package bufpool

import "sync"

var (
	smallBufferSize  = 1 * 1024  // 1KB buffer
	mediumBufferSize = 8 * 1024  // 8KB buffer
	largeBufferSize  = 64 * 1024 // 64KB buffer
)

var (
	pools = []struct {
		size int
		pool sync.Pool
	}{
		{
			size: 128,
			pool: sync.Pool{
				New: func() interface{} {
					return make([]byte, 128)
				},
			},
		},
		{
			size: 512,
			pool: sync.Pool{
				New: func() interface{} {
					return make([]byte, 512)
				},
			},
		},
		{
			size: 1024,
			pool: sync.Pool{
				New: func() interface{} {
					return make([]byte, 1024)
				},
			},
		},
		{
			size: 4096,
			pool: sync.Pool{
				New: func() interface{} {
					return make([]byte, 4096)
				},
			},
		},
		{
			size: 8192,
			pool: sync.Pool{
				New: func() interface{} {
					return make([]byte, 8192)
				},
			},
		},
		{
			size: 16 * 1024,
			pool: sync.Pool{
				New: func() interface{} {
					return make([]byte, 16*1024)
				},
			},
		},
		{
			size: 32 * 1024,
			pool: sync.Pool{
				New: func() interface{} {
					return make([]byte, 32*1024)
				},
			},
		},
		{
			size: 64 * 1024,
			pool: sync.Pool{
				New: func() interface{} {
					return make([]byte, 64*1024)
				},
			},
		},
	}
)

// Get returns a buffer size range from (0, 64]KB,
// panic if size > 64KB.
func Get(size int) []byte {
	for i := range pools {
		if size <= pools[i].size {
			return pools[i].pool.Get().([]byte)
		}
	}
	panic("size too large (max=64KB)")
}

func Put(b []byte) {
	for i := range pools {
		if len(b) == pools[i].size {
			pools[i].pool.Put(b)
		}
	}
}