index.js

// const libgen = require('libgenesis');
const fs = require("fs");
const fp = require("fs/promises");
const https = require("https");
const app = require("express")();
const path = require("path");
const { spawn, execFile } = require("child_process");

const {
  parseLibgenSearch,
  downloadEPUBbooksdl,
  deleteEPUB,
  downloadEPUBbookms,
} = require("./helpers");

const PORT = 80;

app.get("/", (req, res, err) => {
  console.log("request on /", "from", req.headers["x-forwarded-for"] || req.ip);
  res.sendFile(path.join(__dirname, "./index.html"));
});

app.get("/search", async (req, res, next) => {
  const search = req.query.s;
  if (typeof search !== "string") return next({});
  let html;
  let startingIndex;
  try {
    const file = await fp.readFile("./index.html");
    html = file.toString();
    startingIndex = html.search('<tbody id="tableBody">') + 22;
  } catch (err) {
    console.error(
      "There was an issue reading template html from fs",
      err.message
    );
  }

  if (search.length < 1) {
    const modifiedHtml =
      html.slice(0, startingIndex) +
      "<div>Search too short</div>" +
      html.slice(startingIndex);
    res.contentType("text/html");
    res.status(200).send(modifiedHtml);
    return;
  }

  console.log("Search:", search);
  fetch(
    `https://libgen.is/fiction/?q=${search}&criteria=&language=&format=epub`
  )
    .then((response) => {
      console.log("libgen.is returned status", response.status, "for search");
      return response.arrayBuffer();
    })
    .then((buffer) => {
      const libgenHTML = new TextDecoder("utf-8").decode(
        new Uint8Array(buffer)
      );
      // console.log(parseLibgenSearch(html));
      const bookData = parseLibgenSearch(libgenHTML);

      const bookNodes = bookData.map(
        ({ authors, series, title, fileSize, md5 }) => {
          return `
        <tr>
          <td>${authors.join("; ")}</td>
          <td>${series}</td>
          <td>${title}</td>
          <td>${fileSize}</td>
          <td>
            <a href='/download?md5=${md5}' id="downloadButton">GET</a>
          </td>
        </tr>
        `;
        }
      );
      if (bookNodes.length < 1) {
        const modifiedHtml =
          html.slice(0, startingIndex) +
          "<div>Your search returned no results</div>" +
          html.slice(startingIndex);
        res.contentType("text/html");
        res.status(200).send(modifiedHtml);
        return;
      }

      const modifiedHtml =
        html.slice(0, startingIndex) +
        bookNodes.join("") +
        html.slice(startingIndex);
      res.contentType("text/html");
      res.status(200).send(modifiedHtml);
    })
    .catch((error) => {
      console.error("Error:", error);
      next(error);
    });
});

app.get("/download", async (req, res, err) => {
  const start = Date.now();
  const md5 = req.query.md5;
  console.log(
    "download request from:",
    req.headers["x-forwarded-for"] || req.ip
  );
  if (typeof md5 !== "string" || md5.length !== 32) return next({});

  res.setHeader("Content-Disposition", 'attachment; filename=filename.epub"');
  res.setHeader("Content-Type", "application/epub");

  // console.log('Download:', md5);
  if (!fs.existsSync(`./epub/${md5}.kepub.epub`)) {
    try {
      if (!fs.existsSync(`./epub/${md5}.epub`)) {
        try {
          await downloadEPUBbooksdl(md5);
        } catch (err) {
          console.log("falling back to booksms because of error", err.message);
          await downloadEPUBbookms(md5);
        }

        execFile(
          "./kepubify",
          ["-i", "-o", `./epub`, `./epub/${md5}.epub`],
          (err, stdout, stderr) => {
            if (err) {
              console.error("ERROR running kepubify", err.message);
            } else {
              // res.setHeader('Content-Disposition', 'attachment; filename=filename.epub"');
              // res.setHeader('Content-Type', 'application/epub');
              res.download(path.join(__dirname, `./epub/${md5}.kepub.epub`));

              deleteEPUB(md5);
            }
          }
        );
      } else {
        const intervalHandle = setInterval(() => {
          execFile(
            "./kepubify",
            ["-i", "-o", `./epub`, `./epub/${md5}.epub`],
            (err, stdout, stderr) => {
              if (err) {
                // console.error('INVALID EPUB', err.message);
              } else {
                clearInterval(intervalHandle);
                // res.setHeader('Content-Disposition', 'attachment; filename=filename.epub"');
                // res.setHeader('Content-Type', 'application/epub');
                res.download(path.join(__dirname, `./epub/${md5}.kepub.epub`));

                deleteEPUB(md5);
              }
            }
          );
        }, 1000);
      }

      // res.setHeader('Content-disposition', `attachment; filename=${md5}.kepub.epub`);
    } catch (err) {
      console.error(`Error: ${err.message}`);
      deleteEPUB(md5);
      res
        .status(500)
        .send(
          "ERROR downloading book. you can try again but there may be an issue with download servers"
        );
    }
  } else {
    console.log("serving book from cache to:");
    res.download(path.join(__dirname, `./epub/${md5}.kepub.epub`));
  }
  console.log("Book download processing took: ", Date.now() - start);
});

app.use((req, res, next) => {
  console.log(
    "404 request on endpoint",
    req.url,
    "from ip:",
    req.headers["x-forwarded-for"] || req.ip
  );
  res.status(404).send("page not found");
});

app.use((err, req, res, next) => {
  res.status(500).send("Internal Server Error");
});

app.listen(PORT, "0.0.0.0", () => {
  console.log("listening on port: " + PORT);
});

// const parsedData = parseHTML(html);
// console.log(parsedData);

// setInterval(() => {
//   fetch('http://cdn3.booksdl.org/get.php?md5=2c3809164b7d9727b23ca6a9ac654613')
//     .then((res) => {
//       console.log(res.status);
//     })
//     .catch((err) => {
//       console.error(err);
//     });
// }, 1500);