<?php
require_once('phing/Task.php');

class MigrationTask extends Task {

    private $host;

    private $port;

    private $name;

    private $user;

    private $pass;

    private $dir;


    public function setUser($user){
        $this->user = $user;
    }

    public function setPass($pass){
        $this->pass = $pass;
    }

    public function setHost($host){
        $this->host = $host;
    }

    public function setName($name){
        $this->name = $name;
    }

    public function setDir($dir){
        $this->dir = $dir;
    }

    public function main(){


        $dh = opendir($this->dir);

        if(!$dh){
            die("Unable to open {$this->dir} for reading.");
        }

        $files = array();

        while(($file = readdir($dh)) !== false){

            if($file[0] == '.'){
                continue;
            }

            $info = pathinfo($file);

            if($info['extension'] != 'php' ){
                continue;
            }

            $files[] = $file;
        }

        sort($files);

        $this->connect();
        $this->begin();

        foreach($files as $file){
            $this->migrate($file);
        }

        $this->commit();
    }

    private function connect(){

        $dsn = "";

        if(!empty($this->host)){
            $dsn .= "host={$this->host} ";
        }

        if(!empty($this->port)){
            $dsn .= "port={$this->port} ";
        }

        if(!empty($this->name)){
            $dsn .= "dbname={$this->name} ";
        }

        if(!empty($this->user)){
            $dsn .= "user={$this->user} ";
        }

        if(!empty($this->pass)){
            $dsn .= "password={$this->pass} ";
        }

        $dsn = trim($dsn);

        pg_connect($dsn)
                or die("Unable to connect to the database!");

        $result = $this->query("SELECT * FROM information_schema.tables WHERE table_schema='public' AND table_name='schema_migrations'");

        if(empty($result)){
            $this->begin();
            $this->execute("CREATE TABLE schema_migrations(version INTEGER NOT NULL)");
            $this->commit();
        }

    }

    private function begin(){
        pg_query("BEGIN");
    }

    private function commit(){
        pg_query("COMMIT");
    }

    private function execute($sql, $params = null){
        if(empty($params)){
            pg_query($sql);

        } else {

            if(!is_array($params)){
                $params = array($params);
            }

            pg_query_params($sql, $params);
        }

        if(pg_last_error()){
            die(pg_last_error());
        }
    }

    private function query($sql, $params = null){

        if(empty($params)){
            $result = pg_query($sql);

        } else {

            if(!is_array($params)){
                $params = array($params);
            }

            $result = pg_query_params($sql, $params);
        }

        $result = pg_fetch_all($result);

        if(pg_last_error()){
            die(pg_last_error());
        }

        return $result;
    }

    private function migrate($file){


        $version = $this->version($file);

        $result = $this->query('SELECT * FROM schema_migrations WHERE version=$1', $version);

        if(empty($result)){

            echo "[MIGRATING]: {$file}\n";

            $this->run("{$this->dir}/{$file}");
            $this->execute("INSERT INTO schema_migrations VALUES($1)", $version);
        }
    }


    private function version($file){

        $subject    = $file;
        $pattern    = '/^[0-9]{3}/';
        $matches    = array();

        preg_match($pattern, $subject, $matches);

        if(empty($matches[0])){
            die("Unable to exctract version from file: {$file}!");
        }


        $version = (int) $matches[0];

        if($version <= 0){
            die("Invalid version {$version}, extracted from file {$file}!");
        }

        return $version;
    }

    private function run($file){
        require_once($file);
    }
}

// SAMPLE: 001_create_something.php
$this->execute("CREATE TABLE foo(bar INTEGER)");
$this->execute("CREATE TABLE bar(foo INTEGER)");