package httpapi

import (
	"encoding/json"
	"net/http"
	"strconv"
)

type previewChannel struct {
	Name   string `json:"name"`
	HlsURL string `json:"hls_url,omitempty"`
}

// handlePreviewChannels returns available video preview channels.
// GET /v1/preview/channels
func (s *Server) handlePreviewChannels(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		errorJSON(w, http.StatusMethodNotAllowed, "method not allowed")
		return
	}
	if !s.authorize(r, false) {
		errorJSON(w, http.StatusUnauthorized, "unauthorized")
		return
	}

	channels := s.discoverChannels(r)
	if channels == nil {
		channels = make([]previewChannel, 0)
	}
	writeJSON(w, http.StatusOK, map[string]any{"channels": channels})
}

func (s *Server) discoverChannels(r *http.Request) []previewChannel {
	if s.ms == nil {
		return nil
	}
	_, body, err := s.ms.GetGraphs(r.Context())
	if err != nil {
		return nil
	}

	var graphs []struct {
		Name string `json:"name"`
	}
	if err := json.Unmarshal(body, &graphs); err != nil {
		return nil
	}

	baseURL := "http://" + s.hostname + ":" + strconv.Itoa(s.mediaPort)
	var channels []previewChannel
	for _, g := range graphs {
		channels = append(channels, previewChannel{
			Name:   g.Name,
			HlsURL: baseURL + "/hls/" + g.Name + "/index.m3u8",
		})
	}
	return channels
}