DB.php

<?php
/**
 * Created by PhpStorm.
 * User: Craig
 * Date: 10/17/2014
 * Time: 8:36 PM
 */

class DB {

    private $_con;
    private $_method;
    private $_table;
    private $_query;
    private $_fields;
    private $_orderBy;
    private $_result;
    private $_data;
    private $_limit = 0;
    private $_where = [];
    private $_params = [];

    public function __construct($connection) {
        $this->_con = $connection;
        return true;
    }

    public function get($table) {
        $this->_method = 'select';
        $this->_table = $table;
        $this->buildQuery();
        return $this->query();
    }

    public function create($table, array $data) {
        $this->_method = 'insert';
        $this->_table = $table;
        $this->_data = $data;

        $this->buildQuery();
        return $this->query();
    }

    public function update($table, array $data, array $key) {
        $this->_method = 'update';
        $this->_table = $table;
        $this->_data = $data;
        $this->where($key);

        $this->buildQuery();
        return $this->query();

    }

    public function destroy($table, array $key) {
        $this->_method = 'delete';
        $this->_table = $table;
        $this->where($key);

        $this->buildQuery();
        return $this->query();
    }

    public function fields($fields) {
        $this->_fields = $fields;
        return $this;
    }

    public function where($key, $value = null) {
        if (is_array($key)) {
            foreach ($key as $k => $v) {
                $this->_where[$k] = $v;
            }
        } else {
            $this->_where[$key] = $value;
        }

        return $this;
    }

    public function orderBy($key, $order) {
        $this->_orderBy = $key . ' ' . $order;
        return $this;
    }

    public function limit($num) {
        $this->_limit = $num;
        return $this;
    }

    public function group() {

    }

    public function like() {

    }

    public function join() {}

    private function buildQuery() {
        switch ($this->_method) {
            case 'select':
                $this->buildSelect();
                break;
            case 'insert':
                $this->buildInsert();
                break;
            case 'update':
                $this->buildUpdate();
                break;
            case 'delete':
                $this->buildDelete();
                break;
        }
    }

    private function buildSelect() {
        $query = 'SELECT ';
        $query .= ($this->_fields === null) ? '*' : $this->_fields;
        $query .= ' FROM ' . $this->_table;

        $query .= $this->buildWhere();
        $query .= $this->buildOrder();
        $query .= $this->buildLimit();

        $this->_query = $query;
    }

    private function buildInsert() {
        $query = 'INSERT INTO ' . $this->_table;
        $query .= ' (' . implode(', ', array_keys($this->_data)) . ')';
        $query .= ' values (';
        foreach ($this->_data as $key => $value) {
            $query .= ':' . $key;
            $this->_params[':' . $key] = $value;

            end($this->_data);
            if ($key !== key($this->_data)) {
                $query .= ', ';
            }
        }
        $query .= ')';

        $this->_query = $query;
    }

    private function buildUpdate() {
        $query = 'UPDATE ' . $this->_table . ' SET ';
        foreach ($this->_data as $key => $value) {
            $query .= $key . ' = :' . $key;
            $this->_params[':'.$key] = $value;

            end($this->_data);
            if ($key !== key($this->_data)) {
                $query .= ', ';
            }
        }
        $query .= $this->buildWhere();
        $this->_query = $query;
    }

    private function buildDelete() {
        $query = 'DELETE FROM ' . $this->_table;
        $query .= $this->buildWhere();
        $this->_query = $query;
    }

    private function buildWhere() {
        $query = '';
        if (count($this->_where) > 0) {
            $query = ' WHERE ';
            foreach ($this->_where as $key => $value) {
                $query .= $key . ' = :' . $key;
                $this->_params[':' . $key] = $value;

                end($this->_where);
                if ($key !== key($this->_where)) {
                    $query .= ' AND ';
                }
            }
        }
        return $query;
    }

    private function buildOrder() {
        if ($this->_orderBy !== null) {
            return ' ORDER BY ' . $this->_orderBy;
        }
    }

    private function buildLimit() {
        if ($this->_limit > 0) {
            if ($this->_con->getAttribute("PDO::ATTR_ DRIVER_NAME") === 'mysql') {
                return ' LIMIT ' . $this->_limit;
            } else {
                return ' FETCH FIRST ' . $this->_limit . ' ROWS ONLY';
            }
        }
        return '';
    }

    private function query() {
        $this->_result = $this->_con->prepare($this->_query);
        $id = $this->_result->execute($this->_params);

        if ($this->_method === 'select') {
            return $this->_result->fetchAll();
        } else {
            return $id;
        }

    }


}