104 lines
2.2 KiB
Go
104 lines
2.2 KiB
Go
package metrics
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import (
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"context"
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"errors"
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"fmt"
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"io"
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"log/slog"
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"net/http"
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"time"
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vm "github.com/VictoriaMetrics/metrics"
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"go.xsfx.dev/glucose_exporter/api"
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"go.xsfx.dev/glucose_exporter/internal/cache"
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"go.xsfx.dev/glucose_exporter/internal/config"
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)
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var ErrOddDataLength = errors.New("odd data length")
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func Handler(w http.ResponseWriter, r *http.Request) {
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if err := glucose(r.Context(), w); err != nil {
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slog.Error("getting glucose", "err", err)
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vm.GetOrCreateCounter("errors_total").Inc()
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}
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vm.WritePrometheus(w, false)
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}
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//nolint:funlen
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func glucose(ctx context.Context, w io.Writer) error {
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c, err := cache.Load()
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if err != nil {
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return fmt.Errorf("loading cache: %w", err)
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}
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// No token exists or token is expired
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if c.JWT == "" || time.Now().After(time.Time(c.Expires)) {
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slog.Debug("needs a fresh token")
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token, err := api.Login(
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ctx,
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api.BaseURL,
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config.Cfg.Email,
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config.Cfg.Password,
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)
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if err != nil {
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return fmt.Errorf("login: %w", err)
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}
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slog.Debug("got token", "token", token)
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if err := cache.Save(
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cache.Cache{JWT: token.Data.AuthTicket.Token, Expires: token.Data.AuthTicket.Expires},
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); err != nil {
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return fmt.Errorf("saving cache: %w", err)
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}
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}
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// Loading cache again with the new token inside.
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c, err = cache.Load()
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if err != nil {
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return fmt.Errorf("loading cache: %w", err)
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}
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// Getting connections, which includes the glucose data.
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resp, err := api.Connections(ctx, api.BaseURL, c.JWT)
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if err != nil {
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return fmt.Errorf("connections: %w", err)
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}
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// Storing new token to cache.
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if err := cache.Save(cache.Cache{
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JWT: resp.Ticket.Token,
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Expires: resp.Ticket.Expires,
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}); err != nil {
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return fmt.Errorf("saving cache: %w", err)
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}
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if len(resp.Data) != 1 {
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return ErrOddDataLength
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}
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labels := fmt.Sprintf(
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`patient_id="%s",sensor_serialnumber="%s"`,
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resp.Data[0].PatientID,
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resp.Data[0].Sensor.Serialnumber,
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)
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// Writing metrics.
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vm.WriteGaugeUint64(
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w,
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fmt.Sprintf("value_in_mg_per_dl{%s}", labels),
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uint64(resp.Data[0].GlucoseMeasurement.ValueInMgPerDl),
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)
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vm.WriteGaugeUint64(
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w,
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fmt.Sprintf("trend_arrow{%s}", labels),
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uint64(resp.Data[0].GlucoseMeasurement.TrendArrow),
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)
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return nil
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}
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