message: move to lib/message, update naming

Basically, move/rename lib/mu-message* to lib/mu-*.

Add the beginnings of a Message class.

lib/message/mu-contact.hh

@@ -0,0 +1,177 @@
+/*
+** Copyright (C) 2022 Dirk-Jan C. Binnema <djcb@djcbsoftware.nl>
+**
+** This program is free software; you can redistribute it and/or modify it
+** under the terms of the GNU General Public License as published by the
+** Free Software Foundation; either version 3, or (at your option) any
+** later version.
+**
+** This program is distributed in the hope that it will be useful,
+** but WITHOUT ANY WARRANTY; without even the implied warranty of
+** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+** GNU General Public License for more details.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software Foundation,
+** Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+**
+*/
+
+#ifndef MU_MESSAGE_CONTACT_HH__
+#define MU_MESSAGE_CONTACT_HH__
+
+#include <functional>
+#include <string>
+#include <vector>
+#include <functional>
+#include <cctype>
+#include <cstring>
+#include <cstdlib>
+#include <ctime>
+
+#include "mu-fields.hh"
+
+struct _InternetAddressList;
+
+namespace Mu {
+
+/**
+ * Get the hash value for a lowercase value of s; useful for email-addresses
+ *
+ * @param s a string
+ *
+ * @return a hash value.
+ */
+size_t lowercase_hash(const std::string& s);
+
+struct Contact {
+	/**
+	 * Construct a new Contact
+	 *
+	 * @param email_ email address
+	 * @param name_ name or empty
+	 * @param field_id_ contact field id, or {}
+	 * @param message_date_ data for the message for this contact
+	 */
+	Contact(const std::string& email_, const std::string& name_ = "",
+		       std::optional<Field::Id> field_id_ = {},
+		       time_t message_date_ = 0)
+	    : email{email_}, name{name_}, field_id{field_id_},
+	      message_date{message_date_}, personal{}, frequency{1}, tstamp{}
+		{ cleanup_name(); }
+
+	/**
+	 * Construct a new Contact
+	 *
+	 * @param email_ email address
+	 * @param name_ name or empty
+	 * @param message_date_ date of message this contact originate from
+	 * @param personal_ is this a personal contact?
+	 * @param freq_ how often was this contact seen?
+	 * @param tstamp_ timestamp for last change
+	 */
+	Contact(const std::string& email_, const std::string& name_,
+		       time_t message_date_, bool personal_, size_t freq_,
+		       int64_t tstamp_)
+	    : email{email_}, name{name_}, field_id{},
+	      message_date{message_date_}, personal{personal_}, frequency{freq_},
+	      tstamp{tstamp_}
+	{ cleanup_name();}
+
+	/**
+	 * Get the "display name" for this contact; basically, if there's a
+	 * non-empty name, it's
+	 *     Jane Doe <email@example.com>
+	 * otherwise it's just the e-mail address.
+	 *
+	 * @return the display name
+	 */
+	std::string display_name() const;
+
+	/**
+	 * Operator==; based on the hash values (ie. lowercase e-mail address)
+	 *
+	 * @param rhs some other Contact
+	 *
+	 * @return true orf false.
+	 */
+	bool operator== (const Contact& rhs) const noexcept {
+		return hash() == rhs.hash();
+	}
+
+	/**
+	 * Get a hash-value for this contact, which gets lazily calculated. This
+	 * is for use with container classes. This uses the _lowercase_ email
+	 * address.
+	 *
+	 * @return the hash
+	 */
+	size_t hash() const {
+		static size_t cached_hash;
+		if (cached_hash == 0) {
+			cached_hash = lowercase_hash(email);
+		}
+		return  cached_hash;
+	}
+
+	/*
+	 * data members
+	 */
+
+	std::string email;                        /**< Email address for this contact.Not empty */
+	std::string name;                         /**< Name for this contact; can be empty. */
+	std::optional<Field::Id> field_id;  /**< Field Id of contact or nullopt */
+	::time_t    message_date;                 /**< date of the message from which the
+						     * contact originates */
+	bool    personal;                         /**<  A personal message? */
+	size_t  frequency;                        /**< Frequency of this contact */
+	int64_t tstamp;                           /**< Timestamp for this contact */
+
+private:
+	void cleanup_name() { // replace control characters by spaces.
+		for (auto& c: name)
+			if (iscntrl(c))
+				c = ' ';
+	}
+};
+
+using Contacts = std::vector<Contact>;
+
+/**
+ * Create a sequence of Contact objects from an InternetAddressList
+ *
+ * @param addr_lst an address list
+ * @param field_id the field_id for message field for these addresses
+ * @param message_date the date of the message from which the InternetAddressList
+ * originates.
+ *
+ * @return a sequence of Contact objects.
+ */
+Contacts
+make_contacts(/*const*/ struct _InternetAddressList* addr_lst,
+	      Field::Id field_id, ::time_t message_date);
+
+/**
+ * Create a sequence of Contact objects from an InternetAddressList
+ *
+ * @param addrs a string with one more valid addresses (as per internet_address_list_parse())
+ * @param field_id the field_id for message field for these addresses
+ * @param message_date the date of the message from which the addresses originate
+ *
+ * @return a sequence of Contact objects.
+ */
+Contacts
+make_contacts(const std::string& addrs,
+	      Field::Id field_id, ::time_t message_date);
+} // namespace Mu
+
+/**
+ * Implement our hash int std::
+ */
+template<> struct std::hash<Mu::Contact> {
+	std::size_t operator()(const Mu::Contact& c) const noexcept {
+		return c.hash();
+	}
+};
+
+#endif /* MU_CONTACT_HH__ */