import { getSessionState } from "../../runtime";
import { log } from "../../shared/logger";
import type { PluginHookContributions } from "../../types/hook";

type ChatMessageHook = NonNullable<PluginHookContributions["chat.message"]>;

type TodoStatus = "pending" | "in_progress" | "completed" | "cancelled";

interface SessionTodo {
  content: string;
  status: TodoStatus;
}

const STOP_PATTERNS = [
  /\bi['']?m done\b/i,
  /\btask complete\b/i,
  /\btasks? complete\b/i,
  /\ball done\b/i,
  /\bwork is complete\b/i,
  /\bfinished (all tasks|the work|everything)\b/i,
] as const;

function isRecord(value: unknown): value is Record<string, unknown> {
  return typeof value === "object" && value !== null;
}

function isTodoStatus(value: unknown): value is TodoStatus {
  return (
    value === "pending" || value === "in_progress" || value === "completed" || value === "cancelled"
  );
}

function resolveSessionID(input: unknown): string | undefined {
  if (!isRecord(input)) {
    return undefined;
  }

  if (typeof input.sessionID === "string") {
    return input.sessionID;
  }

  if (isRecord(input.message) && typeof input.message.sessionID === "string") {
    return input.message.sessionID;
  }

  return undefined;
}

function resolveMessageText(input: unknown): string {
  if (!isRecord(input)) {
    return "";
  }

  if (typeof input.message === "string") {
    return input.message;
  }

  if (typeof input.content === "string") {
    return input.content;
  }

  if (isRecord(input.message) && typeof input.message.content === "string") {
    return input.message.content;
  }

  return "";
}

function extractPendingTodos(sessionID: string): SessionTodo[] {
  const state = getSessionState(sessionID);
  if (!state) {
    return [];
  }

  const todos = (state as unknown as { todos?: unknown }).todos;
  if (!Array.isArray(todos)) {
    return [];
  }

  return todos
    .filter((todo): todo is SessionTodo => {
      if (!isRecord(todo)) {
        return false;
      }
      return typeof todo.content === "string" && isTodoStatus(todo.status);
    })
    .filter((todo) => todo.status === "pending" || todo.status === "in_progress");
}

function isStopLikeMessage(message: string): boolean {
  return STOP_PATTERNS.some((pattern) => pattern.test(message));
}

function injectReminder(input: unknown, reminder: string): void {
  if (!isRecord(input)) {
    return;
  }
  input.stopGuardMessage = reminder;
}

export function createStopGuardHandler(): ChatMessageHook {
  return async (input: unknown, ..._rest: unknown[]) => {
    const sessionID = resolveSessionID(input);
    if (!sessionID) {
      return;
    }

    const message = resolveMessageText(input);
    if (!isStopLikeMessage(message)) {
      return;
    }

    const pendingTodos = extractPendingTodos(sessionID);
    if (pendingTodos.length === 0) {
      return;
    }

    const reminder = `[stop-guard] Completion claim detected, but ${pendingTodos.length} todo item(s) are still pending. Continue with: ${pendingTodos[0]?.content}`;
    injectReminder(input, reminder);

    log("[stop-guard] Blocked premature stop with pending todos", {
      sessionID,
      pendingCount: pendingTodos.length,
      message,
    });
  };
}