<?php

declare(strict_types=1);

namespace App\Services\TenantConfiguration;

use App\Support\Providers\ProviderReasonCodes;

final class ExchangePowerShellOutputGuard
{
    public function guard(
        ExchangePowerShellProcessResult $result,
        ExchangePowerShellCommandContract $contract,
        ExchangePowerShellRuntimePolicy $policy,
    ): ExchangePowerShellInvocationResult {
        if ($result->timedOut) {
            return ExchangePowerShellInvocationResult::failed(
                reasonCode: ProviderReasonCodes::NetworkUnreachable,
                failureCode: 'execution_failed_timeout',
                message: 'Exchange PowerShell process timed out.',
                summaryCounts: $this->failureSummaryCounts(),
                context: [
                    'output_state' => 'timeout',
                    'timeout_cleanup_attempted' => true,
                    'duration_ms' => $result->durationMs,
                ],
            );
        }

        if ($result->exceptionClass !== null) {
            return ExchangePowerShellInvocationResult::failed(
                reasonCode: ProviderReasonCodes::UnknownError,
                failureCode: 'execution_failed_unexpected_exception',
                message: 'Exchange PowerShell process failed safely.',
                summaryCounts: $this->failureSummaryCounts(),
                context: [
                    'output_state' => 'executor_exception',
                    'duration_ms' => $result->durationMs,
                ],
            );
        }

        if (strlen($result->stdout) > $policy->stdoutMaxBytes) {
            return $this->shapeFailure('execution_failed_stdout_oversized', 'stdout_oversized', $result->durationMs);
        }

        if (strlen($result->stderr) > $policy->stderrMaxBytes) {
            return $this->shapeFailure('execution_failed_stderr_oversized', 'stderr_oversized', $result->durationMs);
        }

        if (! $this->isSafeUtf8Text($result->stdout) || ! $this->isSafeUtf8Text($result->stderr)) {
            return $this->shapeFailure('execution_failed_output_encoding', 'non_utf8_or_binary', $result->durationMs);
        }

        if ($result->exitCode !== 0) {
            return ExchangePowerShellInvocationResult::failed(
                reasonCode: ProviderReasonCodes::ProviderConnectionInvalid,
                failureCode: 'execution_failed_nonzero_exit',
                message: 'Exchange PowerShell process exited unsuccessfully.',
                summaryCounts: $this->failureSummaryCounts(),
                context: [
                    'output_state' => 'nonzero_exit',
                    'duration_ms' => $result->durationMs,
                ],
            );
        }

        if (trim($result->stderr) !== '') {
            return $this->shapeFailure('execution_failed_stderr_present', 'stderr_present', $result->durationMs);
        }

        $stdout = trim($result->stdout);

        if ($stdout === '') {
            return ExchangePowerShellInvocationResult::succeeded([], context: [
                'output_state' => 'empty_collection',
                'item_count' => 0,
                'duration_ms' => $result->durationMs,
            ]);
        }

        if (preg_match('/\AWARNING:/i', $stdout) === 1) {
            return $this->shapeFailure('execution_failed_output_shape_unsafe', 'warning_prefixed', $result->durationMs);
        }

        $decoded = json_decode($stdout, true);

        if (json_last_error() !== JSON_ERROR_NONE || ! is_array($decoded) || ! array_is_list($decoded)) {
            return $this->shapeFailure('execution_failed_shape_unsafe', 'malformed_json_collection', $result->durationMs);
        }

        $items = [];

        foreach ($decoded as $item) {
            if (! is_array($item)) {
                return $this->shapeFailure('execution_failed_shape_unsafe', 'malformed_collection_item', $result->durationMs);
            }

            $items[] = $item;
        }

        if (count($items) > $policy->itemLimit) {
            return $this->shapeFailure('execution_failed_item_limit_exceeded', 'item_limit_exceeded', $result->durationMs);
        }

        return ExchangePowerShellInvocationResult::succeeded($items, context: [
            'output_state' => 'structured_collection',
            'item_count' => count($items),
            'duration_ms' => $result->durationMs,
        ]);
    }

    private function shapeFailure(string $failureCode, string $outputState, int $durationMs): ExchangePowerShellInvocationResult
    {
        return ExchangePowerShellInvocationResult::failed(
            reasonCode: ProviderReasonCodes::ProviderConnectionInvalid,
            failureCode: $failureCode,
            message: 'Exchange PowerShell output was rejected safely.',
            summaryCounts: $this->failureSummaryCounts(),
            context: [
                'output_state' => $outputState,
                'duration_ms' => $durationMs,
            ],
        );
    }

    private function isSafeUtf8Text(string $value): bool
    {
        if ($value === '') {
            return true;
        }

        if (function_exists('mb_check_encoding') && ! mb_check_encoding($value, 'UTF-8')) {
            return false;
        }

        if (preg_match('//u', $value) !== 1) {
            return false;
        }

        return preg_match('/[\x00-\x08\x0B\x0C\x0E-\x1F]/', $value) !== 1;
    }

    /**
     * @return array<string, int>
     */
    private function failureSummaryCounts(): array
    {
        return [
            'total' => 1,
            'processed' => 1,
            'succeeded' => 0,
            'failed' => 1,
            'skipped' => 0,
            'items' => 0,
        ];
    }
}