#include "zero-pinyin-service.h"
#include "parse-pinyin.h"
#include "../sqlite3_util.h"

void
get_candidates_test (const char* preedit_str,
		     const guint fetch_size,
		     GVariantBuilder *candidates_builder,
		     GVariantBuilder *matched_lengths_builder)
{
	if (g_str_equal (preedit_str, "liyifeng")) {
		const gchar *matches[] = {"李易峰", "利益", "礼仪", "离异", "里", "理", "力"};
		guint matched_lengths[] = {8, 4, 4, 4, 2, 2, 2};
		for (guint i = 0; i < G_N_ELEMENTS (matches); ++i) {
			g_variant_builder_add (candidates_builder, "s", matches[i]);
			g_variant_builder_add (matched_lengths_builder, "u", matched_lengths[i]);
		}
	} else if (g_str_equal (preedit_str, "feng")) {
		const gchar *matches[] = {"风", "封", "疯", "丰", "凤"};
		guint matched_lengths[] = {4, 4, 4, 4, 4, 4};
		for (guint i = 0; i < G_N_ELEMENTS (matches); ++i) {
			g_variant_builder_add (candidates_builder, "s", matches[i]);
			g_variant_builder_add (matched_lengths_builder, "u", matched_lengths[i]);
		}
	} else if (g_str_equal (preedit_str, "yifeng")) {
		const gchar *matches[] = {"一封", "遗风", "艺", "依", "一", "以"};
		guint matched_lengths[] = {6, 6, 2, 2, 2, 2};
		for (guint i = 0; i < G_N_ELEMENTS (matches); ++i) {
			g_variant_builder_add (candidates_builder, "s", matches[i]);
			g_variant_builder_add (matched_lengths_builder, "u", matched_lengths[i]);
		}
	}
}

/**
 * build where clause for build_sql_for_n_pinyin().
 *
 * @pylist: the pinyin list.
 * @n: number of Pinyin to use in pylist.
 *
 * returns: where_clause, caller should g_free() result after use.
 */
static char*
build_where_clause (GList* pylist,
		    const guint n)
{
	GString* s = NULL;
	GList* iter = pylist;
	gboolean first_condition_done = FALSE;
	Pinyin* thispy = NULL;
	s = g_string_new (NULL);
	for (guint i = 0; i < n; ++i) {
		g_assert_nonnull (iter);
		thispy = (Pinyin*) iter->data;
		if (thispy->shengmu_i) {
			if (G_LIKELY (first_condition_done)) {
				g_string_append_printf (s, "AND s%u=%d ", i, thispy->shengmu_i);
			} else {
				g_string_append_printf (s, "s%u=%d ", i, thispy->shengmu_i);
				first_condition_done = TRUE;
			}
		}
		if (thispy->yunmu_i) {
			if (G_LIKELY (first_condition_done)) {
				g_string_append_printf (s, "AND y%u=%d ", i, thispy->yunmu_i);
			} else {
				g_string_append_printf (s, "y%u=%d ", i, thispy->yunmu_i);
				first_condition_done = TRUE;
			}
		}
		iter = iter->next;
	}
	gchar* result = s->str;
	g_string_free (s, FALSE);
	return result;
}

/**
 * return a string like ", s0, y0, s1, y1 "
 *
 * caller should g_free() result after use.
 */
char*
build_s_y_fields (const guint n)
{
	GString *s = NULL;
	g_assert_cmpint (n, >=, 1);
	s = g_string_new (NULL);
	for (guint i = 0; i < n; ++i) {
		g_string_append_printf (s, ", s%u, y%u", i, i);
	}
	s = g_string_append (s, " ");
	gchar *result = s->str;
	g_string_free (s, FALSE);
	return result;
}

/**
 * build a SQL to query candidates for first n pinyin in pylist.
 * n can be from 1 to len(pylist).
 *
 * caller should free result with g_free() after use.
 */
static char*
build_sql_for_n_pinyin (GList* pylist,
			const guint n,
			const guint limit)
{
	/* always keep one space after current term */
	GString* sql = NULL;
	gchar* where_clause = NULL;
	sql = g_string_new ("SELECT MAX(user_freq) AS user_freq, "
			    "phrase, MAX(freq) AS freq");
	gchar* s_y_fields = build_s_y_fields (n);
	g_string_append_printf (sql, s_y_fields);
	g_string_append_printf (sql, "FROM (");
	g_string_append_printf (
		sql, "SELECT 0 AS user_freq, phrase, freq");
	g_string_append_printf (sql, s_y_fields);
	g_string_append_printf (
		sql, "FROM maindb.py_phrase_%u WHERE ", n - 1);
	where_clause = build_where_clause (pylist, n);
	g_assert_nonnull (where_clause);
	g_debug ("where_clause=%s", where_clause);
	sql = g_string_append (sql, where_clause);
	sql = g_string_append (sql, "UNION ");
	g_string_append_printf (
		sql, "SELECT user_freq, phrase, freq");
	g_string_append_printf (sql, s_y_fields);
	g_string_append_printf (
		sql, "FROM userdb.py_phrase_%u WHERE ", n - 1);
	sql = g_string_append (sql, where_clause);
	sql = g_string_append (
		sql, ") "
		"WHERE phrase NOT IN (SELECT phrase FROM userdb.not_phrase) "
		"GROUP BY phrase "
		"ORDER BY user_freq DESC, freq DESC ");
	g_string_append_printf (sql, "LIMIT %u;", limit);
	char* result = sql->str;
	g_free (s_y_fields);
	g_free (where_clause);
	g_string_free (sql, FALSE);
	return result;
}

/**
 * For a candidate of length group_size, calculate the matched py length.
 *
 * This is part of get_candidates_for_n_pinyin().
 *
 * see param meaning there.
 */
static guint
get_matched_py_length (const char* preedit_str,
		       GList* pylist,
		       const guint group_size)
{
	guint matched_py_length = 0;
	GList* iter = pylist;

	g_assert_cmpint (group_size, >=, 1);
	/* For usual pinyin string, just add up the Pinyin length. But for
	 * pinyin that contains ', when a Pinyin in pylist is used, also take
	 * the ' before and after it. */
	for (guint i = 0; i < group_size; ++i) {
		while (preedit_str[matched_py_length] == '\'') {
			matched_py_length++;
		}
		matched_py_length += ((Pinyin*) iter->data)->length;
		while (preedit_str[matched_py_length] == '\'') {
			matched_py_length++;
		}
		iter = iter->next;
	}
	return matched_py_length;
}

/**
 * fetch candidates for a fixed word length.
 *
 * @db: sqlite3 db handler.
 * @preedit_str: the pinyin preedit str. can contain '. This is needed to
 *               calculate matched_py_length.
 * @pylist: the pinyin list.
 * @group_size: the fixed word length. use this many pinyin from pinyin list.
 * @limit: fetch this many result is enough for user. more is not a problem though.
 * @candidates: the result candidate list. caller should free this after use.
 *
 * returns: how many candidates fetched.
 */
static guint
get_candidates_for_n_pinyin (sqlite3* db,
			     const char* preedit_str,
			     GList* pylist,
			     const guint group_size,
			     const guint limit,
			     GList** candidates)
{
	const guint DEFAULT_LIMIT = 50;
	GList* result = NULL;	/* GList of Candidate */

	g_assert_nonnull (db);
	g_assert_cmpint (group_size, >=, 1);
	g_assert_cmpint (group_size, <=, g_list_length (pylist));

	gint candidates_count = 0;
	gint r = 0;
	/* build SQL and run SQL query */
	char* sql = NULL;
	sql = build_sql_for_n_pinyin (pylist, group_size, MAX (limit, DEFAULT_LIMIT));
	g_debug ("build_sql_for_n_pinyin result SQL:\n\n%s\n", sql);

	guint matched_py_length = get_matched_py_length (preedit_str, pylist, group_size);

	sqlite3_stmt* stmt = NULL;
	const char* unused;
	Candidate* c = NULL;
	r = sqlite3_prepare_v2 (db, sql, -1, &stmt, &unused);
	g_assert_nonnull (unused);
	g_assert_cmpstr (unused, ==, "");
	if (strlen (unused)) {
		g_warning ("part of sql is unused \"%s\" length=%zu",
			   unused, strlen (unused));
	}
	g_free (sql);
	while (TRUE) {
		r = sqlite3_step (stmt);
		if (r == SQLITE_DONE) {
			break;
		} else if (r == SQLITE_ROW) {
			c = g_new0 (Candidate, 1);
			/* sql SELECT should select these columns in order */
			c->user_freq = sqlite3_column_int (stmt, 0);
			c->str = g_strdup ((const char*) sqlite3_column_text (stmt, 1));
			c->freq = sqlite3_column_int (stmt, 2);
			c->matched_py_length = matched_py_length;
			c->char_len = group_size;
			c->py_indices = g_malloc0 (sizeof (Pinyin*) * group_size);
			for (guint i = 0; i < group_size; ++i) {
				c->py_indices[i] = g_new0 (Pinyin, 1);
				c->py_indices[i]->shengmu_i = sqlite3_column_int (stmt, 3 + i * 2);
				c->py_indices[i]->yunmu_i = sqlite3_column_int (stmt, 4 + i * 2);
				/* we don't care about ->length field */
			}

			if (g_utf8_validate (c->str, -1, NULL)) {
				result = g_list_prepend (result, c);
				candidates_count++;
			} else {
				g_warning ("ignore non utf8 phrase: %s", c->str);
			}
		} else if (r == SQLITE_BUSY) {
			g_warning ("sqlite3_step got SQLITE_BUSY");
			break;
		} else {
			g_warning ("sqlite3_step error: %d (%s)",
				   r, sqlite3_errmsg (db));
			break;
		}
	}
	r = sqlite3_finalize (stmt);
	if (r != SQLITE_OK) {
		g_debug ("sqlite3_finalize error: %d (%s)", r, sqlite3_errmsg (db));
	}

	/* store query result in a new GList */
	*candidates = g_list_reverse (result);
	return candidates_count;
}

static void
add_candidate_to_builders (Candidate *c,
			   GVariantBuilder *candidates_builder,
			   GVariantBuilder *matched_lengths_builder,
			   GVariantBuilder *candidates_pinyin_indices)
{
	g_variant_builder_add (candidates_builder, "s", c->str);
	g_variant_builder_add (matched_lengths_builder, "u", c->matched_py_length);
	GVariantBuilder *py_indices_builder = NULL;
	py_indices_builder = g_variant_builder_new (G_VARIANT_TYPE ("a(ii)"));
	for (guint i = 0; i < c->char_len; ++i) {
		g_variant_builder_add (
			py_indices_builder, "(ii)",
			c->py_indices[i]->shengmu_i,
			c->py_indices[i]->yunmu_i);
		g_debug ("adding (ii) %d %d",
			 c->py_indices[i]->shengmu_i,
			 c->py_indices[i]->yunmu_i);
		g_free (c->py_indices[i]);
	}
	g_debug ("adding a(ii) to aa(ii)");
	g_variant_builder_add (candidates_pinyin_indices, "a(ii)",
			       py_indices_builder);
	g_variant_builder_unref (py_indices_builder);
	g_free (c->str);
	g_free (c->py_indices);
}

void
get_candidates (sqlite3* db,
		const char* preedit_str,
		const guint fetch_size,
		GVariantBuilder *candidates_builder,
		GVariantBuilder *matched_lengths_builder,
		GVariantBuilder *candidates_pinyin_indices)
{
	if (! db) {
		g_warning ("No db connection, can't get candidates.");
		return;
	}
	GList* pylist = NULL;
	guint pylist_len = 0;

	pylist = parse_pinyin (preedit_str, 15);
	pylist_len = g_list_length (pylist);

	guint group_size = pylist_len;
	guint fetched_size = 0;
	guint r = 0;
	GList* candidates = NULL;
	while (fetched_size < fetch_size && group_size > 0) {
		g_message ("phrase length=%u", group_size);
		r = get_candidates_for_n_pinyin (db, preedit_str, pylist, group_size, fetch_size - fetched_size, &candidates);
		if (candidates) {
			GList* iter = g_list_first (candidates);
			Candidate* c = NULL;
			while (iter != NULL) {
				c = (Candidate*) iter->data;
				add_candidate_to_builders (
					c, candidates_builder,
					matched_lengths_builder,
					candidates_pinyin_indices);
				iter = iter->next;
			}
			g_list_free_full (candidates, g_free);
		}
		g_message ("%u candidates found", r);
		fetched_size += r;
		group_size--;
	}
	g_message ("returning %u candidates", fetched_size);
	g_list_free_full (pylist, g_free);
}

/**
 * sub function for commit_candidate()
 */
static void
_update_userdb_py_phrase (sqlite3 *db,
			  const gchar *candidate,
			  GVariant *candidate_pinyin_indices,
			  guint len) /* utf8 length of candidate char */
{
	GString *sql = NULL;
	GVariantIter iter = {0};
	GVariant *child = NULL;
	gint x = 0;
	gint y = 0;
	guint count = 0;
	char *s = NULL;
	gboolean rb = FALSE;

	g_assert_nonnull (db);
	g_assert_nonnull (candidate);
	g_assert_nonnull (candidate_pinyin_indices);

	/* insert candidate maybe */

	sql = g_string_new (NULL);
	g_string_append_printf (sql, "INSERT OR IGNORE INTO userdb.py_phrase_%u (user_freq, phrase, freq", len - 1);
	gchar* s_y_fields = build_s_y_fields (len);
	sql = g_string_append (sql, s_y_fields);
	g_free (s_y_fields);
	s = sqlite3_mprintf (") VALUES (0, %Q, 0", candidate);
	sql = g_string_append (sql, s);
	sqlite3_free (s);
	/* iter over GVariant "a(ii)" */
	g_variant_iter_init (&iter, candidate_pinyin_indices);
	count = 0;
	while ((child = g_variant_iter_next_value (&iter))) {
		g_variant_get (child, "(ii)", &x, &y);
		g_string_append_printf (sql, ", %d, %d", x, y);
		count++;
	}
	if (count != len) {
		g_warning ("candidate length=%u, a(ii) length=%u, mismatch!",
			   len, count);
		g_string_free (sql, TRUE);
		g_assert_not_reached ();
		return;
	}
	g_string_append_printf (sql, ");");
	rb = sqlite3_exec_simple (db, sql->str);
	if (! rb) {
		g_warning ("INSERT candidate to userdb failed");
	} else {
		if (sqlite3_changes (db) == 1) {
			g_message ("candidate %s inserted to userdb", candidate);
		}
	}
	g_string_free (sql, TRUE);

	/* increment user_freq field for candidate */

	sql = g_string_new (NULL);
	g_string_append_printf (sql, "UPDATE userdb.py_phrase_%u "
				"SET user_freq = user_freq + 1 ", len - 1);
	s = sqlite3_mprintf ("WHERE phrase = %Q ", candidate);
	sql = g_string_append (sql, s);
	sqlite3_free (s);
	g_variant_iter_init (&iter, candidate_pinyin_indices);
	count = 0;
	while ((child = g_variant_iter_next_value (&iter))) {
		g_variant_get (child, "(ii)", &x, &y);
		g_string_append_printf (sql, "AND s%d=%d AND y%d=%d ",
					count, x, count, y);
		count++;
	}
	sql = g_string_append (sql, ";");
	rb = sqlite3_exec_simple (db, sql->str);
	if (! rb) {
		g_warning ("UPDATE candidate user_freq failed");
	} else {
		if (sqlite3_changes (db) == 1) {
			g_message ("candidate %s user_freq incremented", candidate);
		} else {
			g_warning ("UPDATE candidate user_freq failed, no match");
		}
	}
	g_string_free (sql, TRUE);
}

static void
_update_userdb_not_phrase (sqlite3 *db,
			   const gchar *candidate)
{
	g_assert_nonnull (db);
	g_assert_nonnull (candidate);
	gboolean rb = FALSE;
	char *sql = sqlite3_mprintf ("DELETE FROM userdb.not_phrase WHERE phrase = %Q;", candidate);
	rb = sqlite3_exec_simple (db, sql);
	if (! rb) {
		g_warning ("DELETE candidate from not_phrase failed");
	} else {
		if (sqlite3_changes (db) == 1) {
			g_message ("candidate %s removed from not_phrase", candidate);
		}
	}
	sqlite3_free (sql);
}

void
commit_candidate (sqlite3 *db,
		  const gchar *candidate,
		  GVariant *candidate_pinyin_indices)
{
	if (! db) {
		g_warning ("No db connection, can't commit candidates.");
		return;
	}
	if (! candidate) {
		g_warning ("candidate should not be NULL. won't commit candidate.");
		return;
	}
	if (! candidate_pinyin_indices) {
		g_warning ("candidate_pinyin_indices should not be NULL. won't commit candidate.");
		return;
	}
	guint len = g_utf8_strlen (candidate, -1);
	if (len <= 1) {
		g_message ("commit single character %s is a no-op", candidate);
		return;
	}
	_update_userdb_py_phrase (db, candidate, candidate_pinyin_indices, len);
	_update_userdb_not_phrase (db, candidate);
}