import { readFile } from "node:fs/promises";
import path from "node:path";
import pdf from "pdf-parse";
import type { ChunkingMode } from "../process/chunking.js";

export interface ParsedDocument {
  title: string;
  content: string;
  mimeType: string;
  chunkMode: ChunkingMode;
}

const documentalExtensions = [".md", ".txt", ".pdf"] as const;
const codeExtensions = [".ts", ".tsx", ".js", ".jsx", ".mjs", ".cjs", ".py", ".json", ".yml", ".yaml"] as const;
const parserExtensions = [...documentalExtensions, ...codeExtensions] as const;

export function supportedParserExtensions(): string[] {
  return [...parserExtensions];
}

export function isSupportedDocument(filePath: string): boolean {
  return parserExtensions.includes(path.extname(filePath).toLowerCase() as (typeof parserExtensions)[number]);
}

export function inferChunkMode(filePath: string): ChunkingMode {
  const extension = path.extname(filePath).toLowerCase();
  if (codeExtensions.includes(extension as (typeof codeExtensions)[number])) {
    return "codigo";
  }
  return "documental";
}

function inferMimeType(extension: string, chunkMode: ChunkingMode): string {
  if (extension === ".pdf") {
    return "application/pdf";
  }
  if (extension === ".md") {
    return "text/markdown";
  }
  if (chunkMode === "codigo") {
    return "text/x-code";
  }
  return "text/plain";
}

export async function parseDocument(filePath: string): Promise<ParsedDocument> {
  const extension = path.extname(filePath).toLowerCase();
  const chunkMode = inferChunkMode(filePath);

  if (extension === ".pdf") {
    const buffer = await readFile(filePath);
    const result = await pdf(buffer);
    return {
      title: path.basename(filePath),
      content: result.text.trim(),
      mimeType: inferMimeType(extension, chunkMode),
      chunkMode
    };
  }

  const content = await readFile(filePath, "utf8");
  return {
    title: path.basename(filePath),
    content,
    mimeType: inferMimeType(extension, chunkMode),
    chunkMode
  };
}