package clientapi

import (
	"net/http"

	"github.com/dariuszjaniak/warp/server/internal/httputil"
	"github.com/dariuszjaniak/warp/server/internal/matrix/roomversion"
	"github.com/dariuszjaniak/warp/server/internal/userapi"
)

// DefaultRoomVersion is what this server creates rooms at. The room
// version registry decides which one that is, and why.
const DefaultRoomVersion = string(roomversion.Default)

// availableRoomVersions is the m.room_versions.available map.
//
// Every version Warp implements is marked stable, because every version
// the spec still lists is stable — the "unstable" marking is for versions
// under development, which we do not implement. Versions 1 and 2 are in
// the registry but not supported, and so are left out: a client offered a
// version it cannot be given would get an error on createRoom.
func availableRoomVersions() map[string]string {
	supported := roomversion.Supported()
	out := make(map[string]string, len(supported))
	for _, v := range supported {
		out[string(v)] = "stable"
	}
	return out
}

// roomVersionsCapability is the m.room_versions capability.
type roomVersionsCapability struct {
	Default   string            `json:"default"`
	Available map[string]string `json:"available"`
}

// booleanCapability is the shape of the several capabilities that are only
// an on/off switch.
type booleanCapability struct {
	Enabled bool `json:"enabled"`
}

type capabilitiesResponse struct {
	Capabilities capabilities `json:"capabilities"`
}

type capabilities struct {
	RoomVersions    roomVersionsCapability `json:"m.room_versions"`
	ChangePassword  booleanCapability      `json:"m.change_password"`
	SetDisplayName  booleanCapability      `json:"m.set_displayname"`
	SetAvatarURL    booleanCapability      `json:"m.set_avatar_url"`
	ThreePIDChanges booleanCapability      `json:"m.3pid_changes"`
}

// handleCapabilities implements GET /_matrix/client/v3/capabilities.
//
// The endpoint needs a token: what a server will let you do depends on who
// you are, and the spec makes it authenticated for that reason.
//
// Every flag here is the truth about this build, not an aspiration.
// Password changes and third-party identifiers arrive with the rest of
// account management in Phase 9, so they report false and clients hide the
// buttons rather than offering something that 404s.
func (c *ClientAPI) handleCapabilities(w http.ResponseWriter, _ *http.Request, _ userapi.Authenticated) error {
	httputil.WriteJSON(w, http.StatusOK, capabilitiesResponse{
		Capabilities: capabilities{
			RoomVersions: roomVersionsCapability{
				Default:   DefaultRoomVersion,
				Available: availableRoomVersions(),
			},
			ChangePassword:  booleanCapability{Enabled: false},
			SetDisplayName:  booleanCapability{Enabled: true},
			SetAvatarURL:    booleanCapability{Enabled: true},
			ThreePIDChanges: booleanCapability{Enabled: false},
		},
	})
	return nil
}