// Copyright 2017 PingCAP, 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,
// See the License for the specific language governing permissions and
// limitations under the License.

package operator

import (
	"strings"

	"github.com/pkg/errors"
)

// OpKind is a bit field to identify operator types.
type OpKind uint32

// Flags for operators.
const (
	OpLeader   OpKind = 1 << iota // Include leader transfer.
	OpRegion                      // Include peer movement.
	OpAdmin                       // Initiated by admin.
	OpAdjacent                    // Initiated by adjacent region scheduler.
	OpReplica                     // Initiated by replica checkers.
	OpBalance                     // Initiated by balancers.
	OpMerge                       // Initiated by merge checkers or merge schedulers.
	OpRange                       // Initiated by range scheduler.
	opMax
)

var flagToName = map[OpKind]string{
	OpLeader:   "leader",
	OpRegion:   "region",
	OpAdmin:    "admin",
	OpAdjacent: "adjacent",
	OpReplica:  "replica",
	OpBalance:  "balance",
	OpMerge:    "merge",
	OpRange:    "range",
}

var nameToFlag = map[string]OpKind{
	"leader":   OpLeader,
	"region":   OpRegion,
	"admin":    OpAdmin,
	"adjacent": OpAdjacent,
	"replica":  OpReplica,
	"balance":  OpBalance,
	"merge":    OpMerge,
	"range":    OpRange,
}

func (k OpKind) String() string {
	var flagNames []string
	for flag := OpKind(1); flag < opMax; flag <<= 1 {
		if k&flag != 0 {
			flagNames = append(flagNames, flagToName[flag])
		}
	}
	if len(flagNames) == 0 {
		return "unknown"
	}
	return strings.Join(flagNames, ",")
}

// ParseOperatorKind converts string (flag name list concat by ',') to OpKind.
func ParseOperatorKind(str string) (OpKind, error) {
	var k OpKind
	for _, flagName := range strings.Split(str, ",") {
		flag, ok := nameToFlag[flagName]
		if !ok {
			return 0, errors.Errorf("unknown flag name: %s", flagName)
		}
		k |= flag
	}
	return k, nil

}