var Q           = require('q');
var _           = require('underscore');
var util        = require('util');
var base        = require('./base');
var mysql       = require('mysql');

// Constructor for the MysqlClient
var MysqlClient = module.exports = function(name, options) {
  base.setup.call(this, MysqlClient, name, options);
};

_.extend(MysqlClient.prototype, base.protoProps, {

  getRawConnection: function() {
    var conn = mysql.createConnection(this.connectionSettings);
        conn.connect();
    return conn;
  },

  // Execute a query on the database.
  // If a `connection` is specified, use it, otherwise
  // acquire a connection, and then dispose of it when we're done.
  query: function (data, connection) {
    data = this.prepData(data);
    var emptyConnection = !connection;
    var debug = this.debug;
    return Q((connection || this.getConnection()))
      .then(function(conn) {
        if (debug) console.log(_.extend(data, {__cid: conn.__cid}));
        return Q.nfinvoke(connection.query, data.sql, (data.bindings || []));
      })
      .then(this.prepResp)
      .fin(function() {
        if (emptyConnection) instance.pool.release(client);
      });
  }
});

// Extends the standard sql grammar.
MysqlClient.grammar = {

  // The keyword identifier wrapper format.
  wrapValue: function(value) {
    return (value !== '*' ? util.format('`%s`', value) : "*");
  }

};

// Grammar for the schema builder.
MysqlClient.schemaGrammar = _.extend({}, MysqlClient.grammar, {

  // The possible column modifiers.
  modifiers: ['Unsigned', 'Nullable', 'Default', 'Increment', 'After'],
  
  // Compile the query to determine if a table exists.
  compileTableExists: function() {
    return 'select * from information_schema.tables where table_schema = ? and table_name = ?';
  },

  // Compile a create table command.
  compileCreateTable: function(blueprint, command) {
    var columns = this.getColumns(blueprint).join(', ');
    return 'create table ' + this.wrapTable(blueprint) + ' (' + columns + ')';
  },

  // Compile an add command.
  compileAdd: function(blueprint, command) {
    var columns = this.prefixArray('add', this.getColumns(blueprint));
    return 'alter table ' + this.wrapTable(blueprint) + ' ' + columns.join(', ');
  },

  // Compile a primary key command.
  compilePrimary: function(blueprint, command) {
    command.name(null);
    return this.compileKey(blueprint, command, 'primary key');
  },
  
  // Compile a unique key command.
  compileUnique: function(blueprint, command) {
    return this.compileKey(blueprint, command, 'unique');
  },

  // Compile a plain index key command.
  compileIndex: function(blueprint, command) {
    return this.compileKey(blueprint, command, 'index');
  },

  // Compile an index creation command.
  compileKey: function(blueprint, command, type) {
    var columns = this.columnize(command.columns);
    var table = this.wrapTable(blueprint);
    return 'alter table ' + table + " add " + type + " " + command.index + "(" + columns + ")";
  },

  // Compile a drop table command.
  compileDropTable: function(blueprint, command) {
    return 'drop table ' + this.wrapTable(blueprint);
  },

  // Compile a drop table (if exists) command.
  compileDropTableIfExists: function(blueprint, command) {
    return 'drop table if exists ' + this.wrapTable(blueprint);
  },
  
  // Compile a drop column command.
  compileDropColumn: function(blueprint, command) {
    var columns = this.prefixArray('drop', this.wrapArray(command.columns));
    return 'alter table ' + this.wrapTable(blueprint) + ' ' + columns.join(', ');
  },
  
  // Compile a drop primary key command.
  compileDropPrimary: function(blueprint, command) {
    return 'alter table ' + this.wrapTable(blueprint) + ' drop primary key';
  },

  // Compile a drop unique key command.
  compileDropUnique: function(blueprint, command) {
    return this.compileDropIndex(blueprint, command);
  },

  // Compile a drop index command.
  compileDropIndex: function(blueprint, command) {
    return 'alter table ' + this.wrapTable(blueprint) + ' drop index ' + command.index;
  },
  
  // Compile a drop foreign key command.
  compileDropForeign: function(blueprint, command) {
    return 'alter table ' + this.wrapTable(blueprint) + " drop foreign key " + command.index;
  },

  // Compile a rename table command.
  compileRenameTable: function(blueprint, command) {
    return 'rename table ' + this.wrapTable(blueprint) + ' to ' + this.wrapTable(command.to);
  },
  
  // Create the column definition for a string type.
  typeString: function(column) {
    return "varchar(" + column.length + ")";
  },

  // Create the column definition for a text type.
  typeText: function(column) {
    switch (column.length) {
      case 'medium':
      case 'mediumtext':
        return 'mediumtext';
      case 'long':
      case 'longtext':
        return 'longtext';
      default:
        return 'text';
    }
  },

  // Create the column definition for a integer type.
  typeInteger: function(column) {
    return 'int(' + column.length + ')';
  },

  // Create the column definition for a tiny integer type.
  typeTinyInteger: function() {
    return 'tinyint';
  },

  // Create the column definition for a float type.
  typeFloat: function(column) {
    return 'float(' + column.total + ',' + column.places + ')';
  },
  
  // Create the column definition for a decimal type.
  typeDecimal: function(column) {
    return 'decimal(' + column.precision + ', ' + column.scale + ')';
  },

  // Create the column definition for a boolean type.
  typeBoolean: function(column) {
    return 'tinyint(1)';
  },

  // Create the column definition for a enum type.
  typeEnum: function(column) {
    return "enum('" + column.allowed.join("', '")  + "')";
  },

  // Create the column definition for a date type.
  typeDate: function(column) {
    return 'date';
  },

  // Create the column definition for a date-time type.
  typeDateTime: function(column) {
    return 'datetime';
  },

  // Create the column definition for a time type.
  typeTime: function(column) {
    return 'time';
  },

  // Create the column definition for a timestamp type.
  typeTimestamp: function(column) {
    return 'timestamp default 0';
  },

  // Create the column definition for a bit type.
  typeBit: function(column) {
    return column.length !== false ? 'bit(' + column.length + ')' : 'bit';
  },

  // Create the column definition for a binary type.
  typeBinary: function(column) {
    return 'blob';
  },

  // Get the SQL for an unsigned column modifier.
  modifyUnsigned: function(blueprint, column) {
    if (column.type == 'integer' && column.isUnsigned) {
      return ' unsigned';
    }
  },

  // Get the SQL for a nullable column modifier.
  modifyNullable: function(blueprint, column) {
    return column.isNullable ? ' null' : ' not null';
  },

  // Get the SQL for a default column modifier.
  modifyDefault: function(blueprint, column) {
    if (column.defaultValue) {
      return " default '" + this.getDefaultValue(column.defaultValue) + "'";
    }
  },

  // Get the SQL for an auto-increment column modifier.
  modifyIncrement: function(blueprint, column) {
    if (column.type == 'integer' && column.autoIncrement) {
      return ' auto_increment primary key';
    }
  }
});