<?php
declare(strict_types=1);
namespace JKingWeb\Arsse\Misc;

class Query {
    protected $body = "";
    protected $qCTE = []; // Common table expression query components
    protected $tCTE = []; // Common table expression type bindings
    protected $vCTE = []; // Common table expression binding values
    protected $jCTE = []; // Common Table Expression joins
    protected $qWhere = []; // WHERE clause components
    protected $tWhere = []; // WHERE clause type bindings
    protected $vWhere = []; // WHERE clause binding values
    protected $order = []; // ORDER BY clause components
    protected $limit = 0;
    protected $offset = 0;


    function __construct(string $body, string $where = "", string $order = "", int $limit = 0, int $offset = 0) {
        if(strlen($body)) $this->body = $body;
        if(strlen($where)) $this->qWhere[] = $where;
        if(strlen($order)) $this->order[] = $order;
        $this->limit = $limit;
        $this->offset = $offset;
    }

    function setCTE(string $body, $types = null, $values = null, string $join = ''): bool {
        if(!strlen($body)) return false;
        $this->qCTE[] = $body;
        if(!is_null($types)) {
            $this->tCTE[] = $types;
            $this->vCTE[] = $values;
        }
        if(strlen($join)) $this->jCTE[] = $join; // the CTE may only participate in subqueries rather than a join on the main query
        return true;
    }

    function setWhere(string $where, $types = null, $values = null): bool {
        if(!strlen($where)) return false;
        $this->qWhere[] = $where;
        if(!is_null($types)) {
            $this->tWhere[] = $types;
            $this->vWhere[] = $values;
        }
        return true;
    }

    function setOrder(string $oder, bool $prepend = false): bool {
        if(!strlen($order)) return false;
        if($prepend) {
            array_unshift($this->order, $order);
        } else {
            $this->order[] = $order;
        }
        return true;
    }

    function getQuery(): string {
        $out = "";
        if(sizeof($this->qCTE)) {
            // start with common table expressions
            $out .= "WITH RECURSIVE ".implode(", ", $this->qCTE)." ";
        }
        // add the body
        $out .= $this->buildQueryBody();
        return $out;
    }

    function pushCTE(string $tableSpec, $types, $values, string $body, string $where = "", string $order = "", int $limit = 0, int $offset = 0): bool {
        // this function takes the query body and converts it to a common table expression, putting it at the bottom of the existing CTE stack
        // all WHERE and ORDER BY parts belong to the new CTE and are removed from the main query
        $b = $this->buildQueryBody();
        array_push($types, $this->getWhereTypes());
        array_push($values, $this->getWhereValues());
        if($this->limit) {
            array_push($types, "strict int");
            array_push($values, $this->limit);
        }
        if($this->offset) {
            array_push($types, "strict int");
            array_push($values, $this->offset);
        }
        $this->setCTE($tableSpec." as (".$this->buildQueryBody().")", $types, $values);
        $this->jCTE = [];
        $this->qWhere = [];
        $this->tWhere = [];
        $this->vWhere = [];
        $this->order = [];
        $this->__construct($body, $where, $order, $limit, $offset);
        return true;
    }

    function getWhereTypes(): array {
        return $this->tWhere;
    }

    function getWhereValues(): array {
        return $this->vWhere;
    }

    function getCTETypes(): array {
        return $this->tCTE;
    }

    function getCTEValues(): array {
        return $this->vCTE;
    }

    protected function buildQueryBody(): string {
        $out = "";
        // add the body
        $out .= $this->body;
        if(sizeof($this->qCTE)) {
            // add any joins against CTEs
            $out .= " ".implode(" ", $this->jCTE);
        }
        // add any WHERE terms
        if(sizeof($this->qWhere)) {
            $out .= " WHERE ".implode(" AND ", $this->qWhere);
        }
        // add any ORDER BY terms
        if(sizeof($this->order)) {
            $out .= " ORDER BY ".implode(", ", $this->order);
        }
        // add LIMIT and OFFSET if the former is specified
        if($this->limit > 0) {
            $out .= " LIMIT ".$this->limit;
            if($this->offset > 0) {
                $out .= " OFFSET ".$this->offset;
            }
        }
        return $out;
    }
}