From 643e81254c7a197fc32fe2e27650e04fc9100ac0 Mon Sep 17 00:00:00 2001
From: Alex Vanin <alexey@nspcc.ru>
Date: Thu, 15 Oct 2020 17:55:12 +0300
Subject: [PATCH] [#25] Add placement policy QL encoder

Signed-off-by: Alex Vanin <alexey@nspcc.ru>
---
 pkg/policy/encode.go      | 163 ++++++++++++++++++++++++++++++++++++++
 pkg/policy/encode_test.go |  36 +++++++++
 2 files changed, 199 insertions(+)
 create mode 100644 pkg/policy/encode.go
 create mode 100644 pkg/policy/encode_test.go

diff --git a/pkg/policy/encode.go b/pkg/policy/encode.go
new file mode 100644
index 000000000..0f08afe95
--- /dev/null
+++ b/pkg/policy/encode.go
@@ -0,0 +1,163 @@
+package policy
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/nspcc-dev/neofs-api-go/v2/netmap"
+)
+
+func Encode(p *netmap.PlacementPolicy) []string {
+	if p == nil {
+		return nil
+	}
+
+	var (
+		replicas  = p.GetReplicas()
+		selectors = p.GetSelectors()
+		filters   = p.GetFilters()
+	)
+
+	// 1 for container backup factor
+	result := make([]string, 0, len(replicas)+len(selectors)+len(filters)+1)
+
+	// first print replicas
+	encodeReplicas(replicas, &result)
+
+	// then backup factor
+	if backupFactor := p.GetContainerBackupFactor(); backupFactor != 0 {
+		result = append(result, fmt.Sprintf("CBF %d", backupFactor))
+	}
+
+	// then selectors
+	encodeSelectors(selectors, &result)
+
+	// then filters
+	encodeFilters(filters, &result)
+
+	return result
+}
+
+func encodeReplicas(replicas []*netmap.Replica, dst *[]string) {
+	builder := new(strings.Builder)
+
+	for _, replica := range replicas {
+		builder.WriteString("REP ")
+		builder.WriteString(strconv.FormatUint(uint64(replica.GetCount()), 10))
+
+		if s := replica.GetSelector(); s != "" {
+			builder.WriteString(" IN ")
+			builder.WriteString(s)
+		}
+
+		*dst = append(*dst, builder.String())
+		builder.Reset()
+	}
+}
+
+func encodeSelectors(selectors []*netmap.Selector, dst *[]string) {
+	builder := new(strings.Builder)
+
+	for _, selector := range selectors {
+		builder.WriteString("SELECT ")
+		builder.WriteString(strconv.FormatUint(uint64(selector.GetCount()), 10))
+
+		if a := selector.GetAttribute(); a != "" {
+			builder.WriteString(" IN")
+
+			switch selector.GetClause() {
+			case netmap.Same:
+				builder.WriteString(" SAME ")
+			case netmap.Distinct:
+				builder.WriteString(" DISTINCT ")
+			default:
+				builder.WriteString(" ")
+			}
+
+			builder.WriteString(a)
+		}
+
+		if f := selector.GetFilter(); f != "" {
+			builder.WriteString(" FROM ")
+			builder.WriteString(f)
+		}
+
+		if n := selector.GetName(); n != "" {
+			builder.WriteString(" AS ")
+			builder.WriteString(n)
+		}
+
+		*dst = append(*dst, builder.String())
+		builder.Reset()
+	}
+}
+
+func encodeFilters(filters []*netmap.Filter, dst *[]string) {
+	builder := new(strings.Builder)
+
+	for _, filter := range filters {
+		builder.WriteString("FILTER ")
+
+		builder.WriteString(encodeFilter(filter))
+
+		*dst = append(*dst, builder.String())
+		builder.Reset()
+	}
+}
+
+func operationString(operation netmap.Operation) string {
+	switch operation {
+	case netmap.EQ:
+		return "EQ"
+	case netmap.NE:
+		return "NE"
+	case netmap.GT:
+		return "GT"
+	case netmap.GE:
+		return "GE"
+	case netmap.LT:
+		return "LT"
+	case netmap.LE:
+		return "LE"
+	case netmap.OR:
+		return "OR"
+	case netmap.AND:
+		return "AND"
+	default:
+		return ""
+	}
+}
+
+func encodeFilter(filter *netmap.Filter) string {
+	builder := new(strings.Builder)
+	unspecified := filter.GetOp() == netmap.UnspecifiedOperation
+
+	if k := filter.GetKey(); k != "" {
+		builder.WriteString(k)
+		builder.WriteString(" ")
+		builder.WriteString(operationString(filter.GetOp()))
+		builder.WriteString(" ")
+		builder.WriteString(filter.GetValue())
+	} else if n := filter.GetName(); unspecified && n != "" {
+		builder.WriteString("@")
+		builder.WriteString(n)
+	}
+
+	for i, subfilter := range filter.GetFilters() {
+		if i != 0 {
+			builder.WriteString(" ")
+			builder.WriteString(operationString(filter.GetOp()))
+			builder.WriteString(" ")
+		}
+
+		builder.WriteString(encodeFilter(subfilter))
+	}
+
+	if n := filter.GetName(); n != "" && !unspecified {
+		builder.WriteString(" AS ")
+		builder.WriteString(n)
+	}
+
+	return builder.String()
+}
diff --git a/pkg/policy/encode_test.go b/pkg/policy/encode_test.go
new file mode 100644
index 000000000..968c69039
--- /dev/null
+++ b/pkg/policy/encode_test.go
@@ -0,0 +1,36 @@
+package policy_test
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/nspcc-dev/neofs-node/pkg/policy"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEncode(t *testing.T) {
+	testCases := []string{
+		`REP 1 IN X
+CBF 1
+SELECT 2 IN SAME Location FROM * AS X`,
+
+		`REP 1
+SELECT 2 IN City FROM Good
+FILTER Country EQ RU AS FromRU
+FILTER @FromRU AND Rating GT 7 AS Good`,
+
+		`REP 7 IN SPB
+SELECT 1 IN City FROM SPBSSD AS SPB
+FILTER City EQ SPB AND SSD EQ true OR City EQ SPB AND Rating GE 5 AS SPBSSD`,
+	}
+
+	for _, testCase := range testCases {
+		q, err := policy.Parse(testCase)
+		require.NoError(t, err)
+
+		got := policy.Encode(q)
+		fmt.Println(strings.Join(got, "\n"))
+		require.Equal(t, testCase, strings.Join(got, "\n"))
+	}
+}