package server

import (
	"context"
	"sync"

	"git.noahlan.cn/noahlan/nnet/v2/internal/logger"
	"git.noahlan.cn/noahlan/nnet/v2/pkg/config"
	"git.noahlan.cn/noahlan/nnet/v2/pkg/executor"
)

// handlerExecutor owns the optional asynchronous handler executor. An
// injected executor is deliberately not owned by the server.
type handlerExecutor struct {
	exec  executor.Executor
	owned bool

	shutdownOnce sync.Once
	shutdownErr  error
}

func newHandlerExecutor(cfg *config.Config, log logger.Logger) *handlerExecutor {
	if cfg == nil || cfg.HandlerExecutionMode != config.HandlerExecutionPerConnection {
		return nil
	}

	if cfg.HandlerExecutor != nil {
		return &handlerExecutor{exec: cfg.HandlerExecutor}
	}

	return &handlerExecutor{
		exec: executor.NewPerKey(executor.Config{
			Workers:   cfg.HandlerWorkers,
			QueueSize: cfg.HandlerQueueSize,
			OnPanic: func(value interface{}) {
				log.Error("Handler panic recovered: %v", value)
			},
		}),
		owned: true,
	}
}

func (h *handlerExecutor) submit(key string, task executor.Task) error {
	if h == nil || h.exec == nil {
		return nil
	}
	return h.exec.Submit(key, task)
}

func (h *handlerExecutor) shutdown(ctx context.Context) error {
	if h == nil || !h.owned || h.exec == nil {
		return nil
	}
	h.shutdownOnce.Do(func() {
		h.shutdownErr = h.exec.Shutdown(ctx)
	})
	return h.shutdownErr
}