package com.vincent.rsf.httpaudit.support;

import com.vincent.rsf.httpaudit.props.HttpAuditProperties;

import javax.servlet.http.HttpServletRequest;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Map;

/**
 * 内外部判定、路径说明、响应截断
 */
public final class HttpAuditSupport {

    private HttpAuditSupport() {
    }

    public static String resolveScope(HttpServletRequest request, HttpAuditProperties props) {
        String path = safePath(request);
        for (String p : props.getExternalPathPrefixes()) {
            if (path.startsWith(p)) {
                return "EXTERNAL";
            }
        }
        return "INTERNAL";
    }

    public static String resolveFunctionDesc(HttpServletRequest request, HttpAuditProperties props) {
        String path = safePath(request);
        Map<String, String> map = props.getPathDescriptions();
        if (map == null || map.isEmpty()) {
            return null;
        }
        List<String> keys = new ArrayList<>(map.keySet());
        keys.sort(Comparator.comparingInt(String::length).reversed());
        for (String k : keys) {
            if (path.startsWith(k)) {
                return map.get(k);
            }
        }
        return null;
    }

    public static String safePath(HttpServletRequest request) {
        String ctx = request.getContextPath();
        String uri = request.getRequestURI();
        if (ctx != null && !ctx.isEmpty() && uri.startsWith(ctx)) {
            return uri.substring(ctx.length());
        }
        return uri != null ? uri : "";
    }

    public static boolean shouldExclude(HttpServletRequest request, HttpAuditProperties props) {
        String path = safePath(request);
        for (String p : props.getExcludePathPrefixes()) {
            if (p != null && !p.isEmpty() && path.startsWith(p)) {
                return true;
            }
        }
        String lower = path.toLowerCase();
        if (lower.endsWith(".js") || lower.endsWith(".css") || lower.endsWith(".ico")
                || lower.endsWith(".png") || lower.endsWith(".jpg") || lower.endsWith(".gif")
                || lower.endsWith(".woff") || lower.endsWith(".woff2") || lower.endsWith(".map")) {
            return true;
        }
        return false;
    }

    public static boolean isQueryLike(HttpServletRequest request) {
        String m = request.getMethod();
        if ("GET".equalsIgnoreCase(m)) {
            return true;
        }
        String path = safePath(request).toLowerCase();
        return path.contains("/page") || path.contains("/list") || path.contains("/query");
    }

    public static String clientIp(HttpServletRequest request) {
        String xff = request.getHeader("X-Forwarded-For");
        if (xff != null && !xff.isEmpty()) {
            int i = xff.indexOf(',');
            return i > 0 ? xff.substring(0, i).trim() : xff.trim();
        }
        String real = request.getHeader("X-Real-IP");
        if (real != null && !real.isEmpty()) {
            return real.trim();
        }
        return request.getRemoteAddr();
    }

    public static Charset resolveCharset(HttpServletRequest request) {
        String enc = request.getCharacterEncoding();
        if (enc == null || enc.isEmpty()) {
            return StandardCharsets.UTF_8;
        }
        try {
            return Charset.forName(enc);
        } catch (Exception e) {
            return StandardCharsets.UTF_8;
        }
    }

    public static String bytesToString(byte[] buf, Charset charset) {
        if (buf == null || buf.length == 0) {
            return "";
        }
        return new String(buf, charset);
    }

    public static String truncateForStore(String s, int maxChars) {
        if (s == null) {
            return null;
        }
        if (s.length() <= maxChars) {
            return s;
        }
        return s.substring(0, maxChars) + "...(truncated,len=" + s.length() + ")";
    }
}