Eric Rakestraw
eb27486466
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103 lines
2.6 KiB
Go
103 lines
2.6 KiB
Go
// FILE: ./internal/sources/nws/observation.go
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package nws
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import (
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"context"
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"encoding/json"
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"strings"
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"time"
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"gitea.maximumdirect.net/ejr/feedkit/config"
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"gitea.maximumdirect.net/ejr/feedkit/event"
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fksources "gitea.maximumdirect.net/ejr/feedkit/sources"
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nwscommon "gitea.maximumdirect.net/ejr/weatherfeeder/internal/providers/nws"
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"gitea.maximumdirect.net/ejr/weatherfeeder/internal/sources/common"
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"gitea.maximumdirect.net/ejr/weatherfeeder/standards"
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)
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// ObservationSource polls an NWS station observation endpoint and emits a RAW observation Event.
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type ObservationSource struct {
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http *fksources.HTTPSource
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}
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func NewObservationSource(cfg config.SourceConfig) (*ObservationSource, error) {
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const driver = "nws_observation"
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hs, err := fksources.NewHTTPSource(driver, cfg, "application/geo+json, application/json")
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if err != nil {
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return nil, err
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}
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return &ObservationSource{http: hs}, nil
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}
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func (s *ObservationSource) Name() string { return s.http.Name }
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func (s *ObservationSource) Kind() event.Kind { return event.Kind("observation") }
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func (s *ObservationSource) Poll(ctx context.Context) ([]event.Event, error) {
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raw, meta, changed, err := s.fetchRaw(ctx)
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if err != nil {
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return nil, err
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}
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if !changed {
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return nil, nil
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}
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// EffectiveAt is optional; for observations it’s naturally the observation timestamp.
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var effectiveAt *time.Time
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if !meta.ParsedTimestamp.IsZero() {
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t := meta.ParsedTimestamp.UTC()
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effectiveAt = &t
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}
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emittedAt := time.Now().UTC()
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eventID := common.ChooseEventID(meta.ID, s.http.Name, effectiveAt, emittedAt)
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return common.SingleRawEvent(
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s.Kind(),
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s.http.Name,
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standards.SchemaRawNWSObservationV1,
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eventID,
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emittedAt,
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effectiveAt,
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raw,
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)
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}
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// ---- RAW fetch + minimal metadata decode ----
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type observationMeta struct {
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ID string `json:"id"`
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Properties struct {
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Timestamp string `json:"timestamp"`
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} `json:"properties"`
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ParsedTimestamp time.Time `json:"-"`
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}
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func (s *ObservationSource) fetchRaw(ctx context.Context) (json.RawMessage, observationMeta, bool, error) {
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raw, changed, err := s.http.FetchJSONIfChanged(ctx)
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if err != nil {
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return nil, observationMeta{}, false, err
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}
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if !changed {
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return nil, observationMeta{}, false, nil
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}
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var meta observationMeta
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if err := json.Unmarshal(raw, &meta); err != nil {
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// If metadata decode fails, still return raw; envelope will fall back to Source:EffectiveAt.
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return raw, observationMeta{}, true, nil
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}
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tsStr := strings.TrimSpace(meta.Properties.Timestamp)
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if tsStr != "" {
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if t, err := nwscommon.ParseTime(tsStr); err == nil {
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meta.ParsedTimestamp = t.UTC()
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}
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}
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return raw, meta, true, nil
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}
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