/*
 * psql - the PostgreSQL interactive terminal
 *
 * Copyright 2000-2002 by PostgreSQL Global Development Group
 *
 * $Header: /cvsroot/pgsql/src/bin/psql/tab-complete.c,v 1.65 2002/11/08 17:37:52 tgl Exp $
 */

/*----------------------------------------------------------------------
 * This file implements a somewhat more sophisticated readline "TAB
 * completion" in psql. It is not intended to be AI, to replace
 * learning SQL, or to relieve you from thinking about what you're
 * doing. Also it does not always give you all the syntactically legal
 * completions, only those that are the most common or the ones that
 * the programmer felt most like implementing.
 *
 * CAVEAT: Tab completion causes queries to be sent to the backend.
 * The number tuples returned gets limited, in most default
 * installations to 101, but if you still don't like this prospect,
 * you can turn off tab completion in your ~/.inputrc (or else
 * ${INPUTRC}) file so:
 *
 *	 $if psql
 *	 set disable-completion on
 *	 $endif
 *
 * See `man 3 readline' or `info readline' for the full details. Also,
 * hence the
 *
 * BUGS:
 *
 * - If you split your queries across lines, this whole things gets
 *	 confused. (To fix this, one would have to read psql's query
 *	 buffer rather than readline's line buffer, which would require
 *	 some major revisions of things.)
 *
 * - Table or attribute names with spaces in it may confuse it.
 *
 * - Quotes, parenthesis, and other funny characters are not handled
 *	 all that gracefully.
 *----------------------------------------------------------------------
 */

#include "postgres_fe.h"
#include "tab-complete.h"

#include "input.h"

/* If we don't have this, we might as well forget about the whole thing: */
#ifdef USE_READLINE

#include <ctype.h>
#ifdef USE_ASSERT_CHECKING
#include <assert.h>
#endif

#include "libpq-fe.h"

#include "common.h"
#include "settings.h"

#ifdef HAVE_RL_FILENAME_COMPLETION_FUNCTION
#define filename_completion_function rl_filename_completion_function
#else
/* missing in some header files */
extern char *filename_completion_function();
#endif

#ifdef HAVE_RL_COMPLETION_MATCHES
#define completion_matches(x, y) rl_completion_matches((x), ((rl_compentry_func_t *)(y)))
#endif

#define BUF_SIZE 2048
#define ERROR_QUERY_TOO_LONG	/* empty */


/* Forward declaration of functions */
static char **psql_completion(char *text, int start, int end);
static char *create_command_generator(char *text, int state);
static char *complete_from_query(char *text, int state);
static char *complete_from_const(char *text, int state);
static char *complete_from_list(char *text, int state);

static PGresult *exec_query(char *query);
char	   *quote_file_name(char *text, int match_type, char *quote_pointer);

/*static char * dequote_file_name(char *text, char quote_char);*/
static char *previous_word(int point, int skip);

/* These variables are used to pass information into the completion functions.
   Realizing that this is the cardinal sin of programming, I don't see a better
   way. */
char	   *completion_charp;	/* if you need to pass a string */
char	  **completion_charpp;	/* if you need to pass a list of strings */
char	   *completion_info_charp;		/* if you need to pass another
										 * string */

/* Store how many records from a database query we want to return at most
(implemented via SELECT ... LIMIT xx). */
static int	completion_max_records;


/* Initialize the readline library for our purposes. */
void
initialize_readline(void)
{
	rl_readline_name = pset.progname;
	rl_attempted_completion_function = (void *) psql_completion;

	rl_basic_word_break_characters = "\t\n@$><=;|&{( ";

	completion_max_records = 100;

	/*
	 * There is a variable rl_completion_query_items for this but
	 * apparently it's not defined everywhere.
	 */
}


/*
 * Queries to get lists of names of various kinds of things, possibly
 * restricted to names matching a partially entered name.  In these queries,
 * the %s will be replaced by the text entered so far, the %d by its length.
 */

#define Query_for_list_of_tables "SELECT relname FROM pg_catalog.pg_class WHERE (relkind='r' or relkind='v') and substr(relname,1,%d)='%s' and pg_catalog.pg_table_is_visible(oid)"
#define Query_for_list_of_indexes "SELECT relname FROM pg_catalog.pg_class WHERE relkind='i' and substr(relname,1,%d)='%s' and pg_catalog.pg_table_is_visible(oid)"
#define Query_for_list_of_databases "SELECT datname FROM pg_catalog.pg_database WHERE substr(datname,1,%d)='%s'"
#define Query_for_list_of_attributes "SELECT a.attname FROM pg_catalog.pg_attribute a, pg_catalog.pg_class c WHERE c.oid = a.attrelid and a.attnum>0 and not a.attisdropped and substr(a.attname,1,%d)='%s' and c.relname='%s' and pg_catalog.pg_table_is_visible(c.oid)"
#define Query_for_list_of_users "SELECT usename FROM pg_catalog.pg_user WHERE substr(usename,1,%d)='%s'"

/* This is a list of all "things" in Pgsql, which can show up after CREATE or
   DROP; and there is also a query to get a list of them.
*/
typedef struct
{
	char	   *name;
	char	   *query;
} pgsql_thing_t;

pgsql_thing_t words_after_create[] = {
	{"AGGREGATE", "SELECT DISTINCT proname FROM pg_catalog.pg_proc WHERE proisagg AND substr(proname,1,%d)='%s'"},
	{"DATABASE", Query_for_list_of_databases},
	{"FUNCTION", "SELECT DISTINCT proname FROM pg_catalog.pg_proc WHERE substr(proname,1,%d)='%s'"},
	{"GROUP", "SELECT groname FROM pg_catalog.pg_group WHERE substr(groname,1,%d)='%s'"},
	{"INDEX", Query_for_list_of_indexes},
	{"OPERATOR", NULL},			/* Querying for this is probably not such
								 * a good idea. */
	{"RULE", "SELECT rulename FROM pg_catalog.pg_rules WHERE substr(rulename,1,%d)='%s'"},
	{"SCHEMA", "SELECT nspname FROM pg_catalog.pg_namespace WHERE substr(nspname,1,%d)='%s'"},
	{"SEQUENCE", "SELECT relname FROM pg_catalog.pg_class WHERE relkind='S' and substr(relname,1,%d)='%s'"},
	{"TABLE", Query_for_list_of_tables},
	{"TEMP", NULL},				/* for CREATE TEMP TABLE ... */
	{"TRIGGER", "SELECT tgname FROM pg_catalog.pg_trigger WHERE substr(tgname,1,%d)='%s'"},
	{"TYPE", "SELECT typname FROM pg_catalog.pg_type WHERE substr(typname,1,%d)='%s'"},
	{"UNIQUE", NULL},			/* for CREATE UNIQUE INDEX ... */
	{"USER", Query_for_list_of_users},
	{"VIEW", "SELECT viewname FROM pg_catalog.pg_views WHERE substr(viewname,1,%d)='%s'"},
	{NULL, NULL}				/* end of list */
};


/* A couple of macros to ease typing. You can use these to complete the given
   string with
   1) The results from a query you pass it. (Perhaps one of those above?)
   2) The items from a null-pointer-terminated list.
   3) A string constant
   4) The list of attributes to the given table.
*/
#define COMPLETE_WITH_QUERY(query) \
do { completion_charp = query; matches = completion_matches(text, complete_from_query); } while(0)
#define COMPLETE_WITH_LIST(list) \
do { completion_charpp = list; matches = completion_matches(text, complete_from_list); } while(0)
#define COMPLETE_WITH_CONST(string) \
do { completion_charp = string; matches = completion_matches(text, complete_from_const); } while(0)
#define COMPLETE_WITH_ATTR(table) \
do {completion_charp = Query_for_list_of_attributes; completion_info_charp = table; matches = completion_matches(text, complete_from_query); } while(0)


/* The completion function. Acc. to readline spec this gets passed the text
   entered to far and its start and end in the readline buffer. The return value
   is some partially obscure list format that can be generated by the readline
   libraries completion_matches() function, so we don't have to worry about it.
*/
static char **
psql_completion(char *text, int start, int end)
{
	/* This is the variable we'll return. */
	char	  **matches = NULL;

	/* These are going to contain some scannage of the input line. */
	char	   *prev_wd,
			   *prev2_wd,
			   *prev3_wd,
			   *prev4_wd;

	static char *sql_commands[] = {
		"ABORT", "ALTER", "ANALYZE", "BEGIN", "CLOSE", "CLUSTER", "COMMENT", "COMMIT", "COPY",
		"CREATE", "DECLARE", "DELETE", "DROP", "EXPLAIN", "FETCH", "GRANT",
		"INSERT", "LISTEN", "LOAD", "LOCK", "MOVE", "NOTIFY", "REINDEX", "RESET",
		"REVOKE", "ROLLBACK", "SELECT", "SET", "SHOW", "TRUNCATE", "UNLISTEN", "UPDATE",
		"VACUUM", NULL
	};

	static char *pgsql_variables[] = {
		/* these SET arguments are known in gram.y */
		"CONSTRAINTS",
		"NAMES",
		"SESSION",
		"TRANSACTION ISOLATION LEVEL",
		/* these are treated in backend/commands/variable.c */
		"DateStyle",
		"TimeZone",
		"client_encoding",
		"server_encoding",
		"seed",

		/*
		 * the rest should match USERSET entries in
		 * backend/utils/misc/guc.c
		 */
		"enable_seqscan",
		"enable_indexscan",
		"enable_tidscan",
		"enable_sort",
		"enable_nestloop",
		"enable_mergejoin",
		"enable_hashjoin",
		"geqo",
		"fsync",
		"server_min_messages",
		"client_min_messages",
		"debug_assertions",
		"log_statement",
		"log_duration",
		"debug_print_parse",
		"debug_print_rewritten",
		"debug_print_plan",
		"debug_pretty_print",
		"show_parser_stats",
		"show_planner_stats",
		"show_executor_stats",
		"show_statement_stats",
		"trace_notify",
		"explain_pretty_print",
		"sql_inheritance",
		"australian_timezones",
		"password_encryption",
		"transform_null_equals",
		"autocommit",

		"default_statistics_target",
		"geqo_threshold",
		"geqo_pool_size",
		"geqo_effort",
		"geqo_generations",
		"geqo_random_seed",
		"sort_mem",
		"vacuum_mem",
		"max_expr_depth",
		"commit_delay",
		"commit_siblings",
		"extra_float_digits",

		"effective_cache_size",
		"random_page_cost",
		"cpu_tuple_cost",
		"cpu_index_tuple_cost",
		"cpu_operator_cost",
		"geqo_selection_bias",

		"default_transaction_isolation",
		"search_path",
		"statement_timeout",
		"log_min_error_statement",
		NULL
	};

	static char *backslash_commands[] = {
		"\\connect", "\\copy", "\\d", "\\da", "\\dd", "\\df", "\\di",
		"\\dl", "\\do", "\\dp", "\\ds", "\\dS", "\\dt", "\\dT", "\\dv",
		"\\e", "\\echo",
		"\\encoding", "\\g", "\\h", "\\i", "\\l",
		"\\lo_import", "\\lo_export", "\\lo_list", "\\lo_unlink",
		"\\o", "\\p", "\\pset", "\\q", "\\qecho", "\\r", "\\set", "\\t",
		"\\timing", "\\unset", "\\x", "\\w", "\\z", "\\!", NULL
	};

	(void) end;					/* not used */

#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
	rl_completion_append_character = ' ';
#endif

	/* Clear a few things. */
	completion_charp = NULL;
	completion_charpp = NULL;
	completion_info_charp = NULL;

	/*
	 * Scan the input line before our current position for the last four
	 * words. According to those we'll make some smart decisions on what
	 * the user is probably intending to type. TODO: Use strtokx() to do
	 * this.
	 */
	prev_wd = previous_word(start, 0);
	prev2_wd = previous_word(start, 1);
	prev3_wd = previous_word(start, 2);
	prev4_wd = previous_word(start, 3);

	/* If a backslash command was started, continue */
	if (text[0] == '\\')
		COMPLETE_WITH_LIST(backslash_commands);

	/* If no previous word, suggest one of the basic sql commands */
	else if (!prev_wd)
		COMPLETE_WITH_LIST(sql_commands);

/* CREATE or DROP */
	/* complete with something you can create or drop */
	else if (strcasecmp(prev_wd, "CREATE") == 0 || strcasecmp(prev_wd, "DROP") == 0)
		matches = completion_matches(text, create_command_generator);

/* ALTER */
	/* complete with what you can alter (TABLE, GROUP, USER) */
	else if (strcasecmp(prev_wd, "ALTER") == 0)
	{
		char	   *list_ALTER[] = {"GROUP", "SCHEMA", "TABLE", "USER", NULL};

		COMPLETE_WITH_LIST(list_ALTER);
	}

	/*
	 * If we detect ALTER TABLE <name>, suggest either ADD, ALTER, or
	 * RENAME
	 */
	else if (strcasecmp(prev3_wd, "ALTER") == 0 && strcasecmp(prev2_wd, "TABLE") == 0)
	{
		char	   *list_ALTER2[] = {"ADD", "ALTER", "RENAME", NULL};

		COMPLETE_WITH_LIST(list_ALTER2);
	}
	/* If we have TABLE <sth> ALTER|RENAME, provide list of columns */
	else if (strcasecmp(prev3_wd, "TABLE") == 0 &&
			 (strcasecmp(prev_wd, "ALTER") == 0 || strcasecmp(prev_wd, "RENAME") == 0))
		COMPLETE_WITH_ATTR(prev2_wd);

	/* complete ALTER GROUP <foo> with ADD or DROP */
	else if (strcasecmp(prev3_wd, "ALTER") == 0 && strcasecmp(prev2_wd, "GROUP") == 0)
	{
		char	   *list_ALTERGROUP[] = {"ADD", "DROP", NULL};

		COMPLETE_WITH_LIST(list_ALTERGROUP);
	}
	/* complete ALTER GROUP <foo> ADD|DROP with USER */
	else if (strcasecmp(prev4_wd, "ALTER") == 0 && strcasecmp(prev3_wd, "GROUP") == 0
			 && (strcasecmp(prev_wd, "ADD") == 0 || strcasecmp(prev_wd, "DROP") == 0))
		COMPLETE_WITH_CONST("USER");
	/* complete {ALTER} GROUP <foo> ADD|DROP USER with a user name */
	else if (strcasecmp(prev4_wd, "GROUP") == 0
			 && (strcasecmp(prev2_wd, "ADD") == 0 || strcasecmp(prev2_wd, "DROP") == 0)
			 && strcasecmp(prev_wd, "USER") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_users);

/* ANALYZE */
	/* If the previous word is ANALYZE, produce list of tables. */
	else if (strcasecmp(prev_wd, "ANALYZE") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);
	/* If we have ANALYZE <table>, complete with semicolon. */
	else if (strcasecmp(prev2_wd, "ANALYZE") == 0)
		COMPLETE_WITH_CONST(";");

/* CLUSTER */
	/* If the previous word is CLUSTER, produce list of indexes. */
	else if (strcasecmp(prev_wd, "CLUSTER") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_indexes);
	/* If we have CLUSTER <sth>, then add "ON" */
	else if (strcasecmp(prev2_wd, "CLUSTER") == 0)
		COMPLETE_WITH_CONST("ON");

	/*
	 * If we have CLUSTER <sth> ON, then add the correct tablename as
	 * well.
	 */
	else if (strcasecmp(prev3_wd, "CLUSTER") == 0 && strcasecmp(prev_wd, "ON") == 0)
	{
		char		query_buffer[BUF_SIZE];		/* Some room to build
												 * queries. */

		if (snprintf(query_buffer, BUF_SIZE,
					 "SELECT c1.relname FROM pg_catalog.pg_class c1, pg_catalog.pg_class c2, pg_catalog.pg_index i WHERE c1.oid=i.indrelid and i.indexrelid=c2.oid and c2.relname='%s' and pg_catalog.pg_table_is_visible(c2.oid)",
					 prev2_wd) == -1)
			ERROR_QUERY_TOO_LONG;
		else
			COMPLETE_WITH_QUERY(query_buffer);
	}

/* COMMENT */
	else if (strcasecmp(prev_wd, "COMMENT") == 0)
		COMPLETE_WITH_CONST("ON");
	else if (strcasecmp(prev2_wd, "COMMENT") == 0 && strcasecmp(prev_wd, "ON") == 0)
	{
		char	   *list_COMMENT[] =
		{"DATABASE", "INDEX", "RULE", "SCHEMA", "SEQUENCE", "TABLE", "TYPE", "VIEW",
			"COLUMN", "AGGREGATE", "FUNCTION", "OPERATOR", "TRIGGER", "CONSTRAINT",
		"DOMAIN", NULL};

		COMPLETE_WITH_LIST(list_COMMENT);
	}
	else if (strcasecmp(prev4_wd, "COMMENT") == 0 && strcasecmp(prev3_wd, "ON") == 0)
		COMPLETE_WITH_CONST("IS");

/* COPY */

	/*
	 * If we have COPY [BINARY] (which you'd have to type yourself), offer
	 * list of tables (Also cover the analogous backslash command)
	 */
	else if (strcasecmp(prev_wd, "COPY") == 0 ||
			 strcasecmp(prev_wd, "\\copy") == 0 ||
			 (strcasecmp(prev2_wd, "COPY") == 0 && strcasecmp(prev_wd, "BINARY") == 0))
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);
	/* If we have COPY|BINARY <sth>, complete it with "TO" or "FROM" */
	else if (strcasecmp(prev2_wd, "COPY") == 0 ||
			 strcasecmp(prev2_wd, "\\copy") == 0 ||
			 strcasecmp(prev2_wd, "BINARY") == 0)
	{
		char	   *list_FROMTO[] = {"FROM", "TO", NULL};

		COMPLETE_WITH_LIST(list_FROMTO);
	}

/* CREATE INDEX */
	/* First off we complete CREATE UNIQUE with "INDEX" */
	else if (strcasecmp(prev2_wd, "CREATE") == 0 && strcasecmp(prev_wd, "UNIQUE") == 0)
		COMPLETE_WITH_CONST("INDEX");
	/* If we have CREATE|UNIQUE INDEX <sth>, then add "ON" */
	else if (strcasecmp(prev2_wd, "INDEX") == 0 &&
			 (strcasecmp(prev3_wd, "CREATE") == 0 || strcasecmp(prev3_wd, "UNIQUE") == 0))
		COMPLETE_WITH_CONST("ON");
	/* Complete ... INDEX <name> ON with a list of tables  */
	else if ((strcasecmp(prev3_wd, "INDEX") == 0 && strcasecmp(prev_wd, "ON") == 0) || (0))
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);

	/*
	 * Complete INDEX <name> ON <table> with a list of table columns
	 * (which should really be in parens)
	 */
	else if (strcasecmp(prev4_wd, "INDEX") == 0 && strcasecmp(prev2_wd, "ON") == 0)
		COMPLETE_WITH_ATTR(prev_wd);
	/* same if you put in USING */
	else if ((strcasecmp(prev4_wd, "ON") == 0 && strcasecmp(prev2_wd, "USING") == 0))
		COMPLETE_WITH_ATTR(prev3_wd);
	/* Complete USING with an index method */
	else if (strcasecmp(prev_wd, "USING") == 0)
	{
		char	   *index_mth[] = {"BTREE", "RTREE", "HASH", "GIST", NULL};

		COMPLETE_WITH_LIST(index_mth);
	}

/* CREATE RULE */
	/* Complete "CREATE RULE <sth>" with "AS" */
	else if (strcasecmp(prev3_wd, "CREATE") == 0 && strcasecmp(prev2_wd, "RULE") == 0)
		COMPLETE_WITH_CONST("AS");
	/* Complete "CREATE RULE <sth> AS with "ON" */
	else if (strcasecmp(prev4_wd, "CREATE") == 0 &&
			 strcasecmp(prev3_wd, "RULE") == 0 &&
			 strcasecmp(prev_wd, "AS") == 0)
		COMPLETE_WITH_CONST("ON");
	/* Complete "RULE * AS ON" with SELECT|UPDATE|DELETE|INSERT */
	else if (strcasecmp(prev4_wd, "RULE") == 0 &&
			 strcasecmp(prev2_wd, "AS") == 0 &&
			 strcasecmp(prev_wd, "ON") == 0)
	{
		char	   *rule_events[] = {"SELECT", "UPDATE", "INSERT", "DELETE", NULL};

		COMPLETE_WITH_LIST(rule_events);
	}
	/* Complete "AS ON <sth with a 'T' :)>" with a "TO" */
	else if (strcasecmp(prev3_wd, "AS") == 0 &&
			 strcasecmp(prev2_wd, "ON") == 0 &&
			 (toupper((unsigned char) prev_wd[4]) == 'T' ||
			  toupper((unsigned char) prev_wd[5]) == 'T'))
		COMPLETE_WITH_CONST("TO");
	/* Complete "AS ON <sth> TO" with a table name */
	else if (strcasecmp(prev4_wd, "AS") == 0 &&
			 strcasecmp(prev3_wd, "ON") == 0 &&
			 strcasecmp(prev_wd, "TO") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);

/* CREATE TABLE */
	/* Complete CREATE TEMP with "TABLE" */
	else if (strcasecmp(prev2_wd, "CREATE") == 0 && strcasecmp(prev_wd, "TEMP") == 0)
		COMPLETE_WITH_CONST("TABLE");

/* CREATE TRIGGER */
	/* is on the agenda . . . */

/* CREATE VIEW */
	/* Complete "CREATE VIEW <name>" with "AS" */
	else if (strcasecmp(prev3_wd, "CREATE") == 0 && strcasecmp(prev2_wd, "VIEW") == 0)
		COMPLETE_WITH_CONST("AS");
	/* Complete "CREATE VIEW <sth> AS with "SELECT" */
	else if (strcasecmp(prev4_wd, "CREATE") == 0 &&
			 strcasecmp(prev3_wd, "VIEW") == 0 &&
			 strcasecmp(prev_wd, "AS") == 0)
		COMPLETE_WITH_CONST("SELECT");

/* DELETE */

	/*
	 * Complete DELETE with FROM (only if the word before that is not "ON"
	 * (cf. rules) or "BEFORE" or "AFTER" (cf. triggers) or GRANT)
	 */
	else if (strcasecmp(prev_wd, "DELETE") == 0 &&
			 !(strcasecmp(prev2_wd, "ON") == 0 ||
			   strcasecmp(prev2_wd, "GRANT") == 0 ||
			   strcasecmp(prev2_wd, "BEFORE") == 0 ||
			   strcasecmp(prev2_wd, "AFTER") == 0))
		COMPLETE_WITH_CONST("FROM");
	/* Complete DELETE FROM with a list of tables */
	else if (strcasecmp(prev2_wd, "DELETE") == 0 && strcasecmp(prev_wd, "FROM") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);
	/* Complete DELETE FROM <table> with "WHERE" (perhaps a safe idea?) */
	else if (strcasecmp(prev3_wd, "DELETE") == 0 && strcasecmp(prev2_wd, "FROM") == 0)
		COMPLETE_WITH_CONST("WHERE");

/* EXPLAIN */

	/*
	 * Complete EXPLAIN [VERBOSE] (which you'd have to type yourself) with
	 * the list of SQL commands
	 */
	else if (strcasecmp(prev_wd, "EXPLAIN") == 0 ||
			 (strcasecmp(prev2_wd, "EXPLAIN") == 0 && strcasecmp(prev_wd, "VERBOSE") == 0))
		COMPLETE_WITH_LIST(sql_commands);

/* FETCH && MOVE */
	/* Complete FETCH with one of FORWARD, BACKWARD, RELATIVE */
	else if (strcasecmp(prev_wd, "FETCH") == 0 || strcasecmp(prev_wd, "MOVE") == 0)
	{
		char	   *list_FETCH1[] = {"FORWARD", "BACKWARD", "RELATIVE", NULL};

		COMPLETE_WITH_LIST(list_FETCH1);
	}
	/* Complete FETCH <sth> with one of ALL, NEXT, PRIOR */
	else if (strcasecmp(prev2_wd, "FETCH") == 0 || strcasecmp(prev2_wd, "MOVE") == 0)
	{
		char	   *list_FETCH2[] = {"ALL", "NEXT", "PRIOR", NULL};

		COMPLETE_WITH_LIST(list_FETCH2);
	}

	/*
	 * Complete FETCH <sth1> <sth2> with "FROM" or "TO". (Is there a
	 * difference? If not, remove one.)
	 */
	else if (strcasecmp(prev3_wd, "FETCH") == 0 || strcasecmp(prev3_wd, "MOVE") == 0)
	{
		char	   *list_FROMTO[] = {"FROM", "TO", NULL};

		COMPLETE_WITH_LIST(list_FROMTO);
	}

/* GRANT && REVOKE*/
	/* Complete GRANT/REVOKE with a list of privileges */
	else if (strcasecmp(prev_wd, "GRANT") == 0 || strcasecmp(prev_wd, "REVOKE") == 0)
	{
		char	   *list_privileg[] = {"SELECT", "INSERT", "UPDATE", "DELETE", "RULE", "REFERENCES", "TRIGGER", "CREATE", "TEMPORARY", "EXECUTE", "USAGE", "ALL", NULL};

		COMPLETE_WITH_LIST(list_privileg);
	}
	/* Complete GRANT/REVOKE <sth> with "ON" */
	else if (strcasecmp(prev2_wd, "GRANT") == 0 || strcasecmp(prev2_wd, "REVOKE") == 0)
		COMPLETE_WITH_CONST("ON");

	/*
	 * Complete GRANT/REVOKE <sth> ON with a list of tables, views,
	 * sequences, and indexes
	 *
	 * XXX should also offer DATABASE, FUNCTION, LANGUAGE, SCHEMA here
	 */
	else if ((strcasecmp(prev3_wd, "GRANT") == 0 || strcasecmp(prev3_wd, "REVOKE") == 0) &&
			 strcasecmp(prev_wd, "ON") == 0)
		COMPLETE_WITH_QUERY("SELECT relname FROM pg_catalog.pg_class "
							"WHERE relkind in ('r','i','S','v') AND "
							"substr(relname,1,%d)='%s' AND pg_catalog.pg_table_is_visible(oid)");
	/* Complete "GRANT * ON * " with "TO" */
	else if (strcasecmp(prev4_wd, "GRANT") == 0 && strcasecmp(prev2_wd, "ON") == 0)
		COMPLETE_WITH_CONST("TO");
	/* Complete "REVOKE * ON * " with "FROM" */
	else if (strcasecmp(prev4_wd, "REVOKE") == 0 && strcasecmp(prev2_wd, "ON") == 0)
		COMPLETE_WITH_CONST("FROM");

	/*
	 * TODO: to complete with user name we need prev5_wd -- wait for a
	 * more general solution there
	 */

/* INSERT */
	/* Complete INSERT with "INTO" */
	else if (strcasecmp(prev_wd, "INSERT") == 0)
		COMPLETE_WITH_CONST("INTO");
	/* Complete INSERT INTO with table names */
	else if (strcasecmp(prev2_wd, "INSERT") == 0 && strcasecmp(prev_wd, "INTO") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);
	/* Complete "INSERT INTO <table> (" with attribute names */
	else if (rl_line_buffer[start - 1] == '(' && strcasecmp(prev3_wd, "INSERT") == 0 && strcasecmp(prev2_wd, "INTO") == 0)
		COMPLETE_WITH_ATTR(prev_wd);

	/*
	 * Complete INSERT INTO <table> with "VALUES" or "SELECT" or "DEFAULT
	 * VALUES"
	 */
	else if (strcasecmp(prev3_wd, "INSERT") == 0 && strcasecmp(prev2_wd, "INTO") == 0)
	{
		char	   *list_INSERT[] = {"DEFAULT VALUES", "SELECT", "VALUES", NULL};

		COMPLETE_WITH_LIST(list_INSERT);
	}
	/* Complete INSERT INTO <table> (attribs) with "VALUES" or "SELECT" */
	else if (strcasecmp(prev4_wd, "INSERT") == 0 && strcasecmp(prev3_wd, "INTO") == 0 &&
			 prev_wd[strlen(prev_wd) - 1] == ')')
	{
		char	   *list_INSERT[] = {"SELECT", "VALUES", NULL};

		COMPLETE_WITH_LIST(list_INSERT);
	}

	/* Insert an open parenthesis after "VALUES" */
	else if (strcasecmp(prev_wd, "VALUES") == 0 && strcasecmp(prev2_wd, "DEFAULT") != 0)
		COMPLETE_WITH_CONST("(");

/* LOCK */
	/* Complete LOCK [TABLE] with a list of tables */
	else if ((strcasecmp(prev_wd, "LOCK") == 0) ||
	 (strcasecmp(prev_wd, "TABLE") == 0 && strcasecmp(prev2_wd, "LOCK")))
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);

	/* For the following, handle the case of a single table only for now */

	/* Complete LOCK [TABLE] <table> with "IN" */
	else if ((strcasecmp(prev2_wd, "LOCK") == 0 && strcasecmp(prev_wd, "TABLE")) ||
			 (strcasecmp(prev2_wd, "TABLE") == 0 && strcasecmp(prev3_wd, "LOCK") == 0))
		COMPLETE_WITH_CONST("IN");

	/* Complete LOCK [TABLE] <table> IN with a lock mode */
	else if (strcasecmp(prev_wd, "IN") == 0 &&
			 (strcasecmp(prev3_wd, "LOCK") == 0 ||
	(strcasecmp(prev3_wd, "TABLE") == 0 && strcasecmp(prev3_wd, "LOCK"))))
	{
		char	   *lock_modes[] = {"ACCESS SHARE MODE", "ROW SHARE MODE", "ROW EXCLUSIVE MODE",
			"SHARE UPDATE EXCLUSIVE MODE", "SHARE MODE", "SHARE ROW EXCLUSIVE MODE",
		"EXCLUSIVE MODE", "ACCESS EXCLUSIVE MODE", NULL};

		COMPLETE_WITH_LIST(lock_modes);
	}

/* NOTIFY */
	else if (strcasecmp(prev_wd, "NOTIFY") == 0)
		COMPLETE_WITH_QUERY("SELECT relname FROM pg_catalog.pg_listener WHERE substr(relname,1,%d)='%s'");

/* REINDEX */
	else if (strcasecmp(prev_wd, "REINDEX") == 0)
	{
		char	   *list_REINDEX[] = {"TABLE", "DATABASE", "INDEX", NULL};

		COMPLETE_WITH_LIST(list_REINDEX);
	}
	else if (strcasecmp(prev2_wd, "REINDEX") == 0)
	{
		if (strcasecmp(prev_wd, "TABLE") == 0)
			COMPLETE_WITH_QUERY(Query_for_list_of_tables);
		else if (strcasecmp(prev_wd, "DATABASE") == 0)
			COMPLETE_WITH_QUERY(Query_for_list_of_databases);
		else if (strcasecmp(prev_wd, "INDEX") == 0)
			COMPLETE_WITH_QUERY(Query_for_list_of_indexes);
	}

/* SELECT */
	/* naah . . . */

/* SET, RESET, SHOW */
	/* Complete with a variable name */
	else if ((strcasecmp(prev_wd, "SET") == 0 && strcasecmp(prev3_wd, "UPDATE") != 0) ||
			 strcasecmp(prev_wd, "RESET") == 0 ||
			 strcasecmp(prev_wd, "SHOW") == 0)
		COMPLETE_WITH_LIST(pgsql_variables);
	/* Complete "SET TRANSACTION ISOLOLATION LEVEL" */
	else if (strcasecmp(prev2_wd, "SET") == 0 && strcasecmp(prev_wd, "TRANSACTION") == 0)
		COMPLETE_WITH_CONST("ISOLATION");
	else if (strcasecmp(prev3_wd, "SET") == 0 &&
			 strcasecmp(prev2_wd, "TRANSACTION") == 0 &&
			 strcasecmp(prev_wd, "ISOLATION") == 0)
		COMPLETE_WITH_CONST("LEVEL");
	else if ((strcasecmp(prev4_wd, "SET") == 0 || strcasecmp(prev4_wd, "AS") == 0) &&
			 strcasecmp(prev3_wd, "TRANSACTION") == 0 &&
			 strcasecmp(prev2_wd, "ISOLATION") == 0 &&
			 strcasecmp(prev_wd, "LEVEL") == 0)
	{
		char	   *my_list[] = {"READ", "SERIALIZABLE", NULL};

		COMPLETE_WITH_LIST(my_list);
	}
	else if (strcasecmp(prev4_wd, "TRANSACTION") == 0 &&
			 strcasecmp(prev3_wd, "ISOLATION") == 0 &&
			 strcasecmp(prev2_wd, "LEVEL") == 0 &&
			 strcasecmp(prev_wd, "READ") == 0)
		COMPLETE_WITH_CONST("COMMITTED");
	/* Complete SET CONSTRAINTS <foo> with DEFERRED|IMMEDIATE */
	else if (strcasecmp(prev3_wd, "SET") == 0 && strcasecmp(prev2_wd, "CONSTRAINTS") == 0)
	{
		char	   *constraint_list[] = {"DEFERRED", "IMMEDIATE", NULL};

		COMPLETE_WITH_LIST(constraint_list);
	}
	/* Complete SET SESSION with AUTHORIZATION or CHARACTERISTICS... */
	else if (strcasecmp(prev2_wd, "SET") == 0 && strcasecmp(prev_wd, "SESSION") == 0)
	{
		char	   *my_list[] = {"AUTHORIZATION",
			"CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL",
		NULL};

		COMPLETE_WITH_LIST(my_list);
	}
	/* Complete SET SESSION AUTHORIZATION with username */
	else if (strcasecmp(prev3_wd, "SET") == 0
			 && strcasecmp(prev2_wd, "SESSION") == 0
			 && strcasecmp(prev_wd, "AUTHORIZATION") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_users);
	/* Complete SET <var> with "TO" */
	else if (strcasecmp(prev2_wd, "SET") == 0 &&
			 strcasecmp(prev4_wd, "UPDATE") != 0)
		COMPLETE_WITH_CONST("TO");
	/* Suggest possible variable values */
	else if (strcasecmp(prev3_wd, "SET") == 0 &&
		   (strcasecmp(prev_wd, "TO") == 0 || strcmp(prev_wd, "=") == 0))
	{
		if (strcasecmp(prev2_wd, "DateStyle") == 0)
		{
			char	   *my_list[] = {"'ISO'", "'SQL'", "'Postgres'", "'European'", "'NonEuropean'", "'German'", "DEFAULT", NULL};

			COMPLETE_WITH_LIST(my_list);
		}
		else if (strcasecmp(prev2_wd, "GEQO") == 0)
		{
			char	   *my_list[] = {"ON", "OFF", "DEFAULT", NULL};

			COMPLETE_WITH_LIST(my_list);
		}
		else
		{
			char	   *my_list[] = {"DEFAULT", NULL};

			COMPLETE_WITH_LIST(my_list);
		}
	}

/* TRUNCATE */
	else if (strcasecmp(prev_wd, "TRUNCATE") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);

/* UNLISTEN */
	else if (strcasecmp(prev_wd, "UNLISTEN") == 0)
		COMPLETE_WITH_QUERY("SELECT relname FROM pg_catalog.pg_listener WHERE substr(relname,1,%d)='%s' UNION SELECT '*'::name");

/* UPDATE */
	/* If prev. word is UPDATE suggest a list of tables */
	else if (strcasecmp(prev_wd, "UPDATE") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);
	/* Complete UPDATE <table> with "SET" */
	else if (strcasecmp(prev2_wd, "UPDATE") == 0)
		COMPLETE_WITH_CONST("SET");

	/*
	 * If the previous word is SET (and it wasn't caught above as the
	 * _first_ word) the word before it was (hopefully) a table name and
	 * we'll now make a list of attributes.
	 */
	else if (strcasecmp(prev_wd, "SET") == 0)
		COMPLETE_WITH_ATTR(prev2_wd);

/* VACUUM */
	else if (strcasecmp(prev_wd, "VACUUM") == 0)
		COMPLETE_WITH_QUERY("SELECT relname FROM pg_catalog.pg_class WHERE relkind='r' and substr(relname,1,%d)='%s' and pg_catalog.pg_table_is_visible(oid) UNION SELECT 'FULL'::name UNION SELECT 'ANALYZE'::name");
	else if (strcasecmp(prev2_wd, "VACUUM") == 0 && (strcasecmp(prev_wd, "FULL") == 0 || strcasecmp(prev_wd, "ANALYZE") == 0))
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);

/* WHERE */
	/* Simple case of the word before the where being the table name */
	else if (strcasecmp(prev_wd, "WHERE") == 0)
		COMPLETE_WITH_ATTR(prev2_wd);

/* ... FROM ... */
	else if (strcasecmp(prev_wd, "FROM") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);


/* Backslash commands */
	else if (strcmp(prev_wd, "\\connect") == 0 || strcmp(prev_wd, "\\c") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_databases);
	else if (strcmp(prev_wd, "\\d") == 0)
		COMPLETE_WITH_QUERY(Query_for_list_of_tables);
	else if (strcmp(prev_wd, "\\h") == 0 || strcmp(prev_wd, "\\help") == 0)
		COMPLETE_WITH_LIST(sql_commands);
	else if (strcmp(prev_wd, "\\pset") == 0)
	{
		char	   *my_list[] = {"format", "border", "expanded", "null", "fieldsep",
			"tuples_only", "title", "tableattr", "pager",
		"recordsep", NULL};

		COMPLETE_WITH_LIST(my_list);
	}
	else if (strcmp(prev_wd, "\\cd") == 0 ||
		 strcmp(prev_wd, "\\e") == 0 || strcmp(prev_wd, "\\edit") == 0 ||
			 strcmp(prev_wd, "\\g") == 0 ||
			 strcmp(prev_wd, "\\i") == 0 || strcmp(prev_wd, "\\include") == 0 ||
		  strcmp(prev_wd, "\\o") == 0 || strcmp(prev_wd, "\\out") == 0 ||
			 strcmp(prev_wd, "\\s") == 0 ||
		   strcmp(prev_wd, "\\w") == 0 || strcmp(prev_wd, "\\write") == 0
		)
		matches = completion_matches(text, filename_completion_function);


	/*
	 * Finally, we look through the list of "things", such as TABLE, INDEX
	 * and check if that was the previous word. If so, execute the query
	 * to get a list of them.
	 */
	else
	{
		int			i;

		for (i = 0; words_after_create[i].name; i++)
			if (strcasecmp(prev_wd, words_after_create[i].name) == 0)
			{
				COMPLETE_WITH_QUERY(words_after_create[i].query);
				break;
			}
	}


	/*
	 * If we still don't have anything to match we have to fabricate some
	 * sort of default list. If we were to just return NULL, readline
	 * automatically attempts filename completion, and that's usually no
	 * good.
	 */
	if (matches == NULL)
	{
		COMPLETE_WITH_CONST("");
#ifdef HAVE_RL_COMPLETION_APPEND_CHARACTER
		rl_completion_append_character = '\0';
#endif
	}


	/* free storage */
	free(prev_wd);
	free(prev2_wd);
	free(prev3_wd);
	free(prev4_wd);

	/* Return our Grand List O' Matches */
	return matches;
}



/* GENERATOR FUNCTIONS

   These functions do all the actual work of completing the input. They get
   passed the text so far and the count how many times they have been called so
   far with the same text.
   If you read the above carefully, you'll see that these don't get called
   directly but through the readline interface.
   The return value is expected to be the full completion of the text, going
   through a list each time, or NULL if there are no more matches. The string
   will be free()'d be readline, so you must run it through strdup() or
   something of that sort.
*/

/* This one gives you one from a list of things you can put after CREATE or DROP
   as defined above.
*/
static char *
create_command_generator(char *text, int state)
{
	static int	list_index,
				string_length;
	char	   *name;

	/* If this is the first time for this completion, init some values */
	if (state == 0)
	{
		list_index = 0;
		string_length = strlen(text);
	}

	/* find something that matches */
	while ((name = words_after_create[list_index++].name))
		if (strncasecmp(name, text, string_length) == 0)
			return xstrdup(name);

	/* if nothing matches, return NULL */
	return NULL;
}


/* This creates a list of matching things, according to a query pointed to
   by completion_charp. The query needs to have a %d and a %s in it, which will
   be replaced by the string length of the text and the text itself. See some
   example queries at the top.
   The query may also have another %s in it, which will be replaced by the value
   of completion_info_charp.
   Ordinarily this would be used to get a list of matching tables or functions,
   etc.
*/
static char *
complete_from_query(char *text, int state)
{
	static int	list_index,
				string_length;
	static PGresult *result = NULL;
	char		query_buffer[BUF_SIZE];
	const char *item;

	/*
	 * If this ist the first time for this completion, we fetch a list of
	 * our "things" from the backend.
	 */
	if (state == 0)
	{
		list_index = 0;
		string_length = strlen(text);

		/* Need to have a query */
		if (completion_charp == NULL)
			return NULL;

		if (snprintf(query_buffer, BUF_SIZE, completion_charp, string_length, text, completion_info_charp) == -1)
		{
			ERROR_QUERY_TOO_LONG;
			return NULL;
		}

		result = exec_query(query_buffer);
	}

	/* Find something that matches */
	if (result && PQresultStatus(result) == PGRES_TUPLES_OK)
		while (list_index < PQntuples(result) && (item = PQgetvalue(result, list_index++, 0)))
			if (strncasecmp(text, item, string_length) == 0)
				return xstrdup(item);

	/* If nothing matches, free the db structure and return null */
	PQclear(result);
	result = NULL;
	return NULL;
}


/* This function returns in order one of a fixed, NULL pointer terminated list
   of strings (if matching). This can be used if there are only a fixed number
   SQL words that can appear at certain spot.
*/
static char *
complete_from_list(char *text, int state)
{
	static int	string_length,
				list_index;
	char	   *item;

	/* need to have a list */
#ifdef USE_ASSERT_CHECKING
	assert(completion_charpp);
#endif

	/* Initialization */
	if (state == 0)
	{
		list_index = 0;
		string_length = strlen(text);
	}

	while ((item = completion_charpp[list_index++]))
		if (strncasecmp(text, item, string_length) == 0)
			return xstrdup(item);

	/* If no more matches, return null. */
	return NULL;
}


/* This function returns one fixed string the first time even if it doesn't
   match what's there, and nothing the second time. This should be used if there
   is only one possibility that can appear at a certain spot, so misspellings
   will be overwritten.
   The string to be passed must be in completion_charp.
*/
static char *
complete_from_const(char *text, int state)
{
	(void) text;				/* We don't care about what was entered
								 * already. */

#ifdef USE_ASSERT_CHECKING
	assert(completion_charp);
#endif
	if (state == 0)
		return xstrdup(completion_charp);
	else
		return NULL;
}



/* HELPER FUNCTIONS */


/* Execute a query and report any errors. This should be the preferred way of
   talking to the database in this file.
   Note that the query passed in here must not have a semicolon at the end
   because we need to append LIMIT xxx.
*/
static PGresult *
exec_query(char *query)
{
	PGresult   *result;
	char		query_buffer[BUF_SIZE];

	if (query == NULL || !pset.db || PQstatus(pset.db) != CONNECTION_OK)
		return NULL;
#ifdef USE_ASSERT_CHECKING
	assert(query[strlen(query) - 1] != ';');
#endif

	if (snprintf(query_buffer, BUF_SIZE, "%s LIMIT %d;", query, completion_max_records) == -1)
	{
		ERROR_QUERY_TOO_LONG;
		return NULL;
	}

	result = PQexec(pset.db, query);

	if (result != NULL && PQresultStatus(result) != PGRES_TUPLES_OK)
	{
#if 0
		psql_error("tab completion: %s failed - %s\n",
				   query, PQresStatus(PQresultStatus(result)));
#endif
		PQclear(result);
		result = NULL;
	}

	return result;
}



/* Return the word (space delimited) before point. Set skip > 0 to skip that
   many words; e.g. skip=1 finds the word before the previous one.
*/
static char *
previous_word(int point, int skip)
{
	int			i,
				start = 0,
				end = -1,
				inquotes = 0;
	char	   *s;

	while (skip-- >= 0)
	{
		/* first we look for a space before the current word */
		for (i = point; i >= 0; i--)
			if (rl_line_buffer[i] == ' ')
				break;

		/* now find the first non-space which then constitutes the end */
		for (; i >= 0; i--)
			if (rl_line_buffer[i] != ' ')
			{
				end = i;
				break;
			}

		/*
		 * If no end found we return null, because there is no word before
		 * the point
		 */
		if (end == -1)
			return NULL;

		/*
		 * Otherwise we now look for the start. The start is either the
		 * last character before any space going backwards from the end,
		 * or it's simply character 0
		 */
		for (start = end; start > 0; start--)
		{
			if (rl_line_buffer[start] == '"')
				inquotes = !inquotes;
			if ((rl_line_buffer[start - 1] == ' ') && inquotes == 0)
				break;
		}

		point = start;
	}

	/* make a copy */
	s = (char *) malloc(end - start + 2);
	if (!s)
	{
		psql_error("out of memory\n");
		if (!pset.cur_cmd_interactive)
			exit(EXIT_FAILURE);
		else
			return NULL;
	}

	strncpy(s, &rl_line_buffer[start], end - start + 1);
	s[end - start + 1] = '\0';

	return s;
}



#if 0

/*
 * Surround a string with single quotes. This works for both SQL and
 * psql internal. Currently disable because it is reported not to
 * cooperate with certain versions of readline.
 */
char *
quote_file_name(char *text, int match_type, char *quote_pointer)
{
	char	   *s;
	size_t		length;

	(void) quote_pointer;		/* not used */

	length = strlen(text) +(match_type == SINGLE_MATCH ? 3 : 2);
	s = malloc(length);
	s[0] = '\'';
	strcpy(s + 1, text);
	if (match_type == SINGLE_MATCH)
		s[length - 2] = '\'';
	s[length - 1] = '\0';
	return s;
}



static char *
dequote_file_name(char *text, char quote_char)
{
	char	   *s;
	size_t		length;

	if (!quote_char)
		return xstrdup(text);

	length = strlen(text);
	s = malloc(length - 2 + 1);
	strncpy(s, text +1, length - 2);
	s[length] = '\0';

	return s;
}
#endif   /* 0 */

#endif   /* USE_READLINE */
