project-ely/internal/game/entity/command/handler.go

package command

import (
	"context"
	"log"
	"sync"
	"time"

	"git.wisellama.rocks/Project-Ely/project-ely/internal/channels"
)

type Entity interface {
	Draw() error
	Update() error
	MoveX(x float32)
	MoveY(y float32)
	SetSpeed(s float32)
}

type CommandHandler struct {
	ctx                context.Context
	timeout            time.Duration
	entity             Entity
	commandChan        chan Command
	drawRequestChan    chan struct{}
	drawResponseChan   chan struct{}
	updateRequestChan  chan struct{}
	updateResponseChan chan struct{}
}

func NewCommandHandler(ctx context.Context, entity Entity) *CommandHandler {
	commandChan := make(chan Command, 10)
	drawRequestChan := make(chan struct{})
	drawResponseChan := make(chan struct{})
	updateRequestChan := make(chan struct{})
	updateResponseChan := make(chan struct{})

	defaultTimeout := time.Second
	return &CommandHandler{
		ctx:                ctx,
		timeout:            defaultTimeout,
		entity:             entity,
		commandChan:        commandChan,
		drawRequestChan:    drawRequestChan,
		drawResponseChan:   drawResponseChan,
		updateRequestChan:  updateRequestChan,
		updateResponseChan: updateResponseChan,
	}
}

func (c *CommandHandler) closeResponses() {
	close(c.drawResponseChan)
	close(c.updateResponseChan)
}

func (c *CommandHandler) CloseRequests() {
	close(c.drawRequestChan)
	close(c.updateRequestChan)
	close(c.commandChan)
}

func (c *CommandHandler) CommandRequest() chan Command {
	return c.commandChan
}

func (c *CommandHandler) DrawRequest() chan struct{} {
	return c.drawRequestChan
}

func (c *CommandHandler) DrawResponse() chan struct{} {
	return c.drawResponseChan
}

func (c *CommandHandler) UpdateRequest() chan struct{} {
	return c.updateRequestChan
}

func (c *CommandHandler) UpdateResponse() chan struct{} {
	return c.updateResponseChan
}

func (c *CommandHandler) Run() {
	defer c.closeResponses()

	wg := sync.WaitGroup{}

	running := true
	for running {
		select {
		case <-c.drawRequestChan:
			wg.Add(1)
			go func() {
				defer wg.Done()
				c.DrawWithTimeout()
				c.drawResponseChan <- struct{}{}
			}()
		case <-c.updateRequestChan:
			wg.Add(1)
			go func() {
				defer wg.Done()
				c.UpdateWithTimeout()
				c.updateResponseChan <- struct{}{}
			}()
		case cmd := <-c.commandChan:
			wg.Add(1)
			go func(cmd Command) {
				defer wg.Done()
				c.HandleWithTimeout(cmd)
			}(cmd)
		case <-c.ctx.Done():
			// Graceful shutdown
			running = false
		}
	}

	wg.Wait()

	// Finish up anything in the queues
	for cmd := range c.commandChan {
		c.HandleWithTimeout(cmd)
	}
	for range c.drawRequestChan {
		c.UpdateWithTimeout()
	}
	for range c.drawRequestChan {
		c.DrawWithTimeout()
	}
}

func (c *CommandHandler) HandleWithTimeout(cmd Command) {
	err := channels.RunWithTimeout(c.timeout, func() error {
		return c.Handle(cmd)
	})
	if err != nil {
		log.Printf("handle with timeout error: %v\n", err)
	}
}

func (c *CommandHandler) Handle(cmd Command) error {
	switch cmd.key {
	case MOVE_X:
		c.entity.MoveX(cmd.value)
	case MOVE_Y:
		c.entity.MoveY(cmd.value)
	case SET_SPEED:
		c.entity.SetSpeed(cmd.value)
	default:
		log.Printf("unknown entity command: %v", cmd.key)
	}

	return nil
}

func (c *CommandHandler) DrawWithTimeout() {
	err := channels.RunWithTimeout(c.timeout, func() error {
		return c.entity.Draw()
	})
	if err != nil {
		log.Printf("draw with timeout error: %v\n", err)
	}
}

func (c *CommandHandler) UpdateWithTimeout() {
	err := channels.RunWithTimeout(c.timeout, func() error {
		return c.entity.Update()
	})
	if err != nil {
		log.Printf("update with timeout error: %v\n", err)
	}
}