package clientapi

import (
	"net/http"

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

// syncResponse is the subset of the /sync body this build can fill in.
type syncResponse struct {
	NextBatch   string          `json:"next_batch"`
	Rooms       syncRooms       `json:"rooms"`
	Presence    syncEventList   `json:"presence"`
	AccountData syncEventList   `json:"account_data"`
	ToDevice    syncEventList   `json:"to_device"`
	DeviceLists syncDeviceLists `json:"device_lists"`
}

type syncRooms struct {
	Join   map[string]any `json:"join"`
	Invite map[string]any `json:"invite"`
	Leave  map[string]any `json:"leave"`
	Knock  map[string]any `json:"knock"`
}

type syncEventList struct {
	Events []any `json:"events"`
}

type syncDeviceLists struct {
	Changed []string `json:"changed"`
	Left    []string `json:"left"`
}

// syncPlaceholderToken is the only stream position this build has.
//
// It is a real token shape rather than an empty string so that a client
// storing it and sending it back as ?since= gets the same answer.
const syncPlaceholderToken = "s0_0"

// handleSync implements GET /_matrix/client/v3/sync as far as this build
// can.
//
// It is a placeholder, and since Phase 3 it is an incomplete answer rather
// than a complete one: there are rooms now, and this reports none of them.
// Filling it in means the event stream — stream tokens, incremental deltas,
// long polling, filters and lazy-loaded members — which is the syncapi of
// PLAN.md phase 4, and which replaces this wholesale.
//
// It stays because of what it does buy: a valid token syncs and a revoked
// one does not, which is the first thing every client and the test suite
// check, and which cannot be observed at all without an endpoint here. A
// client can meanwhile see its rooms through /joined_rooms and read them
// through /rooms/{roomID}/state. See docs/rooms.md.
func (c *ClientAPI) handleSync(w http.ResponseWriter, _ *http.Request, _ userapi.Authenticated) error {
	// The `timeout` parameter is ignored rather than honoured: blocking for
	// 30 seconds to return a response this build cannot change would hold a
	// connection open for nothing.
	httputil.WriteJSON(w, http.StatusOK, syncResponse{
		NextBatch: syncPlaceholderToken,
		Rooms: syncRooms{
			Join:   map[string]any{},
			Invite: map[string]any{},
			Leave:  map[string]any{},
			Knock:  map[string]any{},
		},
		Presence:    syncEventList{Events: []any{}},
		AccountData: syncEventList{Events: []any{}},
		ToDevice:    syncEventList{Events: []any{}},
		DeviceLists: syncDeviceLists{Changed: []string{}, Left: []string{}},
	})
	return nil
}