package log

import (
	"errors"
	"log/slog"
	"net/http"
	"os"
	"strings"

	"github.com/mattn/go-colorable"
	"github.com/mattn/go-isatty"
	slogmulti "github.com/samber/slog-multi"
	"github.com/tigorlazuardi/bluemage/go/config"
	"github.com/tigorlazuardi/bluemage/go/pkg/telemetry"
	"gopkg.in/natefinch/lumberjack.v2"
)

func NewHandler(cfg *config.Config) (slog.Handler, func() error) {
	var handlers []slog.Handler
	cleanup := func() error { return nil }

	if cfg.Bool("log.enable") {
		log, sync := createStandardLogger(cfg)
		cleanup = sync
		handlers = append(handlers, log)
	}

	if cfg.Bool("log.file.enable") {
		log, clean := createFileLogger(cfg)
		cl := cleanup
		cleanup = func() error {
			return errors.Join(cl(), clean())
		}
		handlers = append(handlers, log)
	}

	if cfg.Bool("telemetry.openobserve.enable") && cfg.Bool("telemetry.openobserve.log.enable") {
		log, clean := createO2Logger(cfg)
		cl := cleanup
		handlers = append(handlers, log)
		cleanup = func() error {
			err := cl()
			clean()
			return err
		}
	}

	if len(handlers) == 0 {
		return NullHandler{}, cleanup
	}

	return slogmulti.Fanout(handlers...), cleanup
}

func createFileLogger(cfg *config.Config) (slog.Handler, func() error) {
	output := &lumberjack.Logger{
		Filename:   cfg.String("log.file.path"),
		MaxSize:    15,
		MaxAge:     30,
		MaxBackups: 10,
		LocalTime:  true,
	}
	var lvl slog.Level
	_ = lvl.UnmarshalText(cfg.Bytes("log.level"))
	opts := &slog.HandlerOptions{
		AddSource: cfg.Bool("log.source"),
		Level:     lvl,
	}
	return slog.NewJSONHandler(Lock(AddSync(output)), opts), output.Close
}

func createStandardLogger(cfg *config.Config) (slog.Handler, func() error) {
	var output WriteSyncer
	var cleanup func() error

	if strings.ToLower(cfg.String("log.output")) == "stdout" {
		output = Lock(AddSync(colorable.NewColorableStdout()))
		cleanup = output.Sync
	} else {
		output = Lock(AddSync(colorable.NewColorableStderr()))
		cleanup = output.Sync
	}

	var lvl slog.Level
	_ = lvl.UnmarshalText(cfg.Bytes("log.level"))
	opts := &slog.HandlerOptions{
		AddSource: cfg.Bool("log.source"),
		Level:     lvl,
	}

	if isatty.IsTerminal(os.Stdout.Fd()) {
		return NewPrettyHandler(output, opts), cleanup
	} else {
		return slog.NewJSONHandler(output, opts), cleanup
	}
}

func createO2Logger(cfg *config.Config) (slog.Handler, func()) {
	var lvl slog.Level
	_ = lvl.UnmarshalText(cfg.Bytes("telemetry.openobserve.log.level"))
	opts := &slog.HandlerOptions{
		AddSource: cfg.Bool("telemetry.openobserve.log.source"),
		Level:     lvl,
	}
	handler := telemetry.NewOpenObserveHandler(telemetry.OpenObserveHandlerOptions{
		HandlerOptions: opts,
		BufferSize:     cfg.Int("telemetry.openobserve.log.buffer.size"),
		BufferTimeout:  cfg.Duration("telemetry.openobserve.log.buffer.timeout"),
		Concurrency:    cfg.Int("telemetry.openobserve.log.concurrency"),
		Endpoint:       cfg.String("telemetry.openobserve.log.endpoint"),
		HTTPClient:     http.DefaultClient,
		Username:       cfg.String("telemetry.openobserve.log.username"),
		Password:       cfg.String("telemetry.openobserve.log.password"),
	})
	return handler, handler.Flush
}