// Package log define log struct of wave record project
package log

import (
	"os"
	"sync"

	"github.com/natefinch/lumberjack"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
)

var (
	logger *zap.Logger
	once   sync.Once
)

// CutLogConfig define log config of wave record project
type CutLogConfig struct {
	Level      string `json:"level"`       // Level 最低日志等级，DEBUG<INFO<WARN<ERROR<FATAL INFO-->收集INFO等级以上的日志
	FileName   string `json:"file_name"`   // FileName 日志文件位置
	MaxSize    int    `json:"max_size"`    // MaxSize 进行切割之前,日志文件的最大大小(MB为单位)默认为100MB
	MaxAge     int    `json:"max_age"`     // MaxAge 是根据文件名中编码的时间戳保留旧日志文件的最大天数。
	MaxBackups int    `json:"max_backups"` // MaxBackups 是要保留的旧日志文件的最大数量。默认是保留所有旧的日志文件(尽管 MaxAge 可能仍会导致它们被删除)
}

// getEncoder responsible for setting the log format for encoding
func getEncoder() zapcore.Encoder {
	encodeConfig := zap.NewProductionEncoderConfig()
	// serialization time eg:2006-01-02 15:04:05
	encodeConfig.EncodeTime = zapcore.TimeEncoderOfLayout("2006-01-02 15:04:05")
	encodeConfig.TimeKey = "time"
	encodeConfig.EncodeLevel = zapcore.CapitalLevelEncoder
	encodeConfig.EncodeCaller = zapcore.ShortCallerEncoder
	return zapcore.NewJSONEncoder(encodeConfig)
}

// getLogWriter responsible for setting the location of log storage
func getLogWriter(filename string, maxsize, maxBackup, maxAge int) zapcore.WriteSyncer {
	lumberJackLogger := &lumberjack.Logger{
		Filename:   filename,  // log file position
		MaxSize:    maxsize,   // log file maxsize
		MaxAge:     maxAge,    // maximum number of day files retained
		MaxBackups: maxBackup, // maximum number of old files retained
		Compress:   false,     // whether to compress
	}
	syncFile := zapcore.AddSync(lumberJackLogger)
	// TODO:增加调试输出到控制台设置，其他模式无控制台数据
	syncConsole := zapcore.AddSync(os.Stderr)
	return zapcore.NewMultiWriteSyncer(syncFile, syncConsole)
}

// initLogger return successfully initialized zap logger
func initLogger(lCfg CutLogConfig) *zap.Logger {
	writeSyncer := getLogWriter(lCfg.FileName, lCfg.MaxSize, lCfg.MaxBackups, lCfg.MaxAge)
	encoder := getEncoder()

	l := new(zapcore.Level)
	err := l.UnmarshalText([]byte(lCfg.Level))
	if err != nil {
		panic(err)
	}

	core := zapcore.NewCore(encoder, writeSyncer, l)
	logger = zap.New(core, zap.AddCaller())
	zap.ReplaceGlobals(logger)

	return logger
}

// GetLoggerInstance return instance of zap logger
func GetLoggerInstance(lCfg CutLogConfig) *zap.Logger {
	once.Do(func() {
		logger = initLogger(lCfg)
	})
	return logger
}