pike/glyph Public Public: anyone can read this; nobody can change it.

/**

 * Everything the app can do, as plain functions: `(db, who, input)` in,

 * data or a named failure out. The page, the JSON API, the MCP server and

 * the terminal are doors onto these and decide nothing themselves — so a

 * rule written here holds at every door, and a new door is only a new

 * way to call.

 */

import type { Database } from "bun:sqlite";

import { record, type AuditRow } from "./audit.ts";

import { permit } from "./contract.ts";

import { emit } from "./live.ts";

import { kick } from "./draw.ts";

import { isKind, KINDS, PROMPT_MAX, type Kind } from "./glyph.ts";

import type { Who } from "./who.ts";

export interface Drawing {

  readonly id: number;

  readonly prompt: string;

  readonly kind: Kind;

  readonly status: "drawing" | "done" | "failed";

  /** The SVGs, as a JSON array of strings: `svgsOf` reads it. */

  readonly svgs: string;

  readonly error: string | null;

  readonly author_id: string;

  readonly author_name: string;

  readonly created_at: string;

  readonly updated_at: string;

}

export type Failure =

  | "signin_required"

  | "forbidden"

  | "not_found"

  | "invalid"

  | "busy";

export type Result<T> =

  | { ok: true; value: T }

  | { ok: false; error: Failure; message: string };

const ok = <T>(value: T): Result<T> => ({ ok: true, value });

const fail = <T>(error: Failure, message: string): Result<T> => ({

  ok: false,

  error,

  message,

});

/** The refusal for a "no": who is not signed in is asked to; who is, is told. */

const refuse = <T>(who: Who, signIn: string, no: string): Result<T> =>

  who.role === "anon" ? fail("signin_required", signIn) : fail("forbidden", no);

/**

 * A change, written into the audit trail whichever way it went: the row it

 * made or touched, or the one it was refused. Every action that changes

 * something returns through here, so the trail holds at every door.

 */

const audited = <T extends { readonly id: number }>(

  db: Database,

  who: Who,

  resource: string,

  verb: "create" | "update" | "delete",

  target: number | undefined,

  result: Result<T>,

): Result<T> => {

  record(db, {

    who,

    resource,

    verb,

    target: result.ok ? result.value.id : target,

    outcome: result.ok ? "ok" : result.error,

  });

  return result;

};

/** The SVGs a drawing holds. */

export const svgsOf = (drawing: Drawing): string[] => {

  try {

    const parsed: unknown = JSON.parse(drawing.svgs);

    return Array.isArray(parsed) ? parsed.filter((s) => typeof s === "string") : [];

  } catch {

    return [];

  }

};

/** At most this many drawings are with Claude at once, across everyone. */

export const AT_ONCE = 3;

export function listDrawings(

  db: Database,

  who: Who,

  input: { limit?: number } = {},

): Result<Drawing[]> {

  const limit = Math.min(Math.max(Math.trunc(input.limit ?? 50) || 50, 1), 200);

  // "yes" is every drawing (an admin). For anyone else the table answers with

  // the columns that make a drawing theirs, and the list is theirs alone.

  const may = permit(who, "drawing", "list");

  if (may === "no")

    return refuse(who, "Sign in to see your drawings.", "You may not see these drawings.");

  if (may === "yes")

    return ok(

      db

        .query<Drawing, [number]>("SELECT * FROM drawing ORDER BY id DESC LIMIT ?1")

        .all(limit),

    );

  const mine = may.where.map((column) => `${column} = ?2`).join(" OR ");

  return ok(

    db

      .query<Drawing, [number, string]>(

        `SELECT * FROM drawing WHERE ${mine} ORDER BY id DESC LIMIT ?1`,

      )

      .all(limit, who.role === "anon" ? "" : who.id),

  );

}

/**

 * Ask for a drawing. The row is made at once, `drawing`; Claude fills it in

 * after the response (`src/draw.ts`) and the page hears `drawing.changed`.

 */

export const startDrawing = (

  db: Database,

  who: Who,

  input: { prompt: string; kind?: string },

): Result<Drawing> =>

  audited(db, who, "drawing", "create", undefined, start(db, who, input));

function start(

  db: Database,

  who: Who,

  input: { prompt: string; kind?: string },

): Result<Drawing> {

  if (who.role === "anon" || permit(who, "drawing", "create") !== "yes")

    return refuse(who, "Sign in to draw.", "You may not draw here.");

  const prompt = input.prompt.trim().replace(/\s+/g, " ");

  if (prompt.length === 0 || prompt.length > PROMPT_MAX)

    return fail("invalid", `Describe it in 1 to ${PROMPT_MAX} characters.`);

  const kind = input.kind === undefined || input.kind === "" ? "mark" : input.kind;

  if (!isKind(kind))

    return fail("invalid", `A kind is one of: ${Object.keys(KINDS).join(", ")}.`);

  const busy = db

    .query<{ mine: number; everyone: number }, [string]>(

      "SELECT count(*) FILTER (WHERE author_id = ?1) AS mine, count(*) AS everyone FROM drawing WHERE status = 'drawing'",

    )

    .get(who.id)!;

  if (busy.mine > 0)

    return fail("busy", "Your last drawing is still on the board. One at a time.");

  if (busy.everyone >= AT_ONCE)

    return fail("busy", "Claude is drawing for others right now. Try again in a minute.");

  const drawing = db

    .query<Drawing, [string, string, string, string]>(

      "INSERT INTO drawing (prompt, kind, author_id, author_name) VALUES (?1, ?2, ?3, ?4) RETURNING *",

    )

    .get(prompt, kind, who.id, who.name)!;

  emit("drawing.added", drawing);

  kick(db, drawing.id, prompt, kind);

  return ok(drawing);

}

/**

 * One drawing, for `who` to do `verb` to. The door is asked before the row is

 * looked for, so whoever may not is told that and never learns whether the

 * row exists; whoever may, and asked for nothing, hears `not_found`.

 */

function drawingFor(

  db: Database,

  who: Who,

  verb: "read" | "delete",

  id: number,

  said: { signIn: string; no: string },

): Result<Drawing> {

  const drawing = Number.isInteger(id)

    ? db.query<Drawing, [number]>("SELECT * FROM drawing WHERE id = ?1").get(id)

    : null;

  const row: Readonly<Record<string, unknown>> =

    drawing === null ? { author_id: who.role === "anon" ? null : who.id } : { ...drawing };

  if (permit(who, "drawing", verb, row) !== "yes") return refuse(who, said.signIn, said.no);

  if (drawing !== null) return ok(drawing);

  if (!Number.isInteger(id)) return fail("invalid", "A drawing id is a whole number.");

  return fail("not_found", "No such drawing.");

}

export function getDrawing(db: Database, who: Who, input: { id: number }): Result<Drawing> {

  return drawingFor(db, who, "read", input.id, {

    signIn: "Sign in to see this drawing.",

    no: "Only whoever asked for a drawing can see it.",

  });

}

export const deleteDrawing = (

  db: Database,

  who: Who,

  input: { id: number },

): Result<{ id: number }> =>

  audited(db, who, "drawing", "delete", input.id, remove(db, who, input));

function remove(db: Database, who: Who, input: { id: number }): Result<{ id: number }> {

  const found = drawingFor(db, who, "delete", input.id, {

    signIn: "Sign in to remove a drawing.",

    no: "Only whoever asked for a drawing, or an admin, can remove it.",

  });

  if (!found.ok) return found;

  db.query("DELETE FROM drawing WHERE id = ?1").run(found.value.id);

  emit("drawing.removed", { id: found.value.id });

  return ok({ id: found.value.id });

}

/** Whether `who` may remove `drawing`: the table's answer, for the page and the terminal to draw from. */

export const canDelete = (who: Who, drawing: Drawing): boolean =>

  permit(who, "drawing", "delete", { ...drawing }) === "yes";

/**

 * The audit trail, newest first, for whoever the table lets read it (an

 * admin, as the scaffold has it). `before` pages back by id. Audit rows name

 * no author, so a cell that gave `list` to a row's role would find nothing

 * of its own: anything but "yes" is a refusal here.

 */

export function listAudit(

  db: Database,

  who: Who,

  input: { limit?: number; before?: number } = {},

): Result<AuditRow[]> {

  if (permit(who, "audit", "list") !== "yes")

    return refuse(

      who,

      "Sign in to read the audit trail.",

      "Only an admin can read the audit trail.",

    );

  const limit = Math.min(

    Math.max(Math.trunc(input.limit ?? 100) || 100, 1),

    500,

  );

  const before = Number.isInteger(input.before)

    ? input.before!

    : Number.MAX_SAFE_INTEGER;

  return ok(

    db

      .query<

        AuditRow,

        [number, number]

      >("SELECT * FROM audit WHERE id < ?1 ORDER BY id DESC LIMIT ?2")

      .all(before, limit),

  );

}

export function getAudit(

  db: Database,

  who: Who,

  input: { id: number },

): Result<AuditRow> {

  const row = Number.isInteger(input.id)

    ? db

        .query<AuditRow, [number]>("SELECT * FROM audit WHERE id = ?1")

        .get(input.id)

    : null;

  if (permit(who, "audit", "read", { ...row }) !== "yes")

    return refuse(

      who,

      "Sign in to read the audit trail.",

      "Only an admin can read the audit trail.",

    );

  if (row !== null) return ok(row);

  if (!Number.isInteger(input.id))

    return fail("invalid", "An audit id is a whole number.");

  return fail("not_found", "No such audit row.");

}