<?php

namespace Ulmus;


class QueryBuilder
{

    public Query\Where $where;

    /**
     * Those are the parameters we are going to bind to PDO.
     */
    public array $parameters = [];

    public string $conditionOperator = Query\Where::CONDITION_AND;

    public string $entityClass;

    protected int $parameterIndex = 0;

    protected array $queryStack = [];

    public function __construct($entityClass = "") {
        $this->entityClass = $entityClass;
    }

    public function select($field) : self
    {
        if ( $select = $this->has(Query\Select::class) ) {
            $select->add($field);
        }
        else {
            $select = new Query\Select();
            $select->set($field);
            $this->push($select);
        }

        return $this;
    }

    public function from($table, $alias = null, $database = null) : self
    {
        if ( $database ) {
            $table = "`$database`.".$table;
        }

        if ( $from = $this->has(Query\From::class) ) {
            $from->add($alias ? [ $alias => $table ] : $table);
        }
        else {
            $from = new Query\From();
            $this->push($from);
            $from->set($alias ? [ $alias => $table ] : $table);
        }

        return $this;
    }

    public function open(string $condition = Query\Where::CONDITION_AND) : self
    {
        if ( false !== ($this->where ?? false) ) {
            $this->where->conditionList[] = $new = new Query\Where($this, $condition);
            $this->where = $new;
        }

        return $this;
    }

    public function close() : self
    {
        if ( false !== ($this->where ?? false) && $this->where->parent ) {
            $this->where = $this->where->parent;
        }

        return $this;
    }

    public function where($field, $value, string $operator = Query\Where::OPERATOR_EQUAL, string $condition = Query\Where::CONDITION_AND, bool $not = false) : self
    {
        if ( $this->where ?? false ) {
            $where = $this->where;
        }
        elseif ( false === $where = $this->has(Query\Where::class) ) {
            $this->where = $where = new Query\Where($this);
            $this->push($where);
        }

        $this->conditionOperator = $operator;
        $where->add($field, $value, $operator, $condition, $not);
        return $this;
    }

    public function notWhere($field, $value, string $operator = Query\Where::CONDITION_AND) : self
    {
        return $this->where($field, $value, $operator, true);
    }

    public function groupBy() : self
    {
        //$this->queryBuilder->groupBy();
        return $this;
    }

    public function limit(int $value) : self
    {
        if ( false === $limit = $this->has(Query\Limit::class) ) {
            $limit = new Query\Limit();
            $this->push($limit);
        }

        $limit->set($value);
        return $this;
    }

    public function offset(int $value) : self
    {
        if ( false === $offset = $this->has(Query\Offset::class) ) {
            $offset = new Query\Offset();
            $this->push($offset);
        }

        $offset->set($value);
        return $this;
    }

    public function orderBy(string $field, ? string $direction = null) : self
    {
        if ( false === $orderBy = $this->has(Query\OrderBy::class) ) {
            $orderBy = new Query\OrderBy();
            $this->push($orderBy);
        }

        $orderBy->add($field, $direction);
        return $this;
    }

    public function push(Query\Fragment $queryFragment) : self
    {
        $this->queryStack[] = $queryFragment;
        return $this;
    }

    public function render() : string
    {
        $sql = [];

        usort($this->queryStack, function($q1, $q2) {
            return $q1->order <=> $q2->order;
        });

        foreach($this->queryStack as $fragment) {
            $sql[] = $fragment->render();
        }

        return implode(" ", $sql);
    }

    public function has($class) {
        foreach($this->queryStack as $item) {
            if ( get_class($item) === $class ) {
                return $item;
            }
        }

        return false;
    }

    public function __toString() : string
    {
        return $this->render();
    }

    public function addParameter($value, $key = null) {
        if ( $key === null ) {
            $key = ":p" . $this->parameterIndex++;
        }

        $this->parameters[$key] = $value;
        return $key;
    }
}