/* global CardService, GmailApp, UrlFetchApp */
'use strict';

var API_BASE = 'https://cleanlinks.thewebdexter.com';
var LOGO_URL = 'https://cleanlinks.thewebdexter.com/icons/cleanlinks-icon-512.png';

// ── Entry points ──────────────────────────────────────────────────────────────

// Fired automatically when the user opens any email — scans immediately
function buildContextualUI(e) {
  try {
    var messageId = e.gmail.messageId;
    var accessToken = e.gmail.accessToken;
    GmailApp.setCurrentMessageAccessToken(accessToken);
    var body = GmailApp.getMessageById(messageId).getBody();
    var links = extractLinks(body);

    if (!links.length) {
      return [buildNoLinksCard()];
    }

    var results = cleanAll(links);
    return [buildResultsCard(results)];
  } catch (err) {
    return [buildErrorCard(err.message)];
  }
}

// Shown when no email is open
function buildHomePage() {
  return CardService.newCardBuilder()
    .setHeader(header('Ready'))
    .addSection(CardService.newCardSection()
      .addWidget(CardService.newTextParagraph()
        .setText('Open any email — CleanLinks scans every link automatically and removes tracking parameters.')))
    .build();
}

// Re-scan button action
function doRescan(e) {
  var messageId = e.gmail.messageId;
  var accessToken = e.gmail.accessToken;
  GmailApp.setCurrentMessageAccessToken(accessToken);
  var body = GmailApp.getMessageById(messageId).getBody();
  var links = extractLinks(body);
  var results = links.length ? cleanAll(links) : [];
  return CardService.newActionResponseBuilder()
    .setNavigation(CardService.newNavigation()
      .updateCard(links.length ? buildResultsCard(results) : buildNoLinksCard()))
    .build();
}

// ── Core: parallel clean ──────────────────────────────────────────────────────

function cleanAll(links) {
  var requests = links.map(function(url) {
    return { url: API_BASE + '/api/clean?url=' + encodeURIComponent(url), muteHttpExceptions: true };
  });
  var responses = UrlFetchApp.fetchAll(requests);
  return responses.map(function(resp, i) {
    try {
      var data = JSON.parse(resp.getContentText());
      return data.success ? data : bare(links[i]);
    } catch (_) { return bare(links[i]); }
  });
}

// ── Card builders ─────────────────────────────────────────────────────────────

function buildResultsCard(results) {
  var cleaned = results.filter(function(r) { return r.removed > 0 || r.wasUnwrapped; });
  var totalTrackers = results.reduce(function(s, r) { return s + (r.removed || 0); }, 0);
  var totalLinks = results.length;

  var subtitle = cleaned.length > 0
    ? 'Removed ' + totalTrackers + ' tracker' + (totalTrackers !== 1 ? 's' : '') + ' from ' + cleaned.length + ' of ' + totalLinks + ' links'
    : 'All ' + totalLinks + ' links are already clean';

  var builder = CardService.newCardBuilder()
    .setHeader(header(subtitle));

  if (cleaned.length > 0) {
    var section = CardService.newCardSection()
      .setHeader('Clean URLs — open or copy');
    cleaned.forEach(function(item) {
      section.addWidget(linkWidget(item));
    });
    builder.addSection(section);
  }

  builder.addSection(CardService.newCardSection()
    .addWidget(CardService.newTextButton()
      .setText('Re-scan')
      .setOnClickAction(CardService.newAction().setFunctionName('doRescan'))));

  return builder.build();
}

function buildNoLinksCard() {
  return CardService.newCardBuilder()
    .setHeader(header('No links found'))
    .addSection(CardService.newCardSection()
      .addWidget(CardService.newTextParagraph()
        .setText('This email contains no http/https links.')))
    .build();
}

function buildErrorCard(message) {
  return CardService.newCardBuilder()
    .setHeader(header('CleanLinks'))
    .addSection(CardService.newCardSection()
      .addWidget(CardService.newTextParagraph()
        .setText('Could not read this email: ' + message)))
    .build();
}

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

function linkWidget(item) {
  var url = item.cleaned || item.original;
  var label = '';
  if (item.removed > 0) label = item.removed + ' tracker' + (item.removed !== 1 ? 's' : '') + ' removed';
  if (item.wasUnwrapped && item.unwrappedVia) label += (label ? ' · ' : '') + 'unwrapped from ' + item.unwrappedVia;

  return CardService.newDecoratedText()
    .setTopLabel(hostname(url))
    .setText(trunc(url, 55))
    .setBottomLabel(label || 'already clean')
    .setButton(CardService.newTextButton()
      .setText('Open')
      .setOpenLink(CardService.newOpenLink()
        .setUrl(url)
        .setOpenAs(CardService.OpenAs.FULL_SIZE)
        .setOnClose(CardService.OnClose.NOTHING)));
}

function header(subtitle) {
  return CardService.newCardHeader()
    .setTitle('CleanLinks')
    .setSubtitle(subtitle)
    .setImageUrl(LOGO_URL)
    .setImageStyle(CardService.ImageStyle.CIRCLE);
}

function bare(url) {
  return { original: url, cleaned: url, removed: 0, wasUnwrapped: false };
}

function extractLinks(html) {
  var links = [], seen = {};
  var re = /href=["'](https?:\/\/[^"'<>\s]+)["']/gi;
  var m;
  while ((m = re.exec(html)) !== null) {
    if (!seen[m[1]]) { seen[m[1]] = true; links.push(m[1]); }
  }
  return links;
}

function hostname(url) {
  try { return url.match(/^https?:\/\/([^\/]+)/)[1]; } catch (_) { return url; }
}

function trunc(s, n) {
  return s.length > n ? s.slice(0, n - 1) + '…' : s;
}