<?php
namespace DatabaseHelper;

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

class Table
{
    public Schema $table;

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

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

        $this->table->columns[$colName] = [
            'colName' => $colName,
            'defaultVal' => $default,
            'colType' => $colType,
            'nullable' => $nullable,
            'unique' => $unique
        ];

        return $this;
    }

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

        $this->table->primaryKey = [
            'colName' => $colName,
            'colType' => $colType,
            'autoincrement' => $autoInc
        ];

        return $this->column($colName, $colType);
    }

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

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

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

    public function engine(EngineTypes $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 {
        $sql = "CREATE TABLE `{$this->table->name}` (\n";

        // Add primary key constraint if present
        if (!empty($this->primaryKey))
            $sql .= "  PRIMARY KEY (`{$this->primaryKey['colName']}`),\n";

        foreach ($this->table->columns as $column) {
            if ($column['colName'] !== $this->table->primaryKey['colName']) {
                $sql .= "  `{$column['colName']}` {$column['colType']->value}";

                // Handle nulls, uniqueness, and defaults
                if (!$column['nullable'])
                    $sql .= " NOT NULL";
                if ($column['unique'])
                    $sql .= " UNIQUE";
                if ($column['defaultVal'] !== null) {
                    $default = is_string($column['defaultVal']) ? "'{$column['defaultVal']}'" : $column['defaultVal'];
                    $sql .= " DEFAULT $default";
                }

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

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

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