<?php

namespace Ulmus;

use Ulmus\Query\QueryBuilderInterface;

class QueryBuilder implements Query\QueryBuilderInterface
{
    public Query\Where $where;

    public Query\Having $having;

    public QueryBuilderInterface $parent;

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

    /**
     *
     * Those values are to be inserted or updated
     */
    public array $values = [];

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

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

    protected int $parameterIndex = 0;

    protected array $queryStack = [];

    public function __clone()
    {
        if ($this->where ?? false) {
            #$this->where = clone $this->where;
            #$this->where->queryBuilder = $this;
        }

        if ($this->having ?? false) {
            #$this->having = clone $this->having;
            #$this->having->queryBuiler = $this;
        }

        if ($this->parent ?? false) {
            #$this->parent = clone $this->parent;
        }
    }

    public function select(string|\Stringable|array $field, bool $distinct = false) : self
    {
        if ( null !== ( $select = $this->getFragment(Query\Select::class) ) ) {
            $select->add($field);
        }
        else {
            $select = new Query\Select();
            $select->set($field);
            $this->push($select);
        }

        $select->distinct = $distinct;

        return $this;
    }

    public function insert(array $fieldlist, string $table, ? string $alias = null, ? string $database = null, ? string $schema = null, bool $replace = false) : self
    {
        if ( null === $this->getFragment(Query\Insert::class) ) {
            if ( $schema ) {
                $table = "$schema.$table";
            }

            if ( $database ) {
                $table = "$database.$table";
            }

            $insert = new Query\Insert();
            $this->push($insert);

            $insert->replace = $replace;
            $insert->fieldlist = $fieldlist;
            $insert->alias = $alias;
            $insert->table = $table;
        }

        return $this;
    }

    public function values(array $dataset) : self
    {
        if ( null === ( $values = $this->getFragment(Query\Values::class) ) ) {
            $values = new Query\Values($this);
            $this->push($values);
        }

        $values->add($dataset);

        return $this;
    }

    public function update(string $table, ? string $alias = null, ? string $database = null, ? string $schema = null) : self
    {
        if ( ! $this->getFragment(Query\Update::class) ) {
            if ( $schema ) {
                $table = "$schema.$table";
            }

            if ( $database ) {
                $table = "$database.$table";
            }

            $update = new Query\Update();
            $this->push($update);

            $update->alias = $alias;
            $update->table = $table;
        }

        return $this;
    }

    public function set(array $dataset, ? array $escapedFields = null) : self
    {
        if ( null === ( $set = $this->getFragment(Query\Set::class) ) ) {
            $set = new Query\Set($this);
            $this->push($set);
        }

        $set->set($dataset, $escapedFields);

        return $this;
    }

    public function delete() : self
    {
        if ( ! $this->getFragment(Query\Delete::class) ) {
            $this->push(new Query\Delete());
        }

        return $this;
    }

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

        if ( $database ) {
            $table = "$database.$table";
        }

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

            $from->set($alias ? [ $alias => $table ] : [ $table ]);
        }

        return $this;
    }

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

        return $this;
    }

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

            # if an enclosure was opened, and nothing done, we must remove the unused node
            if ( empty($this->where->conditionList) && (count($this->where->parent->conditionList) === 1) ) {
                unset($this->where->parent->conditionList);
            }

            $this->where = $this->where->parent;
        }

        return $this;
    }

    public function where(string|\Stringable $field, mixed $value, string $operator = Query\Where::OPERATOR_EQUAL, string $condition = Query\Where::CONDITION_AND, bool $not = false) : self
    {
        # Empty IN case
        # if ( [] === $value ) {
        #     return $this;
        # }

        if ( $this->where ?? false ) {
            $where = $this->where;
        }
        elseif ( null === ( $where = $this->getFragment(Query\Where::class) ) ) {
            $this->where = $where = new Query\Where($this);
            $this->push($where);
        }

        $this->whereConditionOperator = $operator;

        $where->add($field, $value, $operator, $condition, $not);

        return $this;
    }

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

    public function having(string|\Stringable $field, mixed $value, string $operator = Query\Where::OPERATOR_EQUAL, string $condition = Query\Where::CONDITION_AND, bool $not = false) : self
    {
        if ( $this->having ?? false ) {
            $having = $this->having;
        }
        elseif ( null === ( $having = $this->getFragment(Query\Having::class) ) ) {
            $this->having = $having = new Query\Having($this);
            $this->push($having);
        }

        $this->havingConditionOperator = $operator;
        $having->add($field, $value, $operator, $condition, $not);

        return $this;
    }

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

        $limit->set($value);

        if ($value === 0) {
            $this->removeFragment(Query\Limit::class);
        }

        return $this;
    }

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

            # A limit is required to match an offset
            if ( null === $limit = $this->getFragment(Query\Limit::class) ) {
                $this->limit(\PHP_INT_MAX);
            }
        }

        $offset->set($value);

        return $this;
    }

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

        $orderBy->add($field, $direction);

        return $this;
    }

    public function groupBy(string|object $field, ? string $direction = null) : self
    {
        if ( null === $groupBy = $this->getFragment(Query\GroupBy::class) ) {
            $groupBy = new Query\GroupBy();
            $this->push($groupBy);
        }

        $groupBy->add($field, $direction);

        return $this;
    }

    public function join(string $type, /*string | QueryBuilder*/ $table, mixed $field, mixed $value, bool $outer = false, ? string $alias = null) : self
    {
        $this->withJoin(...func_get_args());

        return $this;
    }

    public function withJoin(string $type, $table, mixed $field, mixed $value, bool $outer = false, ? string $alias = null) : Query\Join
    {
        $join = new Query\Join($this);

        $this->push($join);

        $join->set($type, $table, $field, $value);

        $join->outer = $outer;

        $join->alias = $alias;

        $join->joinOrder = $this->nextJoinOrder();

        return $join;
    }

    public function showDatabases() : self
    {
        $show = new Query\Show();

        $this->push($show);

        $show->set(Query\Show::SQL_SHOW_DATABASES);

        return $this;
    }

    public function showTables(? string $database = null) : self
    {
        $show = new Query\Show();

        $this->push($show);

        $show->set(Query\Show::SQL_SHOW_TABLES, $database);

        return $this;
    }

    public function showColumns(string $table) : self
    {
        $show = new Query\Show();

        $this->push($show);

        $show->set(Query\Show::SQL_SHOW_COLUMNS, $table);

        return $this;
    }

    public function truncate(string $table, ? string $alias = null, ? string $database = null, ? string $schema = null) : self
    {
        if ( $schema ) {
            $table = "$schema.$table";
        }

        if ( $database ) {
            $table = "$database.$table";
        }

        $truncate = new Query\Truncate($this);

        $this->push($truncate);

        $truncate->set($table);

        return $this;
    }

    public function create(Adapter\AdapterInterface $adapter, array $fieldlist, string $table, ? string $database = null, ? string $schema = null) : self
    {
        if ( null === $this->getFragment(Query\Create::class) ) {
            if ( $schema ) {
                $table = "$schema.$table";
            }

            if ( $database ) {
                $table = "$database.$table";
            }

            $create = new Query\Create($adapter);
            $this->push($create);

            $create->fieldList = $fieldlist;
            $create->table = $table;
        }
        else {
            throw new \Exception("A create SQL fragment was already found within the query builder");
        }

        return $this;
    }

    public function alter(Adapter\AdapterInterface $adapter, array $fieldlist, string $table, ? string $database = null, ? string $schema = null) : self
    {
        if ( null === $this->getFragment(Query\Alter::class) ) {
            if ( $schema ) {
                $table = "$schema.$table";
            }

            if ( $database ) {
                $table = "$database.$table";
            }

            $alter = new Query\Alter($adapter);
            $this->push($alter);

            $alter->fieldList = $fieldlist;
            $alter->table = $table;
        }
        else {
            throw new \Exception("A create SQL fragment was already found within the query builder");
        }

        return $this;
    }

    public function engine(string $value) : self
    {
        if ( null === $engine = $this->getFragment(Query\Engine::class) ) {
            $engine = new Query\Engine();
            $this->push($engine);
        }

        $engine->engine = $value;

        return $this;
    }

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

        return $this;
    }

    public function pull(Query\Fragment $queryFragment) : self
    {
        return array_shift($this->queryStack);
    }

    public function render(bool $skipToken = false) /* : mixed */
    {
        $sql = [];

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

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

        return implode(" ", $sql);
    }

    public function reset() : void
    {
        $this->parameters = $this->values = $this->queryStack = [];
        $this->whereConditionOperator = Query\Where::CONDITION_AND;
        $this->havingConditionOperator = Query\Where::CONDITION_AND;
        $this->parameterIndex = 0;

        unset($this->where, $this->having);
    }

    public function getFragment(string $class, int $index = 0) : ? Query\Fragment
    {
        foreach($this->queryStack as $item) {
            if ( is_a($item, $class, true) ) {
                if ( $index-- === 0 ) {
                    return $item;
                }
            }
        }

        return null;
    }

    public function removeFragment(Query\Fragment|array|\Stringable|string $fragment) : void
    {
        is_object($fragment) && $fragment = get_class($fragment);

        foreach($this->queryStack as $key => $item) {
            if ( get_class($item) === $fragment ) {
                unset($this->queryStack[$key]);
            }
        }

        if ( $fragment === Query\Where::class ) {
            unset($this->where);
        }
        elseif ( $fragment === Query\Having::class ) {
            unset($this->having);
        }
    }

    public function getFragments(Query\Fragment|array|\Stringable|string $fragment = null) : array
    {
        return $fragment !== null ? array_filter($this->queryStack, fn($e) => is_a($e, $fragment, true) ) : $this->queryStack;
    }

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

    public function addParameter(mixed $value, string $key = null) : string
    {
        if ( $this->parent ?? false ) {
            return $this->parent->addParameter($value, $key);
        }

        if ( $key === null ) {
            $key = ":p" . $this->parameterIndex++;
        }

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

        return $key;
    }

    public function addValues(array $values) : void
    {
        $this->values = $values;
    }
    
    protected function nextJoinOrder() : float
    {
        $next = 0;

        foreach($this->getFragments(Query\Join::class) as $join) {
            $next = max($next, $join->joinOrder - Query\Join::ORDER_VALUE);
        }

        return $next + 1;
    }
}