package ringbuffer

import (
	"sync"
)

type RingBuffer struct {
	buffer []string
	size   int
	head   int
	tail   int
	mu     sync.Mutex
}

func NewRingBuffer(size int) *RingBuffer {
	return &RingBuffer{
		buffer: make([]string, size),
		size:   size,
		head:   -1,
		tail:   -1,
	}
}

func (rb *RingBuffer) Add(item string) {
	rb.mu.Lock()
	defer rb.mu.Unlock()

	if (rb.tail+1)%rb.size == rb.head {
		rb.head = (rb.head + 1) % rb.size
	}

	rb.tail = (rb.tail + 1) % rb.size
	rb.buffer[rb.tail] = item

	if rb.head == -1 {
		rb.head = rb.tail
	}
}

func (rb *RingBuffer) GetLast() (string, int) {
	rb.mu.Lock()
	defer rb.mu.Unlock()

	if rb.head == -1 {
		return "", -1
	}

	return rb.buffer[rb.tail], rb.tail
}

func (rb *RingBuffer) WaitForNewItem() string {
	rb.mu.Lock()
	defer rb.mu.Unlock()

	if rb.tail == -1 {
		return ""
	}

	return rb.buffer[rb.tail]
}

func (rb *RingBuffer) IsEmpty() bool {
	rb.mu.Lock()
	defer rb.mu.Unlock()

	return rb.head == -1
}

func (rb *RingBuffer) GetLastPosition() int {
	rb.mu.Lock()
	defer rb.mu.Unlock()

	return rb.tail
}

func (rb *RingBuffer) ContainsItem(item string) bool {
	rb.mu.Lock()
	defer rb.mu.Unlock()

	if rb.head == -1 {
		return false
	}

	for i := 0; i < rb.size; i++ {
		index := (rb.head + i) % rb.size
		if rb.buffer[index] == item {
			return true
		}
	}

	return false
}