package cn.seecoder.codejudge.client;


import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.json.JsonMapper;
import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
import com.fasterxml.jackson.module.paramnames.ParameterNamesModule;
import okhttp3.*;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.validation.constraints.NotNull;
import java.io.IOException;
import java.util.Objects;
import java.util.Optional;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

/**
 * @author kunduin
 */
public class CodeJudgeClient implements CodeJudgeApi {

    private final Logger logger = LoggerFactory.getLogger(getClass());

    private final OkHttpClient client;
    private final ObjectMapper mapper;

    private final String CONFIG_HOST;

    /**
     * 创建client
     *
     * @param host code judge 地址，示例：{@code "http://codejudge.seec.seecoder.cn"}
     */
    public CodeJudgeClient(String host) {
        this.CONFIG_HOST = host;
        client = new OkHttpClient().newBuilder().connectTimeout(60000, TimeUnit.MILLISECONDS).readTimeout(60000,TimeUnit.MILLISECONDS).build();
        mapper = JsonMapper.builder()
                .addModule(new ParameterNamesModule())
                .addModule(new Jdk8Module())
                .addModule(new JavaTimeModule())
                .build();
    }

    /**
     * 判题接口
     *
     * @param judgeDTO 判题信息
     * @return 判题结果
     */
    @Override
    public JudgeResult judge(@NotNull JudgeDTO judgeDTO) {
        HttpUrl httpUrl = createUrlBuilder("/api/judge").build();
        Response response = post(httpUrl, writeRequestBody(judgeDTO));
        return getResponseBody(response, JudgeResult.class)
                .map(judgeResult -> {
                    if (judgeResult.getMessage() == null) {
                        return judgeResult;
                    } else {
                        throw new CodeJudgeSystemException(judgeResult.getMessage());
                    }
                }).orElseThrow(() -> new CodeJudgeSystemException("UN_WRAP"));
    }


    private HttpUrl.Builder createUrlBuilder(final String path) {
        return Objects.requireNonNull(HttpUrl.parse(CONFIG_HOST + path)).newBuilder();
    }

    private Response post(HttpUrl httpUrl, RequestBody requestBody) {
        return requestWithMethod("POST", httpUrl, requestBody);
    }

    private Response requestWithMethod(String method, HttpUrl httpUrl, RequestBody requestBody) {
        Request request = new Request.Builder().url(httpUrl).method(method, requestBody).build();
        try {
            return client.newCall(request).execute();
        } catch (IOException e) {
            logger.error("IOException.", e);
            throw new CodeJudgeSystemException("IO_EXCEPTION");
        }
    }

    private <T> Optional<T> getResponseBody(Response response, Class<T> tClass) {
        return getResponseBody(
                response,
                bodyString -> {
                    try {
                        return mapper.readValue(bodyString, tClass);
                    } catch (JsonProcessingException e) {
                        logger.error("JsonProcessingException.", e);
                        throw new CodeJudgeSystemException("JsonProcessingException");
                    }
                });
    }

    private <T> Optional<T> getResponseBody(Response response, TypeReference<T> typeReference) {
        return getResponseBody(
                response,
                bodyString -> {
                    try {
                        return mapper.readValue(bodyString, typeReference);
                    } catch (JsonProcessingException e) {
                        logger.error("JsonProcessingException.", e);
                        throw new CodeJudgeSystemException("JsonProcessingException");
                    }
                });
    }

    private <T> Optional<T> getResponseBody(Response response, Function<String, T> mapType) {
        return Optional.ofNullable(response.body())
                .map(body -> {
                    try {
                        String bodyString = body.string();
                        return mapType.apply(bodyString);
                    } catch (IOException e) {
                        logger.error("IOException.", e);
                        throw new CodeJudgeSystemException("IOException");
                    }
                });
    }

    private <T> RequestBody writeRequestBody(T obj) {
        if (obj == null) {
            return null;
        }

        try {
            return RequestBody.create(CodeJudgeConstants.JSON, mapper.writeValueAsString(obj));
        } catch (JsonProcessingException e) {
            logger.error("JsonProcessingException.", e);
            throw new CodeJudgeSystemException("JsonProcessingException");
        }
    }

}