package subsonic

import "sort"

func init() {
	register("getOpenSubsonicExtensions", handleGetOpenSubsonicExtensions)
}

// extensionRegistry lists every OpenSubsonic extension VibeSonic
// actually implements and has tests for. Advertising an extension here
// is a promise the corresponding endpoint(s) really work — never add an
// entry just because a route exists. Each feature file registers its
// own entry via registerExtension() in its init().
var extensionRegistry = map[string][]int{}

func registerExtension(name string, versions ...int) {
	if _, exists := extensionRegistry[name]; exists {
		panic("subsonic: duplicate extension registration for " + name)
	}
	extensionRegistry[name] = versions
}

func supportedExtensions() []OpenSubsonicExtension {
	names := make([]string, 0, len(extensionRegistry))
	for n := range extensionRegistry {
		names = append(names, n)
	}
	sort.Strings(names)
	out := make([]OpenSubsonicExtension, 0, len(names))
	for _, n := range names {
		out = append(out, OpenSubsonicExtension{Name: n, Versions: extensionRegistry[n]})
	}
	return out
}

// hasExtension reports whether ext (any version) is advertised — used
// where a feature is fully optional and we want to fail closed if it
// were ever unregistered.
func hasExtension(name string) bool {
	_, ok := extensionRegistry[name]
	return ok
}

func handleGetOpenSubsonicExtensions(rc *Context) *apiError {
	rc.Response = newResponse()
	rc.Response.OpenSubsonicExtensions = supportedExtensions()
	return nil
}