/******************************************************************************
****
****    Database package for the MudOS driver
****
****    History:
****        Sometime:
****            Descartes@Nightmare created and added mSQL support
****
****        Feb 1999:
****            Andrew@Nanvaent restructured to add MySQL support and a
****            framework for other databases to be added.
****
****        Jul 2000:
****            Andrew@Nanvaent's work included in the MudOS proper
****
****    Notes:
****      . This package has been restructured so that it can be compiled into
****        a driver without any database types defined so that you can write
****        stuff without necessarily having the database.
****
****      . No database type has been added that supports commit or rollback,
****        so these functions have not been fully implemented, particularly
****        with regard to error handling.
****
****      . Support for multiple database types is present, if obscure.  When
****        you have multiple types you should have DEFAULT_DB defined to be
****        the default one, and USE_MYSQL/USE_MSQL should be defined to be
****        numbers in the local_options file or equivalent, e.g.:
****            #define USE_MSQL 1
****            #define USE_MYSQL 2
****            #define DEFAULT_DB USE_MSQL
****
****        The value that you defined it to will be that expected when you
****        make a call to db_connect( ... ) as the fourth argument.  Without
****        the fourth argument, the value used will be that for DEFAULT_DB.
****
****      . Adding another database type should involve:
****        + picking your own define name
****        + editing db.h and adding an appropriate member to the dbconn_t
****          union
****        + adding a dbdefn_t definition for it in this file
****        + playing around with the code for deciding between databases in
****          f_db_connect()
****        + writing all the required interface functions as you've defined
****          for the dbdefn_t structure.  Minimum requirements would be
****          connect, close, fetch and execute and cleanup if you need to
****          cleanup memory allocated between searches.
****
****    TODO:
****      . Decent Error Message reporting
****      . Function for showing the current connections (incomplete)
****      . Standardise on return values (only db_exec is nonstandard)
****      . Documentation
****      . Add more databases
****
******************************************************************************/

#include "../std.h"
#include "../md.h"
#include "../master.h"
#include "../lpc_incl.h"
#include "../mapping.h"
#include "../comm.h"
#include "../file_incl.h"
#include "../file.h"
#include "../object.h"
#include "../eoperators.h"
#include "../backend.h"
#include "../swap.h"

#include "db.h"

static int  dbConnAlloc, dbConnUsed;
static db_t *dbConnList;

static db_t * find_db_conn PROT((int));
static int    create_db_conn PROT((void));
static void   free_db_conn PROT((db_t *));

#ifdef USE_MSQL
static int      msql_connect  PROT((dbconn_t *, char *, char *, char *, char *));
static int      msql_close    PROT((dbconn_t *));
static int      msql_execute  PROT((dbconn_t *, char *));
static array_t *msql_fetch    PROT((dbconn_t *, int));
static void     msql_cleanup  PROT((dbconn_t *));
static char *   msql_errormsg PROT((dbconn_t *));

static db_defn_t msql = {
    "mSQL", msql_connect, msql_close, msql_execute, msql_fetch, NULL, NULL, msql_cleanup, NULL, msql_errormsg
};
#endif

#ifdef USE_MYSQL
static int      MySQL_connect  PROT((dbconn_t *, char *, char *, char *, char *));
static int      MySQL_close    PROT((dbconn_t *));
static int      MySQL_execute  PROT((dbconn_t *, char *));
static array_t *MySQL_fetch    PROT((dbconn_t *, int));
static void     MySQL_cleanup  PROT((dbconn_t *));
static char *   MySQL_errormsg PROT((dbconn_t *));

static db_defn_t mysql = {
    "MySQL", MySQL_connect, MySQL_close, MySQL_execute, MySQL_fetch, NULL, NULL, MySQL_cleanup, NULL, MySQL_errormsg
};
#endif

static db_defn_t no_db = {
    "None", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL
};

/* valid_database
 *
 * Calls APPLY_VALID_DATABASE in the master object to provide some
 * security on which objects can tweak your database (we don't want
 * people doing "DELETE * FROM *" or equivalent for us)
 */
static svalue_t *valid_database P2(char *, action, array_t *, info)
{
    svalue_t *ret;

    /*
     * Call valid_database(object ob, string action, mixed *info)
     *
     * Return: string - password for access
     *         int    - 1 for no password, accept, 0 deny
     */
    push_object(current_object);
    push_constant_string(action);
    push_refed_array(info);

    ret = apply_master_ob(APPLY_VALID_DATABASE, 3);
    if (ret && (ret == (svalue_t *)-1 || (ret->type == T_STRING || (ret->type == T_NUMBER && ret->u.number))))
	return ret;

    error("Database security violation attempted\n");
}

/* int db_close(int handle);
 *
 * Closes the connection to the database represented by the named handle
 *
 * Returns 1 on success, 0 on failure
 */
#ifdef F_DB_CLOSE
void f_db_close PROT((void))
{
    int ret = 0;
    db_t *db;
    
    valid_database("close", &the_null_array);

    db = find_db_conn(sp->u.number);
    if (!db) {
	error("Attempt to close an invalid database handle\n");
    }

    /* Cleanup any memory structures left around */
    if (db->type->cleanup) {
	db->type->cleanup(&(db->c));
    }

    if (db->type->close) {
	ret = db->type->close(&(db->c));
    }

    /* Remove the entry from the linked list */
    free_db_conn(db);

    sp->u.number = ret;
}
#endif

/* int db_commit(int handle);
 *
 * Commits the last set of transactions to the database
 * NOTE: MSQL does not have transaction logic, so since
 * MSQL is the only thing supported now, this does nothing
 * I have put it in, however, so people can write properly
 * portable LPC code
 *
 * Returns 1 on success, 0 on failure
 */
#ifdef F_DB_COMMIT
void f_db_commit PROT((void))
{
    int ret = 0;
    db_t *db;

    valid_database("commit", &the_null_array);

    db = find_db_conn(sp->u.number);
    if (!db) {
	error("Attempt to commit an invalid database handle\n");
    }

    if (db->type->commit) {
	ret = db->type->commit(&(db->c));
    }

    sp->u.number = ret;
}
#endif

/* int db_connect(string host, string database, string user, int type)
 *
 * Creates a database connection to the database named by the
 * second argument found on the host named by the first argument.
 * Note that this means you can connect to database servers running on
 * machines other than the one on which the mud is running.  It will
 * connect based on settings established at compile time for the
 * user id and password (if required).
 *
 * Returns a new database handle.
 */
#ifdef F_DB_CONNECT
void f_db_connect PROT((void))
{
    char *database, *host, *user = "", *errormsg = 0;
    db_t *db;
    array_t *info;
    svalue_t *mret;
    int handle, ret = 0, args = 0, type;

#ifdef DEFAULT_DB
    type = DEFAULT_DB;
#else
    type = 0;
#endif

    switch (st_num_arg) {
	case 4: type     = (sp - (args++))->u.number;
	case 3: user     = (sp - (args++))->u.string;
	case 2: database = (sp - (args++))->u.string;
	case 1: host     = (sp - (args++))->u.string;
    }

    info = allocate_empty_array(3);
    info->item[0].type = info->item[1].type = info->item[2].type = T_STRING;
    info->item[0].subtype = info->item[1].subtype = info->item[2].subtype = STRING_MALLOC;
    info->item[0].u.string = string_copy(database, "f_db_connect:1");
    if (*host)
	info->item[1].u.string = string_copy(host, "f_db_connect:2");
    else
	info->item[1] = const0;
    info->item[2].u.string = string_copy(user, "f_db_connect:3");

    mret = valid_database("connect", info);

    handle = create_db_conn();
    if (!handle) {
	pop_n_elems(args);
	push_number(0);
	return;
    }
    db = find_db_conn(handle);

    switch (type) {
	default:
	    /* fallthrough */
#ifdef USE_MSQL
#if USE_MSQL - 0
	case USE_MSQL:
#endif
	    db->type = &msql;
	    break;
#endif
#ifdef USE_MYSQL
#if USE_MYSQL - 0
	case USE_MYSQL:
#endif
	    db->type = &mysql;
	    break;
#endif
    }

    if (db->type->connect) {
	ret = db->type->connect(&(db->c), host, database, user,
		(mret != (svalue_t *)-1 && mret->type == T_STRING ? mret->u.string : 0));
    }

    pop_n_elems(args);

    if (!ret) {
	if (db->type->error) {
	    errormsg = db->type->error(&(db->c));
	    push_malloced_string(errormsg);
	} else {
	    push_number(0);
	}
	free_db_conn(db);
    } else {
	push_number(handle);
    }
}
#endif

/* mixed db_exec(int handle, string sql)
 *
 * Executes the SQL statement passed for the named connection handle.
 * If data needs to be retrieved from this execution, it should be done
 * through db_fetch() after making the call to db_exec()
 *
 * Returns number of rows in result set on success, an error string on failure
 * NOTE: the number of rows on INSERT, UPDATE, and DELETE statements will
 * be zero since there is no result set.
 */
#ifdef F_DB_EXEC
void f_db_exec PROT((void))
{
    int ret = 0;
    char *errormsg;
    db_t *db;
    array_t *info;

    info = allocate_empty_array(1);
    info->item[0].type = T_STRING;
    info->item[0].subtype = STRING_MALLOC;
    info->item[0].u.string = string_copy(sp->u.string, "f_db_exec");
    valid_database("exec", info);

    db = find_db_conn((sp-1)->u.number);
    if (!db) {
	error("Attempt to exec on an invalid database handle\n");
    }

    if (db->type->cleanup) {
	db->type->cleanup(&(db->c));
    }

    if (db->type->execute) {
	ret = db->type->execute(&(db->c), sp->u.string);
    }

    pop_stack();
    if (ret == -1) {
	if (db->type->error) {
	    char *errormsg;

	    errormsg = db->type->error(&(db->c));
	    put_malloced_string(errormsg);
	} else {
	    put_constant_string("Unknown error");
	}
    } else {
	sp->u.number = ret;
    }
}
#endif

/* array db_fetch(int db_handle, int row);
 *
 * Returns the result set from the last database transaction
 * performed through db_exec() on the db handle in question for the row
 * named.  For example, db_exec(10, "SELECT player_name from t_player") might
 * have returned two rows.  Typical code to extract that data might be:
 *     string *res;
 *     mixed rows;
 *     int dbconn, i;
 *
 *     dbconn = db_connect("nightmare.imaginary.com", "db_mud");
 *     if( dbconn < 1 ) return 0;
 *     rows = db_exec(dbconn, "SELECT player_name from t_player");
 *     if( !rows ) write("No rows returned.");
 *     else if( stringp(rows) ) write(rows);
 *     else for(i=1; i<=rows; i++) {
 *         res = db_fetch(dbconn, i);
 *         write(res[0]);
 *     }
 *     db_close(dbconn);
 *     return 1;
 *
 * Returns an array of columns from the named row on success.
 */
#ifdef F_DB_FETCH
void f_db_fetch PROT((void))
{
    db_t *db;
    array_t *ret;

    valid_database("fetch", &the_null_array);

    db = find_db_conn((sp-1)->u.number);
    if (!db) {
	error("Attempt to fetch from an invalid database handle\n");
    }

    if (db->type->fetch) {
	ret = db->type->fetch(&(db->c), sp->u.number);
    } else {
	ret = &the_null_array;
    }

    pop_stack();
    if (!ret) {
	if (db->type->error) {
	    char *errormsg;

	    errormsg = db->type->error(&(db->c));
	    put_malloced_string(errormsg);
	} else {
	    sp->u.number = 0;
	}
    } else {
	put_array(ret);
    }
}
#endif

/* int db_rollback(int handle)
 *
 * Rollsback all db_exec() calls back to the last db_commit() call for the
 * named connection handle.
 * NOTE: MSQL does not support rollbacks
 *
 * Returns 1 on success, 0 on failure
 */
#ifdef F_DB_ROLLBACK
void f_db_rollback PROT((void))
{
    int ret = 0;
    db_t *db;

    valid_database("rollback", &the_null_array);

    db = find_db_conn(sp->u.number);
    if (!db) {
	error("Attempt to rollback an invalid database handle\n");
    }

    if (db->type->rollback) {
	ret = db->type->rollback(&(db->c));
    }

    if (ret > 0) {
	if (db->type->cleanup) {
	    db->type->cleanup(&(db->c));
	}
    }

    sp->u.number = ret;
}
#endif

/* string db_status()
 *
 * Returns a string describing the database package's current status
 */
#ifdef F_DB_STATUS
void f_db_status PROT((void))
{
    int i;
    outbuffer_t out;

    outbuf_zero(&out);

    for (i = 0;  i < dbConnAlloc;  i++) {
	if (dbConnList[i].flags & DB_FLAG_EMPTY) {
	    continue;
	}

	outbuf_addv(&out, "Handle: %d (%s)\n", i + 1, dbConnList[i].type->name);
	if (dbConnList[i].type->status != NULL) {
	    dbConnList[i].type->status(&(dbConnList[i].c), &out);
	}
    }

    outbuf_push(&out);
}
#endif

void db_cleanup PROT((void))
{
    int i;

    for (i = 0;  i < dbConnAlloc;  i++) {
	if (!(dbConnList[i].flags & DB_FLAG_EMPTY)) {
	    if (dbConnList[i].type->cleanup) {
		dbConnList[i].type->cleanup(&(dbConnList[i].c));
	    }

	    if (dbConnList[i].type->close) {
		dbConnList[i].type->close(&(dbConnList[i].c));
	    }

	    dbConnList[i].flags = DB_FLAG_EMPTY;
	    dbConnUsed--;
	}
    }
}

int create_db_conn PROT((void))
{
    int i;

    /* allocate more slots if we need them */
    if (dbConnAlloc == dbConnUsed) {
	i = dbConnAlloc;
	dbConnAlloc += 10;
	if (!dbConnList) {
	    dbConnList = CALLOCATE(dbConnAlloc, db_t, TAG_DB, "create_db_conn");
	} else {
	    dbConnList = RESIZE(dbConnList, dbConnAlloc, db_t, TAG_DB, "create_db_conn");
	}
	while (i < dbConnAlloc) {
	    dbConnList[i++].flags = DB_FLAG_EMPTY;
	}
    }

    for (i = 0;  i < dbConnAlloc;  i++) {
	if (dbConnList[i].flags & DB_FLAG_EMPTY) {
	    dbConnList[i].flags = 0;
	    dbConnList[i].type = &no_db;
	    dbConnUsed++;
	    return i + 1;
	}
    }

    fatal("dbConnAlloc != dbConnUsed, but no empty slots");
}

db_t *find_db_conn P1(int, handle)
{
    if (handle < 1 || handle > dbConnAlloc || dbConnList[handle - 1].flags & DB_FLAG_EMPTY)
	return 0;
    return &(dbConnList[handle - 1]);
}

void free_db_conn P1(db_t *, db)
{
    DEBUG_CHECK(db->flags & DB_FLAG_EMPTY, "Freeing DB connection that is already freed\n");
    DEBUG_CHECK(!dbConnUsed, "Freeing DB connection when dbConnUsed == 0\n");
    dbConnUsed--;
    db->flags |= DB_FLAG_EMPTY;
}

/*
 * MySQL support
 */
#ifdef USE_MYSQL
static void MySQL_cleanup P1(dbconn_t *, c)
{
    *(c->mysql.errormsg) = 0;
    if (c->mysql.results) {
	mysql_free_result(c->mysql.results);
	c->mysql.results = 0;
    }
}

static char *MySQL_errormsg P1(dbconn_t *, c)
{
    if (*(c->mysql.errormsg)) {
	return string_copy(c->mysql.errormsg, "MySQL_errormsg:1");
    }

    return string_copy(mysql_error(c->mysql.handle), "MySQL_errormsg:2");
}

static int MySQL_close P1(dbconn_t *, c)
{
    mysql_close(c->mysql.handle);
    FREE(c->mysql.handle);
    c->mysql.handle = 0;

    return 1;
}

static int MySQL_execute P2(dbconn_t *, c, char *, s)
{
    if (!mysql_query(c->mysql.handle, s)) {
	c->mysql.results = mysql_store_result(c->mysql.handle);
	if (c->mysql.results) {
	    return mysql_num_rows(c->mysql.results);
	}

	/* Queries returning no input can return a NULL handle */
	if (!mysql_errno(c->mysql.handle)) {
	    return 0;
	}
    }

    return -1;
}

static array_t *MySQL_fetch P2(dbconn_t *, c, int, row)
{
    array_t *v;
    MYSQL_ROW target_row;
    unsigned int i, num_fields;

    if (!c->mysql.results) {
	return &the_null_array;
    }
    if (row < 1 || row > mysql_num_rows(c->mysql.results)) {
	return &the_null_array;
    }

    num_fields = mysql_num_fields(c->mysql.results);
    if (num_fields < 1) {
	return &the_null_array;
    }

    mysql_data_seek(c->mysql.results, row - 1);
    target_row = mysql_fetch_row(c->mysql.results);
    if (!target_row) {
	return &the_null_array;
    }

    v = allocate_empty_array(num_fields);
    for (i = 0;  i < num_fields;  i++) {
	MYSQL_FIELD *field;

	field = mysql_fetch_field(c->mysql.results);
	if (!field) {
	    v->item[i] = const0u;
	} else {
	    switch (field->type) {
		case FIELD_TYPE_TINY:
		case FIELD_TYPE_SHORT:
		case FIELD_TYPE_DECIMAL:
		case FIELD_TYPE_LONG:
		    v->item[i].type = T_NUMBER;
		    v->item[i].u.number = atoi(target_row[i]);
		    break;

		case FIELD_TYPE_FLOAT:
		case FIELD_TYPE_DOUBLE:
		    v->item[i].type = T_REAL;
		    v->item[i].u.real = atof(target_row[i]);
		    break;

		case FIELD_TYPE_TINY_BLOB:
		case FIELD_TYPE_MEDIUM_BLOB:
		case FIELD_TYPE_LONG_BLOB:
		case FIELD_TYPE_BLOB:
		case FIELD_TYPE_STRING:
		case FIELD_TYPE_VAR_STRING:
                    if (field->flags & BINARY_FLAG) {
#ifndef NO_BUFFER_TYPE
		        v->item[i].type = T_BUFFER;
		        v->item[i].u.buf = allocate_buffer(field->length);
		        write_buffer(v->item[i].u.buf, 0, target_row[i], field->length);
#else
                        v->item[i] = const0u;
#endif
                    } else {
		        v->item[i].type = T_STRING;
		        if (target_row[i]) {
			    v->item[i].subtype = STRING_MALLOC;
			    v->item[i].u.string = string_copy(target_row[i], "MySQL_fetch");
		        } else {
			    v->item[i].subtype = STRING_CONSTANT;
			    v->item[i].u.string = "";
		        }
                    }
		    break;

		default:
		    v->item[i] = const0u;
		    break;
	    }
	}
    }

    mysql_field_seek(c->mysql.results, 0);
    return v;
}

static int MySQL_connect P5(dbconn_t *, c, char *, host, char *, database, char *, username, char *, password)
{
    int ret;
    MYSQL *tmp;

    tmp = ALLOCATE(MYSQL, TAG_DB, "MySQL_connect");
    *(c->mysql.errormsg) = 0;

    c->mysql.handle = mysql_connect(tmp, host, username, password);
    if (!c->mysql.handle) {
	strncpy(c->mysql.errormsg, mysql_error(tmp), sizeof(c->mysql.errormsg));
	c->mysql.errormsg[sizeof(c->mysql.errormsg) - 1] = 0;
	FREE(tmp);
	return 0;
    }

    ret = mysql_select_db(c->mysql.handle, database);
    if (ret) {
	strncpy(c->mysql.errormsg, mysql_error(c->mysql.handle), sizeof(c->mysql.errormsg));
	c->mysql.errormsg[sizeof(c->mysql.errormsg) - 1] = 0;
	mysql_close(c->mysql.handle);
	c->mysql.handle = 0;
	FREE(tmp);
	return 0;
    }

    c->mysql.results = 0;
    return 1;
}
#endif

/*
 * mSQL support
 */
#ifdef USE_MSQL
static void msql_cleanup P1(dbconn_t *, c)
{
    if (c->msql.result_set) {
	msqlFreeResult(c->msql.result_set);
	c->msql.result_set = 0;
    }
}

static int msql_close P1(dbconn_t *, c)
{
    msqlClose(c->msql.handle);
    c->msql.handle = -1;

    return 1;
}

static int msql_execute P2(dbconn_t *, c, char *, s)
{
    if (msqlQuery(c->msql.handle, s) != -1) {
	c->msql.result_set = msqlStoreResult();
	if (!c->msql.result_set) {
	    /* Query was an UPDATE or INSERT or DELETE */
	    return 0;
	}
	return msqlNumRows(c->msql.result_set);
    }

    return -1;
}

static array_t *msql_fetch P2(dbconn_t *, c, int, row)
{
    int i, num_fields;
    m_row this_row;
    array_t *v;

    if (!c->msql.result_set) {
	return &the_null_array;
    }
    if (row < 1 || row > msqlNumRows(c->msql.result_set)) {
	return &the_null_array;
    }

    num_fields = msqlNumFields(c->msql.result_set);
    if (num_fields < 1) {
	return &the_null_array;
    }

    msqlDataSeek(c->msql.result_set, row - 1);
    this_row = msqlFetchRow(c->msql.result_set);
    if (!this_row) {
	return &the_null_array;
    }

    v = allocate_empty_array(num_fields);
    for (i = 0;  i < num_fields;  i++) {
	m_field *field;

	field = msqlFetchField(c->msql.result_set);
	if (!field || !this_row[i]) {
	    v->item[i] = const0u;
	} else {
	    switch (field->type) {
		case INT_TYPE:
		case UINT_TYPE:
		    v->item[i].type = T_NUMBER;
		    v->item[i].u.number = atoi(this_row[i]);
		    break;

		case REAL_TYPE:
		case MONEY_TYPE:
		    v->item[i].type = T_REAL;
		    v->item[i].u.real = atof(this_row[i]);
		    break;

		case CHAR_TYPE:
		case TEXT_TYPE:
		case DATE_TYPE:
		case TIME_TYPE:
		    v->item[i].type = T_STRING;
		    v->item[i].subtype = STRING_MALLOC;
		    v->item[i].u.string = string_copy(this_row[i], "msql_fetch");
		    break;

		default:
		    v->item[i] = const0u;
		    break;
	    }
	}
    }

    msqlFieldSeek(c->msql.result_set, 0);
    return v;
}

static int msql_connect P5(dbconn_t *, c, char *, host, char *, database, char *, username, char *, password)
{
    c->msql.handle = msqlConnect(host);
    if (c->msql.handle < 1) {
	return 0;
    }

    if (msqlSelectDB(c->msql.handle, database) == -1) {
	msqlClose(c->msql.handle);
	return 0;
    }

    c->msql.result_set = 0;
    return 1;
}

static char *msql_errormsg P1(dbconn_t *, c)
{
    return string_copy(msqlErrMsg, "msql_errormsg");
}
#endif