package com.loan.system.domain.entity;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.*;
import org.apache.commons.io.output.ByteArrayOutputStream;
import org.apache.commons.lang3.exception.ExceptionUtils;

import javax.persistence.*;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import java.io.IOException;
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
import java.util.Base64;
import java.util.zip.GZIPOutputStream;

@Entity
@Table(name = "exception_log")
@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class ExceptionLog {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id", nullable = false)
    private Long id;

    @Size(max = 120)
    @Column(name = "exception_type", length = 120)
    private String exceptionType;

    @Size(max = 500)
    @Column(name = "message", length = 500)
    private String message;

    @Size(max = 200)
    @Column(name = "summary", length = 200)
    private String summary;

    @Size(max = 200)
    @Column(name = "cause", length = 200)
    private String cause;

    @Lob
    @Column(name = "stack_trace")
    private String stackTrace;

    @Size(max = 255)
    @Column(name = "url")
    private String url;

    @Column(name = "user_id")
    private Long userId;

    @Size(max = 45)
    @Column(name = "ip", length = 45)
    private String ip;

    @Size(max = 300)
    @Column(name = "user_agent", length = 300)
    private String userAgent;

    @Size(max = 10)
    @Column(name = "method", length = 10)
    private String method;

    @Lob
    @Column(name = "params")
    private String params;

    @Column(name = "is_resolve")
    private Boolean isResolve;

    @NotNull
    @Column(name = "create_time", nullable = false)
    private String createTime;

    private static final ObjectMapper MAPPER = new ObjectMapper();

    /** 快速构建：只传异常 + 请求上下文 */
    public static ExceptionLog build(Exception e, String url, String method,
                                     String ip, String userAgent, Long userId,
                                     Object paramsObj) {
        Throwable root = ExceptionUtils.getRootCause(e);
        if (root == null) root = e;

        return ExceptionLog.builder()
                .exceptionType(e.getClass().getSimpleName())
                .message(trim(e.getMessage(), 500))
                .summary(buildSummary(e))
                .cause(root.getClass().getSimpleName())
                .stackTrace(compressTrace(e, 50))
                .url(trim(url, 255))
                .method(trim(method, 10))
                .ip(trim(ip, 45))
                .userAgent(trim(userAgent, 300))
                .userId(userId == null ? 0L : userId)
                .params(toJson(paramsObj))
                .createTime(LocalDateTime.now().format(DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss")))
                .build();
    }

    /** 摘要：类名 + 第一行堆栈 */
    private static String buildSummary(Exception e) {
        StringBuilder sb = new StringBuilder(e.getClass().getSimpleName());
        if (e.getMessage() != null) {
            sb.append(": ").append(trim(e.getMessage(), 120));
        }
        if (e.getStackTrace().length > 0) {
            StackTraceElement first = e.getStackTrace()[0];
            sb.append(" at ")
                    .append(first.getClassName())
                    .append(":")
                    .append(first.getLineNumber());
        }
        return trim(sb.toString(), 200);
    }

    /** 截取堆栈前 max 行并 GZIP + Base64 */
    private static String compressTrace(Exception e, int max) {
        String raw = ExceptionUtils.getStackTrace(e);
        String[] lines = raw.split("\n");
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < Math.min(max, lines.length); i++) {
            sb.append(lines[i]).append('\n');
        }
        try (ByteArrayOutputStream bos = new ByteArrayOutputStream();
             GZIPOutputStream gzip = new GZIPOutputStream(bos)) {
            gzip.write(sb.toString().getBytes("UTF-8"));
            gzip.finish();
            return Base64.getEncoder().encodeToString(bos.toByteArray());
        } catch (IOException ignored) {
            return "";
        }
    }

    private static String toJson(Object obj) {
        if (obj == null) return null;
        try {
            JsonNode node = MAPPER.valueToTree(obj);
            // TODO 这里可继续做脱敏
            return MAPPER.writeValueAsString(node);
        } catch (Exception ignore) {
            return null;
        }
    }

    private static String trim(String str, int max) {
        if (str == null) return "";
        return str.length() > max ? str.substring(0, max) : str;
    }

}