first commit

way too late.

doormen/doormen.go

@@ -0,0 +1,118 @@
+package doormen
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"strconv"
+	"time"
+
+	"github.com/didiercrunch/doorman/shared"
+	"gopkg.in/mgo.v2/bson"
+)
+
+const epsilon float64 = 0.0001
+
+type DoormanValue struct {
+	Name        string  `json:"name" bson:"name"`
+	Probability float64 `json:"probability" bson:"probability"`
+}
+
+type DoormanId struct {
+	Id   bson.ObjectId `json:"id,omitempty" bson:"_id"`
+	Name string        `json:"name" bson:"name"`
+}
+
+func (wId *DoormanId) AsJson() string {
+	if wId.Id == "" {
+		return `{}`
+	}
+	return fmt.Sprintf(`{"%v":"%v"}`, wId.Id.Hex(), wId.Name)
+}
+
+type DoormanDefinition struct {
+	Id     bson.ObjectId  `json:"id,omitempty" bson:"_id"`
+	Name   string         `json:"name" bson:"name"`
+	Values []*DoormanValue `json:"values" bson:"values"`
+}
+
+func NewDoormanDefinition(name string) *DoormanDefinition {
+	return &DoormanDefinition{Id: bson.NewObjectId(), Name: name}
+}
+
+// a way to quickly create doormen in tests.  do not use in real code.  will
+// panic if a doorman is wrongly specify
+func QuickNewDoormanDefinition(name string, probs ...float64) *DoormanDefinition {
+	ret := NewDoormanDefinition(name)
+	for i, prob := range probs {
+		ret.Values = append(ret.Values, &DoormanValue{"T" + strconv.Itoa(i), prob})
+	}
+	if err := ret.Validate(); err != nil {
+		panic(err)
+	}
+	return ret
+}
+
+func (dmd *DoormanDefinition) ValidateDoormanValueNames() error {
+	m := make(map[string]bool)
+	for _, w := range dmd.Values {
+		if name := w.Name; name == "" {
+			return errors.New("doorman value cannot be empty")
+		} else {
+			m[name] = true
+		}
+	}
+	if len(m) != len(dmd.Values) {
+		return errors.New("doorman value names must be unique within a doorman")
+	}
+	return nil
+}
+
+func (dmd *DoormanDefinition) ValidateDoormanValueProbabilities() error {
+	var sum float64 = 0
+	for _, w := range dmd.Values {
+		if p := w.Probability; p < 0-epsilon || p > 1+epsilon {
+			return errors.New(fmt.Sprintf("doorman value %v is out of range", p))
+		} else {
+			sum += p
+		}
+	}
+	if sum < 0-epsilon || sum > 1+epsilon {
+		return errors.New("the sum of the probability must be 1.0")
+	}
+	return nil
+}
+
+func (dmd *DoormanDefinition) Validate() (err error) {
+	switch {
+	case dmd.Name == "":
+		err = errors.New("name cannot be empty")
+	case len(dmd.Values) < 2:
+		err = errors.New("need at least 2 values")
+	case dmd.ValidateDoormanValueNames() != nil:
+		err = dmd.ValidateDoormanValueNames()
+	case dmd.ValidateDoormanValueProbabilities() != nil:
+		err = dmd.ValidateDoormanValueProbabilities()
+	}
+	return
+}
+
+func (dmd *DoormanDefinition) CanBeUpdatedBy(dmd2 *DoormanDefinition) error {
+	if dmd.Name != dmd2.Name {
+		return errors.New("cannot change doorman name")
+	}
+	if len(dmd.Values) != len(dmd2.Values) {
+		return errors.New("cannot change the number of cases in doorman")
+	}
+	return nil
+}
+
+func (dmd *DoormanDefinition) AsDoormanUpdatePayload() ([]byte, error) {
+	wu := &shared.DoormanUpdater{Id: dmd.Id.Hex()}
+	wu.Timestamp = time.Now().Unix()
+	wu.Probabilities = make([]float64, len(dmd.Values))
+	for i, value := range dmd.Values {
+		wu.Probabilities[i] = value.Probability
+	}
+	return json.Marshal(wu)
+}