import { existsSync, readFileSync } from "node:fs";
import { dirname, isAbsolute, join, resolve } from "node:path";
import { log } from "../../../shared/logger";

type ToolExecuteAfterInput = {
  tool?: string;
};

type ToolExecuteAfterOutput = {
  title?: string;
  output?: string;
};

function resolveReadPath(workspaceDirectory: string, title?: string): string | null {
  if (!title) {
    return null;
  }

  if (isAbsolute(title)) {
    return title;
  }

  return resolve(workspaceDirectory, title);
}

export function createReadmeInjectorHandler(workspaceDirectory: string) {
  return async (input: unknown, output: unknown): Promise<void> => {
    const typedInput = input as ToolExecuteAfterInput;
    const typedOutput = output as ToolExecuteAfterOutput;

    if (typedInput.tool?.toLowerCase() !== "read") {
      return;
    }

    const filePath = resolveReadPath(workspaceDirectory, typedOutput.title);
    if (!filePath || typeof typedOutput.output !== "string") {
      return;
    }

    const readmePath = join(dirname(filePath), "README.md");
    if (!existsSync(readmePath)) {
      return;
    }

    try {
      const content = readFileSync(readmePath, "utf8");
      typedOutput.output += `\n\n[Project README: ${readmePath}]\n${content}`;
    } catch (error) {
      log("[readme-injector] Failed to read README.md", {
        readmePath,
        error: String(error),
      });
    }
  };
}