<?php
namespace DatabaseHelper;

use DatabaseHelper\enums\Aggregation;
use DatabaseHelper\enums\Charset;
use DatabaseHelper\enums\Collation;
use DatabaseHelper\enums\Engine;
use http\Exception\InvalidArgumentException;

class Schema
{
    public string $name = '';

    public array $columns = [];
    public array $primaryKey = [];
    public array $foreignKeys = [];

    public Engine $engine = Engine::INNODB;
    public Charset $charset = Charset::UTF8;
    public Collation $collation = Collation::UTF8_GENERAL_CI;

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

    public function requireColumn(string $col): void {
        if (!$this->existsColumn($col))
            throw new InvalidArgumentException("Column '$col' is not defined.");
    }

    public function existsColumn(string $col): bool {
        return isset($this->columns[$col]);
    }

    public function existsReference(Schema $schema): bool {
        foreach ($this->foreignKeys as $foreignKey)
            if ($foreignKey['table'] == $schema->name)
                return true;
        return false;
    }

    public function countEntries(): int {
        return Database::makeQuery($this)
            ->aggregate('*', 'count', Aggregation::COUNT)
            ->query();
    }

    public function columnType(string $col) {
        return $this->columns[$col]['type'];
    }

    public function primaryKey() {
        return $this->columns['primary']['name'];
    }

    public function copy(): Schema {
        $copy = new Schema($this->name);
        $copy->columns = genericDeepCopy($this->columns);
        $copy->primaryKey = genericDeepCopy($this->primaryKey);
        $copy->foreignKeys = genericDeepCopy($this->foreignKeys);
        $copy->engine = $this->engine;
        $copy->charset = $this->charset;
        $copy->collation = $this->collation;
        return $copy;
    }

    public function include(Schema $other): void {
        // Create a copy of the other schema.
        $otherCopy = $other->copy();

        // Add any column that isn't already defined.
        foreach ($otherCopy->columns as $colName => $colDef)
            if (!isset($this->columns[$colName]))
                $this->columns[$colName] = $colDef;

        // Add any foreign key that doesn't already exist.
        foreach ($other->foreignKeys as $colName => $foreignKey)
            if (!isset($this->foreignKeys[$colName]))
                $this->foreignKeys[$colName] = $foreignKey;
    }
}