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// Copyright 2018 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package firestore
import (
"bytes"
"fmt"
"math"
"sort"
"strings"
tspb "github.com/golang/protobuf/ptypes/timestamp"
pb "google.golang.org/genproto/googleapis/firestore/v1beta1"
)
// Returns a negative number, zero, or a positive number depending on whether a is
// less than, equal to, or greater than b according to Firestore's ordering of
// values.
func compareValues(a, b *pb.Value) int {
ta := typeOrder(a)
tb := typeOrder(b)
if ta != tb {
return compareInt64s(int64(ta), int64(tb))
}
switch a := a.ValueType.(type) {
case *pb.Value_NullValue:
return 0 // nulls are equal
case *pb.Value_BooleanValue:
av := a.BooleanValue
bv := b.GetBooleanValue()
switch {
case av && !bv:
return 1
case bv && !av:
return -1
default:
return 0
}
case *pb.Value_IntegerValue:
return compareNumbers(float64(a.IntegerValue), toFloat(b))
case *pb.Value_DoubleValue:
return compareNumbers(a.DoubleValue, toFloat(b))
case *pb.Value_TimestampValue:
return compareTimestamps(a.TimestampValue, b.GetTimestampValue())
case *pb.Value_StringValue:
return strings.Compare(a.StringValue, b.GetStringValue())
case *pb.Value_BytesValue:
return bytes.Compare(a.BytesValue, b.GetBytesValue())
case *pb.Value_ReferenceValue:
return compareReferences(a.ReferenceValue, b.GetReferenceValue())
case *pb.Value_GeoPointValue:
ag := a.GeoPointValue
bg := b.GetGeoPointValue()
if ag.Latitude != bg.Latitude {
return compareFloat64s(ag.Latitude, bg.Latitude)
}
return compareFloat64s(ag.Longitude, bg.Longitude)
case *pb.Value_ArrayValue:
return compareArrays(a.ArrayValue.Values, b.GetArrayValue().Values)
case *pb.Value_MapValue:
return compareMaps(a.MapValue.Fields, b.GetMapValue().Fields)
default:
panic(fmt.Sprintf("bad value type: %v", a))
}
}
// Treats NaN as less than any non-NaN.
func compareNumbers(a, b float64) int {
switch {
case math.IsNaN(a):
if math.IsNaN(b) {
return 0
}
return -1
case math.IsNaN(b):
return 1
default:
return compareFloat64s(a, b)
}
}
// Return v as a float64, assuming it's an Integer or Double.
func toFloat(v *pb.Value) float64 {
if x, ok := v.ValueType.(*pb.Value_IntegerValue); ok {
return float64(x.IntegerValue)
}
return v.GetDoubleValue()
}
func compareTimestamps(a, b *tspb.Timestamp) int {
if c := compareInt64s(a.Seconds, b.Seconds); c != 0 {
return c
}
return compareInt64s(int64(a.Nanos), int64(b.Nanos))
}
func compareReferences(a, b string) int {
// Compare path components lexicographically.
pa := strings.Split(a, "/")
pb := strings.Split(b, "/")
return compareSequences(len(pa), len(pb), func(i int) int {
return strings.Compare(pa[i], pb[i])
})
}
func compareArrays(a, b []*pb.Value) int {
return compareSequences(len(a), len(b), func(i int) int {
return compareValues(a[i], b[i])
})
}
func compareMaps(a, b map[string]*pb.Value) int {
sortedKeys := func(m map[string]*pb.Value) []string {
var ks []string
for k := range m {
ks = append(ks, k)
}
sort.Strings(ks)
return ks
}
aks := sortedKeys(a)
bks := sortedKeys(b)
return compareSequences(len(aks), len(bks), func(i int) int {
if c := strings.Compare(aks[i], bks[i]); c != 0 {
return c
}
k := aks[i]
return compareValues(a[k], b[k])
})
}
func compareSequences(len1, len2 int, compare func(int) int) int {
for i := 0; i < len1 && i < len2; i++ {
if c := compare(i); c != 0 {
return c
}
}
return compareInt64s(int64(len1), int64(len2))
}
func compareFloat64s(a, b float64) int {
switch {
case a < b:
return -1
case a > b:
return 1
default:
return 0
}
}
func compareInt64s(a, b int64) int {
switch {
case a < b:
return -1
case a > b:
return 1
default:
return 0
}
}
// Return an integer corresponding to the type of value stored in v, such that
// comparing the resulting integers gives the Firestore ordering for types.
func typeOrder(v *pb.Value) int {
switch v.ValueType.(type) {
case *pb.Value_NullValue:
return 0
case *pb.Value_BooleanValue:
return 1
case *pb.Value_IntegerValue:
return 2
case *pb.Value_DoubleValue:
return 2
case *pb.Value_TimestampValue:
return 3
case *pb.Value_StringValue:
return 4
case *pb.Value_BytesValue:
return 5
case *pb.Value_ReferenceValue:
return 6
case *pb.Value_GeoPointValue:
return 7
case *pb.Value_ArrayValue:
return 8
case *pb.Value_MapValue:
return 9
default:
panic(fmt.Sprintf("bad value type: %v", v))
}
}
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