// BOU 2026 - Best Project voting app
// Serves the voting page and logs every vote (Name, UID, Email, Project, Timestamp)
// into an Excel file on disk, one row per voter (re-voting updates their row).

const path = require("path");
const fs = require("fs");
const express = require("express");
const ExcelJS = require("exceljs");

const PORT = process.env.PORT || 3000;
const ADMIN_KEY = process.env.ADMIN_KEY || "change-me"; // set a real secret before deploying
const VOTES_FILE = path.join(__dirname, "data", "votes.xlsx");

const PROJECTS = [
  { id: "1", name: "Global Account – DAS (Adecco)", who: "Sathiaseelan Arumugam" },
  { id: "2", name: "PCB & IC Package Team", who: "Syam" },
  { id: "3", name: "Product Engineering / Embedded", who: "Munajat Abdul Hadi" },
  { id: "4", name: "CIS", who: "Shunmuganainar Chockalingam" },
  { id: "5", name: "ATE", who: "Kother" },
  { id: "6", name: "Manufacturing POD", who: "Rohan Chowdhary" },
  { id: "7", name: "Manufacturing", who: "Hasrul Hasni" },
];
const PROJECT_IDS = new Set(PROJECTS.map((p) => p.id));

const HEADERS = ["Name", "UID", "Email", "Project ID", "Project Name", "Timestamp"];

// --- tiny write queue so concurrent votes never corrupt the Excel file ---
let writeQueue = Promise.resolve();
function withWriteLock(fn) {
  const result = writeQueue.then(fn, fn);
  writeQueue = result.catch(() => {});
  return result;
}

async function loadWorkbook() {
  const wb = new ExcelJS.Workbook();
  if (fs.existsSync(VOTES_FILE)) {
    await wb.xlsx.readFile(VOTES_FILE);
  } else {
    fs.mkdirSync(path.dirname(VOTES_FILE), { recursive: true });
    const ws = wb.addWorksheet("Votes");
    ws.addRow(HEADERS);
    ws.getRow(1).font = { bold: true };
  }
  const ws = wb.getWorksheet("Votes") || wb.addWorksheet("Votes");
  if (ws.rowCount === 0) {
    ws.addRow(HEADERS);
    ws.getRow(1).font = { bold: true };
  }
  return { wb, ws };
}

async function recordVote({ name, uid, email, projectId }) {
  return withWriteLock(async () => {
    const { wb, ws } = await loadWorkbook();
    const project = PROJECTS.find((p) => p.id === projectId);

    // find an existing row for this UID (column 2) so re-voting updates it
    let existingRow = null;
    ws.eachRow((row, rowNumber) => {
      if (rowNumber === 1) return;
      if (String(row.getCell(2).value) === String(uid)) existingRow = row;
    });

    const values = [name, uid, email, project.id, project.name, new Date().toISOString()];
    if (existingRow) {
      existingRow.values = [, ...values]; // keep 1-based column alignment
    } else {
      ws.addRow(values);
    }

    await wb.xlsx.writeFile(VOTES_FILE);
  });
}

async function tallyResults() {
  const { ws } = await loadWorkbook();
  const counts = {};
  let total = 0;
  const voters = [];
  ws.eachRow((row, rowNumber) => {
    if (rowNumber === 1) return;
    const projectId = String(row.getCell(4).value || "");
    if (!projectId) return;
    counts[projectId] = (counts[projectId] || 0) + 1;
    total += 1;
    voters.push({
      name: row.getCell(1).value,
      uid: row.getCell(2).value,
      email: row.getCell(3).value,
      projectId,
    });
  });
  return { counts, total, voters };
}

// --- app ---
const app = express();
app.use(express.json());
app.use(express.static(path.join(__dirname, "public")));

app.get("/api/projects", (req, res) => res.json(PROJECTS));

app.post("/api/vote", async (req, res) => {
  const { name, uid, email, projectId } = req.body || {};
  if (!name || !uid || !email || !projectId) {
    return res.status(400).json({ ok: false, error: "Name, UID, email and a project choice are all required." });
  }
  if (!/^\S+@\S+\.\S+$/.test(email)) {
    return res.status(400).json({ ok: false, error: "That email address doesn't look valid." });
  }
  if (!PROJECT_IDS.has(String(projectId))) {
    return res.status(400).json({ ok: false, error: "Unknown project." });
  }
  try {
    await recordVote({ name: String(name).trim(), uid: String(uid).trim(), email: String(email).trim(), projectId: String(projectId) });
    res.json({ ok: true });
  } catch (err) {
    console.error(err);
    res.status(500).json({ ok: false, error: "Could not save your vote. Please try again." });
  }
});

function requireAdmin(req, res, next) {
  const key = req.query.key || req.headers["x-admin-key"];
  if (key !== ADMIN_KEY) return res.status(401).json({ ok: false, error: "Invalid admin key." });
  next();
}

app.get("/api/results", requireAdmin, async (req, res) => {
  try {
    const { counts, total } = await tallyResults();
    res.json({ ok: true, projects: PROJECTS, counts, total });
  } catch (err) {
    console.error(err);
    res.status(500).json({ ok: false, error: "Could not load results." });
  }
});

app.get("/api/export", requireAdmin, async (req, res) => {
  if (!fs.existsSync(VOTES_FILE)) {
    return res.status(404).json({ ok: false, error: "No votes recorded yet." });
  }
  res.download(VOTES_FILE, "bou2026-votes.xlsx");
});

app.listen(PORT, () => {
  console.log(`BOU 2026 voting app listening on port ${PORT}`);
  if (ADMIN_KEY === "change-me") {
    console.warn("WARNING: set a real ADMIN_KEY environment variable before sharing this app.");
  }
});