Add weather API bundle adapter

internal/timeutil/parse.go

@@ -2,6 +2,8 @@ package timeutil
 
 import (
 	"fmt"
+	"regexp"
+	"strconv"
 	"strings"
 	"time"
 )
@@ -10,6 +12,12 @@ const DateLayout = "2006-01-02"
 const LocalDateTimeLayout = "2006-01-02T15:04"
 
 func LoadLocation(name string) (*time.Location, error) {
+	if location, ok := timezoneAliases[name]; ok {
+		return location, nil
+	}
+	if location, ok := parseUTCOffset(name); ok {
+		return location, nil
+	}
 	location, err := time.LoadLocation(name)
 	if err == nil {
 		return location, nil
@@ -24,6 +32,52 @@ func LoadLocation(name string) (*time.Location, error) {
 	return nil, fmt.Errorf("load timezone %q: %w", name, err)
 }
 
+var timezoneAliases = map[string]*time.Location{
+	"Chicago": mustLocation("America/Chicago"),
+	"Stl":     mustLocation("America/Chicago"),
+	"EST":     time.FixedZone("EST", -5*60*60),
+	"EDT":     time.FixedZone("EDT", -4*60*60),
+	"CST":     time.FixedZone("CST", -6*60*60),
+	"CDT":     time.FixedZone("CDT", -5*60*60),
+	"MST":     time.FixedZone("MST", -7*60*60),
+	"MDT":     time.FixedZone("MDT", -6*60*60),
+	"PST":     time.FixedZone("PST", -8*60*60),
+	"PDT":     time.FixedZone("PDT", -7*60*60),
+}
+
+func mustLocation(name string) *time.Location {
+	location, err := time.LoadLocation(name)
+	if err != nil {
+		panic(err)
+	}
+	return location
+}
+
+var utcOffsetPattern = regexp.MustCompile(`^([+-])(\d{1,2})(?::?(\d{2}))?$`)
+
+func parseUTCOffset(value string) (*time.Location, bool) {
+	matches := utcOffsetPattern.FindStringSubmatch(value)
+	if matches == nil {
+		return nil, false
+	}
+	hours, err := strconv.Atoi(matches[2])
+	if err != nil || hours > 23 {
+		return nil, false
+	}
+	minutes := 0
+	if matches[3] != "" {
+		minutes, err = strconv.Atoi(matches[3])
+		if err != nil || minutes > 59 {
+			return nil, false
+		}
+	}
+	offset := (hours*60 + minutes) * 60
+	if matches[1] == "-" {
+		offset = -offset
+	}
+	return time.FixedZone(value, offset), true
+}
+
 func LocalDate(now time.Time, location *time.Location) time.Time {
 	local := now.In(location)
 	return time.Date(local.Year(), local.Month(), local.Day(), 0, 0, 0, 0, location)