// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package slog

import (
	
	
	
	
	
)

// A Level is the importance or severity of a log event.
// The higher the level, the more important or severe the event.
type Level int

// Names for common levels.
//
// Level numbers are inherently arbitrary,
// but we picked them to satisfy three constraints.
// Any system can map them to another numbering scheme if it wishes.
//
// First, we wanted the default level to be Info, Since Levels are ints, Info is
// the default value for int, zero.
//
// Second, we wanted to make it easy to use levels to specify logger verbosity.
// Since a larger level means a more severe event, a logger that accepts events
// with smaller (or more negative) level means a more verbose logger. Logger
// verbosity is thus the negation of event severity, and the default verbosity
// of 0 accepts all events at least as severe as INFO.
//
// Third, we wanted some room between levels to accommodate schemes with named
// levels between ours. For example, Google Cloud Logging defines a Notice level
// between Info and Warn. Since there are only a few of these intermediate
// levels, the gap between the numbers need not be large. Our gap of 4 matches
// OpenTelemetry's mapping. Subtracting 9 from an OpenTelemetry level in the
// DEBUG, INFO, WARN and ERROR ranges converts it to the corresponding slog
// Level range. OpenTelemetry also has the names TRACE and FATAL, which slog
// does not. But those OpenTelemetry levels can still be represented as slog
// Levels by using the appropriate integers.
const (
	LevelDebug Level = -4
	LevelInfo  Level = 0
	LevelWarn  Level = 4
	LevelError Level = 8
)

// String returns a name for the level.
// If the level has a name, then that name
// in uppercase is returned.
// If the level is between named values, then
// an integer is appended to the uppercased name.
// Examples:
//
//	LevelWarn.String() => "WARN"
//	(LevelInfo+2).String() => "INFO+2"
func ( Level) () string {
	 := func( string,  Level) string {
		if  == 0 {
			return 
		}
		return fmt.Sprintf("%s%+d", , )
	}

	switch {
	case  < LevelInfo:
		return ("DEBUG", -LevelDebug)
	case  < LevelWarn:
		return ("INFO", -LevelInfo)
	case  < LevelError:
		return ("WARN", -LevelWarn)
	default:
		return ("ERROR", -LevelError)
	}
}

// MarshalJSON implements [encoding/json.Marshaler]
// by quoting the output of [Level.String].
func ( Level) () ([]byte, error) {
	// AppendQuote is sufficient for JSON-encoding all Level strings.
	// They don't contain any runes that would produce invalid JSON
	// when escaped.
	return strconv.AppendQuote(nil, .String()), nil
}

// UnmarshalJSON implements [encoding/json.Unmarshaler]
// It accepts any string produced by [Level.MarshalJSON],
// ignoring case.
// It also accepts numeric offsets that would result in a different string on
// output. For example, "Error-8" would marshal as "INFO".
func ( *Level) ( []byte) error {
	,  := strconv.Unquote(string())
	if  != nil {
		return 
	}
	return .parse()
}

// AppendText implements [encoding.TextAppender]
// by calling [Level.String].
func ( Level) ( []byte) ([]byte, error) {
	return append(, .String()...), nil
}

// MarshalText implements [encoding.TextMarshaler]
// by calling [Level.AppendText].
func ( Level) () ([]byte, error) {
	return .AppendText(nil)
}

// UnmarshalText implements [encoding.TextUnmarshaler].
// It accepts any string produced by [Level.MarshalText],
// ignoring case.
// It also accepts numeric offsets that would result in a different string on
// output. For example, "Error-8" would marshal as "INFO".
func ( *Level) ( []byte) error {
	return .parse(string())
}

func ( *Level) ( string) ( error) {
	defer func() {
		if  != nil {
			 = fmt.Errorf("slog: level string %q: %w", , )
		}
	}()

	 := 
	 := 0
	if  := strings.IndexAny(, "+-");  >= 0 {
		 = [:]
		,  = strconv.Atoi([:])
		if  != nil {
			return 
		}
	}
	switch strings.ToUpper() {
	case "DEBUG":
		* = LevelDebug
	case "INFO":
		* = LevelInfo
	case "WARN":
		* = LevelWarn
	case "ERROR":
		* = LevelError
	default:
		return errors.New("unknown name")
	}
	* += Level()
	return nil
}

// Level returns the receiver.
// It implements [Leveler].
func ( Level) () Level { return  }

// A LevelVar is a [Level] variable, to allow a [Handler] level to change
// dynamically.
// It implements [Leveler] as well as a Set method,
// and it is safe for use by multiple goroutines.
// The zero LevelVar corresponds to [LevelInfo].
type LevelVar struct {
	val atomic.Int64
}

// Level returns v's level.
func ( *LevelVar) () Level {
	return Level(int(.val.Load()))
}

// Set sets v's level to l.
func ( *LevelVar) ( Level) {
	.val.Store(int64())
}

func ( *LevelVar) () string {
	return fmt.Sprintf("LevelVar(%s)", .Level())
}

// AppendText implements [encoding.TextAppender]
// by calling [Level.AppendText].
func ( *LevelVar) ( []byte) ([]byte, error) {
	return .Level().AppendText()
}

// MarshalText implements [encoding.TextMarshaler]
// by calling [LevelVar.AppendText].
func ( *LevelVar) () ([]byte, error) {
	return .AppendText(nil)
}

// UnmarshalText implements [encoding.TextUnmarshaler]
// by calling [Level.UnmarshalText].
func ( *LevelVar) ( []byte) error {
	var  Level
	if  := .UnmarshalText();  != nil {
		return 
	}
	.Set()
	return nil
}

// A Leveler provides a [Level] value.
//
// As Level itself implements Leveler, clients typically supply
// a Level value wherever a Leveler is needed, such as in [HandlerOptions].
// Clients who need to vary the level dynamically can provide a more complex
// Leveler implementation such as *[LevelVar].
type Leveler interface {
	Level() Level
}