/*
 * Copyright 2021 CloudWeGo Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package utils

import (
	"errors"
	"runtime"
)

// ErrRingFull means the ring is full.
var ErrRingFull = errors.New("ring is full")

// Deprecated: it's not used by kitex anymore.
// NewRing creates a ringbuffer with fixed size.
func NewRing(size int) *Ring {
	if size <= 0 {
		panic("new ring with size <=0")
	}
	r := &Ring{}

	// check len(rings):
	// 1. len = P/4
	// 2. len <= size
	numP := runtime.GOMAXPROCS(0)
	r.length = (numP + 3) / 4
	if r.length > size {
		r.length = size
	}

	// make rings
	per := size / r.length
	r.rings = make([]*ring, r.length)
	for i := 0; i < r.length-1; i++ {
		r.rings[i] = newRing(per)
	}
	r.rings[r.length-1] = newRing(size - per*(r.length-1))
	return r
}

// Deprecated: it's not used by kitex anymore.
// Ring implements a fixed size hash list to manage data
type Ring struct {
	length int
	rings  []*ring
}

// Push appends item to the ring.
func (r *Ring) Push(obj interface{}) error {
	if r.length == 1 {
		return r.rings[0].Push(obj)
	}

	idx := getGoroutineID() % r.length
	for i := 0; i < r.length; i, idx = i+1, (idx+1)%r.length {
		err := r.rings[idx].Push(obj)
		if err == nil {
			return nil
		}
	}
	return ErrRingFull
}

// Pop returns the last item and removes it from the ring.
func (r *Ring) Pop() interface{} {
	if r.length == 1 {
		return r.rings[0].Pop()
	}

	idx := getGoroutineID() % r.length
	for i := 0; i < r.length; i, idx = i+1, (idx+1)%r.length {
		obj := r.rings[idx].Pop()
		if obj != nil {
			return obj
		}
	}
	return nil
}

// Dump dumps the data in the ring.
func (r *Ring) Dump() interface{} {
	m := &ringDump{}
	dumpList := make([]*ringDump, 0, r.length)
	idx := getGoroutineID() % r.length
	for i := 0; i < r.length; i, idx = i+1, (idx+1)%r.length {
		curDump := &ringDump{}
		r.rings[idx].Dump(curDump)
		dumpList = append(dumpList, curDump)
		m.Cap += curDump.Cap
		m.Len += curDump.Len
	}
	m.Array = make([]interface{}, 0, m.Len)
	for _, shardData := range dumpList {
		for i := 0; i < shardData.Len; i++ {
			m.Array = append(m.Array, shardData.Array[i])
		}
	}
	return m
}
