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 that is meaningful before
// there are any rooms.
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 Phase 1 can be at.
//
// 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, which is
// the correct one: nothing has happened.
const syncPlaceholderToken = "s0_0"

// handleSync implements GET /_matrix/client/v3/sync as far as Phase 1 can.
//
// This is a placeholder, and deliberately a working one. There are no rooms
// until Phase 3 and no event streams until Phase 4, so an empty sync is not
// a lie — it is the complete state of this server. What it buys in the
// meantime is the thing every client and the test suite check first: that a
// valid token syncs and a revoked one does not. Without it, "logging out
// invalidates the session" cannot be observed at all.
//
// Phase 4 replaces this wholesale with the syncapi: stream tokens, long
// polling, filters and lazy-loaded members.
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 that 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
}