// Copyright 2015 The Cockroach Authors.
//
// 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. See the AUTHORS file
// for names of contributors.
//
// Author: Ben Darnell

package storage

import (
	"bytes"
	"fmt"
	"strings"

	"golang.org/x/net/context"

	"github.com/cockroachdb/cockroach/pkg/security"
	"github.com/cockroachdb/cockroach/pkg/util/log"
	"github.com/coreos/etcd/raft"
	"github.com/coreos/etcd/raft/raftpb"
)

// init installs an adapter to use clog for log messages from raft which
// don't belong to any range.
func init() {
	raft.SetLogger(&raftLogger{ctx: context.Background()})
}

// *clogLogger implements the raft.Logger interface. Note that all methods
// must be defined on the pointer type rather than the value type because
// (at least in the go 1.4 compiler), methods on a value type called through
// an interface pointer go through an additional layer of indirection that
// appears on the stack, and would make all our stack frame offsets incorrect.
//
// Raft is fairly verbose at the "info" level, so we map "info" messages to
// clog.V(1) and "debug" messages to clog.V(2).
//
// This file is named raft.go instead of something like logger.go because this
// file's name is used to determine the vmodule parameter: --vmodule=raft=1
type raftLogger struct {
	ctx context.Context
}

func (r *raftLogger) Debug(v ...interface{}) {
	if log.V(3) {
		log.InfofDepth(r.ctx, 1, "", v...)
	}
}

func (r *raftLogger) Debugf(format string, v ...interface{}) {
	if log.V(3) {
		log.InfofDepth(r.ctx, 1, format, v...)
	}
}

func (r *raftLogger) Info(v ...interface{}) {
	if log.V(2) {
		log.InfofDepth(r.ctx, 1, "", v...)
	}
}

func (r *raftLogger) Infof(format string, v ...interface{}) {
	if log.V(2) {
		log.InfofDepth(r.ctx, 1, format, v...)
	}
}

func (r *raftLogger) Warning(v ...interface{}) {
	log.WarningfDepth(r.ctx, 1, "", v...)
}

func (r *raftLogger) Warningf(format string, v ...interface{}) {
	log.WarningfDepth(r.ctx, 1, format, v...)
}

func (r *raftLogger) Error(v ...interface{}) {
	log.ErrorfDepth(r.ctx, 1, "", v...)
}

func (r *raftLogger) Errorf(format string, v ...interface{}) {
	log.ErrorfDepth(r.ctx, 1, format, v...)
}

func (r *raftLogger) Fatal(v ...interface{}) {
	log.FatalfDepth(r.ctx, 1, "", v...)
}

func (r *raftLogger) Fatalf(format string, v ...interface{}) {
	log.FatalfDepth(r.ctx, 1, format, v...)
}

func (r *raftLogger) Panic(v ...interface{}) {
	s := fmt.Sprint(v...)
	log.ErrorfDepth(r.ctx, 1, s)
	if is14231Error(s) {
		log.Shout(r.ctx, log.Severity_ERROR, is14231HelpMessage)
	}
	panic(s)
}

func (r *raftLogger) Panicf(format string, v ...interface{}) {
	s := fmt.Sprintf(format, v...)
	log.ErrorfDepth(r.ctx, 1, s)
	if is14231Error(s) {
		log.Shout(r.ctx, log.Severity_ERROR, is14231HelpMessage)
	}
	panic(fmt.Sprintf(format, v...))
}

// Returns whether the provided error message matches the error observed in
// issue #14231. Such errors are likely to be the result of wiping a store's
// data directory and bringing it back online without join flags but with the
// same address, node ID, and store ID, and join flags. While we should prevent
// these errors in our next release, for now the best we can do is help users
// understand them.
//
// TODO(#14231): Remove this method once the issue is fixed (hopefully in 1.2).
func is14231Error(s string) bool {
	return strings.Contains(s, "is out of range [lastIndex(") &&
		strings.Contains(s, "Was the raft log corrupted, truncated, or lost?")
}

// TODO(#14231): Remove this once the issue is fixed (hopefully in 1.2).
const is14231HelpMessage = "Server crashing due to missing data. Was the server restarted with a\n" +
	"different store directory than before? A --join parameter must be specified\n" +
	"in order to make restarts with a new store directory safe. Please try again\n" +
	"with a new directory and a valid --join flag. If this server was started with\n" +
	"its old data or with a valid --join parameter and you are still seeing this,\n" +
	"please report an issue at https://github.com/cockroachdb/cockroach/issues/new"

func logRaftReady(ctx context.Context, ready raft.Ready) {
	if log.V(5) {
		var buf bytes.Buffer
		if ready.SoftState != nil {
			fmt.Fprintf(&buf, "  SoftState updated: %+v\n", *ready.SoftState)
		}
		if !raft.IsEmptyHardState(ready.HardState) {
			fmt.Fprintf(&buf, "  HardState updated: %+v\n", ready.HardState)
		}
		for i, e := range ready.Entries {
			fmt.Fprintf(&buf, "  New Entry[%d]: %.200s\n",
				i, raft.DescribeEntry(e, raftEntryFormatter))
		}
		for i, e := range ready.CommittedEntries {
			fmt.Fprintf(&buf, "  Committed Entry[%d]: %.200s\n",
				i, raft.DescribeEntry(e, raftEntryFormatter))
		}
		if !raft.IsEmptySnap(ready.Snapshot) {
			snap := ready.Snapshot
			snap.Data = nil
			fmt.Fprintf(&buf, "  Snapshot updated: %v\n", snap)
		}
		for i, m := range ready.Messages {
			fmt.Fprintf(&buf, "  Outgoing Message[%d]: %.200s\n",
				i, raftDescribeMessage(m, raftEntryFormatter))
		}
		log.Infof(ctx, "raft ready\n%s", buf.String())
	}
}

// This is a fork of raft.DescribeMessage with a tweak to avoid logging
// snapshot data.
func raftDescribeMessage(m raftpb.Message, f raft.EntryFormatter) string {
	var buf bytes.Buffer
	fmt.Fprintf(&buf, "%x->%x %v Term:%d Log:%d/%d", m.From, m.To, m.Type, m.Term, m.LogTerm, m.Index)
	if m.Reject {
		fmt.Fprintf(&buf, " Rejected")
		if m.RejectHint != 0 {
			fmt.Fprintf(&buf, "(Hint:%d)", m.RejectHint)
		}
	}
	if m.Commit != 0 {
		fmt.Fprintf(&buf, " Commit:%d", m.Commit)
	}
	if len(m.Entries) > 0 {
		fmt.Fprintf(&buf, " Entries:[")
		for i, e := range m.Entries {
			if i != 0 {
				buf.WriteString(", ")
			}
			buf.WriteString(raft.DescribeEntry(e, f))
		}
		fmt.Fprintf(&buf, "]")
	}
	if !raft.IsEmptySnap(m.Snapshot) {
		snap := m.Snapshot
		snap.Data = nil
		fmt.Fprintf(&buf, " Snapshot:%v", snap)
	}
	return buf.String()
}

func raftEntryFormatter(data []byte) string {
	if len(data) == 0 {
		return "[empty]"
	}
	commandID, _ := DecodeRaftCommand(data)
	return fmt.Sprintf("[%x] [%d]", commandID, len(data))
}

var _ security.RequestWithUser = &RaftMessageRequest{}

// GetUser implements security.RequestWithUser.
// Raft messages are always sent by the node user.
func (*RaftMessageRequest) GetUser() string {
	return security.NodeUser
}