package mediator

import (
	"context"
	"fmt"
	"reflect"
)

type RequestHandler[TRequest any, TResponse any] interface {
	Handle(ctx context.Context, request TRequest) (TResponse, error)
}

type Mediator struct {
	handlers map[reflect.Type]interface{}
}

func NewMediator() *Mediator {
	return &Mediator{
		handlers: make(map[reflect.Type]interface{}),
	}
}

func Register[TRequest any, TResponse any](m *Mediator, handler RequestHandler[TRequest, TResponse]) {
	var req TRequest
	t := reflect.TypeOf(req)
	m.handlers[t] = handler
}

func Send[TRequest any, TResponse any](m *Mediator, ctx context.Context, request TRequest) (TResponse, error) {
	t := reflect.TypeOf(request)
	handler, ok := m.handlers[t]
	if !ok {
		var zero TResponse
		return zero, fmt.Errorf("handler not found for %v", t)
	}

	h, ok := handler.(RequestHandler[TRequest, TResponse])
	if !ok {
		var zero TResponse
		return zero, fmt.Errorf("handler type mismatch")
	}

	return h.Handle(ctx, request)
}