import type { Dirent } from "node:fs";
import { readdir } from "node:fs/promises";
import { join } from "node:path";

import type { StartStep, WorkflowMessage } from "@uncaged/nerve-core";

import type { ExplorerMeta } from "../roles/explorer.js";
import type { QuestionerMeta } from "../roles/questioner.js";

async function walkMarkdownFiles(rootDir: string, base: string): Promise<string[]> {
  const out: string[] = [];
  let entries: Dirent[];
  try {
    entries = (await readdir(rootDir, { withFileTypes: true })) as Dirent[];
  } catch {
    return out;
  }
  for (const e of entries) {
    const name = e.name;
    const rel = base ? `${base}/${name}` : name;
    const full = join(rootDir, name);
    if (e.isDirectory()) {
      out.push(...(await walkMarkdownFiles(full, rel)));
    } else if (e.isFile() && name.endsWith(".md")) {
      out.push(rel.replace(/\\/g, "/"));
    }
  }
  return out;
}

/** Enumerate all markdown files under `.knowledge/` as repo-relative paths; seed line first if present. */
export async function bootstrapKnowledgeQueue(cwd: string, startContent: string): Promise<string[]> {
  const knowledgeDir = join(cwd, ".knowledge");
  const relFiles = await walkMarkdownFiles(knowledgeDir, "");
  const paths = relFiles.map((f) => `.knowledge/${f}`);
  const seed = startContent.trim().split(/\r?\n/u)[0]?.trim() ?? "";
  if (paths.length === 0 && seed.length > 0) {
    return [seed];
  }
  if (seed.length > 0 && paths.includes(seed)) {
    return [seed, ...paths.filter((p) => p !== seed)];
  }
  if (seed.length > 0 && !paths.includes(seed)) {
    return [seed, ...paths];
  }
  return [...paths].sort();
}

function lastIndexOfRole(messages: WorkflowMessage[], role: string): number {
  for (let i = messages.length - 1; i >= 0; i--) {
    if (messages[i].role === role) return i;
  }
  return -1;
}

/** Next queue for questioner: bootstrap, or continue after answerer / explorer. */
export async function resolveQueueForQuestioner(
  start: StartStep,
  messages: WorkflowMessage[],
  cwd: string,
): Promise<string[]> {
  const lastQi = lastIndexOfRole(messages, "questioner");
  if (lastQi === -1) {
    return bootstrapKnowledgeQueue(cwd, start.content);
  }
  const qMeta = messages[lastQi].meta as QuestionerMeta;
  const tail = messages.slice(lastQi + 1);
  const explorerMsg = tail.find((m) => m.role === "explorer");
  if (explorerMsg) {
    const eMeta = explorerMsg.meta as ExplorerMeta;
    return [...qMeta.remaining_queue, ...eMeta.new_cards];
  }
  return qMeta.remaining_queue;
}