feat(parse_iso_Date): Added timezone parsing.

mustache/format.odin

@@ -7,12 +7,15 @@ import "core:time"
 import "core:time/datetime"
 
 Date_Components :: struct {
-	year:   int,
-	month:  int,
-	day:    int,
-	hour:   int,
-	minute: int,
-	second: int,
+	year:           int,
+	month:          int,
+	day:            int,
+	hour:           int,
+	minute:         int,
+	second:         int,
+	offset_seconds: int,
+	has_offset:     bool,
+	tz_abbr:        string,
 }
 
 // TODO: Use some kind of scanner interface
@@ -38,6 +41,9 @@ parse_iso_date :: proc(iso: string) -> (c: Date_Components, ok: bool) {
 		c.second = parse_2_digits(iso, 17)
 	}
 
+	parse_offset(iso, &c)
+
+	c.tz_abbr = "UTC"
 	return c, true
 }
 
@@ -48,6 +54,54 @@ parse_2_digits :: proc(s: string, offset: int) -> int {
 	return (int(s[offset]) - 0x30) * 10 + (int(s[offset + 1]) - 0x30)
 }
 
+// parse_offset parses the timezone suffix of an ISO 8601 string (Z,
+// +HH:MM, +HHMM, -HH:MM, -HHMM). Skips fractional seconds if present.
+// Does nothing if no recognizable offset is found.
+parse_offset :: proc(iso: string, c: ^Date_Components) {
+	pos := 19
+	if pos >= len(iso) {
+		return
+	}
+
+	// Skip fractional seconds (e.g., .123)
+	if iso[pos] == '.' {
+		pos += 1
+		for pos < len(iso) && iso[pos] >= '0' && iso[pos] <= '9' {
+			pos += 1
+		}
+	}
+
+	if pos >= len(iso) {
+		return
+	}
+
+	switch iso[pos] {
+	case 'Z', 'z':
+		c.has_offset = true
+	case '+', '-':
+		sign := 1 if iso[pos] == '+' else -1
+		pos += 1
+		if pos + 1 >= len(iso) {
+			return
+		}
+		hours := parse_2_digits(iso, pos)
+		pos += 2
+
+		minutes := 0
+		if pos < len(iso) && iso[pos] == ':' {
+			pos += 1
+		}
+		if pos + 1 < len(iso) {
+			minutes = parse_2_digits(iso, pos)
+		}
+
+		c.offset_seconds = sign * (hours * 3600 + minutes * 60)
+		c.has_offset = true
+	case:
+		// no recognizable offset
+	}
+}
+
 format_date :: proc(
 	dt: Date_Components,
 	fmt: string,
@@ -80,7 +134,12 @@ match_token :: proc(b: ^strings.Builder, dt: Date_Components, s: string) -> int
 		s,
 		"2006",
 	) {strings.write_string(b, fmt.tprintf("%04d", dt.year)); return 4}
-	if strings.has_prefix(s, "MST") {strings.write_string(b, "UTC"); return 3}
+	if strings.has_prefix(s, "MST") {
+		abbr := dt.tz_abbr
+		if len(abbr) == 0 do abbr = "UTC"
+		strings.write_string(b, abbr)
+		return 3
+	}
 	if strings.has_prefix(s, "Jan") {emit_month_abbr(b, dt); return 3}
 	if strings.has_prefix(s, "Mon") {emit_weekday(b, dt, full = false); return 3}
 	if strings.has_prefix(

mustache/format_test.odin

@@ -17,6 +17,9 @@ test_parse_iso_date_extracts_time :: proc(t: ^testing.T) {
 	testing.expect_value(t, c.hour, 8)
 	testing.expect_value(t, c.minute, 49)
 	testing.expect_value(t, c.second, 54)
+	testing.expect_value(t, c.has_offset, true)
+	testing.expect_value(t, c.offset_seconds, -14400)
+	testing.expect_value(t, c.tz_abbr, "UTC")
 }
 
 @(test)
@@ -26,6 +29,8 @@ test_parse_iso_date_lowercase_t :: proc(t: ^testing.T) {
 	testing.expect_value(t, c.hour, 8)
 	testing.expect_value(t, c.minute, 49)
 	testing.expect_value(t, c.second, 54)
+	testing.expect_value(t, c.has_offset, true)
+	testing.expect_value(t, c.offset_seconds, 0)
 }
 
 @(test)
@@ -35,6 +40,7 @@ test_parse_iso_date_date_only_zero_time :: proc(t: ^testing.T) {
 	testing.expect_value(t, c.hour, 0)
 	testing.expect_value(t, c.minute, 0)
 	testing.expect_value(t, c.second, 0)
+	testing.expect_value(t, c.has_offset, false)
 }
 
 @(test)
@@ -49,6 +55,47 @@ test_parse_iso_date_too_short_errors :: proc(t: ^testing.T) {
 	testing.expect(t, !ok, "input shorter than 10 chars should fail")
 }
 
+@(test)
+test_parse_offset_positive_colon :: proc(t: ^testing.T) {
+	c, ok := parse_iso_date("2026-03-15T08:49:54+07:00")
+	testing.expect(t, ok, "should parse")
+	testing.expect_value(t, c.has_offset, true)
+	testing.expect_value(t, c.offset_seconds, 25200)
+}
+
+@(test)
+test_parse_offset_positive_no_colon :: proc(t: ^testing.T) {
+	c, ok := parse_iso_date("2026-03-15T08:49:54+0530")
+	testing.expect(t, ok, "should parse")
+	testing.expect_value(t, c.has_offset, true)
+	testing.expect_value(t, c.offset_seconds, 19800)
+}
+
+@(test)
+test_parse_offset_hours_only :: proc(t: ^testing.T) {
+	c, ok := parse_iso_date("2026-03-15T08:49:54+05")
+	testing.expect(t, ok, "should parse")
+	testing.expect_value(t, c.has_offset, true)
+	testing.expect_value(t, c.offset_seconds, 18000)
+}
+
+@(test)
+test_parse_offset_none_with_time :: proc(t: ^testing.T) {
+	c, ok := parse_iso_date("2026-03-15T08:49:54")
+	testing.expect(t, ok, "should parse")
+	testing.expect_value(t, c.has_offset, false)
+	testing.expect_value(t, c.offset_seconds, 0)
+}
+
+@(test)
+test_parse_offset_skips_fractional_seconds :: proc(t: ^testing.T) {
+	c, ok := parse_iso_date("2026-03-15T08:49:54.123Z")
+	testing.expect(t, ok, "should parse")
+	testing.expect_value(t, c.has_offset, true)
+	testing.expect_value(t, c.offset_seconds, 0)
+	testing.expect_value(t, c.second, 54)
+}
+
 // ---------------------------------------------------------------------------
 // format_date / match_token
 // ---------------------------------------------------------------------------
@@ -140,9 +187,9 @@ test_format_date_month_day_numeric_padding :: proc(t: ^testing.T) {
 }
 
 @(test)
-test_format_date_mst_always_utc :: proc(t: ^testing.T) {
-	// Date_Components carries no offset yet, so MST is a hardcoded
-	// placeholder until real timezone support lands.
+test_format_date_mst_defaults_utc :: proc(t: ^testing.T) {
+	// Date_Components constructed directly (not via parse_iso_date)
+	// defaults to UTC for the MST token.
 	dt := Date_Components{year = 2026, month = 1, day = 1, hour = 12}
 	result := format_date(dt, "MST")
 	testing.expect_value(t, result, "UTC")