package pipeline

import (
	"git.noahlan.cn/noahlan/nnet/entity"
	"sync"
)

type (
	Func func(entity entity.NetworkEntity, v interface{}) error

	// Pipeline 消息管道
	Pipeline interface {
		Outbound() Channel
		Inbound() Channel
	}

	pipeline struct {
		outbound, inbound *pipelineChannel
	}

	Channel interface {
		PushFront(h Func)
		PushBack(h Func)
		Process(entity entity.NetworkEntity, v interface{}) error
	}

	pipelineChannel struct {
		mu       sync.RWMutex
		handlers []Func
	}
)

func New() Pipeline {
	return &pipeline{
		outbound: &pipelineChannel{},
		inbound:  &pipelineChannel{},
	}
}

func (p *pipeline) Outbound() Channel {
	return p.outbound
}

func (p *pipeline) Inbound() Channel {
	return p.inbound
}

// PushFront 将func压入slice首位
func (p *pipelineChannel) PushFront(h Func) {
	p.mu.Lock()
	defer p.mu.Unlock()

	handlers := make([]Func, len(p.handlers)+1)
	handlers[0] = h
	copy(handlers[1:], p.handlers)

	p.handlers = handlers
}

// PushBack 将func压入slice末位
func (p *pipelineChannel) PushBack(h Func) {
	p.mu.Lock()
	defer p.mu.Unlock()

	p.handlers = append(p.handlers, h)
}

// Process 处理所有的pipeline方法
func (p *pipelineChannel) Process(entity entity.NetworkEntity, v interface{}) error {
	if len(p.handlers) < 1 {
		return nil
	}

	p.mu.RLock()
	defer p.mu.RUnlock()

	for _, handler := range p.handlers {
		err := handler(entity, v)
		if err != nil {
			return err
		}
	}
	return nil
}