about 51.5, -0.12", l)
	}
}

// A link cycle must terminate (at most 4 hops) rather than hang.
func TestZonePointLinkLoopTerminates(t *testing.T) {
	links := map[string]string{"a/x": "a/y", "a/y": "a/x"}
	if _, ok := resolveLinks("a/x", links, map[string]Point{}); ok {
		t.Fatal("a link loop resolved to a point")
	}
}

// Every country with more than one zone.tab row needs an override naming
// its principal zone: a tzdata refresh that gives a country a second row
// fails here instead of silently averaging a continent (spec §6.2).
func TestCountryOverridesCoverEveryMultiZoneCountry(t *testing.T) {
	for cc, n := range zoneRowsPerCountry() {
		if n < 2 {
			continue
		}
		zone, ok := countryOverride[cc]
		if !ok {
			t.Errorf("country %s has %d zone.tab rows and no override", cc, n)
			continue
		}
		if _, ok := ZonePoint(zone); !ok {
			t.Errorf("override for %s names %q, which is not in zone.tab", cc, zone)
		}
	}
	for cc := range countryOverride {
		if zoneRowsPerCountry()[cc] < 2 {
			t.Errorf("override for %s is unused: it has fewer than two rows", cc)
		}
	}
}

func TestCountryPoint(t *testing.T) {
	for _, cc := range []string{"GB", "IE", "US", "AU", "IN", "gb"} {
		if _, ok := CountryPoint(cc); !ok {
			t.Errorf("CountryPoint(%q) unmapped", cc)
		}
	}
	us, _ := CountryPoint("US")
	ny, _ := ZonePoint("America/New_York")
	if us != ny {
		t.Errorf("US = %v, want its principal zone New York %v", us, ny)
	}
	if _, ok := CountryPoint("ZZ"); ok {
		t.Error("CountryPoint(ZZ) mapped")
	}
}

func TestTZDataVersion(t *testing.T) {
	if v := TZDataVersion(); v == "" || strings.ContainsAny(v, " \n") {
		t.Fatalf("TZDataVersion = %q", v)
	}
}