package app

import (
	"go.uber.org/fx"
	"go.uber.org/fx/fxevent"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"sync/atomic"
	"universe.mrlokop.dev/core/config"
	"universe.mrlokop.dev/core/errors"
	"universe.mrlokop.dev/core/modules"
)

var (
	ErrAlreadyStarted = errors.Type("ErrAlreadyStarted", "already started")
	ErrUnknownModule  = errors.Type("ErrUnknownModule", "specified module does not exist")
)

type Application interface {
	Config() *config.UniverseConfig
	Run() error
}

type UniverseApplication struct {
	fx      *fx.App
	config  *config.UniverseConfig
	options []fx.Option
	started atomic.Bool
}

func (app *UniverseApplication) Config() *config.UniverseConfig {
	return app.config
}

func (app *UniverseApplication) Run() error {
	if !app.started.CompareAndSwap(false, true) {
		return ErrAlreadyStarted.CreateEmpty()
	}

	options := make([]fx.Option, 0)
	options = append(options, app.options...)
	options = append(options,
		fx.Provide(func() Application {
			return app
		}),
		fx.WithLogger(func(log *zap.Logger) fxevent.Logger {
			logger := &fxevent.ZapLogger{Logger: log.WithOptions(zap.AddCallerSkip(2))}
			logger.UseLogLevel(zapcore.DebugLevel)
			return logger
		}),
	)

	if app.config.Modules != nil && len(app.config.Modules) > 0 {
		for id, modConf := range app.config.Modules {
			kind := modConf["kind"].(string)
			module := modules.GetModule(kind)
			if module == nil {
				return ErrUnknownModule.Builder().
					Messagef("module '%s' is not registered", kind).
					WithField("module", kind).
					Build()
			}

			option, err := module.Create(id, modConf)
			if err != nil {
				return err
			}

			options = append(options, option)
		}
	}

	app.fx = fx.New(options...)
	app.fx.Run()
	return nil
}

func (app *UniverseApplication) WithOption(options ...fx.Option) *UniverseApplication {
	if app.started.Load() {
		panic(ErrAlreadyStarted)
	}

	app.options = append(app.options, options...)
	return app
}

func NewUniverseApplication(config *config.UniverseConfig) *UniverseApplication {
	return &UniverseApplication{config: config}
}