package logger

import (
	"fmt"
	"os"

	"gcy_hpc_server/internal/config"

	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"gopkg.in/natefinch/lumberjack.v2"
)

func NewLogger(cfg config.LogConfig) (*zap.Logger, error) {
	level := applyDefault(cfg.Level, "info")

	var zapLevel zapcore.Level
	if err := zapLevel.UnmarshalText([]byte(level)); err != nil {
		return nil, fmt.Errorf("invalid log level %q: %w", level, err)
	}

	encoding := applyDefault(cfg.Encoding, "json")
	encoderConfig := zap.NewProductionEncoderConfig()
	encoderConfig.TimeKey = "ts"
	encoderConfig.EncodeTime = zapcore.ISO8601TimeEncoder
	encoderConfig.EncodeLevel = zapcore.CapitalLevelEncoder

	var encoder zapcore.Encoder
	switch encoding {
	case "console":
		encoder = zapcore.NewConsoleEncoder(encoderConfig)
	default:
		encoder = zapcore.NewJSONEncoder(encoderConfig)
	}

	var syncers []zapcore.WriteSyncer

	stdout := true
	if cfg.OutputStdout != nil {
		stdout = *cfg.OutputStdout
	}
	if stdout {
		syncers = append(syncers, zapcore.AddSync(os.Stdout))
	}

	if cfg.FilePath != "" {
		maxSize := applyDefaultInt(cfg.MaxSize, 100)
		maxBackups := applyDefaultInt(cfg.MaxBackups, 5)
		maxAge := applyDefaultInt(cfg.MaxAge, 30)
		compress := cfg.Compress || (cfg.MaxSize == 0 && cfg.MaxBackups == 0 && cfg.MaxAge == 0)

		lj := &lumberjack.Logger{
			Filename:   cfg.FilePath,
			MaxSize:    maxSize,
			MaxBackups: maxBackups,
			MaxAge:     maxAge,
			Compress:   compress,
		}
		syncers = append(syncers, zapcore.AddSync(lj))
	}

	if len(syncers) == 0 {
		syncers = append(syncers, zapcore.AddSync(os.Stdout))
	}

	writeSyncer := syncers[0]
	if len(syncers) > 1 {
		writeSyncer = zapcore.NewMultiWriteSyncer(syncers...)
	}

	core := zapcore.NewCore(encoder, writeSyncer, zapLevel)

	opts := []zap.Option{
		zap.AddCaller(),
		zap.AddStacktrace(zapcore.ErrorLevel),
	}

	return zap.New(core, opts...), nil
}

func applyDefault(val, def string) string {
	if val == "" {
		return def
	}
	return val
}

func applyDefaultInt(val, def int) int {
	if val == 0 {
		return def
	}
	return val
}