Replace deprecated smhi pmp3g api with new SNOW api

[nopil3os]

SMHI deactivated the pmp3g api this month, breaking the wego backend.

This attempts to rejig it for the new api: https://opendata.smhi.se/metfcst/snow1gv1/introduction

Used Gemini to generate most of this.

[kordianbruck]

Can you update your branch please to the latest master? I've fixed the lint warnings in master today.

[Copilot]

Pull request overview

Updates the SMHI backend to use the new snow1g API endpoint after the old pmp3g endpoint was deactivated.

Changes:

• Replaced the SMHI response model/types to match the new SNOW API response shape.
• Updated parsing logic to read values from the new data object and use the new time field.
• Switched the SMHI request URL to the snow1g/version/1 endpoint.

Comments suppressed due to low confidence (2)

backends/smhi.go:186

• The loop over forecast.TimeSeries never updates currentPrediction, so parseCurrent always returns the first timeseries entry regardless of the current time. Update currentPrediction as you iterate (e.g., keep the latest prediction with ts <= now), and then break once ts.After(now) is true.

	for _, prediction := range forecast.TimeSeries {
		ts, err := time.Parse(time.RFC3339, prediction.Time)
		if err != nil {
			log.Fatalf("Failed to parse timestamp: %v\n", err)
		}

		if ts.After(currentTime) {
			break

backends/smhi.go:160

• ts is parsed from the API timestamp (likely with an explicit timezone), but the day-bucketing logic compares ts.Day() against a separately initialized currentTime (time.Now() earlier). If local time != the API timezone, day boundaries can be off. Consider initializing the “current day” from the first parsed ts (or converting both to the same location with In(...)) so grouping is consistent.

		ts, err := time.Parse(time.RFC3339, prediction.Time)
		if err != nil {
			log.Fatalf("Failed to parse timestamp: %v\n", err)
		}

		if ts.Day() != currentTime.Day() {

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[nopil3os]

sorry for the mess. this is the first time I'm doing a PR /o\
I'm not sure about the precipitation. in the old api it was in mm/h and in the new one it's kg/m2. I think that's equivalent?

https://opendata.smhi.se/metfcst/snow1gv1/parameters
https://web.archive.org/web/20231207074455/http://opendata.smhi.se/apidocs/metfcst/parameters.html

[kordianbruck]

Should be, thanks for the updates. Looks good from what I can tell.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated 3 comments.

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[Copilot]

parseCurrent iterates over forecast.TimeSeries but never updates currentPrediction, so it always returns the first entry regardless of the timestamps. Update currentPrediction inside the loop (e.g., set it to the latest prediction not after currentTime) before breaking so the "current" condition reflects the correct time slot.

[Copilot]

Day grouping in parseForecast depends on comparing ts.Day() to currentTime.Day(), but currentTime/day.Date are initialized from time.Now() earlier in the function rather than the first forecast timestamp. If the first prediction.Time is in a different day/timezone than the local clock, this can mis-group days. Consider initializing currentTime/day.Date from the first parsed prediction.Time (and in a consistent timezone) before applying the grouping logic.

[Copilot]

The old smhiWuri assignment is left in place as a commented-out line. This is effectively dead code and can be confusing to maintainers; consider removing it (or turning it into a proper comment explaining the deprecation) to keep the constant definition unambiguous.