/*
 *	PROGRAM:	Dynamic SQL runtime support
 *	MODULE:		preparse.cpp
 *	DESCRIPTION:	Dynamic SQL pre parser / parser on client side. 
 *			This module will probably change to a YACC parser.
 *
 * The contents of this file are subject to the Interbase Public
 * License Version 1.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy
 * of the License at http://www.Inprise.com/IPL.html
 *
 * Software distributed under the License is distributed on an
 * "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express
 * or implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code was created by Inprise Corporation
 * and its predecessors. Portions created by Inprise Corporation are
 * Copyright (C) Inprise Corporation.
 *
 * All Rights Reserved.
 * Contributor(s): ______________________________________.
 */

#include "firebird.h"
#include <stdlib.h>
#include <string.h>
#include "../jrd/common.h"
#include "../jrd/ibase.h"
#include "../dsql/chars.h"
#include "../dsql/sqlda.h"
#include "../dsql/prepa_proto.h"
#include "../dsql/utld_proto.h"
#include "../jrd/gds_proto.h"

enum pp_vals {
	PP_CREATE = 0,
	PP_DATABASE = 1,
	PP_SCHEMA = 2,
	PP_PAGE_SIZE = 3,
	PP_USER = 4,
	PP_PASSWORD = 5,
	PP_PAGESIZE = 6,
	PP_LENGTH = 7,
	PP_PAGES = 8,
	PP_PAGE = 9,
	PP_SET = 10,
	PP_NAMES = 11
};


const int MAX_TOKEN_SIZE = 1024;


// use stuff_dpb in place of STUFF to avoid confusion with BLR STUFF
// macro defined in dsql.h

static inline void stuff_dpb(SCHAR*& dpb, const SCHAR blr)
{
	*dpb++ = blr;
}

static inline void stuff_dpb_long(SCHAR*& dpb, const SLONG blr)
{
	stuff_dpb(dpb, blr);
	stuff_dpb(dpb, blr >> 8);
	stuff_dpb(dpb, blr >> 16);
	stuff_dpb(dpb, blr >> 24);
}

static void generate_error(ISC_STATUS*, const SCHAR*, SSHORT, SSHORT);
static SSHORT get_next_token(const SCHAR**, const SCHAR*, SCHAR*, USHORT*);
static SSHORT get_token(ISC_STATUS*, SSHORT, bool, const SCHAR**,
	const SCHAR* const, SCHAR*, USHORT*);

struct pp_table {
	SCHAR symbol[10];
	SSHORT length;
	SSHORT code;
};

static const pp_table pp_symbols[] = {
	{"CREATE", 6, PP_CREATE},
	{"DATABASE", 8, PP_DATABASE},
	{"SCHEMA", 6, PP_SCHEMA},
	{"PAGE_SIZE", 9, PP_PAGE_SIZE},
	{"USER", 4, PP_USER},
	{"PASSWORD", 8, PP_PASSWORD},
	{"PAGESIZE", 8, PP_PAGESIZE},
	{"LENGTH", 6, PP_LENGTH},
	{"PAGES", 5, PP_PAGES},
	{"PAGE", 4, PP_PAGE},
	{"SET", 3, PP_SET},
	{"NAMES", 5, PP_NAMES},
	{"", 0, 0}
};

// define the tokens 

enum token_vals {
	NO_MORE_TOKENS = -1,
	TOKEN_TOO_LONG = -2,
	UNEXPECTED_END_OF_COMMAND = -3,
	UNEXPECTED_TOKEN = -4,
	STRING = 257,
	NUMERIC = 258,
	SYMBOL = 259
};

/**
  
 	PREPARSE_execute
  
    @brief

    @param user_status
    @param db_handle
    @param trans_handle
    @param stmt_length
    @param stmt
    @param stmt_eaten
    @param dialect

 **/
bool PREPARSE_execute(
		ISC_STATUS* user_status,
		FB_API_HANDLE* db_handle,
		FB_API_HANDLE* trans_handle,
		USHORT stmt_length,
		const SCHAR* stmt,
		bool* stmt_eaten,
		USHORT dialect)
{
	char* const token = (SCHAR *) gds__alloc((SLONG) MAX_TOKEN_SIZE + 1);
// FREE: by return(s) in this procedure 
	if (!token) {				// NOMEM: 
		user_status[0] = isc_arg_gds;
		user_status[1] = isc_virmemexh;
		user_status[2] = isc_arg_end;
		return false;
	}

	if (!stmt_length)
		stmt_length = strlen(stmt);
	const char* const stmt_end = stmt + stmt_length;

	USHORT token_length;
	if (get_token(user_status, SYMBOL, false, &stmt, stmt_end, token,
				  &token_length) ||
		token_length != pp_symbols[PP_CREATE].length ||
		strcmp(token, pp_symbols[PP_CREATE].symbol)) 
	{
		gds__free((SLONG *) token);
		return false;
	}

	if (get_token(user_status, SYMBOL, false, &stmt, stmt_end, token,
				  &token_length) ||
		(token_length != pp_symbols[PP_DATABASE].length &&
		 token_length != pp_symbols[PP_SCHEMA].length) ||
		(strcmp(token, pp_symbols[PP_DATABASE].symbol) &&
		 strcmp(token, pp_symbols[PP_SCHEMA].symbol))) 
	{
		gds__free((SLONG *) token);
		return false;
	}

	if (get_token(user_status, STRING, false, &stmt, stmt_end, token,
				  &token_length))
	{
		gds__free((SLONG *) token);
		return true;
	}

    TEXT file_name[MAX_TOKEN_SIZE + 1];
	strcpy(file_name, token);
	*stmt_eaten = false;
	char* const dpb_array = (SCHAR*) gds__alloc((SLONG) 2 * MAX_TOKEN_SIZE + 25);
	char* dpb = dpb_array;
// FREE: by following return(s) in this procedure 
	if (!dpb_array) {			// NOMEM: 
		user_status[0] = isc_arg_gds;
		user_status[1] = isc_virmemexh;
		user_status[2] = isc_arg_end;
		gds__free((SLONG *) token);
		return true;
	}

	stuff_dpb(dpb, isc_dpb_version1);
	stuff_dpb(dpb, isc_dpb_overwrite);
	stuff_dpb(dpb, 1);
	stuff_dpb(dpb, 0);
	stuff_dpb(dpb, isc_dpb_sql_dialect);
	stuff_dpb(dpb, 4);
	stuff_dpb_long(dpb, dialect);

	SLONG page_size = 0;
	bool matched;
	do {
		const SSHORT result = get_next_token(&stmt, stmt_end, token, &token_length);
		if (result == NO_MORE_TOKENS) {
			*stmt_eaten = true;
			break;
		}
		else if (result < 0)
			break;

		matched = false;
		for (int i = 3; pp_symbols[i].length && !matched; i++) {
			if (token_length == pp_symbols[i].length &&
				!strcmp(token, pp_symbols[i].symbol)) 
			{
				bool get_out = false;
				SCHAR* ch;
				SSHORT l;
				// CVC: What's strange, this routine doesn't check token_length
				// but it proceeds blindly, trying to exhaust the token itself.

				switch (pp_symbols[i].code) {
				case PP_PAGE_SIZE:
				case PP_PAGESIZE:
					if (get_token(user_status, '=', true, &stmt, stmt_end,
								  token, &token_length) ||
						get_token(user_status, NUMERIC, false, &stmt,
								  stmt_end, token, &token_length))
					{
						get_out = true;
						break;
					}
					page_size = atol(token);
					stuff_dpb(dpb, isc_dpb_page_size);
					stuff_dpb(dpb, 4);
					stuff_dpb_long(dpb, page_size);
					matched = true;
					break;

				case PP_USER:
					if (get_token(user_status, STRING, false, &stmt, stmt_end,
								  token, &token_length))
					{
						get_out = true;
						break;
					}

					stuff_dpb(dpb, isc_dpb_user_name);
					l = token_length;
					stuff_dpb(dpb, l);
					ch = token;
					while (*ch)
						stuff_dpb(dpb, *ch++);
					matched = true;
					break;

				case PP_PASSWORD:
					if (get_token(user_status, STRING, false, &stmt, stmt_end,
								  token, &token_length))
					{
						get_out = true;
						break;
					}

					stuff_dpb(dpb, isc_dpb_password);
					l = token_length;
					stuff_dpb(dpb, l);
					ch = token;
					while (*ch)
						stuff_dpb(dpb, *ch++);
					matched = true;
					break;

				case PP_SET:
					if (get_token(user_status, SYMBOL, false, &stmt, stmt_end,
								  token, &token_length) ||
						token_length != pp_symbols[PP_NAMES].length ||
						strcmp(token, pp_symbols[PP_NAMES].symbol) ||
						get_token(user_status, STRING, false, &stmt, stmt_end,
								  token, &token_length))
					{
						get_out = true;
						break;
					}

					stuff_dpb(dpb, isc_dpb_lc_ctype);
					l = token_length;
					stuff_dpb(dpb, l);
					ch = token;
					while (*ch)
						stuff_dpb(dpb, *ch++);
					matched = true;
					break;

				case PP_LENGTH:
					// Skip a token for value 

					if (get_token(user_status, '=', true, &stmt, stmt_end,
								  token, &token_length) ||
						get_token(user_status, NUMERIC, false, &stmt,
								  stmt_end, token, &token_length))
					{
						get_out = true;
						break;
					}

					matched = true;
					break;

				case PP_PAGE:
				case PP_PAGES:
					matched = true;
					break;
				}

				if (get_out) {
					gds__free((SLONG *) dpb_array);
					gds__free((SLONG *) token);
					return true;
				}
			}
		}

	} while (matched);

	const USHORT dpb_len = dpb - dpb_array;

// This code is because 3.3 server does not recognize isc_dpb_overwrite. 
	FB_API_HANDLE temp_db_handle = 0;
	if (!isc_attach_database(user_status, 0, file_name, &temp_db_handle,
							 dpb_len, dpb_array) ||
		user_status[1] != isc_io_error) {
		if (!user_status[1]) {
			// Swallow status from detach.
			ISC_STATUS_ARRAY temp_status;
			isc_detach_database(temp_status, &temp_db_handle);
		}
		if (!user_status[1] || user_status[1] == isc_bad_db_format) {
			user_status[0] = isc_arg_gds;
			user_status[1] = isc_io_error;
			user_status[2] = isc_arg_string;
			user_status[3] = (ISC_STATUS) "open";
			user_status[4] = isc_arg_string;
			user_status[5] = (ISC_STATUS) file_name;
			user_status[6] = isc_arg_gds;
			user_status[7] = isc_db_or_file_exists;
			user_status[8] = isc_arg_end;
			UTLD_save_status_strings(user_status);
		}
		if (dpb_array)
			gds__free((SLONG *) dpb_array);
		gds__free((SLONG *) token);
		return true;
	}

	isc_create_database(user_status, 0, file_name,
						(db_handle), dpb_len,
						dpb_array, 0);

	if (dpb_array)
		gds__free((SLONG *) dpb_array);
	gds__free((SLONG *) token);

	return true;
}


/**
  
 	generate_error
  
    @brief

    @param user_status
    @param token
    @param error
    @param result

 **/
static void generate_error(
						   ISC_STATUS* user_status,
						   const SCHAR* token, SSHORT error, SSHORT result)
{
	TEXT err_string[MAX_TOKEN_SIZE + 3];

	user_status[0] = isc_arg_gds;
	user_status[1] = isc_sqlerr;
	user_status[2] = isc_arg_number;
	user_status[3] = -104;
	user_status[4] = isc_arg_gds;

	switch (error) {
	case UNEXPECTED_END_OF_COMMAND:
		user_status[5] = isc_command_end_err;
		user_status[6] = isc_arg_end;
		break;

	case UNEXPECTED_TOKEN:
	case TOKEN_TOO_LONG:
		if (result) {
			err_string[0] = (TEXT) result;
			strcpy(err_string + 1, token);
			const size_t length = strlen(token);
			err_string[length + 1] = (TEXT) result;
			err_string[length + 2] = '\0';
		}
		else
			strcpy(err_string, token);
		user_status[5] = isc_token_err;
		user_status[6] = isc_arg_gds;
		user_status[7] = isc_random;
		user_status[8] = isc_arg_string;
		user_status[9] = (ISC_STATUS) err_string;
		user_status[10] = isc_arg_end;
		UTLD_save_status_strings(user_status);
		break;
	}
}


/**
  
 	get_next_token
  
    @brief

    @param stmt
    @param stmt_end
    @param token
    @param token_length

 **/
static SSHORT get_next_token(
							 const SCHAR** stmt,
							 const SCHAR* stmt_end,
							 SCHAR* token, USHORT* token_length)
{
	UCHAR c, char_class;

	*token_length = 0;
	const SCHAR* s = *stmt;

	for (;;) {
		if (s >= stmt_end) {
			*stmt = s;
			return NO_MORE_TOKENS;
		}
		c = *s++;
		if (c == '/' && s < stmt_end && *s == '*') {
			s++;
			while (s < stmt_end) {
				c = *s++;
				if (c == '*' && s < stmt_end && *s == '/')
					break;
			}
			s++;
			continue;
		}
		char_class = classes[c];
		if (!(char_class & CHR_WHITE))
			break;
	}

/* At this point c contains character and class contains character class.
   s is pointing to next character. */

	const SCHAR* const start_of_token = s - 1;

/* In here we handle only 4 cases, STRING, INTEGER, arbitrary
   SYMBOL and single character punctuation. */

// token can be up to MAX_TOKEN_SIZE and 1 is for null termination 

	SCHAR* p = token;
	const char* const token_end = token + MAX_TOKEN_SIZE + 1;
	if (char_class & CHR_QUOTE) {
		for (; p < token_end; p++) {
			if (s >= stmt_end)
				return UNEXPECTED_END_OF_COMMAND;

			/* *s is quote - if next != quote we're at the end */

			if ((*s == c) && ((++s == stmt_end) || (*s != c)))
				break;
			*p = *s++;
		}
		*stmt = s;
		if (p >= token_end) {
			// '=' used as then there is no place for null termination 

			*token_length = MAX_TOKEN_SIZE;
			token[MAX_TOKEN_SIZE] = '\0';
			return TOKEN_TOO_LONG;
		}
		*token_length = (s - start_of_token) - 2;
		*p = '\0';
		return STRING;
	}

/* Is it an integer? */

	if (char_class & CHR_DIGIT) {
		for (; s < stmt_end && (classes[c = *s] & CHR_DIGIT); ++s); // empty body
		const ptrdiff_t length = (s - start_of_token);
		*stmt = s;
		if (length > MAX_TOKEN_SIZE) {
			memcpy(token, start_of_token, MAX_TOKEN_SIZE);
			token[MAX_TOKEN_SIZE] = '\0';
			*token_length = MAX_TOKEN_SIZE;
			return TOKEN_TOO_LONG;
		}
		memcpy(token, start_of_token, length);
		token[length] = '\0';
		*token_length = length;
		return NUMERIC;
	}

// Is is a symbol 

	if (char_class & CHR_LETTER) {
		*p++ = UPPER(c);
		for (; s < stmt_end && (classes[static_cast<UCHAR>(*s)] & CHR_IDENT) && p < token_end; s++) {
			*p++ = UPPER(*s);
		}

		// what happend to token size check. It went to hell 

		*stmt = s;
		if (p >= token_end) {
			*token_length = MAX_TOKEN_SIZE;
			token[MAX_TOKEN_SIZE] = '\0';
			return TOKEN_TOO_LONG;
		}
		*token_length = s - start_of_token;
		*p = 0;
		return SYMBOL;
	}

// What remains at this point for us is the single character punctuation.

	*stmt = s;

	return (c == ';' ? NO_MORE_TOKENS : c);
}


/**
  
 	get_token
  
    @brief

    @param status
    @param token_type
    @param optional
    @param stmt
    @param stmt_end
    @param token
    @param token_length

 **/
static SSHORT get_token(ISC_STATUS* status,
						SSHORT token_type,
						bool optional,
						const SCHAR** stmt,
						const SCHAR* const stmt_end,
						SCHAR* token,
						USHORT* token_length)
{
	const SCHAR* temp_stmt = *stmt;
	const SSHORT result = get_next_token(&temp_stmt, stmt_end, token, token_length);

	switch (result) {
	case NO_MORE_TOKENS:
		*stmt = temp_stmt;
		generate_error(status, token, UNEXPECTED_END_OF_COMMAND, 0);
		return FB_FAILURE;

	case UNEXPECTED_END_OF_COMMAND:
	case TOKEN_TOO_LONG:
		*stmt = temp_stmt;

		// generate error here 

		generate_error(status, token, result, 0);
		return FB_FAILURE;
	}

// Some token was found 

	if (result == token_type) {
		*stmt = temp_stmt;
		return FB_SUCCESS;
	}

	if (optional)
		return FB_SUCCESS;

/* generate error here and return failure; */

	*stmt = temp_stmt;
	generate_error(status, token, UNEXPECTED_TOKEN,
				   (result == STRING) ? *(temp_stmt - 1) : 0);
	return FB_FAILURE;
}