#import "Database.h"
#import <sqlite/sqlite.h>
#import <cmath>
#import <vector>

@implementation Database {
    sqlite3* $db;
}

// Maxinum number of variables per query, https://www.sqlite.org/c3ref/c_limit_attached.html#sqlitelimitvariablenumber.
// Actual number is 32766. We use 32666 to add a buffer in the event that other variables
const NSInteger MAX_VARIABLE_COUNT = 32666;

- (id _Nonnull) initWithPath:(NSURL*_Nonnull) path openFlags:(int) openFlags busyTimeout:(int) busyTimeout error:(NSError*_Nullable*_Nonnull) error
{
    const char * cxxPath = [[path path] UTF8String];

    NSURL* filePath = [path URLByDeletingLastPathComponent];
    NSFileManager* fs = [[NSFileManager alloc] init];
    if (![fs fileExistsAtPath:[filePath path]]) {
        NSError* fsError;
        [fs createDirectoryAtURL:filePath withIntermediateDirectories:true attributes:nil error:&fsError];
        if (fsError) {
            *error = [[NSError alloc]
                initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
                code:SQLITE_CANTOPEN
                userInfo:@{
                    NSLocalizedDescriptionKey: [NSString stringWithFormat:@"Could not make directories for path (%s)", cxxPath],
                    NSUnderlyingErrorKey: fsError
                }
            ];
            return self;
        }
    }

    int status = sqlite3_open_v2(cxxPath, &(self->$db), openFlags, nullptr);
    if (status != SQLITE_OK) {
        *error = [[NSError alloc]
            initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
            code:status
            userInfo:@{
                NSLocalizedDescriptionKey: [NSString stringWithFormat:@"%s (%s)", sqlite3_errstr(status), cxxPath]
            }
        ];
        return self;
    }

    sqlite3_busy_timeout(self->$db, busyTimeout);

    return self;
}

- (nullable NSNumber*) getHandle {
    return [[NSNumber alloc] initWithLong:(long)self->$db];
}

- (NSArray*_Nullable) run:(NSString*_Nonnull) sql params:(NSDictionary*_Nullable) params error:(NSError*_Nullable*_Nonnull) error {
    sqlite3_stmt* statement;
    
    NSMutableArray* arrayKeys = [[NSMutableArray alloc] init];
    if (![params isEqual:[NSNull null]]) {
        NSArray* keys = [params allKeys];
        for (NSUInteger i = 0, count = [keys count]; i < count; ++i) {
            if ([[params objectForKey:keys[i]] isKindOfClass:[NSArray class]]) {
                [arrayKeys addObject:keys[i]];
            }
        }
    }
    
    if ([arrayKeys count] != 0) {
        NSMutableDictionary* newParams = [NSMutableDictionary dictionaryWithDictionary:params];
        for (NSUInteger i = 0, count = [arrayKeys count]; i < count; ++i) {
            NSString* key = arrayKeys[i];
            NSString* colonKey = [@":" stringByAppendingString:key];
            NSArray* value = [params objectForKey:key];
            // The range that respresents the old parameter name.
            NSRange range = [sql rangeOfString: colonKey];
            
            // Remove old param name
            [newParams removeObjectForKey:key];
            
            while (range.location != NSNotFound) {
                // Remove old param name.
                sql = [sql stringByReplacingCharactersInRange:range withString:@""];
                NSMutableString* newParamsString = [[NSMutableString alloc] init];
                for (NSUInteger vi = 0, vcount = [value count]; vi < vcount; ++vi) {
                    // :$ + key + "_" + vi
                    // The $ serves 2 purposes
                    // 1 - ensures paramName is different for array parameter key. E.X :ids will not match with :$ids_0.
                    // 2 - $ is a reserved character for parameter names and is not included in the parameter format enforcement of the plugin.
                    NSMutableString* paramName = [NSMutableString stringWithFormat:@"%@%@%@%lu", @"$", key, @"_", (unsigned long)vi];
                    // Add new param name with the value
                    [newParams setValue:value[vi] forKey:paramName];
                    [paramName insertString:@":" atIndex:0];
                    
                    // If this is not the last new param, add a comma
                    if (vi + 1 < vcount) {
                        [paramName appendString:@","];
                    }
                    [newParamsString appendString:paramName];
                }
            
                // Insert new params into the sql
                sql = [sql stringByReplacingCharactersInRange:NSMakeRange(range.location, 0) withString:newParamsString];


                // Search for duplicate param name of old param name. Note earlier we removed the first occurrence of old param name. The second occurrence, if any, is now the first occurrence.
                range = [sql rangeOfString: colonKey];
            }
        }
        params = newParams;
    }
    
    const char * cxxSql = [sql UTF8String];
    int status = sqlite3_prepare_v2(self->$db, cxxSql, (int)strlen(cxxSql), &statement, 0);
    if (status != SQLITE_OK) {
        *error = [[NSError alloc]
            initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
            code:status
            userInfo:@{
                NSLocalizedDescriptionKey: [NSString stringWithUTF8String:sqlite3_errstr(status)],
                ERROR_DETAILS_KEY: @{
                    ERROR_QUERY_KEY: sql
                }
            }
        ];
        sqlite3_finalize(statement);
        return nil;
    }

    [self $bindParams:statement params:params error: error];
    if (*error != nil) {
        sqlite3_finalize(statement);
        return nil;
    }
    
    NSMutableArray* results = [[NSMutableArray alloc] init];
    int columnCount = sqlite3_column_count(statement);
    
    while (true) {
        int status = sqlite3_step(statement);

        if (status == SQLITE_ROW) {
            [results addObject:[self $buildRowObject:statement columnCount: columnCount error: error]];
                if (*error != nil) {
                    sqlite3_finalize(statement);
                    return nil;
                }
        }
        else if (status == SQLITE_DONE) {
            break;
        }
        else {
            *error = [[NSError alloc]
                initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
                code:status
                userInfo:@{
                    NSLocalizedDescriptionKey: [NSString stringWithUTF8String:sqlite3_errstr(status)],
                    ERROR_DETAILS_KEY: @{
                        ERROR_QUERY_KEY: sql
                    }
                }
            ];
            sqlite3_finalize(statement);
            return nil;
        }
    }
    
    sqlite3_finalize(statement);
    
    return [[NSArray alloc] initWithArray:results];
}

- (void) bulkRun:(NSString*_Nonnull) sql params:(NSArray*_Nullable) params error:(NSError*_Nullable*_Nonnull) error {
    sqlite3_stmt* statement;
    int status;
    
    // Prepare VALUES string
    NSInteger rows = [params count];
    // It is invalid to have a variable number of columns, so assume the column count is the same across all rows is okay.
    NSInteger columns = [params[0] count];

    NSInteger chunkSize = floor((double)MAX_VARIABLE_COUNT / (double)columns);
    NSInteger iterationsRequired = ceil((double)rows / (double)chunkSize);
    NSInteger lastIterationLength = rows - (chunkSize * (iterationsRequired - 1));

    /*
        (columns * 2) - last comma + ( and )
        (?,?)
        (2 * 2) - 1 + 2
        4 + 1
        5
    */
    NSUInteger rowStringCapacity = (columns * 2) - 1 + 2;
    // Each row of values will look the exact same while they are unbounded. For that reason, let's prepare a string that we can re-use.
    NSMutableString* row = [NSMutableString stringWithCapacity:rowStringCapacity];
    [row appendString:@"("];
    for (NSInteger i = 0; i < columns; ++i) {
        [row appendString:@"?"];
        if ((i + 1) < columns) {
            [row appendString:@","];
        }
    }
    [row appendString:@")"];
    
    /*
        (rows * rowStringCapacity) + commas - last comma + "VALUES "
        VALUES (?,?),(?,?)
        (2 * 5) + 2 - 1 + 7
        10 + 8
        18
    */
    NSUInteger valuesStringCapacity = (chunkSize * rowStringCapacity) + chunkSize - 1 + 7;
    NSInteger lastIterationValuesStringCapacity = (lastIterationLength * rowStringCapacity) + lastIterationLength - 1 + 7;
    // Use our prepared re-useable row string to actually prepare the VALUES string.
    NSMutableString* values = [NSMutableString stringWithCapacity:valuesStringCapacity];
    [values appendString:@"VALUES "];
    for (NSInteger i = 0; i < chunkSize; ++i) {
        [values appendString:row];
        if ((i + 1) < chunkSize) {
            [values appendString:@","];
        }
    }
    
    NSMutableString* lastIterationValues = [NSMutableString stringWithCapacity:lastIterationValuesStringCapacity];
    [lastIterationValues appendString:@"VALUES "];
    for (NSInteger i = 0; i < lastIterationLength; ++i) {
        [lastIterationValues appendString:row];
        if ((i + 1) < lastIterationLength) {
            [lastIterationValues appendString:@","];
        }
    }
    
    // Replace :BulkInsertValue with VALUES string
    NSRange range = [sql rangeOfString: @":BulkInsertValue"];
    NSString* chunkSql = [sql stringByReplacingCharactersInRange:range withString:values];
    
    const char * cxxSql = [chunkSql UTF8String];
    status = sqlite3_prepare_v2(self->$db, cxxSql, (int)strlen(cxxSql), &statement, 0);
    if (status != SQLITE_OK) {
        *error = [[NSError alloc]
            initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
            code:status
            userInfo:@{
                NSLocalizedDescriptionKey: [NSString stringWithUTF8String:sqlite3_errstr(status)],
                ERROR_DETAILS_KEY: @{
                    ERROR_QUERY_KEY: chunkSql
                }
            }
        ];
        sqlite3_finalize(statement);
        return;
    }
    
    for (NSInteger i = 0; i < iterationsRequired; ++i) {
        NSInteger varsStartIndex = i * chunkSize;
        NSInteger varsEndIndex;
        
        if (i + 1 == iterationsRequired) {
            varsEndIndex = varsStartIndex + lastIterationLength;
            chunkSql = [sql stringByReplacingCharactersInRange:range withString:lastIterationValues];
            
            sqlite3_finalize(statement);
            const char * cxxSql = [chunkSql UTF8String];
            status = sqlite3_prepare_v2(self->$db, cxxSql, (int)strlen(cxxSql), &statement, 0);
            if (status != SQLITE_OK) {
                *error = [[NSError alloc]
                    initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
                    code:status
                    userInfo:@{
                        NSLocalizedDescriptionKey: [NSString stringWithUTF8String:sqlite3_errstr(status)],
                        ERROR_DETAILS_KEY: @{
                            ERROR_QUERY_KEY: chunkSql
                        }
                    }
                ];
                sqlite3_finalize(statement);
                return;
            }
        }
        else {
            varsEndIndex = (i + 1) * chunkSize;
        }
        
        sqlite3_reset(statement);
        [self $bindBulkParams:statement params:params startIndex: varsStartIndex endIndex: varsEndIndex error: error];
        if (*error != nil) {
            sqlite3_finalize(statement);
            return;
        }
        status = sqlite3_step(statement);
        if (status != SQLITE_DONE) {
            *error = [[NSError alloc]
                initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
                code:status
                userInfo:@{
                    NSLocalizedDescriptionKey: [NSString stringWithUTF8String:sqlite3_errstr(status)],
                    ERROR_DETAILS_KEY: @{
                        ERROR_QUERY_KEY: chunkSql
                    }
                }
            ];
            return;
        }
    }
    sqlite3_finalize(statement);
}

- (void) close {
    sqlite3_close_v2(self->$db);
}

- (void) $bindBulkParams:(sqlite3_stmt*_Nonnull) statement params:(NSArray*_Nonnull) params startIndex:(NSInteger) startIndex endIndex:(NSInteger) endIndex error:(NSError*_Nullable*_Nonnull) error {
    // index is 1-base: https://www.sqlite.org/c3ref/bind_blob.html
    int index = 0;
    for (NSInteger x = startIndex; x < endIndex; ++x) {
        NSArray* row = params[x];
        for (NSInteger y = 0, ylength = [row count]; y < ylength; ++y) {
            index++;
            
            [self $bindParam:statement
                index:index
                value:row[y]
        parameterKeyForError:[NSString stringWithFormat:@"%@@%ld%@%ld%@", @"params[", (long)x, @"][", (long)y, @"]"]
                error:error
            ];
            if (*error != nil) {
                return;
            }
        }
    }
}

- (void) $bindParams:(sqlite3_stmt*_Nonnull) statement params:(NSDictionary*_Nullable) params error:(NSError*_Nullable*_Nonnull) error {
    if (![params isEqual:[NSNull null]]) {
        for (NSString* key in params) {
            id value = [params valueForKey:key];
            int index = [TPISQLiteUtilities lookupVariableIndex:statement var:key];
            if (index == 0) {
                *error = [[NSError alloc]
                    initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
                    code: TPISQLite_ERROR_CODE_BIND_PARAMETER_ERROR
                    userInfo:@{
                        NSLocalizedDescriptionKey: [NSString stringWithFormat: @"Could not bind parameter \"%@\"", key],
                        ERROR_DETAILS_KEY: @{
                            ERROR_QUERY_KEY: [NSString stringWithUTF8String: sqlite3_sql(statement)]
                        }
                    }
                ];
                return;
            }

            [self $bindParam:statement index:index value:value parameterKeyForError:key error:error];
            if (*error != nil) {
                return;
            }
        }
    }
}

- (void) $bindParam:(sqlite3_stmt*_Nonnull) statement index:(int) index value:(id _Nullable) value parameterKeyForError:(NSString*_Nonnull) parameterKeyForError error:(NSError*_Nullable*_Nonnull) error {
    int status;

    if ([value isEqual:[NSNull null]] || value == nil) {
        status = sqlite3_bind_null(statement, index);
    }
    else if ([value isKindOfClass:[NSString class]]) {
        const char * val = [value UTF8String];
        status = sqlite3_bind_text(statement, index, val, (int)strlen(val), SQLITE_TRANSIENT);
    }
    else if ([value isKindOfClass:[NSNumber class]]) {
        if (fmod([value doubleValue], 1) == 0.0) {
            status = sqlite3_bind_int64(statement, index, [value longValue]);
        }
        else {
            status = sqlite3_bind_double(statement, index, [value doubleValue]);
        }
    }
    else if ([value isKindOfClass:[NSDictionary class]]) {
        NSDictionary* val = value;
        NSString* objType = [val objectForKey:@"type"];
        if ([objType isEqual: @"bytearray"]) {
            NSArray* jByteArray = [val objectForKey:@"value"];
            std::vector<uint8_t> bytes(jByteArray.count);
            for (int i = 0, length = (int)jByteArray.count; i < length; ++i) {
                bytes[i] = [((NSNumber*)[jByteArray objectAtIndex:i]) intValue] & 0xFF;
            }
            status = sqlite3_bind_blob(statement, index, &bytes, (int)jByteArray.count - 1, SQLITE_TRANSIENT);
        }
        else {
            *error = [[NSError alloc]
                initWithDomain:ERROR_DOMAIN
                code:ERROR_CODE_UNHANDLED_PARAMETER_TYPE
                userInfo:@{
                    NSLocalizedDescriptionKey: [NSString stringWithFormat: @"Unhandled Complex Parameter Object for type \"%@\"", objType],
                    ERROR_DETAILS_KEY: @{
                        ERROR_QUERY_KEY: [NSString stringWithUTF8String: sqlite3_sql(statement)]
                    }
                }
            ];
            return;
        }
    }
    else {
        *error = [[NSError alloc]
            initWithDomain:ERROR_DOMAIN
            code:ERROR_CODE_UNHANDLED_PARAMETER_TYPE
            userInfo:@{
                NSLocalizedDescriptionKey: [NSString stringWithFormat: @"Unhandled Parameter Type for key \"%@\"", parameterKeyForError],
                ERROR_DETAILS_KEY: @{
                    ERROR_QUERY_KEY: [NSString stringWithUTF8String: sqlite3_sql(statement)]
                }
            }
        ];
        return;
    }

    if (status != SQLITE_OK) {
        *error = [[NSError alloc]
            initWithDomain: [TPISQLite_SQLITE_ERROR_DOMAIN mutableCopy]
            code: status
            userInfo:@{
                NSLocalizedDescriptionKey: [NSString stringWithUTF8String:sqlite3_errstr(status)],
                ERROR_DETAILS_KEY: @{
                    ERROR_QUERY_KEY: [NSString stringWithUTF8String: sqlite3_sql(statement)]
                }
            }
        ];
        return;
    }
}

- (NSDictionary*_Nullable) $buildRowObject:(sqlite3_stmt*_Nonnull) statement columnCount:(int) columnCount error:(NSError*_Nullable*_Nonnull) error {
    NSMutableDictionary* row = [[NSMutableDictionary alloc] initWithCapacity:columnCount];
    
    for (int i = 0; i < columnCount; i++) {
        int columnType = sqlite3_column_type(statement, i);
        NSString* columnName = [NSString stringWithUTF8String: sqlite3_column_name(statement, i)];
        id value;
        if (columnType == SQLITE_INTEGER) {
            value = [NSNumber numberWithLong: sqlite3_column_int64(statement, i)];
        }
        else if (columnType == SQLITE_FLOAT) {
            value = [NSNumber numberWithDouble: sqlite3_column_double(statement, i)];
        }
        else if (columnType == SQLITE_TEXT) {
            value = [NSString stringWithUTF8String: (const char *)sqlite3_column_text(statement, i)];
        }
        else if (columnType == SQLITE_BLOB) {
            value = [[NSArray alloc] init];
            const unsigned char * bytes = (unsigned char *)sqlite3_column_blob(statement, i);
            int length = sqlite3_column_bytes(statement, i);
            for (int i = 0; i < length; i++) {
                [value addObject:[NSNumber numberWithInt: bytes[i]]];
            }
        }
        else if (columnType == SQLITE_NULL) {
            value = [NSNull null];
        }
        else {
            *error = [[NSError alloc]
                initWithDomain:ERROR_DOMAIN
                code:ERROR_CODE_UNSUPPORTED_COLUMN_TYPE
                userInfo:@{
                    NSLocalizedDescriptionKey: [NSString stringWithFormat: @"Unhandled Column Type \"%d\"", columnType],
                    ERROR_DETAILS_KEY: @{
                        ERROR_QUERY_KEY: [NSString stringWithUTF8String: sqlite3_sql(statement)]
                    }
                }
            ];
            return nil;
        }
        [row setValue:value forKey:columnName];
    }
    
    return [[NSDictionary alloc] initWithDictionary:row];
}

@end