//
//  SPDatabaseData.m
//  sequel-pro
//
//  Created by Stuart Connolly (stuconnolly.com) on May 20, 2009.
//  Copyright (c) 2009 Stuart Connolly. All rights reserved.
//
//  Permission is hereby granted, free of charge, to any person
//  obtaining a copy of this software and associated documentation
//  files (the "Software"), to deal in the Software without
//  restriction, including without limitation the rights to use,
//  copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the
//  Software is furnished to do so, subject to the following
//  conditions:
//
//  The above copyright notice and this permission notice shall be
//  included in all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
//  OTHER DEALINGS IN THE SOFTWARE.
//
//  More info at <https://github.com/sequelpro/sequelpro>

#import "SPDatabaseData.h"
#import "SPServerSupport.h"
#import "SPDatabaseCharacterSets.h"

#import <SPMySQL/SPMySQL.h>

@interface SPDatabaseData ()

- (NSString *)_getSingleVariableValue:(NSString *)variable;
- (NSArray *)_getDatabaseDataForQuery:(NSString *)query;
+ (NSArray *)_relabelCollationResult:(NSArray *)data;

NSInteger _sortMySQL4CharsetEntry(NSDictionary *itemOne, NSDictionary *itemTwo, void *context);
NSInteger _sortMySQL4CollationEntry(NSDictionary *itemOne, NSDictionary *itemTwo, void *context);
NSInteger _sortStorageEngineEntry(NSDictionary *itemOne, NSDictionary *itemTwo, void *context);

@end

@implementation SPDatabaseData

@synthesize connection;
@synthesize serverSupport;

#pragma mark -
#pragma mark Initialisation

- (id)init
{
	if ((self = [super init])) {
		characterSetEncoding = nil;
		defaultCollationForCharacterSet = nil;
		defaultCollation = nil;
		defaultCharacterSetEncoding = nil;
		serverDefaultCollation = nil;
		serverDefaultCharacterSetEncoding = nil;
		
		collations             = [[NSMutableArray alloc] init];
		characterSetCollations = [[NSMutableArray alloc] init];
		storageEngines         = [[NSMutableArray alloc] init];
		characterSetEncodings  = [[NSMutableArray alloc] init];
		
		cachedCollationsByEncoding = [[NSMutableDictionary alloc] init];
		
		charsetCollationLock = [[NSObject alloc] init];
	}
	
	return self;
}

#pragma mark -
#pragma mark Public API

/**
 * Reset all the cached values.
 *
 * This method is NOT thread-safe! (except for charset/collation data)
 */
- (void)resetAllData
{
	[storageEngines removeAllObjects];
	
	@synchronized(charsetCollationLock) {
		SPClear(characterSetEncoding);
		SPClear(defaultCollationForCharacterSet);
		SPClear(defaultCharacterSetEncoding);
		SPClear(defaultCollation);
		SPClear(serverDefaultCharacterSetEncoding);
		SPClear(serverDefaultCollation);
		
		[collations removeAllObjects];
		[characterSetEncodings removeAllObjects];
		[characterSetCollations removeAllObjects];
	}
}

/**
 * Returns all of the database's currently available collations by querying information_schema.collations.
 *
 * This method is thread-safe.
 */
- (NSArray *)getDatabaseCollations
{
	@synchronized(charsetCollationLock) {
		if ([collations count] == 0) {
			
			// Try to retrieve the available collations from the database
			if ([serverSupport supportsInformationSchema]) {
				[collations addObjectsFromArray:[self _getDatabaseDataForQuery:@"SELECT * FROM `information_schema`.`collations` ORDER BY `collation_name` ASC"]];	
			}
			else if([serverSupport supportsShowCollation]) {
				//use the 4.1-style query
				NSArray *supportedCollations = [self _getDatabaseDataForQuery:@"SHOW COLLATION"];
				//apply the sorting
				supportedCollations = [supportedCollations sortedArrayUsingFunction:_sortMySQL4CollationEntry context:nil];
				//convert the output to the information_schema style
				[collations addObjectsFromArray:[SPDatabaseData _relabelCollationResult:supportedCollations]];
			}
			
			// If that failed, get the list of collations from the hard-coded list
			if (![collations count]) {
				const SPDatabaseCharSets *c = SPGetDatabaseCharacterSets();
#warning This probably won't work as intended. See my comment in getDatabaseCollationsForEncoding:
				do {
					[collations addObject:@{
						@"ID"                 : @(c->nr),
						@"CHARACTER_SET_NAME" : [NSString stringWithCString:c->name encoding:NSUTF8StringEncoding],
						@"COLLATION_NAME"     : [NSString stringWithCString:c->collation encoding:NSUTF8StringEncoding],
						// description is not present in information_schema.collations
					}];
					
					++c;
				} 
				while (c->nr != 0);
			}
		}
			
		return [NSArray arrayWithArray:collations];
	}
}

/**
 * Returns all of the database's currently available collations allowed for the supplied encoding by 
 * querying information_schema.collations.
 *
 * This method is thread-safe.
 */ 
- (NSArray *)getDatabaseCollationsForEncoding:(NSString *)encoding
{
	@synchronized(charsetCollationLock) {
		if (encoding && ((characterSetEncoding == nil) || (![characterSetEncoding isEqualToString:encoding]) || ([characterSetCollations count] == 0))) {
			
			[characterSetEncoding release];
			SPClear(defaultCollationForCharacterSet); //depends on encoding
			[characterSetCollations removeAllObjects];
			
			characterSetEncoding = [[NSString alloc] initWithString:encoding];

			NSArray *cachedCollations = [cachedCollationsByEncoding objectForKey:characterSetEncoding];
			if([cachedCollations count]) {
				[characterSetCollations addObjectsFromArray:cachedCollations];
				goto copy_return;
			}

			// Try to retrieve the available collations for the supplied encoding from the database
			if ([serverSupport supportsInformationSchema]) {
				[characterSetCollations addObjectsFromArray:[self _getDatabaseDataForQuery:[NSString stringWithFormat:@"SELECT * FROM `information_schema`.`collations` WHERE character_set_name = '%@' ORDER BY `collation_name` ASC", characterSetEncoding]]];
			}
			else if([serverSupport supportsShowCollation]) {
				//use the 4.1-style query (as every collation name starts with the charset name we can use the prefix search)
				NSArray *supportedCollations = [self _getDatabaseDataForQuery:[NSString stringWithFormat:@"SHOW COLLATION LIKE '%@%%'",characterSetEncoding]];
				//apply the sorting
				supportedCollations = [supportedCollations sortedArrayUsingFunction:_sortMySQL4CollationEntry context:nil];
				
				[characterSetCollations addObjectsFromArray:[SPDatabaseData _relabelCollationResult:supportedCollations]];
			}

			// If that failed, get the list of collations matching the supplied encoding from the hard-coded list
			if (![characterSetCollations count]) {
				const SPDatabaseCharSets *c = SPGetDatabaseCharacterSets();
#warning I don't think this will work. The hardcoded list is supposed to be used with pre 4.1 mysql servers, \
         which don't have information_schema or SHOW COLLATION. But before 4.1 there were no real collations and \
         even the charsets had different names (e.g. charset "latin1_de" which now is "latin1" + "latin1_german2_ci")
				do {
					NSString *charSet = [NSString stringWithCString:c->name encoding:NSUTF8StringEncoding];

					if ([charSet isEqualToString:characterSetEncoding]) {
						[characterSetCollations addObject:@{
							@"COLLATION_NAME" : [NSString stringWithCString:c->collation encoding:NSUTF8StringEncoding]
						}];
					}

					++c;
				} 
				while (c->nr != 0);
			}

			if ([characterSetCollations count]) {
				[cachedCollationsByEncoding setObject:[NSArray arrayWithArray:characterSetCollations] forKey:characterSetEncoding];
			}

		}
copy_return:
		return [NSArray arrayWithArray:characterSetCollations]; //copy because it is a mutable array and we keep changing it
	}
}

/** Get the collation that is marked as default for a given encoding by the server
 * @param encoding The encoding, e.g. @"latin1"
 * @return The default collation (e.g. @"latin1_swedish_ci") or 
 *         nil if either encoding was nil or the server does not provide the neccesary details
 *
 * This method is thread-safe.
 */
- (NSString *)getDefaultCollationForEncoding:(NSString *)encoding
{
	if(!encoding) return nil;
	// if (
	//   - we have not yet fetched info about the default collation OR
	//   - encoding is different than the one we currently know about
	// ) => we need to load it from server, otherwise just return cached value
	@synchronized(charsetCollationLock) {
		if ((defaultCollationForCharacterSet == nil) || (![characterSetEncoding isEqualToString:encoding])) {
			NSArray *cols = [self getDatabaseCollationsForEncoding:encoding]; //will clear stored encoding and collation if neccesary
			for (NSDictionary *collation in cols) {
#warning This won't work for the hardcoded list (see above)
				if([[[collation objectForKey:@"IS_DEFAULT"] lowercaseString] isEqualToString:@"yes"]) {
					defaultCollationForCharacterSet = [[NSString alloc] initWithString:[collation objectForKey:@"COLLATION_NAME"]];
					break;
				}
			}
		}
		return [[defaultCollationForCharacterSet copy] autorelease]; // -copy accepts nil, -stringWithString: does not
	}
}

/** Get the name of the mysql charset a given collation belongs to.
 * @param collation Name of the collation (e.g. "latin1_swedish_ci")
 * @return name of the charset (e.g. "latin1") or nil if unknown
 *
 * According to the MySQL doc every collation can only ever belong to a single charset.
 *
 * This method is thread-safe.
 */
- (NSString *)getEncodingFromCollation:(NSString *)collation {
	if([collation length]) { //shortcut for nil and @""
		for(NSDictionary *coll in [self getDatabaseCollations]) {
			if([[coll objectForKey:@"COLLATION_NAME"] isEqualToString:collation]) {
				return [coll objectForKey:@"CHARACTER_SET_NAME"];
			}
		}
	}
	return nil;
}

/**
 * Returns all of the database's available storage engines.
 *
 * This method is NOT thread-safe!
 */
- (NSArray *)getDatabaseStorageEngines
{	
	if ([storageEngines count] == 0) {
		if ([serverSupport isMySQL3] || [serverSupport isMySQL4]) {
			[storageEngines addObject:@{@"Engine" : @"MyISAM"}];
			
			// Check if InnoDB support is enabled
			NSString *result = [self _getSingleVariableValue:@"have_innodb"];
			
			if(result && [result isEqualToString:@"YES"])
				[storageEngines addObject:@{@"Engine" : @"InnoDB"}];
			
			// Before MySQL 4.1 the MEMORY engine was known as HEAP and the ISAM engine was included
			if ([serverSupport supportsPre41StorageEngines]) {
				[storageEngines addObject:@{@"Engine" : @"HEAP"}];
				[storageEngines addObject:@{@"Engine" : @"ISAM"}];
			}
			else {
				[storageEngines addObject:@{@"Engine" : @"MEMORY"}];
			}
			
			// BLACKHOLE storage engine was added in MySQL 4.1.11
			if ([serverSupport supportsBlackholeStorageEngine]) {
				[storageEngines addObject:@{@"Engine" : @"BLACKHOLE"}];
			}
				
			// ARCHIVE storage engine was added in MySQL 4.1.3
			if ([serverSupport supportsArchiveStorageEngine]) {
				[storageEngines addObject:@{@"Engine" : @"ARCHIVE"}];
			}
			
			// CSV storage engine was added in MySQL 4.1.4
			if ([serverSupport supportsCSVStorageEngine]) {
				[storageEngines addObject:@{@"Engine" : @"CSV"}];
			}
		}
		// The table information_schema.engines didn't exist until MySQL 5.1.5
		else {
			if ([serverSupport supportsInformationSchemaEngines])
			{
				// Check the information_schema.engines table is accessible
				SPMySQLResult *result = [connection queryString:@"SHOW TABLES IN information_schema LIKE 'ENGINES'"];
				
				if ([result numberOfRows] == 1) {
					
					// Table is accessible so get available storage engines
					// Note, that the case of the column names specified in this query are important.
					[storageEngines addObjectsFromArray:[self _getDatabaseDataForQuery:@"SELECT Engine, Support FROM `information_schema`.`engines` WHERE SUPPORT IN ('DEFAULT', 'YES')"]];				
				}
			}
			else {				
				// Get storage engines
				NSArray *engines = [self _getDatabaseDataForQuery:@"SHOW STORAGE ENGINES"];
				
				// We only want to include engines that are supported
				for (NSDictionary *engine in engines) 
				{				
					if (([[engine objectForKey:@"Support"] isEqualToString:@"DEFAULT"]) ||
						([[engine objectForKey:@"Support"] isEqualToString:@"YES"]))
					{
						[storageEngines addObject:engine];
					}
				}				
			}
		}
	}
	
	return [storageEngines sortedArrayUsingFunction:_sortStorageEngineEntry context:nil];
}

/**
 * Returns all of the database's currently available character set encodings 
 * @return [{Charset: 'utf8',Description: 'UTF-8 Unicode', Default collation: 'utf8_general_ci',Maxlen: 3},...]
 *         The Array is never empty and never nil but results might be unreliable.
 *
 * On MySQL 5+ this will query information_schema.character_sets
 * On MySQL 4.1+ this will query SHOW CHARACTER SET
 * Else a hardcoded list will be returned
 *
 * This method is thread-safe.
 */ 
- (NSArray *)getDatabaseCharacterSetEncodings
{
	@synchronized(charsetCollationLock) {
		if ([characterSetEncodings count] == 0) {
			
			// Try to retrieve the available character set encodings from the database
			// Check the information_schema.character_sets table is accessible
			if ([serverSupport supportsInformationSchema]) {
				[characterSetEncodings addObjectsFromArray:[self _getDatabaseDataForQuery:@"SELECT * FROM `information_schema`.`character_sets` ORDER BY `character_set_name` ASC"]];
			} 
			else if ([serverSupport supportsShowCharacterSet]) {
				NSArray *supportedEncodings = [self _getDatabaseDataForQuery:@"SHOW CHARACTER SET"];
				
				supportedEncodings = [supportedEncodings sortedArrayUsingFunction:_sortMySQL4CharsetEntry context:nil];
				
				for (NSDictionary *anEncoding in supportedEncodings) 
				{
					NSDictionary *convertedEncoding = [NSDictionary dictionaryWithObjectsAndKeys:
						[anEncoding objectForKey:@"Charset"],           @"CHARACTER_SET_NAME",
						[anEncoding objectForKey:@"Description"],       @"DESCRIPTION",
						[anEncoding objectForKey:@"Default collation"], @"DEFAULT_COLLATE_NAME",
						[anEncoding objectForKey:@"Maxlen"],            @"MAXLEN",
					nil];
					
					[characterSetEncodings addObject:convertedEncoding];
				}
			}

			// If that failed, get the list of character set encodings from the hard-coded list
			if (![characterSetEncodings count]) {			
				const SPDatabaseCharSets *c = SPGetDatabaseCharacterSets();
#warning This probably won't work as intended. See my comment in getDatabaseCollationsForEncoding:
				do {
					[characterSetEncodings addObject:@{
						@"CHARACTER_SET_NAME" : [NSString stringWithCString:c->name encoding:NSUTF8StringEncoding],
						@"DESCRIPTION"        : [NSString stringWithCString:c->description encoding:NSUTF8StringEncoding]
					}];

					++c;
				} 
				while (c->nr != 0);
			}
		}
			
		return [NSArray arrayWithArray:characterSetEncodings]; //return a copy since we keep changing it
	}
}

/**
 * Returns the databases's default character set encoding.
 *
 * @return The default encoding as a string
 *
 * This method is thread-safe.
 */
- (NSString *)getDatabaseDefaultCharacterSet
{
	@synchronized(charsetCollationLock) {
		if (!defaultCharacterSetEncoding) {
			NSString *variable = [serverSupport supportsCharacterSetAndCollationVars] ? @"character_set_database" : @"character_set";
			
			defaultCharacterSetEncoding = [[self _getSingleVariableValue:variable] retain];
		}
		
		return [[defaultCharacterSetEncoding copy] autorelease];
	}
}

/**
 * Returns the database's default collation.
 *
 * @return The default collation as a string
 *
 * This method is thread-safe.
 */
- (NSString *)getDatabaseDefaultCollation
{
	@synchronized(charsetCollationLock) {
		if (!defaultCollation && [serverSupport supportsCharacterSetAndCollationVars]) {
			defaultCollation = [[self _getSingleVariableValue:@"collation_database"] retain];
		}
			
		return [[defaultCollation copy] autorelease];
	}
}

/**
 * Returns the server's default character set encoding.
 *
 * @return The default encoding as a string
 *
 * This method is thread-safe.
 */
- (NSString *)getServerDefaultCharacterSet
{
	@synchronized(charsetCollationLock) {
		if (!serverDefaultCharacterSetEncoding) {
			NSString *variable = [serverSupport supportsCharacterSetAndCollationVars] ? @"character_set_server" : @"character_set";
			
			serverDefaultCharacterSetEncoding = [[self _getSingleVariableValue:variable] retain];
		}
		
		return [[serverDefaultCharacterSetEncoding copy] autorelease];
	}
}

/**
 * Returns the server's default collation.
 *
 * @return The default collation as a string (nil on MySQL 3 databases)
 *
 * This method is thread-safe.
 */
- (NSString *)getServerDefaultCollation
{
	@synchronized(charsetCollationLock) {
		if (!serverDefaultCollation) {
			serverDefaultCollation = [[self _getSingleVariableValue:@"collation_server"] retain];
		}
		
		return [[serverDefaultCollation copy] autorelease];
	}
}

/**
 * Returns the database's default storage engine.
 *
 * @return The default storage engine as a string
 *
 * This method is NOT thread-safe!
 */
- (NSString *)getDatabaseDefaultStorageEngine
{
	if (!defaultStorageEngine) {

		// Determine which variable to use based on server version.  'table_type' has been available since MySQL 3.23.0.
		NSString *storageEngineKey = @"table_type";

		// Post 5.5, storage_engine was deprecated; use default_storage_engine
		if ([serverSupport isEqualToOrGreaterThanMajorVersion:5 minor:5 release:0]) {
			storageEngineKey = @"default_storage_engine";

		// For the rest of 5.x, use storage_engine
		} else if ([serverSupport isEqualToOrGreaterThanMajorVersion:5 minor:0 release:0]) {
			storageEngineKey = @"storage_engine";
		}

		// Retrieve the corresponding value for the determined key, ensuring return as a string
		defaultStorageEngine = [[self _getSingleVariableValue:storageEngineKey] retain];
	}
	
	return defaultStorageEngine;
}

#pragma mark -
#pragma mark Private API

/**
 * Look up the value of a single server variable
 * @param variable The name of a server variable. Must not contain wildcards
 * @return The value as string or nil if no such variable exists or the result is ambigious
 */
- (NSString *)_getSingleVariableValue:(NSString *)variable
{
	SPMySQLResult *result = [connection queryString:[NSString stringWithFormat:@"SHOW VARIABLES LIKE %@", [variable tickQuotedString]]];;
	
	[result setReturnDataAsStrings:YES];
	
	if([connection queryErrored])
		SPLog(@"server variable lookup failed for '%@': %@ (%lu)",variable,[connection lastErrorMessage],[connection lastErrorID]);
	
	if ([result numberOfRows] != 1)
		return nil;
	
	return [[result getRowAsDictionary] objectForKey:@"Value"];
}

/**
 * Executes the supplied query against the current connection and returns the result as an array of 
 * NSDictionarys, one for each row.
 */
- (NSArray *)_getDatabaseDataForQuery:(NSString *)query
{
	SPMySQLResult *result = [connection queryString:query];
	
	if ([connection queryErrored]) return @[];
	
	[result setReturnDataAsStrings:YES];
	
	return [result getAllRows];
}

/**
 * Converts the output of a MySQL 4.1 style "SHOW COLLATION" to the format of a MySQL 5.0 style "SELECT * FROM information_schema.collations"
 */
+ (NSArray *)_relabelCollationResult:(NSArray *)data
{
	NSMutableArray *outData = [[NSMutableArray alloc] initWithCapacity:[data count]];
	
	for (NSDictionary *aCollation in data)
	{
		NSDictionary *convertedCollation = [NSDictionary dictionaryWithObjectsAndKeys:
											[aCollation objectForKey:@"Collation"], @"COLLATION_NAME",
											[aCollation objectForKey:@"Charset"],   @"CHARACTER_SET_NAME",
											[aCollation objectForKey:@"Id"],        @"ID",
											[aCollation objectForKey:@"Default"],   @"IS_DEFAULT",
											[aCollation objectForKey:@"Compiled"],  @"IS_COMPILED",
											[aCollation objectForKey:@"Sortlen"],   @"SORTLEN",
											nil];
		
		[outData addObject:convertedCollation];
	}
	return [outData autorelease];
}

/**
 * Sorts a 4.1-style SHOW CHARACTER SET result by the Charset key.
 */
NSInteger _sortMySQL4CharsetEntry(NSDictionary *itemOne, NSDictionary *itemTwo, void *context)
{
	return [[itemOne objectForKey:@"Charset"] compare:[itemTwo objectForKey:@"Charset"]];
}

/**
 * Sorts a 4.1-style SHOW COLLATION result by the Collation key.
 */
NSInteger _sortMySQL4CollationEntry(NSDictionary *itemOne, NSDictionary *itemTwo, void *context)
{
	return [[itemOne objectForKey:@"Collation"] compare:[itemTwo objectForKey:@"Collation"]];
}

/**
 * Sorts a storage engine array by the Engine key.
 */
NSInteger _sortStorageEngineEntry(NSDictionary *itemOne, NSDictionary *itemTwo, void *context)
{
	return [[itemOne objectForKey:@"Engine"] compare:[itemTwo objectForKey:@"Engine"]];
}

#pragma mark -
#pragma mark Other

- (void)dealloc
{
	[self resetAllData];
	
	SPClear(storageEngines);
	@synchronized(charsetCollationLock) {
		SPClear(collations);
		SPClear(characterSetEncodings);
		SPClear(characterSetCollations);
		SPClear(cachedCollationsByEncoding);
	}
	SPClear(charsetCollationLock);
	
	[super dealloc];
}

@end