package com.sb.web.account.service;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.sb.web.common.exception.ApiException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.stereotype.Service;
import org.springframework.web.client.RestClient;

import java.util.Base64;
import java.util.List;
import java.util.Map;

/**
 * Google Cloud Vision 영수증 OCR. 이미지(byte) → 전체 텍스트.
 * API 키는 환경변수(GOOGLE_VISION_API_KEY)로만 주입하며, 프론트엔드엔 노출하지 않는다.
 */
@Slf4j
@Service
public class VisionOcrService {

    private static final String ENDPOINT = "https://vision.googleapis.com/v1/images:annotate";

    private final RestClient restClient = RestClient.builder().build();
    private final ObjectMapper objectMapper;
    private final String apiKey;

    public VisionOcrService(ObjectMapper objectMapper,
                            @Value("${google.vision.api-key:}") String apiKey) {
        this.objectMapper = objectMapper;
        this.apiKey = apiKey;
    }

    public boolean isEnabled() {
        return apiKey != null && !apiKey.isBlank();
    }

    /** 영수증 이미지에서 전체 텍스트 추출 */
    public String recognize(byte[] image) {
        if (!isEnabled()) {
            throw new ApiException(HttpStatus.SERVICE_UNAVAILABLE, "영수증 OCR이 설정되지 않았습니다.");
        }
        String content = Base64.getEncoder().encodeToString(image);
        Map<String, Object> body = Map.of(
                "requests", List.of(Map.of(
                        "image", Map.of("content", content),
                        "features", List.of(Map.of("type", "DOCUMENT_TEXT_DETECTION")),
                        "imageContext", Map.of("languageHints", List.of("ko"))
                ))
        );

        String responseJson;
        try {
            responseJson = restClient.post()
                    .uri(ENDPOINT + "?key=" + apiKey)
                    .contentType(MediaType.APPLICATION_JSON)
                    .body(body)
                    .retrieve()
                    .body(String.class);
        } catch (Exception e) {
            log.warn("Vision OCR 호출 실패: {}", e.getMessage());
            throw new ApiException(HttpStatus.BAD_GATEWAY, "영수증 인식 서버 호출에 실패했습니다.");
        }

        try {
            JsonNode r0 = objectMapper.readTree(responseJson).path("responses").path(0);
            if (r0.has("error")) {
                log.warn("Vision OCR 오류 응답: {}", r0.path("error").path("message").asText());
                throw new ApiException(HttpStatus.BAD_GATEWAY, "영수증 인식에 실패했습니다.");
            }
            return r0.path("fullTextAnnotation").path("text").asText("");
        } catch (ApiException e) {
            throw e;
        } catch (Exception e) {
            log.warn("Vision OCR 응답 파싱 실패: {}", e.getMessage());
            throw new ApiException(HttpStatus.BAD_GATEWAY, "영수증 인식 결과를 처리하지 못했습니다.");
        }
    }
}