Collaboration on charts, for people and agents, in Issho's rooms: a chart's spec is a shared state of the room (Issho.State), that everyone changes with the same functions, and that is a valid chart after every change.

Fude draws charts on its own; this module is only for a chart that others change too: a report two people build at once, a chart an agent makes beside you. It is compiled when Issho is in your deps.

The document

A shared chart is a document of a room. Define it in your policy, from the chart your app keeps, and save it in :on_change:

def document(_who, "report:" <> id = doc) do
  report = Reports.get!(id)
  Fude.Issho.document(report.chart, on_change: &Reports.save_chart(report, &1, &2))
end

Fude.Issho.document/2 gives Issho the chart's spec, with an id for each layer and annotation (so that two changes to two layers at once both stay), and a hook that refuses a change that would make the chart invalid: the person or the agent who made it gets every error, with where it is. :on_change gets the chart after each change and who made it, and answers :ok or {:error, reason} to refuse it.

In a LiveView

def mount(%{"id" => id}, _session, socket) do
  room = "report:" <> id
  report = Reports.get!(id)

  if connected?(socket),
    do: {:ok, _} = Issho.Live.join(MyApp.Issho, socket.assigns.current_user, room)

  {:ok, Fude.Issho.assign(socket, :chart, room, room, report.chart)}
end

def handle_event("title", %{"title" => title}, socket) do
  :ok = Fude.Issho.change(socket, :chart, &Fude.title(&1, title))
  {:noreply, socket}
end

<.chart id="revenue" spec={@chart} data={@sales} issho="report:7" />

@chart is the chart's spec, and changes as anyone changes it. change/3 takes a function of the chart, made with Fude's own functions (Fude.title/3, Fude.annotate/3, Fude.layers/3), and sends only what it changed. The issho attribute of <.chart> is the chart's document: the people in the room see each other's pointers on its marks, at the same data on every screen (Fude.Issho.Place).

Agents

An agent uses the same chart: tools/0 gives read_chart, which says what a chart shows (its spec, and the table of its data when your app gives it), and change_chart, which takes the spec as the agent wants it and sends what changed. Issho's point tool points at a mark, in Fude.Issho.Place's terms, and its update_state changes a spec by paths too. Every change passes the same hook as a person's.

The data of a chart is your app's, read as the agent:

config :fude, Fude.Issho, data: {MyApp.Reports, :chart_data}

def chart_data("report:" <> id, ctx), do: {:ok, Reports.sales(id, ctx.opts[:on_behalf_of])}