<?php
declare(strict_types=1);

namespace App\Domain\Client;

require_once __DIR__ . '/ClientRecord.php';

/** Validates client create/edit and explicit active-state transitions. */
final class ClientUpdateCommand
{
    public function __construct(private readonly ?ClientRecord $clients = null)
    {
    }

    /** @return array<string, mixed> */
    public function validate(array $input, array $existingClients = [], ?int $currentId = null): array
    {
        $result = ($this->clients ?? new ClientRecord())->validate($input);
        $nameKey = $this->duplicateKey(is_string($result['name'] ?? null) ? $result['name'] : '');
        if ($nameKey !== '' && $this->hasDuplicate($nameKey, $existingClients, $currentId)) {
            $result['errors']['name'] = 'Client name is already in use.';
        }
        $result['valid'] = $result['errors'] === [];
        return $result;
    }

    /** @return array<string, mixed> */
    public function validateForCreate(array $input, array $existingClients = []): array
    {
        return $this->validate($input, $existingClients);
    }

    /** @return array<string, mixed> */
    public function validateForEdit(int $id, array $input, array $existingClients = []): array
    {
        $errors = [];
        if ($id < 1) $errors['id'] = 'Client ID must be a positive integer.';
        $result = $this->validate($input, $existingClients, $id);
        $result['id'] = $id;
        $result['errors'] = [...$errors, ...$result['errors']];
        $result['valid'] = $result['errors'] === [];
        return $result;
    }

    /** @return array{valid: bool, id: int, status: string, errors: array<string, string>} */
    public function validateDeactivate(array $client): array
    {
        return $this->validateTransition($client, 'active', 'inactive');
    }

    /** @return array{valid: bool, id: int, status: string, errors: array<string, string>} */
    public function validateReactivate(array $client): array
    {
        return $this->validateTransition($client, 'inactive', 'active');
    }

    /** @return array{valid: bool, id: int, status: string, errors: array<string, string>} */
    public function deactivate(array $client): array
    {
        return $this->validateDeactivate($client);
    }

    /** @return array{valid: bool, id: int, status: string, errors: array<string, string>} */
    public function reactivate(array $client): array
    {
        return $this->validateReactivate($client);
    }

    /** @return array<string, mixed> */
    public function display(array $client): array
    {
        return ($this->clients ?? new ClientRecord())->display($client);
    }

    /** @return array<string, mixed> */
    public function toDisplay(array $client): array
    {
        return $this->display($client);
    }

    /** @return array{valid: bool, id: int, status: string, errors: array<string, string>} */
    private function validateTransition(array $client, string $from, string $to): array
    {
        $id = $this->positiveId($client['id'] ?? null);
        $status = strtolower(trim(is_scalar($client['status'] ?? null) ? (string) $client['status'] : ''));
        $errors = [];
        if ($id === null) $errors['id'] = 'Client ID must be a positive integer.';
        if ($status !== $from) $errors['status'] = "Only {$from} clients can be changed to {$to}.";
        return ['valid' => $errors === [], 'id' => $id ?? 0, 'status' => $to, 'errors' => $errors];
    }

    private function hasDuplicate(string $candidate, array $rows, ?int $currentId): bool
    {
        foreach ($rows as $row) {
            $name = is_array($row) ? ($row['name'] ?? null) : $row;
            if (!is_scalar($name) || $this->duplicateKey((string) $name) !== $candidate) continue;
            $rowId = is_array($row) ? $this->positiveId($row['id'] ?? null) : null;
            if ($currentId === null || $rowId !== $currentId) return true;
        }
        return false;
    }

    private function duplicateKey(string $value): string
    {
        $collapsed = preg_replace('/\s+/u', ' ', trim($value));
        return strtolower($collapsed === false ? trim($value) : $collapsed);
    }

    private function positiveId(mixed $value): ?int
    {
        if (is_int($value) && $value > 0) return $value;
        if (is_string($value) && preg_match('/^[1-9]\d*$/', trim($value)) === 1) {
            $id = filter_var(trim($value), FILTER_VALIDATE_INT);
            return $id === false ? null : $id;
        }
        return null;
    }
}