/*
** Copyright (C) 2008-2010 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.
**
*/

#if HAVE_CONFIG_H
#include "config.h"
#endif /*HAVE_CONFIG_H*/

#include <cstdio>
#include <xapian.h>
#include <cstring>

#include "mu-msg.h"
#include "mu-msg-contact.h"
#include "mu-store.h"
#include "mu-util.h"
#include "mu-str.h"
#include "mu-msg-flags.h"

/* number of new messages after which we commit to the database */
#define MU_STORE_TRX_SIZE 6666

/* http://article.gmane.org/gmane.comp.search.xapian.general/3656 */
#define MU_STORE_MAX_TERM_LENGTH 240

struct _MuStore {
	Xapian::WritableDatabase *_db;

	char *_version;
	
	/* transaction handling */
	bool   _in_transaction;
	int    _processed;
	size_t _trx_size;
};


static void
add_synonym_for_flag (MuMsgFlags flag, Xapian::WritableDatabase *db)
{
	std::string pfx (1, mu_msg_field_xapian_prefix
			 (MU_MSG_FIELD_ID_FLAGS));

	db->clear_synonyms (pfx + mu_msg_flag_name (flag));
	db->add_synonym (pfx + mu_msg_flag_name (flag),
			 pfx + (std::string(1, mu_msg_flag_char (flag))));
}


static void
add_synonym_for_prio (MuMsgPrio prio, Xapian::WritableDatabase *db)
{
	std::string pfx (1, mu_msg_field_xapian_prefix
			 (MU_MSG_FIELD_ID_PRIO));
	
	std::string s1 (pfx + mu_msg_prio_name (prio));
	std::string s2 (pfx + (std::string(1, mu_msg_prio_char (prio))));
	
	db->clear_synonyms (s1);
	db->clear_synonyms (s2);
	
	db->add_synonym (s1, s2);
}


static void
add_synonyms (MuStore *store)
{
	mu_msg_flags_foreach ((MuMsgFlagsForeachFunc)add_synonym_for_flag,
			      store->_db);
	mu_msg_prio_foreach ((MuMsgPrioForeachFunc)add_synonym_for_prio,
			     store->_db);
}

static gboolean
check_version (MuStore *store)
{
	/* FIXME clear up versioning semantics */
	const gchar *version;

	version = mu_store_version (store); 

	/* no version yet? it must be a new db then; we'll set the version */
	if (!version)  {
		if (!mu_store_set_version (store, MU_XAPIAN_DB_VERSION)) {
			g_warning ("failed to set database version");
			return FALSE;
		}
		return TRUE; /* ok, done. */
	}
	
	/* we have a version, but is it the right one? */
	if (std::strcmp (version, MU_XAPIAN_DB_VERSION) != 0) {
		g_warning ("expected db version %s, but got %s",
			   MU_XAPIAN_DB_VERSION, version);
		return FALSE;
	}
	
	return TRUE;
}

MuStore*
mu_store_new  (const char* xpath, GError **err)
{
	MuStore *store (0);
	
	g_return_val_if_fail (xpath, NULL);
	
	try {
		store = g_new0(MuStore,1);
		store->_db = new Xapian::WritableDatabase
			(xpath,Xapian::DB_CREATE_OR_OPEN);
		if (!check_version (store)) {
			mu_store_destroy (store);
			return NULL;
		}

		/* keep count of processed docs */
		store->_trx_size = MU_STORE_TRX_SIZE; 
		store->_in_transaction = false;
		store->_processed = 0;
		
		add_synonyms (store);
		
		MU_WRITE_LOG ("%s: opened %s", __FUNCTION__, xpath);

		return store;

	} MU_XAPIAN_CATCH_BLOCK_G_ERROR(err,MU_ERROR_XAPIAN);		

	try { delete store->_db; } MU_XAPIAN_CATCH_BLOCK;
	
	g_free (store);
	return NULL;
}


void
mu_store_destroy (MuStore *store)
{
	if (!store)
		return;

	try {
		mu_store_flush (store);
		
		MU_WRITE_LOG ("closing xapian database with %d documents",
			      (int)store->_db->get_doccount());

		g_free (store->_version);
		delete store->_db;
		g_free (store);

	} MU_XAPIAN_CATCH_BLOCK;
}



unsigned
mu_store_count (MuStore *store)
{
	g_return_val_if_fail (store, 0);

	try {
		return store->_db->get_doccount();
		
	} MU_XAPIAN_CATCH_BLOCK;

	return 0;
}


const char*
mu_store_version (MuStore *store)
{
	g_return_val_if_fail (store, NULL);

	try {
		std::string v;
		v = store->_db->get_metadata (MU_XAPIAN_VERSION_KEY);

		g_free (store->_version);
		return store->_version =
			v.empty() ? NULL : g_strdup (v.c_str());
	
	} MU_XAPIAN_CATCH_BLOCK;

	return NULL;
}

gboolean
mu_store_set_version (MuStore *store, const char* version)
{
	g_return_val_if_fail (store, FALSE);
	g_return_val_if_fail (version, FALSE);
	
	try {
		store->_db->set_metadata (MU_XAPIAN_VERSION_KEY, version);
		return TRUE;
		
	} MU_XAPIAN_CATCH_BLOCK;

		return FALSE;
}


static void
begin_trx_if (MuStore *store, gboolean cond)
{
	if (cond) {
		g_debug ("beginning Xapian transaction");
		store->_db->begin_transaction();
		store->_in_transaction = true;
	}
}

static void
commit_trx_if (MuStore *store, gboolean cond)
{
	if (cond) {
		g_debug ("comitting Xapian transaction");
		store->_in_transaction = false;
		store->_db->commit_transaction();
	}
}

static void
rollback_trx_if (MuStore *store, gboolean cond)
{
	if (cond) {
		g_debug ("rolling back Xapian transaction");
		store->_in_transaction = false;
		store->_db->cancel_transaction();
	}
}



void
mu_store_flush (MuStore *store)
{
	g_return_if_fail (store);
	
	try {
		commit_trx_if (store, store->_in_transaction);
		store->_db->flush (); /* => commit, post X 1.1.x */

	} MU_XAPIAN_CATCH_BLOCK;
}


static void
add_terms_values_date (Xapian::Document& doc, MuMsg *msg,
		       MuMsgFieldId mfid)
{
	char datebuf[13]; /* YYYYMMDDHHMMSS */
	static const std::string pfx (1, mu_msg_field_xapian_prefix(mfid));
	gint64 num = mu_msg_get_field_numeric (msg, mfid);
	
	if (G_UNLIKELY(strftime(datebuf, sizeof(datebuf), "%Y%m%d%H%M",
				localtime((const time_t*)&num)) == 0))
		g_return_if_reached();
	
	const std::string numstr (Xapian::sortable_serialise((double)num));
	doc.add_value ((Xapian::valueno)mfid, numstr);
	doc.add_value ((Xapian::valueno)MU_MSG_PSEUDO_FIELD_ID_DATESTR,
		       datebuf);
}


static void
add_terms_values_number (Xapian::Document& doc, MuMsg *msg, 
			 MuMsgFieldId mfid)
{
	const std::string pfx (1, mu_msg_field_xapian_prefix(mfid));
	gint64 num = mu_msg_get_field_numeric (msg, mfid);
	const std::string numstr (Xapian::sortable_serialise((double)num));
	
	doc.add_value ((Xapian::valueno)mfid, numstr);
	
	if (mfid == MU_MSG_FIELD_ID_FLAGS) {
		const char* flags, *cur;
		cur = flags = mu_msg_flags_str_s ((MuMsgFlags)num);
		while (cur && *cur) {
			char kar = tolower (*cur);
			doc.add_term  (pfx + kar);
			++cur;
		}

	} else if (mfid == MU_MSG_FIELD_ID_PRIO) {
		doc.add_term (pfx + std::string(1,
			      mu_msg_prio_char((MuMsgPrio)num)));

	} else 
		doc.add_term  (pfx + numstr);
}

static void
add_terms_values_string (Xapian::Document& doc, MuMsg *msg,
			 MuMsgFieldId mfid)
{
	const char *orig;
	char *val;
		
	orig = mu_msg_get_field_string (msg, mfid);
	if (!orig)
		return;
	val = g_strdup (orig);
		
	const std::string prefix (1, mu_msg_field_xapian_prefix(mfid));

	/* the value is what we'll display; the unchanged original */
	if (mu_msg_field_xapian_value(mfid)) 			 
		doc.add_value ((Xapian::valueno)mfid, val);

	/* now, let's create some search terms... */
	if (mu_msg_field_normalize (mfid))
		mu_str_normalize_in_place (val, TRUE);
	if (mu_msg_field_xapian_escape (mfid))
		mu_str_ascii_xapian_escape_in_place (val);
	
	if (mu_msg_field_xapian_index (mfid)) {
		Xapian::TermGenerator termgen;
		termgen.set_document (doc);
		termgen.index_text_without_positions (val, 1, prefix);
	}
	
	if (mu_msg_field_xapian_term(mfid))
		doc.add_term (prefix + std::string(val, 0, MU_STORE_MAX_TERM_LENGTH));
	
	g_free (val);
}

static void
add_terms_values_body (Xapian::Document& doc, MuMsg *msg,
		       MuMsgFieldId mfid)
{
	const char *str;
	char *norm;
	
	if (mu_msg_get_flags(msg) & MU_MSG_FLAG_ENCRYPTED)
		return; /* ignore encrypted bodies */

	str = mu_msg_get_body_text (msg);
	if (!str) /* FIXME: html->txt fallback needed */
		str = mu_msg_get_body_html (msg);
	
	if (!str)  
		return; /* no body... */
	
	Xapian::TermGenerator termgen;
	termgen.set_document(doc);
	
	norm = mu_str_normalize (str, TRUE);
	termgen.index_text_without_positions
		(norm, 1,
		 std::string(1, mu_msg_field_xapian_prefix(mfid)));
	g_free (norm);
}

struct _MsgDoc {
	Xapian::Document	*_doc;
	MuMsg			*_msg;
};
typedef struct _MsgDoc		 MsgDoc;

static void
add_terms_values (MuMsgFieldId mfid, MsgDoc* msgdoc)
{
	/* note: contact-stuff (To/Cc/From) will handled in
	 * add_contact_info, not here */
	if (!mu_msg_field_xapian_index(mfid) &&
	    !mu_msg_field_xapian_term(mfid) &&
	    !mu_msg_field_xapian_value(mfid))
		return;

	switch (mfid) {
	case MU_MSG_FIELD_ID_DATE:
		add_terms_values_date (*msgdoc->_doc, msgdoc->_msg, mfid);
		break;
	case MU_MSG_FIELD_ID_BODY_TEXT:
		add_terms_values_body (*msgdoc->_doc, msgdoc->_msg, mfid);
		break;
	default:	
		if (mu_msg_field_is_numeric (mfid)) 
			add_terms_values_number (*msgdoc->_doc, msgdoc->_msg,
						 mfid);
		else if (mu_msg_field_type (mfid) ==
			 MU_MSG_FIELD_TYPE_STRING)
			add_terms_values_string (*msgdoc->_doc,
						 msgdoc->_msg,
						 mfid);
		else
			g_return_if_reached ();
	}
}


static void
each_contact_info (MuMsgContact *contact, MsgDoc *data)
{
	const std::string *pfxp;

	static const std::string to_pfx (1,
		mu_msg_field_xapian_prefix(MU_MSG_FIELD_ID_TO));
	static const std::string from_pfx (1,
		mu_msg_field_xapian_prefix(MU_MSG_FIELD_ID_FROM));
	static const std::string cc_pfx (1,
		mu_msg_field_xapian_prefix(MU_MSG_FIELD_ID_CC));

	/* use ptr to string to prevent copy... */
	switch (contact->type) {
	case MU_MSG_CONTACT_TYPE_TO:   pfxp  = &to_pfx; break;
	case MU_MSG_CONTACT_TYPE_FROM: pfxp  = &from_pfx; break;
	case MU_MSG_CONTACT_TYPE_CC:   pfxp  = &cc_pfx; break;
	default: return;
		/* other types (like bcc) are ignored */
	}
	
	if (contact->name && strlen(contact->name) > 0) {
		Xapian::TermGenerator termgen;
		termgen.set_document (*data->_doc);
		char *norm = mu_str_normalize (contact->name, TRUE);
		termgen.index_text_without_positions (norm, 1, *pfxp);
		g_free (norm);
	}

	/* don't normalize e-mail address, but do lowercase it */
	if (contact->address && contact->address[0] != '\0') {
		char *escaped =
			mu_str_ascii_xapian_escape (contact->address);
		data->_doc->add_term
			(std::string (*pfxp + escaped, 0, MU_STORE_MAX_TERM_LENGTH));
		g_free (escaped);
	}
}


/* get a unique id for this message */
static std::string
get_message_uid (const char* path)
{
	static const std::string pathprefix 
		(1, mu_msg_field_xapian_prefix(MU_MSG_FIELD_ID_PATH));

	return pathprefix + path;
}

static const std::string
get_message_uid (MuMsg *msg)
{
	return get_message_uid (mu_msg_get_path(msg));
}

MuResult
mu_store_store (MuStore *store, MuMsg *msg)
{	
	g_return_val_if_fail (store, MU_ERROR);
	g_return_val_if_fail (msg, MU_ERROR);

	try {
		Xapian::Document newdoc;
		Xapian::docid id;
		MsgDoc msgdoc = { &newdoc, msg };
		const std::string uid(get_message_uid(msg));

		begin_trx_if (store, !store->_in_transaction);
		/* we must add a unique term, so we can replace
		 * matching documents */
		newdoc.add_term (uid);
		mu_msg_field_foreach
			((MuMsgFieldForEachFunc)add_terms_values, &msgdoc);
		/* also store the contact-info as separate terms */
		mu_msg_contact_foreach
			(msg,
			 (MuMsgContactForeachFunc)each_contact_info,
			 &msgdoc);
			
		/* we replace all existing documents for this file */
		id = store->_db->replace_document (uid, newdoc);
		++store->_processed;
		commit_trx_if (store,
			       store->_processed % store->_trx_size == 0);

		return MU_OK;

	} MU_XAPIAN_CATCH_BLOCK;

	rollback_trx_if (store, store->_in_transaction);

	return MU_ERROR;
}


MuResult
mu_store_remove (MuStore *store, const char* msgpath)
{
	g_return_val_if_fail (store, MU_ERROR);
	g_return_val_if_fail (msgpath, MU_ERROR);

	try {
		const std::string uid (get_message_uid (msgpath));

		begin_trx_if (store, !store->_in_transaction);
		
		store->_db->delete_document (uid);
		g_debug ("deleting %s", msgpath);
		
		++store->_processed;

		/* do we need to commit now? */
		bool commit_now = store->_processed % store->_trx_size == 0;
		commit_trx_if (store, commit_now);

		return MU_OK; 
		
	} MU_XAPIAN_CATCH_BLOCK_RETURN (MU_ERROR);
	
}

gboolean
mu_store_contains_message (MuStore *store, const char* path)
{
	g_return_val_if_fail (store, FALSE);
	g_return_val_if_fail (path, FALSE);
	
	try {
		const std::string uid (get_message_uid(path));
		return store->_db->term_exists (uid) ? TRUE: FALSE;
		
	} MU_XAPIAN_CATCH_BLOCK_RETURN (FALSE);
}



time_t
mu_store_get_timestamp (MuStore *store, const char* msgpath)
{
	g_return_val_if_fail (store, 0);
	g_return_val_if_fail (msgpath, 0);
	
	try {
		const std::string stamp (store->_db->get_metadata (msgpath));
		if (stamp.empty())
			return 0;
	
		return (time_t) g_ascii_strtoull (stamp.c_str(), NULL, 10);
		
	} MU_XAPIAN_CATCH_BLOCK_RETURN (0);

	return 0;
}


void
mu_store_set_timestamp (MuStore *store, const char* msgpath, 
			time_t stamp)
{
	g_return_if_fail (store);
	g_return_if_fail (msgpath);

	try {
		char buf[21];
		sprintf (buf, "%" G_GUINT64_FORMAT, (guint64)stamp);
		store->_db->set_metadata (msgpath, buf);
				
	} MU_XAPIAN_CATCH_BLOCK;
}


MuResult
mu_store_foreach (MuStore *self, 
		  MuStoreForeachFunc func, void *user_data)  
{
	g_return_val_if_fail (self, MU_ERROR);
	g_return_val_if_fail (func, MU_ERROR);
	
	try {
		Xapian::Enquire enq (*self->_db);
		enq.set_query  (Xapian::Query::MatchAll);
		enq.set_cutoff (0,0);
		
		Xapian::MSet matches
			(enq.get_mset (0, self->_db->get_doccount()));
		if (matches.empty())
			return MU_OK; /* database is empty */
		
		for (Xapian::MSet::iterator iter = matches.begin();
		     iter != matches.end(); ++iter) {
			Xapian::Document doc (iter.get_document());
			const std::string path(
				doc.get_value(MU_MSG_FIELD_ID_PATH));

			MuResult res = func (path.c_str(), user_data);
			if (res != MU_OK)
				return res;
		}
		
	} MU_XAPIAN_CATCH_BLOCK_RETURN (MU_ERROR);

	return MU_OK;
}