// Pure /goal command parsing. No I/O, no pi imports.
//
// Verbs (Q1, locked with Jason 2026-08-28):
//   bare        -> status
//   stop        -> pause the loop, goal retained
//   clear       -> remove the goal entirely
//   resume      -> continue a paused goal
//   <text>      -> set (or replace) the active goal
//   --max N / --max=N   run-limit option on set (Q4); remainder is the goal text
//
// Only the exact words stop/clear/resume are verbs; anything else is goal text.

export type GoalCommand =
  | { kind: "status" }
  | { kind: "stop" }
  | { kind: "clear" }
  | { kind: "resume" }
  | { kind: "set"; text: string; max?: number; waitTimeoutSeconds?: number }
  | { kind: "error"; message: string };

export function parseGoalCommand(raw: string): GoalCommand {
  const input = (raw ?? "").trim();
  if (input === "") return { kind: "status" };

  const lower = input.toLowerCase();
  if (lower === "stop") return { kind: "stop" };
  if (lower === "clear") return { kind: "clear" };
  if (lower === "resume") return { kind: "resume" };

  let max: number | undefined;
  let text = input;

  let waitTimeoutSeconds: number | undefined;
  const waitOption = text.match(/(?:^|\s)--wait-timeout(?:=|\s+)([^\s]+)(?=\s|$)/);
  if (waitOption) {
    const n = Number(waitOption[1]);
    if (!Number.isInteger(n) || n < 10 || n > 86400 || String(n) !== waitOption[1]) {
      return { kind: "error", message: "--wait-timeout must be an integer from 10 to 86400 seconds" };
    }
    waitTimeoutSeconds = n;
    text = text.replace(waitOption[0], " ").trim();
  }
  if (/(?:^|\s)--wait-timeout(?:=|\s|$)/.test(text)) {
    return { kind: "error", message: "--wait-timeout requires one value from 10 to 86400 seconds" };
  }

  const inline = text.match(/(?:^|\s)--max=([^\s]+)(?:\s|$)/);
  if (inline) {
    const parsed = parseMax(inline[1]);
    if (typeof parsed === "string") return { kind: "error", message: parsed };
    max = parsed;
    text = text.replace(inline[0], " ").trim();
  } else {
    const spaced = text.match(/(?:^|\s)--max\s+([^\s]+)(?:\s|$)/);
    if (spaced) {
      const parsed = parseMax(spaced[1]);
      if (typeof parsed === "string") return { kind: "error", message: parsed };
      max = parsed;
      text = text.replace(spaced[0], " ").trim();
    } else if (/(?:^|\s)--max(?:\s|$)/.test(text)) {
      return { kind: "error", message: '--max requires a positive integer (e.g. "--max 40")' };
    }
  }

  text = text.trim();
  if (text === "") {
    return { kind: "error", message: "goal text required (verbs: stop, clear, resume)" };
  }
  return { kind: "set", text, max, ...(waitTimeoutSeconds === undefined ? {} : { waitTimeoutSeconds }) };
}

function parseMax(raw: string): number | string {
  const n = Number.parseInt(raw, 10);
  if (!Number.isInteger(n) || n < 1 || String(n) !== raw) {
    return `--max must be a positive integer, got "${raw}"`;
  }
  return n;
}