const fs = require("fs");
const { parse } = require("csv-parse/sync");
const { DynamoDBClient } = require("@aws-sdk/client-dynamodb");
const { DynamoDBDocumentClient, BatchGetCommand } = require("@aws-sdk/lib-dynamodb");

const ddb = DynamoDBDocumentClient.from(new DynamoDBClient({ region: "us-east-1" }));
const CSV_PATH = process.argv[2];
if (!CSV_PATH) { console.error("Usage: node simulate-csv.cjs <csv-path>"); process.exit(1); }

const cancelStatuses = ["voided", "cancelled", "canceled", "marked as void"];
const statusRank = { "scheduled": 1, "payment submitted": 2, "issued": 3, "outstanding": 4, "cleared": 5 };

function toISODate(mdy) {
  const p = String(mdy).split("/");
  if (p.length !== 3) return null;
  const [mm, dd, yyyy] = p;
  return `${yyyy}-${mm.padStart(2, "0")}-${dd.padStart(2, "0")}`;
}

(async () => {
  const text = fs.readFileSync(CSV_PATH, "utf-8");
  const rows = parse(text, { columns: true, skip_empty_lines: true, trim: true })
    .map((r) => Object.fromEntries(Object.entries(r).map(([k, v]) => [String(k).trim(), typeof v === "string" ? v.trim() : v])));

  const validRows = rows.filter((r) => (r["Check Number"] || "").trim());
  console.log(`CSV rows: ${rows.length} total, ${validRows.length} with check numbers`);

  // Batch get existing records
  const keys = validRows.map((r) => ({ pk: `payment#${r["Check Number"].trim()}` }));
  const existing = {};
  for (let i = 0; i < keys.length; i += 100) {
    const batch = keys.slice(i, i + 100);
    const res = await ddb.send(new BatchGetCommand({ RequestItems: { PaymentsDashboard: { Keys: batch } } }));
    for (const item of res.Responses.PaymentsDashboard) existing[item.pk] = item;
  }
  console.log(`DDB records found for: ${Object.keys(existing).length} of ${validRows.length}\n`);

  const today = new Date().toISOString().slice(0, 10);
  const newChecks = [];
  const cancelChecks = [];
  const statusChanges = [];
  const frozenByBank = [];
  const frozenByRank = [];
  const newNonChecks = [];

  for (const row of validRows) {
    const checkNumber = row["Check Number"].trim();
    const method = (row["Method"] || "").trim();
    let status = (row["Status"] || "").trim();
    const sendOn = (row["Send Payment On"] || "").trim();

    if (method === "ACH" && !cancelStatuses.includes(status.toLowerCase())) {
      const sendDate = toISODate(sendOn);
      if (sendDate && sendDate <= today) status = "Cleared";
    }

    const pk = `payment#${checkNumber}`;
    const ex = existing[pk];

    const bankConfirmed = ex?.clear_status === "Cleared";
    if (bankConfirmed) status = "Cleared";

    let frozenReason = null;
    if (ex) {
      const oldRank = statusRank[(ex.status || "").toLowerCase()] || 0;
      const newRank = statusRank[status.toLowerCase()] || 0;
      if (oldRank === 5) {
        if (status !== ex.status) frozenReason = `cleared→${status} blocked`;
        status = ex.status;
      } else if (newRank < oldRank && !cancelStatuses.includes(status.toLowerCase())) {
        if (status !== ex.status) frozenReason = `${ex.status}→${status} regressed`;
        status = ex.status;
      }
    }

    if (frozenReason) {
      if (bankConfirmed) frozenByBank.push({ checkNumber, payee: row["Payee"], reason: frozenReason });
      else frozenByRank.push({ checkNumber, payee: row["Payee"], reason: frozenReason });
    } else if (ex && ex.status !== status) {
      statusChanges.push({ checkNumber, payee: row["Payee"], from: ex.status, to: status });
    }

    if (method !== "Check") {
      if (!ex) newNonChecks.push({ checkNumber, payee: row["Payee"], method, status, amount: row["Amount in USD"] });
      continue;
    }

    if (!ex) {
      newChecks.push({ checkNumber, payee: row["Payee"], amount: row["Amount in USD"], status, sendOn });
    } else if (cancelStatuses.includes(status.toLowerCase()) && !cancelStatuses.includes((ex.status || "").toLowerCase())) {
      cancelChecks.push({ checkNumber, payee: row["Payee"], from: ex.status, amount: row["Amount in USD"] });
    }
  }

  console.log(`========= WOULD HIT BoA =========`);
  console.log(`NEW checks → add_Issue: ${newChecks.length}`);
  for (const c of newChecks) console.log(`  ${c.checkNumber} | ${c.payee} | $${c.amount} | ${c.status} | ${c.sendOn}`);

  console.log(`\nCancellations → cancel_Issue: ${cancelChecks.length}`);
  for (const c of cancelChecks) console.log(`  ${c.checkNumber} | ${c.payee} | ${c.from}→cancel | $${c.amount}`);

  console.log(`\n========= DDB-ONLY CHANGES =========`);
  console.log(`Status changes (existing records): ${statusChanges.length}`);
  for (const c of statusChanges.slice(0, 30)) console.log(`  ${c.checkNumber} | ${c.payee} | ${c.from} → ${c.to}`);
  if (statusChanges.length > 30) console.log(`  ... +${statusChanges.length - 30} more`);

  console.log(`\nNew non-check rows (ACH/etc., DDB only): ${newNonChecks.length}`);
  for (const c of newNonChecks.slice(0, 10)) console.log(`  ${c.checkNumber} | ${c.payee} | ${c.method} | ${c.status} | $${c.amount}`);
  if (newNonChecks.length > 10) console.log(`  ... +${newNonChecks.length - 10} more`);

  console.log(`\n========= BLOCKED / FROZEN =========`);
  console.log(`Frozen by bank-confirmed Cleared: ${frozenByBank.length}`);
  for (const c of frozenByBank.slice(0, 10)) console.log(`  ${c.checkNumber} | ${c.payee} | ${c.reason}`);
  console.log(`\nFrozen by status-rank protection: ${frozenByRank.length}`);
  for (const c of frozenByRank.slice(0, 10)) console.log(`  ${c.checkNumber} | ${c.payee} | ${c.reason}`);
})();