import (
  "errors"
  "time"

  "github.com/go-ldap/ldap/v3"
  "github.com/opencloud-eu/opencloud/services/graph/pkg/metrics"
  "github.com/prometheus/client_golang/prometheus"
)

{{ $decorator := (or .Vars.DecoratorName (printf "Prometheus%s" .Interface.Name)) }}

// {{$decorator}} implements {{.Interface.Type}} interface with all methods wrapped
// with Prometheus metrics
type {{$decorator}} struct {
  delegate {{.Interface.Type}}
  metric   *prometheus.HistogramVec
}

var _ {{.Interface.Type}} = &{{$decorator}}{}

// returns an instance of the {{.Interface.Type}} decorated with prometheus metric
func New{{$decorator}}(delegate {{.Interface.Type}}, metric *prometheus.HistogramVec) {{$decorator}} {
  return {{$decorator}} {
    delegate: delegate,
    metric: metric,
  }
}

{{range $method := .Interface.Methods}}
  // {{$method.Name}} implements {{$.Interface.Type}}.{{$method.Name}}
  func (_d {{$decorator}}) {{$method.Declaration}} {
    _since := time.Now()
    defer func() {
      duration := time.Since(_since).Seconds()
      result := MetricResultSuccess
      {{- if $method.ReturnsError}}
      if err != nil {
        result = MetricResultFailure
        if err == ErrReadOnly {
          result = MetricResultReadOnly
        }
        if e, ok := errorcode.ToError(err); ok {
          if e.GetCode() == errorcode.ItemNotFound {
            result = MetricResultNotFound
          }
        }
      } else {
        {{- if or (hasPrefix "Get" $method.Name) }}
          {{- range $i, $result := $method.Results }}
            {{- if and (hasPrefix "*" $result.Type) (not (hasPrefix "*[]" $result.Type)) }}
              // it's a get operation that returns a pointer (and not an array): check whether that's nil or not
              if {{$result.Name}} == nil {
                result = MetricResultNotFound
              }{{break}}
            {{end}}
          {{end}}
        {{end}}
        {{- range $i, $result := $method.Results }}
          {{- if eq $result.Type "error" }}
            if e, ok := errorcode.ToError(err); ok {
              if e.GetCode() == errorcode.ItemNotFound {
                result = MetricResultNotFound
              }
            }
          {{end}}
        {{end}}
      }
      {{end}}
      _d.metric.WithLabelValues(MetricOp{{upFirst $method.Name}}, result).Observe(duration)
    }()
    {{$method.Pass "_d.delegate."}}
  }
{{end}}