/**
 * @file promptTokens — splits a prompt into plain text, `/command` and
 * `@path` tokens, so the prompt box and a sent message colour them the same
 * way. A token starts a word (the line start or after whitespace), like the
 * prompt box's autocomplete, so `a/b`, `me@x.io` and `/home/x` stay text.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

export type PromptToken = { kind: "text" | "slash" | "mention"; text: string };

/** A token's colours, shared by the prompt box and a sent message; `@path`
 *  takes the chat's path-link violet. */
export const TOKEN_TONE = {
  slash: "bg-accent/15 text-accent",
  mention: "bg-violet-500/15 text-violet-700 dark:text-violet-300",
} as const;

// `/name` (plugin skills are `plugin:name`) ending the word; `@path` minus a
// trailing full stop or comma, which is prose.
const TOKEN_RE = /(?<=^|\s)(?:\/[\w:.-]+(?=\s|$)|@[^\s]*[^\s.,;:!?)])/g;

export function promptTokens(text: string): PromptToken[] {
  const out: PromptToken[] = [];
  let at = 0;
  for (const m of text.matchAll(TOKEN_RE)) {
    if (m.index > at) out.push({ kind: "text", text: text.slice(at, m.index) });
    out.push({ kind: m[0][0] === "/" ? "slash" : "mention", text: m[0] });
    at = m.index + m[0].length;
  }
  if (at < text.length) out.push({ kind: "text", text: text.slice(at) });
  return out;
}