var MassMailerContacts = {
  parseCsv: function (text) {
    if (text.charCodeAt(0) === 65279) text = text.substring(1);
    var rows = [], row = [], field = "", quoted = false, started = false;
    for (var i = 0; i < text.length; i++) {
      var ch = text.charAt(i);
      if (quoted) {
        if (ch === '"') {
          if (text.charAt(i + 1) === '"') { field += '"'; i++; }
          else quoted = false;
        } else field += ch;
      } else if (ch === '"') {
        if (field.length !== 0) throw new Error("Unexpected quote in CSV row " + (rows.length + 1));
        quoted = true;
        started = true;
      } else if (ch === ",") {
        row.push(field); field = ""; started = true;
      } else if (ch === "\r" || ch === "\n") {
        row.push(field); field = "";
        if (started || row.length > 1) rows.push(row);
        row = []; started = false;
        if (ch === "\r" && text.charAt(i + 1) === "\n") i++;
      } else {
        field += ch;
        started = true;
      }
    }
    if (quoted) throw new Error("Unclosed quote in CSV");
    if (started || row.length > 0 || field.length > 0) {
      row.push(field);
      rows.push(row);
    }
    return rows;
  },

  emailKey: function (email) {
    return email.replace(/^\s+|\s+$/g, "").toLowerCase();
  },

  isEmail: function (email) {
    return email.length <= 254 && /^[^\s@,;<>]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$/.test(email);
  },

  isoDate: function (value) {
    if (!/^\d{4}-\d{2}-\d{2}$/.test(value)) return false;
    var year = Number(value.substring(0, 4));
    var month = Number(value.substring(5, 7));
    var day = Number(value.substring(8, 10));
    var date = new Date(year, month - 1, day);
    return date.getFullYear() === year && date.getMonth() === month - 1 && date.getDate() === day;
  },

  preview: function (text, fallbackSource, existing, suppressed) {
    var rows = this.parseCsv(text);
    if (rows.length < 2) throw new Error("CSV needs a header and at least one contact row");
    var headers = {}, i, key;
    for (i = 0; i < rows[0].length; i++) {
      key = rows[0][i].replace(/^\s+|\s+$/g, "").toLowerCase();
      if (headers["$" + key] !== undefined) throw new Error("Duplicate CSV header: " + key);
      headers["$" + key] = i;
    }
    if (headers.$email === undefined) throw new Error("CSV needs an email column");
    var accepted = [], rejected = [], seen = {};
    for (i = 1; i < rows.length; i++) {
      var cells = rows[i];
      var email = this.cell(cells, headers, "email");
      var emailKey = this.emailKey(email);
      var businessName = this.cell(cells, headers, "business_name");
      var source = this.cell(cells, headers, "source_reference") || fallbackSource;
      var acquiredAt = this.cell(cells, headers, "acquired_at");
      var reason = "";
      if (cells.length > rows[0].length) reason = "Too many columns";
      else if (!this.isEmail(email)) reason = "Invalid email";
      else if (!source) reason = "Missing source reference";
      else if (source.length > 2048) reason = "Source reference too long";
      else if (businessName.length > 200) reason = "Business name too long";
      else if (acquiredAt && !this.isoDate(acquiredAt)) reason = "acquired_at must be YYYY-MM-DD";
      else if (suppressed[emailKey]) reason = "Suppressed address";
      else if (existing[emailKey]) reason = "Already imported";
      else if (seen[emailKey]) reason = "Duplicate in CSV";
      var item = { line: i + 1, email: email, emailKey: emailKey,
        businessName: businessName, source: source, acquiredAt: acquiredAt, reason: reason };
      if (reason) rejected.push(item);
      else { accepted.push(item); seen[emailKey] = true; }
    }
    return { accepted: accepted, rejected: rejected };
  },

  cell: function (cells, headers, name) {
    if (headers["$" + name] === undefined) return "";
    return (cells[headers["$" + name]] || "").replace(/^\s+|\s+$/g, "");
  }
};