Eric Rakestraw
0cc2862170
feedkit now contains a reusable core, while weatherfeeder is a concrete implementation that includes weather-specific functions.
102 lines
2.9 KiB
Go
102 lines
2.9 KiB
Go
package event
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import (
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"errors"
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"strings"
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"time"
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)
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// ErrInvalidEvent is a sentinel error so callers can do:
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//
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// if errors.Is(err, event.ErrInvalidEvent) { ... }
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var ErrInvalidEvent = errors.New("invalid event")
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// ValidationError reports one or more problems with an Event.
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//
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// We keep this structured so you get ALL issues in one pass rather than fixing
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// them one-by-one.
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type ValidationError struct {
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Problems []string
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}
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func (e *ValidationError) Error() string {
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if e == nil || len(e.Problems) == 0 {
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return "invalid event"
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}
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var b strings.Builder
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b.WriteString("invalid event:\n")
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for _, p := range e.Problems {
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b.WriteString(" - ")
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b.WriteString(p)
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b.WriteString("\n")
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}
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return strings.TrimRight(b.String(), "\n")
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}
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// Is lets errors.Is(err, ErrInvalidEvent) work.
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func (e *ValidationError) Is(target error) bool {
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return target == ErrInvalidEvent
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}
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// Event is the domain-agnostic envelope moved through scheduler → pipeline → dispatcher → sinks.
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//
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// Payload is intentionally "any":
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// - domain code can set it to a struct (recommended), a map, or some other JSON-marshable type.
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// - feedkit infrastructure never type-asserts Payload.
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//
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// If you plan to persist/emit events as JSON, ensure Payload is JSON-marshable.
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type Event struct {
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// ID should be stable for dedupe/storage purposes.
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// Often: "<provider>:<source>:<upstream-id-or-timestamp>".
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ID string `json:"id"`
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// Kind is used for routing/policy.
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Kind Kind `json:"kind"`
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// Source is the configured source name (e.g. "OpenMeteoObservation", "NWSAlertsSTL").
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Source string `json:"source"`
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// EmittedAt is when *your daemon* emitted this event (typically time.Now().UTC()).
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EmittedAt time.Time `json:"emitted_at"`
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// EffectiveAt is optional: the timestamp the payload is "about" (e.g. observation time).
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EffectiveAt *time.Time `json:"effective_at,omitempty"`
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// Schema is optional but strongly recommended once multiple domains exist.
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// Examples:
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// "weather.observation.v1"
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// "news.article.v1"
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// It helps sinks and downstream consumers interpret Payload.
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Schema string `json:"schema,omitempty"`
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// Payload is domain-defined and must be non-nil.
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Payload any `json:"payload"`
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}
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// Validate enforces basic invariants that infrastructure depends on.
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// Domain-specific validation belongs in domain code (or domain processors).
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func (e Event) Validate() error {
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var problems []string
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if strings.TrimSpace(e.ID) == "" {
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problems = append(problems, "ID is required")
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}
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if strings.TrimSpace(string(e.Kind)) == "" {
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problems = append(problems, "Kind is required")
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}
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if strings.TrimSpace(e.Source) == "" {
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problems = append(problems, "Source is required")
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}
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if e.EmittedAt.IsZero() {
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problems = append(problems, "EmittedAt must be set (non-zero)")
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}
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if e.Payload == nil {
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problems = append(problems, "Payload must be non-nil")
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}
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if len(problems) > 0 {
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return &ValidationError{Problems: problems}
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}
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return nil
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}
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