<?php namespace DBDiff\SQLGen\Dialect;

class MySQLDialect implements SQLDialectInterface {

public function quote(string $name): string {

return '`' . str_replace('`', '``', $name) . '`';

}

public function getDriver(): string {

return 'mysql';

}

public function isMySQLOnly(): bool {

return true;

}

public function dropIndex(string $table, string $key): string {

$t = $this->quote($table);

if ($key === 'PRIMARY') {

return "ALTER TABLE $t DROP PRIMARY KEY;";

}

$k = $this->quote($key);

return "ALTER TABLE $t DROP INDEX $k;";

}

public function dropTrigger(string $trigger, string $table): string {

return "DROP TRIGGER IF EXISTS " . $this->quote($trigger) . ";";

}

/**

* MySQL uses ADD without the COLUMN keyword for backwards-compat.

* Both forms are valid MySQL SQL; the shorter form matches pre-existing

* migration baselines and expected test files.

*/

public function addColumn(string $table, string $colDef): string {

$t = $this->quote($table);

return "ALTER TABLE $t ADD $colDef;";

}

public function dropColumn(string $table, string $col): string {

$t = $this->quote($table);

$c = $this->quote($col);

return "ALTER TABLE $t DROP $c;";

}

public function changeColumn(string $table, string $col, string $newDef): string {

$t = $this->quote($table);

$c = $this->quote($col);

// MySQL CHANGE keeps the same column name; the newDef already contains

// the backtick-quoted name as the first token.

return "ALTER TABLE $t CHANGE $c $newDef;";

}

/**

* MySQL requires DROP FOREIGN KEY for FK constraints.

* Detects the constraint type from the schema DDL fragment.

*/

public function dropConstraint(string $table, string $name, string $schema): string {

$t = $this->quote($table);

$n = $this->quote($name);

if (stripos($schema, 'FOREIGN KEY') !== false) {

return "ALTER TABLE $t DROP FOREIGN KEY $n;";

}

return "ALTER TABLE $t DROP CONSTRAINT $n;";

}

}