bake: add rfc3339parse function

Signed-off-by: CrazyMax <[email protected]>

Author: crazy-max

bake/hclparser/stdlib.go

@@ -94,6 +94,7 @@ var stdlibFunctions = []funcDef{
 	{name: "replace", fn: stdlib.ReplaceFunc},
 	{name: "reverse", fn: stdlib.ReverseFunc},
 	{name: "reverselist", fn: stdlib.ReverseListFunc},
+	{name: "rfc3339parse", factory: rfc3339ParseFunc},
 	{name: "rsadecrypt", fn: crypto.RsaDecryptFunc},
 	{name: "sanitize", factory: sanitizeFunc},
 	{name: "sethaselement", fn: stdlib.SetHasElementFunc},
@@ -248,6 +249,61 @@ func timestampFunc() function.Function {
 	})
 }
 
+// rfc3339ParseFunc, given an RFC3339 timestamp string, will parse and return an
+// object representation of that date and time.
+//
+// This function is similar to the `rfc3339_parse` function in Terraform: https://registry.terraform.io/providers/hashicorp/time/latest/docs/functions/rfc3339_parse
+// See also https://github.com/hashicorp/terraform-provider-time/blob/69f9f399b3ba82a6cf8e03052b00aeeddb0b74e1/internal/provider/function_rfc3339_parse.go
+func rfc3339ParseFunc() function.Function {
+	return function.New(&function.Spec{
+		Params: []function.Parameter{
+			{
+				Name:        "timestamp",
+				Description: "RFC3339 timestamp string to parse",
+				Type:        cty.String,
+			},
+		},
+		Type: function.StaticReturnType(cty.Object(map[string]cty.Type{
+			"year":         cty.Number,
+			"year_day":     cty.Number,
+			"day":          cty.Number,
+			"month":        cty.Number,
+			"month_name":   cty.String,
+			"weekday":      cty.Number,
+			"weekday_name": cty.String,
+			"hour":         cty.Number,
+			"minute":       cty.Number,
+			"second":       cty.Number,
+			"unix":         cty.Number,
+			"iso_year":     cty.Number,
+			"iso_week":     cty.Number,
+		})),
+		Impl: func(args []cty.Value, retType cty.Type) (cty.Value, error) {
+			ts := args[0].AsString()
+			rfc3339, err := time.Parse(time.RFC3339, ts)
+			if err != nil {
+				return cty.NilVal, err
+			}
+			isoYear, isoWeek := rfc3339.ISOWeek()
+			return cty.ObjectVal(map[string]cty.Value{
+				"year":         cty.NumberIntVal(int64(rfc3339.Year())),
+				"year_day":     cty.NumberIntVal(int64(rfc3339.YearDay())),
+				"day":          cty.NumberIntVal(int64(rfc3339.Day())),
+				"month":        cty.NumberIntVal(int64(rfc3339.Month())),
+				"month_name":   cty.StringVal(rfc3339.Month().String()),
+				"weekday":      cty.NumberIntVal(int64(rfc3339.Weekday())),
+				"weekday_name": cty.StringVal(rfc3339.Weekday().String()),
+				"hour":         cty.NumberIntVal(int64(rfc3339.Hour())),
+				"minute":       cty.NumberIntVal(int64(rfc3339.Minute())),
+				"second":       cty.NumberIntVal(int64(rfc3339.Second())),
+				"unix":         cty.NumberIntVal(int64(rfc3339.Unix())),
+				"iso_year":     cty.NumberIntVal(int64(isoYear)),
+				"iso_week":     cty.NumberIntVal(int64(isoWeek)),
+			}), nil
+		},
+	})
+}
+
 func Stdlib() map[string]function.Function {
 	funcs := make(map[string]function.Function, len(stdlibFunctions))
 	for _, v := range stdlibFunctions {

bake/hclparser/stdlib_test.go

@@ -197,3 +197,32 @@ func TestSanitize(t *testing.T) {
 		})
 	}
 }
+
+func TestRfc3339ParseFunc(t *testing.T) {
+	fn := rfc3339ParseFunc()
+	input := cty.StringVal("2024-06-01T15:04:05Z")
+	got, err := fn.Call([]cty.Value{input})
+	require.NoError(t, err)
+
+	expected := map[string]cty.Value{
+		"year":         cty.NumberIntVal(2024),
+		"year_day":     cty.NumberIntVal(153),
+		"day":          cty.NumberIntVal(1),
+		"month":        cty.NumberIntVal(6),
+		"month_name":   cty.StringVal("June"),
+		"weekday":      cty.NumberIntVal(6),
+		"weekday_name": cty.StringVal("Saturday"),
+		"hour":         cty.NumberIntVal(15),
+		"minute":       cty.NumberIntVal(4),
+		"second":       cty.NumberIntVal(5),
+		"unix":         cty.NumberIntVal(1717254245),
+		"iso_year":     cty.NumberIntVal(2024),
+		"iso_week":     cty.NumberIntVal(22),
+	}
+	for k, v := range expected {
+		require.True(t, got.GetAttr(k).RawEquals(v), "field %s: got %v, want %v", k, got.GetAttr(k), v)
+	}
+
+	_, err = fn.Call([]cty.Value{cty.StringVal("not-a-date")})
+	require.Error(t, err)
+}