/*
   Copyright 2014 CoreOS, Inc.

   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 raft

import (
	"reflect"
	"testing"

	pb "github.com/coreos/etcd/raft/raftpb"
)

func TestUnstableMaybeFirstIndex(t *testing.T) {
	tests := []struct {
		entries []pb.Entry
		offset  uint64
		snap    *pb.Snapshot

		wok    bool
		windex uint64
	}{
		// no snapshot
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			false, 0,
		},
		{
			[]pb.Entry{}, 0, nil,
			false, 0,
		},
		// has snapshot
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			true, 5,
		},
		{
			[]pb.Entry{}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			true, 5,
		},
	}

	for i, tt := range tests {
		u := unstable{
			entries:  tt.entries,
			offset:   tt.offset,
			snapshot: tt.snap,
		}
		index, ok := u.maybeFirstIndex()
		if ok != tt.wok {
			t.Errorf("#%d: ok = %t, want %t", i, ok, tt.wok)
		}
		if index != tt.windex {
			t.Errorf("#%d: index = %d, want %d", i, index, tt.windex)
		}
	}
}

func TestMaybeLastIndex(t *testing.T) {
	tests := []struct {
		entries []pb.Entry
		offset  uint64
		snap    *pb.Snapshot

		wok    bool
		windex uint64
	}{
		// last in entries
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			true, 5,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			true, 5,
		},
		// last in snapshot
		{
			[]pb.Entry{}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			true, 4,
		},
		// empty unstable
		{
			[]pb.Entry{}, 0, nil,
			false, 0,
		},
	}

	for i, tt := range tests {
		u := unstable{
			entries:  tt.entries,
			offset:   tt.offset,
			snapshot: tt.snap,
		}
		index, ok := u.maybeLastIndex()
		if ok != tt.wok {
			t.Errorf("#%d: ok = %t, want %t", i, ok, tt.wok)
		}
		if index != tt.windex {
			t.Errorf("#%d: index = %d, want %d", i, index, tt.windex)
		}
	}
}

func TestUnstableMaybeTerm(t *testing.T) {
	tests := []struct {
		entries []pb.Entry
		offset  uint64
		snap    *pb.Snapshot
		index   uint64

		wok   bool
		wterm uint64
	}{
		// term from entries
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			5,
			true, 1,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			6,
			false, 0,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			4,
			false, 0,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			5,
			true, 1,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			6,
			false, 0,
		},
		// term from snapshot
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			4,
			true, 1,
		},
		{
			[]pb.Entry{}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			5,
			false, 0,
		},
		{
			[]pb.Entry{}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			4,
			true, 1,
		},
		{
			[]pb.Entry{}, 0, nil,
			5,
			false, 0,
		},
	}

	for i, tt := range tests {
		u := unstable{
			entries:  tt.entries,
			offset:   tt.offset,
			snapshot: tt.snap,
		}
		term, ok := u.maybeTerm(tt.index)
		if ok != tt.wok {
			t.Errorf("#%d: ok = %t, want %t", i, ok, tt.wok)
		}
		if term != tt.wterm {
			t.Errorf("#%d: term = %d, want %d", i, term, tt.wterm)
		}
	}
}

func TestUnstableRestore(t *testing.T) {
	u := unstable{
		entries:  []pb.Entry{{Index: 5, Term: 1}},
		offset:   5,
		snapshot: &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
	}
	s := pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 6, Term: 2}}
	u.restore(s)

	if u.offset != s.Metadata.Index+1 {
		t.Errorf("offset = %d, want %d", u.offset, s.Metadata.Index+1)
	}
	if len(u.entries) != 0 {
		t.Errorf("len = %d, want 0", len(u.entries))
	}
	if !reflect.DeepEqual(u.snapshot, &s) {
		t.Errorf("snap = %v, want %v", u.snapshot, &s)
	}
}

func TestUnstableStableTo(t *testing.T) {
	tests := []struct {
		entries     []pb.Entry
		offset      uint64
		snap        *pb.Snapshot
		index, term uint64

		woffset uint64
		wlen    int
	}{
		{
			[]pb.Entry{}, 0, nil,
			5, 1,
			0, 0,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			5, 1, // stable to the first entry
			6, 0,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}, {Index: 6, Term: 1}}, 5, nil,
			5, 1, // stable to the first entry
			6, 1,
		},
		{
			[]pb.Entry{{Index: 6, Term: 2}}, 5, nil,
			6, 1, // stable to the first entry and term mismatch
			5, 1,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			4, 1, // stable to old entry
			5, 1,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			4, 2, // stable to old entry
			5, 1,
		},
		// with snapshot
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			5, 1, // stable to the first entry
			6, 0,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}, {Index: 6, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			5, 1, // stable to the first entry
			6, 1,
		},
		{
			[]pb.Entry{{Index: 6, Term: 2}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 5, Term: 1}},
			6, 1, // stable to the first entry and term mismatch
			5, 1,
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 1}},
			4, 1, // stable to snapshot
			5, 1,
		},
		{
			[]pb.Entry{{Index: 5, Term: 2}}, 5, &pb.Snapshot{Metadata: pb.SnapshotMetadata{Index: 4, Term: 2}},
			4, 1, // stable to old entry
			5, 1,
		},
	}

	for i, tt := range tests {
		u := unstable{
			entries:  tt.entries,
			offset:   tt.offset,
			snapshot: tt.snap,
		}
		u.stableTo(tt.index, tt.term)
		if u.offset != tt.woffset {
			t.Errorf("#%d: offset = %d, want %d", i, u.offset, tt.woffset)
		}
		if len(u.entries) != tt.wlen {
			t.Errorf("#%d: len = %d, want %d", i, len(u.entries), tt.wlen)
		}
	}
}

func TestUnstableTruncateAndAppend(t *testing.T) {
	tests := []struct {
		entries  []pb.Entry
		offset   uint64
		snap     *pb.Snapshot
		toappend []pb.Entry

		woffset  uint64
		wentries []pb.Entry
	}{
		// append to the end
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			[]pb.Entry{{Index: 6, Term: 1}, {Index: 7, Term: 1}},
			5, []pb.Entry{{Index: 5, Term: 1}, {Index: 6, Term: 1}, {Index: 7, Term: 1}},
		},
		// replace the unstable entries
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			[]pb.Entry{{Index: 5, Term: 2}, {Index: 6, Term: 2}},
			5, []pb.Entry{{Index: 5, Term: 2}, {Index: 6, Term: 2}},
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}}, 5, nil,
			[]pb.Entry{{Index: 4, Term: 2}, {Index: 5, Term: 2}, {Index: 6, Term: 2}},
			4, []pb.Entry{{Index: 4, Term: 2}, {Index: 5, Term: 2}, {Index: 6, Term: 2}},
		},
		// truncate the existing entries and append
		{
			[]pb.Entry{{Index: 5, Term: 1}, {Index: 6, Term: 1}, {Index: 7, Term: 1}}, 5, nil,
			[]pb.Entry{{Index: 6, Term: 2}},
			5, []pb.Entry{{Index: 5, Term: 1}, {Index: 6, Term: 2}},
		},
		{
			[]pb.Entry{{Index: 5, Term: 1}, {Index: 6, Term: 1}, {Index: 7, Term: 1}}, 5, nil,
			[]pb.Entry{{Index: 7, Term: 2}, {Index: 8, Term: 2}},
			5, []pb.Entry{{Index: 5, Term: 1}, {Index: 6, Term: 1}, {Index: 7, Term: 2}, {Index: 8, Term: 2}},
		},
	}

	for i, tt := range tests {
		u := unstable{
			entries:  tt.entries,
			offset:   tt.offset,
			snapshot: tt.snap,
		}
		u.truncateAndAppend(tt.toappend)
		if u.offset != tt.woffset {
			t.Errorf("#%d: offset = %d, want %d", i, u.offset, tt.woffset)
		}
		if !reflect.DeepEqual(u.entries, tt.wentries) {
			t.Errorf("#%d: entries = %v, want %v", i, u.entries, tt.wentries)
		}
	}
}