package api

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

const upstreamDownAfter = 10 * time.Second

// HandleStatus returns the current stream status as JSON.
// GET /api/status
func (a *App) HandleStatus(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}

	a.mu.RLock()
	status := a.Status
	a.mu.RUnlock()

	// Detect upstream health from the hub. Once the hub receives data, the
	// channel is considered live; if no data arrives within the threshold
	// after a switch, flag upstream_down so all watchers see the warning.
	gotData, since := a.Hub.GotData()
	if status.Transitioning && gotData {
		a.mu.Lock()
		a.Status.Transitioning = false
		a.Status.UpstreamDown = false
		a.mu.Unlock()
		status.Transitioning = false
		status.UpstreamDown = false
	} else if status.Transitioning && !gotData && since >= upstreamDownAfter {
		a.mu.Lock()
		a.Status.UpstreamDown = true
		a.mu.Unlock()
		status.UpstreamDown = true
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(status)
}