import fs from "node:fs/promises";
import path from "node:path";

type AnyObj = Record<string, unknown>;

function asObj(v: unknown): AnyObj {
  return v && typeof v === "object" ? (v as AnyObj) : {};
}

function extractTextMessageContent(content: unknown): string | undefined {
  if (typeof content === "string") return content;
  if (!Array.isArray(content)) return;

  const chunks: string[] = [];
  for (const block of content) {
    if (!block || typeof block !== "object") continue;
    const candidate = block as { type?: unknown; text?: unknown };
    if (candidate.type === "text" && typeof candidate.text === "string") {
      chunks.push(candidate.text);
    }
  }

  const out = chunks.join("\n").trim();
  return out.length ? out : undefined;
}

function stripResetSuffix(fileName: string): string {
  const i = fileName.indexOf(".reset.");
  return i === -1 ? fileName : fileName.slice(0, i);
}

async function findPreviousSessionFile(params: {
  sessionsDir: string;
  currentSessionFile?: string;
  sessionId?: string;
}): Promise<string | undefined> {
  try {
    const files = await fs.readdir(params.sessionsDir);
    const fileSet = new Set(files);

    const baseFromReset = params.currentSessionFile
      ? stripResetSuffix(path.basename(params.currentSessionFile))
      : undefined;

    if (baseFromReset && fileSet.has(baseFromReset)) {
      return path.join(params.sessionsDir, baseFromReset);
    }

    const trimmedSessionId = params.sessionId?.trim();
    if (trimmedSessionId) {
      const canonicalFile = `${trimmedSessionId}.jsonl`;
      if (fileSet.has(canonicalFile)) return path.join(params.sessionsDir, canonicalFile);

      const topicVariants = files
        .filter(
          (name) =>
            name.startsWith(`${trimmedSessionId}-topic-`) &&
            name.endsWith(".jsonl") &&
            !name.includes(".reset."),
        )
        .sort()
        .reverse();

      if (topicVariants.length > 0) {
        return path.join(params.sessionsDir, topicVariants[0]!);
      }
    }

    if (!params.currentSessionFile) return;

    const nonResetJsonl = files
      .filter((name) => name.endsWith(".jsonl") && !name.includes(".reset."))
      .sort()
      .reverse();

    if (nonResetJsonl.length > 0) {
      return path.join(params.sessionsDir, nonResetJsonl[0]!);
    }
  } catch {
    // ignore
  }

  return undefined;
}

async function resolveSessionFile(params: {
  workspaceDir: string;
  currentSessionFile?: string;
  sessionId?: string;
}): Promise<string | undefined> {
  let current = params.currentSessionFile;

  if (current && !current.includes(".reset.")) return current;

  const dirs = new Set<string>();
  if (current) dirs.add(path.dirname(current));
  dirs.add(path.join(params.workspaceDir, "sessions"));

  for (const sessionsDir of dirs) {
    const recovered = await findPreviousSessionFile({
      sessionsDir,
      currentSessionFile: current,
      sessionId: params.sessionId,
    });
    if (recovered) return recovered;
  }

  return current;
}

async function getFullSessionContent(sessionFilePath: string): Promise<string | null> {
  try {
    const raw = await fs.readFile(sessionFilePath, "utf-8");
    const lines = raw.trim().split("\n");
    const allMessages: string[] = [];

    for (const line of lines) {
      try {
        const entry = JSON.parse(line) as AnyObj;
        if (entry.type !== "message") continue;

        const message = asObj(entry.message);
        const role = message.role;
        if (role !== "user" && role !== "assistant") continue;

        const text = extractTextMessageContent(message.content);
        if (!text) continue;
        if (text.startsWith("/")) continue;

        allMessages.push(`${String(role)}: ${text}`);
      } catch {
        // ignore broken line
      }
    }

    if (allMessages.length === 0) return null;
    return allMessages.join("\n\n");
  } catch {
    return null;
  }
}

function resolveTimezone(cfg: AnyObj): string {
  const raw = asObj(asObj(cfg.agents).defaults).userTimezone;
  const tz = typeof raw === "string" ? raw.trim() : "";

  if (tz) {
    try {
      Intl.DateTimeFormat("en-US", { timeZone: tz }).format(new Date());
      return tz;
    } catch {
      // ignore invalid timezone
    }
  }

  return Intl.DateTimeFormat().resolvedOptions().timeZone || "UTC";
}

function formatDatePartsInTimezone(date: Date, timeZone: string): { dateStr: string; timeStr: string } {
  const dtf = new Intl.DateTimeFormat("en-CA", {
    timeZone,
    year: "numeric",
    month: "2-digit",
    day: "2-digit",
    hour: "2-digit",
    minute: "2-digit",
    second: "2-digit",
    hour12: false,
    hourCycle: "h23",
  });

  const parts = dtf.formatToParts(date);
  const get = (type: Intl.DateTimeFormatPartTypes) => parts.find((p) => p.type === type)?.value ?? "00";

  const dateStr = `${get("year")}-${get("month")}-${get("day")}`;
  const timeStr = `${get("hour")}:${get("minute")}:${get("second")}`;
  return { dateStr, timeStr };
}

function slugifyLocal(text: string): string {
  return text
    .toLowerCase()
    .replace(/[^a-z0-9\s-]/g, " ")
    .replace(/\s+/g, "-")
    .replace(/-+/g, "-")
    .replace(/^-|-$/g, "")
    .slice(0, 80);
}

function buildSlugExcerpt(full: string): string {
  const lines = full
    .split("\n")
    .map((s) => s.trim())
    .filter(Boolean);

  const tail = lines.slice(-24).join("\n");
  return tail.slice(-3000);
}

async function getUniqueFilePath(dir: string, filename: string): Promise<string> {
  const candidate = path.join(dir, filename);
  try {
    await fs.access(candidate);
  } catch {
    return candidate;
  }

  const parsed = path.parse(filename);
  for (let i = 1; ; i += 1) {
    const name = `${parsed.name}-${i}${parsed.ext}`;
    const p = path.join(dir, name);
    try {
      await fs.access(p);
    } catch {
      return p;
    }
  }
}

async function generateSlug(params: {
  excerpt: string;
  cfg: AnyObj;
  fallbackDate: Date;
  timeZone: string;
}): Promise<string> {
  const { excerpt, cfg, fallbackDate, timeZone } = params;

  if (excerpt.trim()) {
    try {
      const mod = await import("/root/.nvm/versions/node/v25.8.1/lib/node_modules/openclaw/dist/llm-slug-generator.js");
      const fn = (mod as { generateSlugViaLLM?: (p: { sessionContent: string; cfg: unknown }) => Promise<string | null> })
        .generateSlugViaLLM;
      if (typeof fn === "function") {
        const slug = await fn({ sessionContent: excerpt, cfg });
        if (slug && typeof slug === "string" && slug.trim()) return slugifyLocal(slug);
      }
    } catch {
      // fall through to deterministic fallback
    }

    const det = slugifyLocal(excerpt.split("\n").join(" "));
    if (det) return det.split("-").slice(0, 8).join("-");
  }

  const { timeStr } = formatDatePartsInTimezone(fallbackDate, timeZone);
  return timeStr.replace(/:/g, "").slice(0, 4);
}

const handler = async (event: {
  type: string;
  action: string;
  sessionKey: string;
  timestamp: Date;
  context?: AnyObj;
}) => {
  if (event.type !== "command" || (event.action !== "new" && event.action !== "reset")) return;

  try {
    const context = asObj(event.context);
    const cfg = asObj(context.cfg);

    const workspaceDirRaw = context.workspaceDir;
    const workspaceDir =
      typeof workspaceDirRaw === "string" && workspaceDirRaw.trim().length > 0
        ? workspaceDirRaw
        : "/root/.openclaw/workspace";

    const sessionEntry = asObj(context.previousSessionEntry ?? context.sessionEntry);
    const sessionId = typeof sessionEntry.sessionId === "string" ? sessionEntry.sessionId : "unknown";
    const initialSessionFile =
      typeof sessionEntry.sessionFile === "string" && sessionEntry.sessionFile.trim().length > 0
        ? sessionEntry.sessionFile
        : undefined;

    const sessionFile = await resolveSessionFile({
      workspaceDir,
      currentSessionFile: initialSessionFile,
      sessionId,
    });

    if (!sessionFile) return;

    const fullContext = await getFullSessionContent(sessionFile);
    if (!fullContext) return;

    const timeZone = resolveTimezone(cfg);
    const now = new Date(event.timestamp);
    const { dateStr, timeStr } = formatDatePartsInTimezone(now, timeZone);

    const excerpt = buildSlugExcerpt(fullContext);
    const slug = await generateSlug({ excerpt, cfg, fallbackDate: now, timeZone });

    const memoryDir = path.join(workspaceDir, "memory");
    await fs.mkdir(memoryDir, { recursive: true });

    const filename = `${dateStr}-${slug}.md`;
    const memoryFilePath = await getUniqueFilePath(memoryDir, filename);

    const source = typeof context.commandSource === "string" ? context.commandSource : "unknown";

    const out = [
      `# Session: ${dateStr} ${timeStr} (${timeZone})`,
      "",
      `- **Session Key**: ${event.sessionKey}`,
      `- **Session ID**: ${sessionId}`,
      `- **Source**: ${source}`,
      "",
      "## Full Session Context",
      "",
      fullContext,
      "",
    ].join("\n");

    await fs.writeFile(memoryFilePath, out, "utf-8");
    console.log(`[session-memory-cus] Saved session context: ${memoryFilePath}`);
  } catch (err) {
    const msg = err instanceof Error ? `${err.name}: ${err.message}` : String(err);
    console.error(`[session-memory-cus] Failed: ${msg}`);
  }
};

export default handler;