// Copyright 2017 gf Author(https://github.com/gogf/gf). All Rights Reserved.
//
// This Source Code Form is subject to the terms of the MIT License.
// If a copy of the MIT was not distributed with this file,
// You can obtain one at https://github.com/gogf/gf.

// Package gchan provides graceful channel for no panic operations.
//
// It's safe to call Chan.Push/Close functions repeatedly.
package gchan

import (
	"errors"

	"github.com/gogf/gf/container/gtype"
)

// Graceful channel.
type Chan struct {
	channel chan interface{}
	closed  *gtype.Bool
}

// New creates a graceful channel with given <limit>.
func New(limit int) *Chan {
	return &Chan{
		channel: make(chan interface{}, limit),
		closed:  gtype.NewBool(),
	}
}

// Push pushes <value> to channel.
// It is safe to be called repeatedly.
func (c *Chan) Push(value interface{}) error {
	if c.closed.Val() {
		return errors.New("channel is closed")
	}
	c.channel <- value
	return nil
}

// Pop pops value from channel.
// If there's no value in channel, it would block to wait.
// If the channel is closed, it will return a nil value immediately.
func (c *Chan) Pop() interface{} {
	return <-c.channel
}

// Close closes the channel.
// It is safe to be called repeatedly.
func (c *Chan) Close() {
	if !c.closed.Set(true) {
		close(c.channel)
	}
}

// See Len.
func (c *Chan) Size() int {
	return c.Len()
}

// Len returns the length of the channel.
func (c *Chan) Len() int {
	return len(c.channel)
}

// Cap returns the capacity of the channel.
func (c *Chan) Cap() int {
	return cap(c.channel)
}