<?php

namespace Illuminate\Database\Schema;

use Illuminate\Database\Connection;
use Illuminate\Database\Query\Expression;
use Illuminate\Support\Collection;
use Illuminate\Support\Fluent;
use Illuminate\Support\Str;

class BlueprintState
{
    /**
     * The blueprint instance.
     *
     * @var \Illuminate\Database\Schema\Blueprint
     */
    protected $blueprint;

    /**
     * The connection instance.
     *
     * @var \Illuminate\Database\Connection
     */
    protected $connection;

    /**
     * The columns.
     *
     * @var \Illuminate\Database\Schema\ColumnDefinition[]
     */
    private $columns;

    /**
     * The primary key.
     *
     * @var \Illuminate\Database\Schema\IndexDefinition|null
     */
    private $primaryKey;

    /**
     * The indexes.
     *
     * @var \Illuminate\Database\Schema\IndexDefinition[]
     */
    private $indexes;

    /**
     * The foreign keys.
     *
     * @var \Illuminate\Database\Schema\ForeignKeyDefinition[]
     */
    private $foreignKeys;

    /**
     * Create a new blueprint state instance.
     *
     * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
     * @param  \Illuminate\Database\Connection  $connection
     */
    public function __construct(Blueprint $blueprint, Connection $connection)
    {
        $this->blueprint = $blueprint;
        $this->connection = $connection;

        $schema = $connection->getSchemaBuilder();
        $table = $blueprint->getTable();

        $this->columns = (new Collection($schema->getColumns($table)))->map(fn ($column) => new ColumnDefinition([
            'name' => $column['name'],
            'type' => $column['type_name'],
            'full_type_definition' => $column['type'],
            'nullable' => $column['nullable'],
            'default' => is_null($column['default']) ? null : new Expression(Str::wrap($column['default'], '(', ')')),
            'autoIncrement' => $column['auto_increment'],
            'collation' => $column['collation'],
            'comment' => $column['comment'],
            'virtualAs' => ! is_null($column['generation']) && $column['generation']['type'] === 'virtual'
                ? $column['generation']['expression']
                : null,
            'storedAs' => ! is_null($column['generation']) && $column['generation']['type'] === 'stored'
                ? $column['generation']['expression']
                : null,
        ]))->all();

        [$primary, $indexes] = (new Collection($schema->getIndexes($table)))->map(fn ($index) => new IndexDefinition([
            'name' => match (true) {
                $index['primary'] => 'primary',
                $index['unique'] => 'unique',
                default => 'index',
            },
            'index' => $index['name'],
            'columns' => $index['columns'],
        ]))->partition(fn ($index) => $index->name === 'primary');

        $this->indexes = $indexes->all();
        $this->primaryKey = $primary->first();

        $this->foreignKeys = (new Collection($schema->getForeignKeys($table)))->map(fn ($foreignKey) => new ForeignKeyDefinition([
            'columns' => $foreignKey['columns'],
            'on' => new Expression($foreignKey['foreign_table']),
            'references' => $foreignKey['foreign_columns'],
            'onUpdate' => $foreignKey['on_update'],
            'onDelete' => $foreignKey['on_delete'],
        ]))->all();
    }

    /**
     * Get the primary key.
     *
     * @return \Illuminate\Database\Schema\IndexDefinition|null
     */
    public function getPrimaryKey()
    {
        return $this->primaryKey;
    }

    /**
     * Get the columns.
     *
     * @return \Illuminate\Database\Schema\ColumnDefinition[]
     */
    public function getColumns()
    {
        return $this->columns;
    }

    /**
     * Get the indexes.
     *
     * @return \Illuminate\Database\Schema\IndexDefinition[]
     */
    public function getIndexes()
    {
        return $this->indexes;
    }

    /**
     * Get the foreign keys.
     *
     * @return \Illuminate\Database\Schema\ForeignKeyDefinition[]
     */
    public function getForeignKeys()
    {
        return $this->foreignKeys;
    }

    /**
     * Update the blueprint's state.
     *
     * @param  \Illuminate\Support\Fluent  $command
     * @return void
     */
    public function update(Fluent $command)
    {
        switch ($command->name) {
            case 'alter':
                // Already handled...
                break;

            case 'add':
                $this->columns[] = $command->column;
                break;

            case 'change':
                foreach ($this->columns as &$column) {
                    if ($column->name === $command->column->name) {
                        $column = $command->column;
                        break;
                    }
                }

                break;

            case 'renameColumn':
                foreach ($this->columns as $column) {
                    if ($column->name === $command->from) {
                        $column->name = $command->to;
                        break;
                    }
                }

                if ($this->primaryKey) {
                    $this->primaryKey->columns = str_replace($command->from, $command->to, $this->primaryKey->columns);
                }

                foreach ($this->indexes as $index) {
                    $index->columns = str_replace($command->from, $command->to, $index->columns);
                }

                foreach ($this->foreignKeys as $foreignKey) {
                    $foreignKey->columns = str_replace($command->from, $command->to, $foreignKey->columns);
                }

                break;

            case 'dropColumn':
                $this->columns = array_values(
                    array_filter($this->columns, fn ($column) => ! in_array($column->name, $command->columns))
                );

                break;

            case 'primary':
                $this->primaryKey = $command;
                break;

            case 'unique':
            case 'index':
                $this->indexes[] = $command;
                break;

            case 'renameIndex':
                foreach ($this->indexes as $index) {
                    if ($index->index === $command->from) {
                        $index->index = $command->to;
                        break;
                    }
                }

                break;

            case 'foreign':
                $this->foreignKeys[] = $command;
                break;

            case 'dropPrimary':
                $this->primaryKey = null;
                break;

            case 'dropIndex':
            case 'dropUnique':
                $this->indexes = array_values(
                    array_filter($this->indexes, fn ($index) => $index->index !== $command->index)
                );

                break;

            case 'dropForeign':
                $this->foreignKeys = array_values(
                    array_filter($this->foreignKeys, fn ($fk) => $fk->columns !== $command->columns)
                );

                break;
        }
    }
}
