<?php

//  Simple PDO wrapper to ease database interactions, always returning multi-dimensional array for consistency
class PDOWrapper
{
    public $dbc;


    //  Establish database connection
    public function __construct($db_host, $db_name, $db_user, $db_pass)
    {
        try {
             $this->dbc = new PDO("mysql:host=$db_host;dbname=$db_name", $db_user, $db_pass);
             return $this->dbc;
        }
        catch (Exception $error) {
            return $error;
        }
    } // END constructor method


    //  Force multi-dimensional array
    public function return_array($data)
    {
        $return_array = [];
        return $return_array['data'] = $data;
    } //  END return_array method


    //  TODO: Build try/catch method?


    //  Get table columns
    public function getColumns($table)
    {
        try {
            $stmt = $this->dbc->prepare("SELECT * FROM " . $table);
            $stmt->execute();
            $array = $stmt->fetch(PDO::FETCH_ASSOC);
        }
        catch (Exception $error) {
            return $error;
        }

        //  Parse through returned results and build array of table columns
        $columns_array = [];
        foreach ($array as $column => $field) {
            $columns_array[] = $column;
        }

        //  Return multi-dimensional array
        $this->return_array($columns_array);
    } //  END getColumns method


    //  Show tables in database
    public function getTables()
    {
        $stmt = $this->dbc->prepare("SHOW TABLES;");
        $stmt->execute();
        $results = $stmt->fetch();

        //  Return multi-dimensional array
        $this->return_array($results);
    } //  END getTables method


    //  Query database dynamically
    public function select($table, $where_assoc_array = [], $limit = 'display_all')
    {
        //  Handle default 'display_all' value given for human reliability
        if ($limit == 'display_all') {
            $limit = '';
        }
        else {
            $limit = ' LIMIT ' . $limit;
        }

        //  Build 'where' clause
        if (!empty($where_assoc_array)) {
            $where_clause = 'WHERE ';
            foreach ($where_assoc_array as $column => $field) {
                $where_clause .= $column . " = " . $field . " AND ";
            }

            //  Trim off extra 'AND' off end of string
            rtrim($where_clause, ' AND ');
        }
        else {
            $where_clause = '';
        }

        try {
            //  Build statement
            $stmt = $this->dbc->prepare("SELECT * FROM" . $table . $where_clause . $limit . ";");
            $results = $stmt->fetchAll(PDO::FETCH_ASSOC);

            //  Return multi-dimensional array
            return $this->return_array($results);
        }
        catch (Exception $error) {
            return $this->return_array($error);
        }
    } //  END select method


    //  Insert into database dynamically
    public function insert($table, $assoc_array)
    {
        $columns_array = [];
        $values_array = [];

        //  Parse array given
        foreach ($assoc_array as $key => $value) {
            $columns_array[] = $key;
            $values_array[] = $value;
        }

        //  Build insert statement
        $stmt = $this->dbc->prepare("INSERT INTO" . $table . " (" . $columns_array . ") VALUES (" . $values_array . ");");
        $stmt->execute();
        $results = $stmt->fetch();

        //  Return multi-dimensional array
        $this->return_array($results);
    } //  END insert method


    //  Update values dynamically
    public function update($table, $assoc_array, $where_assoc_array = [])
    {
        $stmt_middle = '';

        //  Parse array given
        foreach ($assoc_array as $key => $value) {
            $stmt_middle .= $key . " = '" . $value . "', ";
        }

        //  Trim off extra comma
        rtrim($stmt_middle, ', ');

        //  Build statement
        $stmt_begin = "UPDATE" . $table . "SET ";
        $stmt_end = "WHERE ";

        //  Parse array to build 'WHERE' clause
        foreach ($where_assoc_array as $key => $value) {
            $stmt_end .= $key . " = " . $value . " AND ";
        }
        //  Trim off extra 'AND' off end of string
        rtrim($stmt_end, ' AND ');

        try {
            //  Build update statement
            $stmt = $this->dbc->prepare($stmt_begin . $stmt_middle . $stmt_end);
            $stmt->execute();
            $results = $stmt->fetch();

            //  Return multi-dimensional array
            $this->return_array($results);
        }
        catch (Exception $error) {
            $this->return_array($error);
        }
    } //  END update method


    //  Delete rows from table
    public function delete($table, $assoc_array)
    {
        // TODO:
    } //  END delete method
}