package gfs

import "testing"

const sampleIdx = `1:0:d=2024010100:HGT:1000 mb:0 hour fcst:
2:289012:d=2024010100:HGT:975 mb:0 hour fcst:
3:541876:d=2024010100:TMP:1000 mb:0 hour fcst:
4:789012:d=2024010100:UGRD:1000 mb:0 hour fcst:
5:1045678:d=2024010100:VGRD:1000 mb:0 hour fcst:
6:1298765:d=2024010100:UGRD:975 mb:0 hour fcst:
7:1567890:d=2024010100:UGRD:2 m above ground:0 hour fcst:
8:1812345:d=2024010100:VGRD:975 mb:0 hour fcst:
9:2098765:d=2024010100:HGT:500 mb:3 hour fcst:
`

func TestParseIdx(t *testing.T) {
	entries := ParseIdx([]byte(sampleIdx))
	if len(entries) != 9 {
		t.Fatalf("expected 9 entries, got %d", len(entries))
	}
	if e := entries[0]; e.Index != 1 || e.Offset != 0 || e.Variable != "HGT" || e.LevelMB != 1000 || e.Hour != 0 || e.EndOffset != 289012 {
		t.Errorf("entry 0: %+v", e)
	}
	if e := entries[6]; e.LevelMB != 0 {
		t.Errorf("non-pressure level should have LevelMB=0, got %d", e.LevelMB)
	}
	if e := entries[len(entries)-1]; e.EndOffset != -1 {
		t.Errorf("last entry EndOffset: got %d, want -1", e.EndOffset)
	}
}

func TestFilterIdx(t *testing.T) {
	entries := ParseIdx([]byte(sampleIdx))
	want := map[string]bool{"HGT": true, "UGRD": true, "VGRD": true}
	filtered := FilterIdx(entries, want)
	// HGT@1000, HGT@975, UGRD@1000, VGRD@1000, UGRD@975, VGRD@975 = 6
	// HGT@500 at 3hr is last entry (no EndOffset), so dropped.
	if len(filtered) != 6 {
		t.Errorf("expected 6, got %d", len(filtered))
	}
}

func TestParseLevelMB(t *testing.T) {
	cases := []struct {
		in   string
		want int
	}{
		{"1000 mb", 1000}, {"975 mb", 975}, {"1 mb", 1},
		{"2 m above ground", 0}, {"surface", 0}, {"tropopause", 0},
	}
	for _, c := range cases {
		if got := parseLevelMB(c.in); got != c.want {
			t.Errorf("parseLevelMB(%q) = %d, want %d", c.in, got, c.want)
		}
	}
}

func TestParseHour(t *testing.T) {
	cases := []struct {
		in   string
		want int
	}{
		{"0 hour fcst", 0}, {"3 hour fcst", 3}, {"192 hour fcst", 192}, {"anl", 0},
	}
	for _, c := range cases {
		if got := parseHour(c.in); got != c.want {
			t.Errorf("parseHour(%q) = %d, want %d", c.in, got, c.want)
		}
	}
}