package webapp

import "net/http"

// handleApps lists the inventory rows the most recent refresh loop
// persisted. Each row links to the detail view at /apps/:id, which
// Phase 1 implements as a single-process summary (comm, cmdline,
// cwd, ports, uptime).
func (s *Server) handleApps(w http.ResponseWriter, r *http.Request) {
	writeNoStore(w)
	sess, _ := sessionFromContext(r.Context())
	apps := s.inventory.Snapshot()
	data := appsPageData{
		basePageData: s.newBasePage(r, "Discovered apps", sess),
		Apps:         apps,
	}
	if err := s.templates.Execute(w, "apps.html", data); err != nil {
		s.deps.Logger.Printf("render apps: %v", err)
		http.Error(w, "template error", http.StatusInternalServerError)
	}
}

// handleAppDetail renders the detail page for a single inventory
// row. Phase 1 has no grouping, so :id is the row index in the
// snapshot (matching the table id column).
func (s *Server) handleAppDetail(w http.ResponseWriter, r *http.Request) {
	writeNoStore(w)
	sess, _ := sessionFromContext(r.Context())
	id := r.PathValue("id")
	apps := s.inventory.Snapshot()
	var found *DiscoveredApp
	for i := range apps {
		if idMatch(&apps[i], id, i) {
			found = &apps[i]
			break
		}
	}
	if found == nil {
		http.NotFound(w, r)
		return
	}
	data := appDetailPageData{
		basePageData: s.newBasePage(r, "App: "+found.Name, sess),
		App:          *found,
	}
	if err := s.templates.Execute(w, "app_detail.html", data); err != nil {
		s.deps.Logger.Printf("render app detail: %v", err)
		http.Error(w, "template error", http.StatusInternalServerError)
	}
}

// idMatch matches either by pid (when id is a positive integer) or
// by name (otherwise). Keeps URLs short and avoids leaking pids to
// browser history.
func idMatch(a *DiscoveredApp, id string, idx int) bool {
	if a.Name == id {
		return true
	}
	if id == pidOrIndex(a, idx) {
		return true
	}
	return false
}

func pidOrIndex(a *DiscoveredApp, idx int) string {
	if a.PID > 0 {
		return itoa(a.PID)
	}
	return itoa(idx)
}

func itoa(n int) string {
	const digits = "0123456789"
	if n == 0 {
		return "0"
	}
	neg := n < 0
	if neg {
		n = -n
	}
	var buf [20]byte
	i := len(buf)
	for n > 0 {
		i--
		buf[i] = digits[n%10]
		n /= 10
	}
	if neg {
		i--
		buf[i] = '-'
	}
	return string(buf[i:])
}

type appsPageData struct {
	basePageData
	Apps []DiscoveredApp
}

type appDetailPageData struct {
	basePageData
	App DiscoveredApp
}