<?php

namespace App\Services\FlowTester;

use Exception;

/**
 * 플로우 실행 엔진
 *
 * 플로우 정의를 받아 단계별로 실행하고 결과를 반환합니다.
 *
 * 실행 흐름:
 * 1. 플로우 정의 로드 및 검증
 * 2. 의존성 기반 실행 순서 결정 (TopSort)
 * 3. 변수 바인딩 초기화
 * 4. 각 단계 순차 실행
 * 5. 결과 수집 및 반환
 */
class FlowExecutor
{
    private VariableBinder $binder;

    private DependencyResolver $resolver;

    private ResponseValidator $validator;

    private HttpClient $httpClient;

    /**
     * 실행 로그
     */
    private array $executionLog = [];

    /**
     * 실행 상태
     */
    private string $status = 'PENDING';

    /**
     * 현재 진행 상황
     */
    private int $completedSteps = 0;

    private int $totalSteps = 0;

    public function __construct(
        ?VariableBinder $binder = null,
        ?DependencyResolver $resolver = null,
        ?ResponseValidator $validator = null,
        ?HttpClient $httpClient = null
    ) {
        $this->binder = $binder ?? new VariableBinder;
        $this->resolver = $resolver ?? new DependencyResolver;
        $this->validator = $validator ?? new ResponseValidator;
        $this->httpClient = $httpClient ?? new HttpClient;
    }

    /**
     * 플로우 실행
     *
     * @param  array  $flowDefinition  플로우 정의 JSON
     * @param  array  $inputVariables  입력 변수 (실행 시 주입)
     * @return array 실행 결과
     */
    public function execute(array $flowDefinition, array $inputVariables = []): array
    {
        $startTime = microtime(true);
        $this->reset();

        try {
            // 1. 플로우 정의 검증
            $this->validateFlowDefinition($flowDefinition);

            // 2. 설정 적용
            $this->applyConfig($flowDefinition['config'] ?? []);

            // 3. 전역 변수 초기화
            $variables = array_merge(
                $flowDefinition['variables'] ?? [],
                $inputVariables
            );
            $this->binder->setVariables($variables);

            // 4. 스텝 정보 추출
            $steps = $flowDefinition['steps'] ?? [];
            $this->totalSteps = count($steps);

            if ($this->totalSteps === 0) {
                return $this->buildResult($startTime, 'SUCCESS', 'No steps to execute');
            }

            // 5. 의존성 정렬
            $orderedStepIds = $this->resolver->resolve($steps);
            $stepMap = $this->buildStepMap($steps);

            // 6. 실행 상태 변경
            $this->status = 'RUNNING';

            // 7. 각 단계 실행
            $stopOnFailure = $flowDefinition['config']['stopOnFailure'] ?? true;

            foreach ($orderedStepIds as $stepId) {
                $step = $stepMap[$stepId];
                $stepResult = $this->executeStep($step);

                $this->executionLog[] = $stepResult;

                if ($stepResult['success']) {
                    $this->completedSteps++;
                } else {
                    if (! ($step['continueOnFailure'] ?? false) && $stopOnFailure) {
                        $this->status = 'FAILED';

                        return $this->buildResult(
                            $startTime,
                            'FAILED',
                            "Step '{$stepId}' failed: ".($stepResult['error'] ?? 'Unknown error'),
                            $stepId
                        );
                    }
                    // continueOnFailure가 true면 계속 진행
                }
            }

            // 8. 최종 상태 결정
            $this->status = $this->completedSteps === $this->totalSteps ? 'SUCCESS' : 'PARTIAL';

            return $this->buildResult($startTime, $this->status);
        } catch (Exception $e) {
            $this->status = 'FAILED';

            return $this->buildResult($startTime, 'FAILED', $e->getMessage());
        }
    }

    /**
     * 단일 스텝 실행
     */
    private function executeStep(array $step): array
    {
        $stepId = $step['id'];
        $stepName = $step['name'] ?? $stepId;
        $startTime = microtime(true);

        try {
            // 1. 딜레이 적용
            $delay = $step['delay'] ?? 0;
            if ($delay > 0) {
                usleep($delay * 1000); // ms → μs
            }

            // 2. 변수 바인딩
            $endpoint = $this->binder->bind($step['endpoint']);
            $headers = $this->binder->bind($step['headers'] ?? []);
            $body = $this->binder->bind($step['body'] ?? []);

            // 3. HTTP 요청 실행
            $method = strtoupper($step['method']);
            $response = $this->httpClient->request($method, $endpoint, [
                'headers' => $headers,
                'body' => $body,
            ]);

            // 4. HTTP 에러 체크
            if ($response['error']) {
                return $this->buildStepResult($stepId, $stepName, $startTime, false, [
                    'error' => $response['error'],
                    'request' => [
                        'method' => $method,
                        'endpoint' => $endpoint,
                        'headers' => $headers,
                        'body' => $body,
                    ],
                ]);
            }

            // 5. 응답 검증
            $expect = $step['expect'] ?? [];
            $validation = $this->validator->validate($response, $expect);

            // 6. 변수 추출
            $extracted = [];
            if (isset($step['extract'])) {
                $extracted = $this->validator->extractValues($response['body'], $step['extract']);
                $this->binder->setStepResult($stepId, $extracted, $response['body']);
            }

            // 7. 결과 구성
            $success = $validation['success'];

            return $this->buildStepResult($stepId, $stepName, $startTime, $success, [
                'request' => [
                    'method' => $method,
                    'endpoint' => $endpoint,
                    'headers' => $headers,
                    'body' => $body,
                ],
                'response' => [
                    'status' => $response['status'],
                    'body' => $response['body'],
                    'duration' => $response['duration'],
                ],
                'extracted' => $extracted,
                'validation' => $validation,
                'error' => $success ? null : implode('; ', $validation['errors']),
            ]);
        } catch (Exception $e) {
            return $this->buildStepResult($stepId, $stepName, $startTime, false, [
                'error' => $e->getMessage(),
            ]);
        }
    }

    /**
     * 플로우 정의 검증
     */
    private function validateFlowDefinition(array $definition): void
    {
        // steps 필드 필수
        if (! isset($definition['steps']) || ! is_array($definition['steps'])) {
            throw new Exception('Flow definition must have a "steps" array');
        }

        // 각 스텝 검증
        foreach ($definition['steps'] as $index => $step) {
            if (! isset($step['id'])) {
                throw new Exception("Step at index {$index} must have an 'id' field");
            }
            if (! isset($step['method'])) {
                throw new Exception("Step '{$step['id']}' must have a 'method' field");
            }
            if (! isset($step['endpoint'])) {
                throw new Exception("Step '{$step['id']}' must have an 'endpoint' field");
            }
        }

        // 의존성 검증
        $validation = $this->resolver->validate($definition['steps']);
        if (! $validation['valid']) {
            throw new Exception('Dependency validation failed: '.implode('; ', $validation['errors']));
        }
    }

    /**
     * 설정 적용
     */
    private function applyConfig(array $config): void
    {
        // Base URL
        if (isset($config['baseUrl'])) {
            $this->httpClient->setBaseUrl($config['baseUrl']);
        }

        // Timeout
        if (isset($config['timeout'])) {
            $timeout = (int) ($config['timeout'] / 1000); // ms → s
            $this->httpClient->setTimeout(max(1, $timeout));
        }

        // 기본 헤더
        if (isset($config['headers'])) {
            $this->httpClient->setDefaultHeaders($config['headers']);
        }

        // 인증
        if (isset($config['apiKey'])) {
            $this->httpClient->setApiKey($config['apiKey']);
        }
        if (isset($config['bearerToken'])) {
            $this->httpClient->setBearerToken($config['bearerToken']);
        }
    }

    /**
     * 스텝 맵 구성 (id → step)
     */
    private function buildStepMap(array $steps): array
    {
        $map = [];
        foreach ($steps as $step) {
            $map[$step['id']] = $step;
        }

        return $map;
    }

    /**
     * 스텝 결과 구성
     */
    private function buildStepResult(
        string $stepId,
        string $stepName,
        float $startTime,
        bool $success,
        array $details = []
    ): array {
        $duration = (int) ((microtime(true) - $startTime) * 1000);

        return array_merge([
            'stepId' => $stepId,
            'stepName' => $stepName,
            'success' => $success,
            'duration' => $duration,
            'timestamp' => date('Y-m-d H:i:s'),
        ], $details);
    }

    /**
     * 최종 결과 구성
     */
    private function buildResult(
        float $startTime,
        string $status,
        ?string $errorMessage = null,
        ?string $failedStep = null
    ): array {
        $duration = (int) ((microtime(true) - $startTime) * 1000);

        return [
            'status' => $status,
            'duration' => $duration,
            'totalSteps' => $this->totalSteps,
            'completedSteps' => $this->completedSteps,
            'failedStep' => $failedStep,
            'errorMessage' => $errorMessage,
            'executionLog' => $this->executionLog,
            'startedAt' => date('Y-m-d H:i:s', (int) $startTime),
            'completedAt' => date('Y-m-d H:i:s'),
        ];
    }

    /**
     * 상태 초기화
     */
    private function reset(): void
    {
        $this->executionLog = [];
        $this->status = 'PENDING';
        $this->completedSteps = 0;
        $this->totalSteps = 0;
        $this->binder->reset();
    }

    /**
     * 현재 진행 상황 조회
     */
    public function getProgress(): array
    {
        return [
            'status' => $this->status,
            'completedSteps' => $this->completedSteps,
            'totalSteps' => $this->totalSteps,
            'percent' => $this->totalSteps > 0
                ? round(($this->completedSteps / $this->totalSteps) * 100, 1)
                : 0,
        ];
    }

    /**
     * 실행 로그 조회
     */
    public function getExecutionLog(): array
    {
        return $this->executionLog;
    }

    /**
     * 현재 상태 조회
     */
    public function getStatus(): string
    {
        return $this->status;
    }
}