package root

import (
	"context"
	"fmt"
	"io"
	"os"

	"github.com/databricks/cli/libs/cmdio"
	"github.com/databricks/cli/libs/flags"
	"github.com/databricks/cli/libs/log"
	"github.com/fatih/color"
	"golang.org/x/exp/slog"
)

const (
	envLogFile   = "DATABRICKS_LOG_FILE"
	envLogLevel  = "DATABRICKS_LOG_LEVEL"
	envLogFormat = "DATABRICKS_LOG_FORMAT"
)

type friendlyHandler struct {
	slog.Handler
	w io.Writer
}

var (
	levelTrace = color.New(color.FgYellow).Sprint("TRACE")
	levelDebug = color.New(color.FgYellow).Sprint("DEBUG")
	levelInfo  = color.New(color.FgGreen).Sprintf("%5s", "INFO")
	levelWarn  = color.New(color.FgMagenta).Sprintf("%5s", "WARN")
	levelError = color.New(color.FgRed).Sprint("ERROR")
)

func (l *friendlyHandler) coloredLevel(rec slog.Record) string {
	switch rec.Level {
	case log.LevelTrace:
		return levelTrace
	case slog.LevelDebug:
		return levelDebug
	case slog.LevelInfo:
		return levelInfo
	case slog.LevelWarn:
		return levelWarn
	case log.LevelError:
		return levelError
	}
	return ""
}

func (l *friendlyHandler) Handle(ctx context.Context, rec slog.Record) error {
	t := fmt.Sprintf("%02d:%02d", rec.Time.Hour(), rec.Time.Minute())
	attrs := ""
	rec.Attrs(func(a slog.Attr) {
		attrs += fmt.Sprintf(" %s%s%s",
			color.CyanString(a.Key),
			color.CyanString("="),
			color.YellowString(a.Value.String()))
	})
	msg := fmt.Sprintf("%s %s %s%s\n",
		color.MagentaString(t),
		l.coloredLevel(rec),
		rec.Message,
		attrs)
	_, err := l.w.Write([]byte(msg))
	return err
}

func makeLogHandler(opts slog.HandlerOptions) (slog.Handler, error) {
	switch logOutput {
	case flags.OutputJSON:
		return opts.NewJSONHandler(logFile.Writer()), nil
	case flags.OutputText:
		w := logFile.Writer()
		if cmdio.IsTTY(w) {
			return &friendlyHandler{
				Handler: opts.NewTextHandler(w),
				w:       w,
			}, nil
		}
		return opts.NewTextHandler(w), nil

	default:
		return nil, fmt.Errorf("invalid log output mode: %s", logOutput)
	}
}

func initializeLogger(ctx context.Context) (context.Context, error) {
	opts := slog.HandlerOptions{}
	opts.Level = logLevel.Level()
	opts.AddSource = true
	opts.ReplaceAttr = log.ReplaceAttrFunctions{
		log.ReplaceLevelAttr,
		log.ReplaceSourceAttr,
	}.ReplaceAttr

	// Open the underlying log file if the user configured an actual file to log to.
	err := logFile.Open()
	if err != nil {
		return nil, err
	}

	handler, err := makeLogHandler(opts)
	if err != nil {
		return nil, err
	}

	slog.SetDefault(slog.New(handler))
	return log.NewContext(ctx, slog.Default()), nil
}

var logFile = flags.NewLogFileFlag()
var logLevel = flags.NewLogLevelFlag()
var logOutput = flags.OutputText

func init() {
	// Configure defaults from environment, if applicable.
	// If the provided value is invalid it is ignored.
	if v, ok := os.LookupEnv(envLogFile); ok {
		logFile.Set(v)
	}
	if v, ok := os.LookupEnv(envLogLevel); ok {
		logLevel.Set(v)
	}
	if v, ok := os.LookupEnv(envLogFormat); ok {
		logOutput.Set(v)
	}

	RootCmd.PersistentFlags().Var(&logFile, "log-file", "file to write logs to")
	RootCmd.PersistentFlags().Var(&logLevel, "log-level", "log level")
	RootCmd.PersistentFlags().Var(&logOutput, "log-format", "log output format (text or json)")
	RootCmd.RegisterFlagCompletionFunc("log-file", logFile.Complete)
	RootCmd.RegisterFlagCompletionFunc("log-level", logLevel.Complete)
	RootCmd.RegisterFlagCompletionFunc("log-format", logOutput.Complete)
}