package resp

import (
	"bufio"
	"encoding/json"
	"fmt"
	"time"

	"github.com/gofiber/fiber/v3"
)

type SSEManager struct {
	c     fiber.Ctx
	event string
	ch    chan string
	id    int64
}

func (m *SSEManager) Send(msg string) {
	m.ch <- msg
}

func (m *SSEManager) JSON(data any) {
	bs, err := json.Marshal(data)
	if err != nil {
		m.ch <- err.Error()
		return
	}

	m.ch <- string(bs)
}

func (m *SSEManager) Writer() func(w *bufio.Writer) {
	return func(w *bufio.Writer) {
		for msg := range m.ch {
			fmt.Fprintf(w, "event: %s\nid: %d\ntimestamp: %d\ndata: %s\n\n", m.event, m.id, time.Now().UnixMilli(), msg)
			w.Flush()
			m.id++
		}
		w.Flush()
	}
}

func (m *SSEManager) Close() {
	close(m.ch)
}

// SSE create a new SSEManager
// example:
//
//	func someHandler(c fiber.Ctx) error {
//		m := resp.SSE(c, "test")
//		go func() {
//			defer m.Close()
//			for i := range 10 {
//				m.Send("test" + strconv.Itoa(i))
//				time.Sleep(1 * time.Second)
//			}
//		}()
//
//		return c.SendStreamWriter(m.Writer())
//	}
func SSE(c fiber.Ctx, event string) *SSEManager {
	c.Set("Content-Type", "text/event-stream")
	c.Set("Cache-Control", "no-cache")
	c.Set("Connection", "keep-alive")
	c.Set("Transfer-Encoding", "chunked")

	return &SSEManager{
		c:     c,
		event: event,
		id:    0,
		ch:    make(chan string, 1),
	}
}