<?php
namespace DatabaseHelper;

use DatabaseHelper\enums\CascadeTypes;
use DatabaseHelper\enums\CharsetTypes;
use DatabaseHelper\enums\CollationTypes;
use DatabaseHelper\enums\ColumnTypes;
use DatabaseHelper\enums\DatabaseEngines;
use InvalidArgumentException;

class Table
{
    public Schema $table;

    public function __construct(string $tableName) {
        Database::standardizeTableNames($tableName);
        $this->table = new Schema($tableName);
    }

    public function column(string $name, ColumnTypes $type, mixed $default = null, bool $isNullable = false, bool $isUnique = false): Table {
        if(isset($this->columns[$name]))
            throw new InvalidArgumentException('Column name already exists.');

        $this->table->columns[$name] = [
            'name' => $name,
            'default' => $default,
            'type' => $type,
            'isNullable' => $isNullable,
            'isUnique' => $isUnique
        ];

        return $this;
    }

    public function primary(string $name, ColumnTypes $type, bool $autoInc = false): Table {
        if(isset($this->primaryKey))
            throw new InvalidArgumentException('Primary column already exists.');

        $this->table->primaryKey = [
            'name' => $name,
            'autoInc' => $autoInc
        ];

        return $this->column($name, $type);
    }

    public function reference(Schema $foreignTable, CascadeTypes $onDelete = CascadeTypes::CASCADE, CascadeTypes $onUpdate = CascadeTypes::CASCADE): Table {
        $name = $foreignTable->primaryKey();
        if(isset($this->columns[$name]))
            throw new InvalidArgumentException('Column name already exists.');

        $this->table->foreignKeys[] = [
            'name' => $name,
            'table' => $foreignTable->name,
            'onDelete' => $onDelete,
            'onUpdate' => $onUpdate
        ];

        $this->table->columns[$name] = $foreignTable->columns[$name];
        return $this;
    }

    public function engine(DatabaseEngines $engine): Table {
        $this->table->engine = $engine;
        return $this;
    }

    public function charset(CharsetTypes $charset): Table {
        $this->table->charset = $charset;
        return $this;
    }

    public function collation(CollationTypes $collation): Table {
        $this->table->collation = $collation;
        return $this;
    }

    public function toSql(): string {
        $primaryKey = $this->table->primaryKey();

        $sql = "CREATE TABLE `{$this->table->name}` (\n";
        $sql .= "  PRIMARY KEY (`$primaryKey`),\n";

        foreach ($this->table->columns as $col) {
            if ($col['name'] !== $primaryKey) {
                $sql .= "  `{$col['name']}` {$col['type']->toString()}";
                // Handle nulls, uniqueness, and defaults
                if (!$col['isNullable'])
                    $sql .= " NOT NULL";
                if ($col['isUnique'])
                    $sql .= " UNIQUE";
                if ($col['default'] !== null) {
                    $default = is_string($col['default']) ? "'{$col['default']}'" : $col['default'];
                    $sql .= " DEFAULT $default";
                }

                $sql .= ",\n";
            }
        }

        // Add secondary constraints if present
        foreach ($this->table->foreignKeys as $key) {
            $sql .= "  FOREIGN KEY (`{$key['name']}`) REFERENCES `{$key['table']}` (`{$key['name']}`)";
            $sql .= " ON DELETE {$key['onDelete']->toString()} ON UPDATE {$key['onUpdate']->toString()},\n";
        }

        // Close the SQL string and add constraints
        $sql = rtrim($sql, ",\n") . "\n) ";
        $sql .= "ENGINE={$this->table->engine->toString()} ";
        $sql .= "CHARSET={$this->table->charset->toString()} ";
        $sql -= "COLLATE={$this->table->collation->toString()};";
        return esc_sql($sql);
    }

    public function create(): Schema {
        global $wpdb;

        if (empty($this->primaryKey))
            throw new InvalidArgumentException('A primary key must be defined.');
        $table_name = $wpdb->prefix . $this->table->name;

        if ($wpdb->get_var("SHOW TABLES LIKE '$table_name'") !== $table_name) {
            $sql = $this->toSql();
            require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
            dbDelta($sql);
        }
        return $this->table;
    }
}