package support;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

/**
 * MOAD-0004: A Logged Secret.
 *
 * Defect: HTTP request headers are serialized to a log string verbatim.
 * Authorization, Cookie, X-API-Key, and Proxy-Authorization headers contain
 * bearer tokens and session credentials.  Once logged, these persist across
 * restarts, propagate through log aggregation pipelines, and remain readable
 * for weeks at retention-period scale.
 *
 * Fix: apply a credential denylist at the log-serialization layer.
 * Redact or omit headers whose names match known credential carriers.
 * Functional behavior (routing, auth checks) is unaffected.
 *
 * Scanner detects: header-map serialization (toString, stream map, for-each
 * with string append) without a denylist filter on known credential header names.
 */
public class Moad0004Algorithm {

    /** Headers that carry credentials and must never appear in logs. */
    public static final Set<String> CREDENTIAL_HEADERS = Set.of(
        "authorization",
        "cookie",
        "x-api-key",
        "proxy-authorization",
        "x-auth-token"
    );

    /** Result of a log operation: the string written and a count of leaked credentials. */
    public static final class Result {
        public final String logLine;
        public final int    credentialLeakCount;

        public Result(String logLine, int credentialLeakCount) {
            this.logLine            = logLine;
            this.credentialLeakCount = credentialLeakCount;
        }
    }

    // ── Defective: logs all headers verbatim ─────────────────────────────────

    /**
     * Serializes the full header map to a log line with no filtering.
     * DEFECT: credential headers appear in cleartext in the log string.
     */
    public static Result logDefective(Map<String, String> headers) {
        StringBuilder sb = new StringBuilder("REQUEST headers: ");
        int leaks = 0;
        for (Map.Entry<String, String> e : headers.entrySet()) {
            sb.append(e.getKey()).append('=').append(e.getValue()).append(' ');
            if (CREDENTIAL_HEADERS.contains(e.getKey().toLowerCase())) {
                leaks++;
            }
        }
        return new Result(sb.toString().trim(), leaks);
    }

    // ── Fixed: redacts credential headers before serialization ────────────────

    private static final String REDACTED = "[REDACTED]";

    /**
     * Serializes the header map, replacing credential header values with [REDACTED].
     * FIX: credential headers appear in the log line with redacted values.
     * Downstream consumers still see header names (for debugging) but not values.
     */
    public static Result logFixed(Map<String, String> headers) {
        StringBuilder sb = new StringBuilder("REQUEST headers: ");
        for (Map.Entry<String, String> e : headers.entrySet()) {
            String value = CREDENTIAL_HEADERS.contains(e.getKey().toLowerCase())
                ? REDACTED
                : e.getValue();
            sb.append(e.getKey()).append('=').append(value).append(' ');
        }
        return new Result(sb.toString().trim(), 0);
    }

    /** Build a representative HTTP request header map for testing. */
    public static Map<String, String> sampleHeaders() {
        Map<String, String> h = new LinkedHashMap<>();
        h.put("Host",          "api.example.com");
        h.put("Content-Type",  "application/json");
        h.put("Authorization", "Bearer eyJhbGciOiJSUzI1NiJ9.secret.token");
        h.put("Cookie",        "session=abc123def456; csrf=xyz");
        h.put("X-Request-Id",  "req-7f3a9c");
        h.put("X-Api-Key",     "sk-prod-1234567890abcdef");
        h.put("Accept",        "application/json");
        return h;
    }
}