feat: refactor

internal/downloader/idx_test.go

@@ -0,0 +1,110 @@
+package downloader
+
+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))
+	}
+
+	// Check first entry
+	e := entries[0]
+	if e.Index != 1 || e.Offset != 0 || e.Variable != "HGT" || e.LevelMB != 1000 || e.Hour != 0 {
+		t.Errorf("entry 0: got %+v", e)
+	}
+	if e.EndOffset != 289012 {
+		t.Errorf("entry 0 EndOffset: got %d, want 289012", e.EndOffset)
+	}
+
+	// Check "2 m above ground" is not a pressure level
+	e = entries[6] // UGRD at "2 m above ground"
+	if e.LevelMB != 0 {
+		t.Errorf("non-pressure level should have LevelMB=0, got %d", e.LevelMB)
+	}
+
+	// Last entry should have EndOffset = -1
+	last := entries[len(entries)-1]
+	if last.EndOffset != -1 {
+		t.Errorf("last entry EndOffset: got %d, want -1", last.EndOffset)
+	}
+}
+
+func TestFilterIdx(t *testing.T) {
+	entries := ParseIdx([]byte(sampleIdx))
+	filtered := FilterIdx(entries, neededVariables)
+
+	// Should include HGT/UGRD/VGRD at pressure levels, exclude TMP and "above ground"
+	// And exclude last entry (no EndOffset)
+	for _, e := range filtered {
+		if !neededVariables[e.Variable] {
+			t.Errorf("unexpected variable %s", e.Variable)
+		}
+		if e.LevelMB <= 0 {
+			t.Errorf("non-pressure level included: %+v", e)
+		}
+		if e.Length() <= 0 {
+			t.Errorf("entry with unknown length included: %+v", e)
+		}
+	}
+
+	// Count expected: HGT@1000, HGT@975, UGRD@1000, VGRD@1000, UGRD@975, VGRD@975 = 6
+	// But HGT@500 at 3hr fcst is the last entry (no EndOffset), so excluded
+	if len(filtered) != 6 {
+		t.Errorf("expected 6 filtered entries, got %d", len(filtered))
+		for _, e := range filtered {
+			t.Logf("  %s %d mb (offset %d, len %d)", e.Variable, e.LevelMB, e.Offset, e.Length())
+		}
+	}
+}
+
+func TestParseLevelMB(t *testing.T) {
+	tests := []struct {
+		input string
+		want  int
+	}{
+		{"1000 mb", 1000},
+		{"975 mb", 975},
+		{"1 mb", 1},
+		{"2 m above ground", 0},
+		{"surface", 0},
+		{"tropopause", 0},
+	}
+	for _, tt := range tests {
+		got := parseLevelMB(tt.input)
+		if got != tt.want {
+			t.Errorf("parseLevelMB(%q) = %d, want %d", tt.input, got, tt.want)
+		}
+	}
+}
+
+func TestParseHour(t *testing.T) {
+	tests := []struct {
+		input string
+		want  int
+	}{
+		{"0 hour fcst", 0},
+		{"3 hour fcst", 3},
+		{"192 hour fcst", 192},
+		{"anl", 0},
+	}
+	for _, tt := range tests {
+		got := parseHour(tt.input)
+		if got != tt.want {
+			t.Errorf("parseHour(%q) = %d, want %d", tt.input, got, tt.want)
+		}
+	}
+}