/**
 * ExpertVoice Order Reporter — GTM Server-Side Custom Tag Template
 *
 * ─── WHAT YOU'LL NEED BEFORE STARTING ────────────────────────────────────────
 * This template assumes your checkout sends the standard GA4 e-commerce
 * "purchase" event shape:
 *   transaction_id, value, tax, shipping, currency, coupon,
 *   items: [{ item_id, item_name, price, quantity }, ...]
 * If your checkout instead pushes a custom dataLayer event with different
 * field names, the getEventData() key paths below will need to be adjusted
 * to match. Check your container's Preview mode to confirm your event's
 * real field names before wiring this up.
 *
 * ─── SETUP INSTRUCTIONS ──────────────────────────────────────────────────────
 *
 * STEP 1 — CONFIGURE
 *   Fill in REPORTING_ID and (optionally) PREFIXES in the CODE section below
 *   before creating the template. Look up your Reporting ID at:
 *   https://advocacy.expertvoice.com/app/configure#pixel
 *
 * STEP 2 — CREATE THE CUSTOM TAG TEMPLATE
 *   In your GTM Server-Side container: Templates → New (under "Tag
 *   Templates") → this opens the Template Editor with four tabs:
 *   Info, Fields, Code, Permissions.
 *
 * STEP 3 — INFO TAB
 *   Name: "ExpertVoice Order Reporter"
 *   (Fields tab can be left empty — this template has no configurable UI
 *   fields; everything needed is hardcoded in the CODE section, so the
 *   template stays fully self-contained.)
 *
 * STEP 4 — CODE TAB
 *   Paste the contents of the CODE section below.
 *
 * STEP 5 — PERMISSIONS TAB
 *   GTM will prompt for the required permissions automatically the first
 *   time you click "Save" — accept them. You should see:
 *     - send_http:  scoped to expertvoice.com
 *     - read_event_data
 *     - logToConsole  (for debugging only; safe to leave enabled)
 *
 * STEP 6 — CREATE THE TAG
 *   Tags → New → choose the "ExpertVoice Order Reporter" custom template
 *   you just created as the tag type.
 *   Trigger: fire on your purchase/order-completed event trigger (whatever
 *   trigger fires for a completed order in your server container).
 *
 * STEP 7 — TEST
 *   Use GTM Server-Side's Preview mode, complete a test order, and confirm
 *   in Preview that this tag fired successfully (green checkmark). Once
 *   confirmed, let your ExpertVoice contact know so we can verify the order
 *   was received correctly on our end.
 */


/* ═══════════════════════════════════════════════════════════════════════════
   CODE  —  paste into the "Code" tab of the Template Editor
   ═══════════════════════════════════════════════════════════════════════════ */

const getEventData = require('getEventData');
const sendHttpRequest = require('sendHttpRequest');
const JSON = require('JSON');
const logToConsole = require('logToConsole');
const makeString = require('makeString');

// ─── Configuration ────────────────────────────────────────────────────────────

// Enter your ExpertVoice Reporting ID
// (format: exp-123-12345 — look it up at
// https://advocacy.expertvoice.com/app/configure#pixel)
const REPORTING_ID = '';

// OPTIONAL. Comma-separated list of coupon code prefixes (case-insensitive)
// used to filter which orders get sent. Leaving this as an empty array
// sends ALL orders to ExpertVoice — that's safe to do either way, since
// ExpertVoice only stores/counts orders whose code matches one it actually
// issued. Filtering here just avoids sending noise for orders that would
// be discarded on our end anyway. Example: const PREFIXES = ['EV-', 'EXP-'];
const PREFIXES = [];

// ─── Helpers ─────────────────────────────────────────────────────────────────

function hasMatchingPrefix(code, prefixes) {
  if (prefixes.length === 0) return true;
  if (!code) return false;
  const lowerCode = code.toLowerCase();
  for (let i = 0; i < prefixes.length; i++) {
    if (lowerCode.indexOf(prefixes[i].toLowerCase()) === 0) return true;
  }
  return false;
}

// ─── Main ─────────────────────────────────────────────────────────────────────

const idParts = REPORTING_ID.split('-');
const PIXEL_ID = idParts[1];
const ORG_ID = idParts[2];

const couponCode = getEventData('coupon') || '';

if (!hasMatchingPrefix(couponCode, PREFIXES)) {
  logToConsole('ExpertVoice: no matching prefix, order not reported.');
  data.gtmOnSuccess();
} else {
  const items = getEventData('items') || [];

  const products = items.map(function(item) {
    return {
      id: makeString(item.item_id || ''),
      name: item.item_name || '',
      sku: makeString(item.item_id || ''),
      upc: '',
      price: makeString(item.price || ''),
      quantity: item.quantity || 1
    };
  });

  const tax = getEventData('tax') || 0;
  const shipping = getEventData('shipping') || 0;

  // Some GA4 implementations report "value" as the grand total, already
  // including shipping (rather than a pre-shipping subtotal). Back shipping
  // out here so "subtotal" reflects the post-discount, pre-tax/shipping
  // amount actually charged. If your dataLayer's "value" already excludes
  // shipping, remove the "- shipping" below.
  const subtotal = (getEventData('value') || 0) - shipping;

  // msrp_subtotal (pre-discount) is derived by summing the line items
  // directly, since GA4's standard purchase event doesn't include a
  // separate pre-discount subtotal field. discount is then whatever
  // difference exists between that sum and the actual post-discount
  // "subtotal" above. Clamped at 0 so rounding noise or an items/value
  // mismatch never produces a negative discount.
  const itemsTotal = items.reduce(function(sum, item) {
    return sum + (Number(item.price) || 0) * (item.quantity || 1);
  }, 0);
  const discount = Math.max(0, itemsTotal - subtotal);

  const payload = {
    action: 'REDIRECT-ORDERPLACED',
    appName: 'external-redirect',
    data: {
      custom: {},
      eventDate: makeString(Date.now()),
      order: {
        code: [couponCode],
        currency: getEventData('currency') || 'USD',
        discount: makeString(discount.toFixed(2)),
        id: makeString(getEventData('transaction_id') || ''),
        msrp_subtotal: makeString(itemsTotal.toFixed(2)),
        shipping_address: {
          city: '',
          country: '',
          postal_code: '',
          state: ''
        },
        subtotal: makeString(subtotal.toFixed(2)),
        total: makeString((subtotal + tax + shipping).toFixed(2)),
        tax: makeString(tax.toFixed(2)),
        shipping: makeString(shipping.toFixed(2))
      },
      orgId: ORG_ID,
      pageCategory: 'order-app-gtm',
      pixelId: PIXEL_ID,
      products: products,
      version: '3.0'
    },
    mfgId: ORG_ID,
    referrer: null,
    url: 'gtm-server-side',
    userAgent: 'gtm-server-side',
    version: 1
  };

  sendHttpRequest(
    'https://www.expertvoice.com/pixel-gateway/ext/1.0/gateway',
    {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json; charset=UTF-8',
        'Accept': 'application/json',
        'x-codingscape-dev': '1'
      },
      timeout: 5000
    },
    JSON.stringify(payload)
  ).then((result) => {
    if (result.statusCode >= 200 && result.statusCode < 300) {
      data.gtmOnSuccess();
    } else {
      logToConsole('ExpertVoice: non-2xx response', result.statusCode);
      data.gtmOnFailure();
    }
  }).catch(() => {
    logToConsole('ExpertVoice: request failed or timed out');
    data.gtmOnFailure();
  });
}

/* ═══════════════════════════════════════════════════════════════════════════
   NOTES ON FIELD MAPPING / GAPS
   ═══════════════════════════════════════════════════════════════════════════

   - shipping_address is left blank — GA4's standard purchase event schema
     does not carry a shipping address. If your dataLayer includes one
     under a custom key, add it via additional getEventData() calls.
   - discount is derived, not read directly — GA4's standard schema
     doesn't include a distinct discount field, so it's calculated as
     (sum of line items) - (post-shipping-adjusted "value"). This is an
     approximation: it will also capture any other gap between your
     items array and your "value" field (e.g. a line item that isn't
     reflected in "value" for some other reason), not strictly promo
     codes only. If your dataLayer has a real discount field, prefer
     wiring it in directly via getEventData('discount') instead.
   - id/sku both use item_id since GA4's schema doesn't have a distinct
     SKU field by default — adjust if your items array carries a separate
     sku property under a custom key.
   - Prefix filtering only applies to the order-level coupon field, not
     to individual line items.

   If you run into any issues, or your checkout event doesn't match the
   assumed schema above, contact your ExpertVoice partner representative —
   we're happy to help adjust the template for your specific setup.
*/