/*******************************************************************************
 * Copyright (C) 2026, Leo Galambos
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice, this
 *    list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
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 * 3. All advertising materials mentioning features or use of this software must
 *    display the following acknowledgement:
 *    This product includes software developed by the Egothor project.
 *
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 *    may be used to endorse or promote products derived from this software without
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package zeroecho.pki.spi.bootstrap;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Properties;

/**
 * Reads component configuration from system properties using a prefix
 * convention.
 *
 * <p>
 * Convention:
 * </p>
 * <ul>
 * <li>Select provider: {@code -Dzeroecho.pki.&lt;component&gt;=&lt;id&gt;}</li>
 * <li>Provider config:
 * {@code -Dzeroecho.pki.&lt;component&gt;.&lt;key&gt;=&lt;value&gt;}</li>
 * </ul>
 *
 * <p>
 * Values may be sensitive and must not be logged. Callers may log keys only.
 * </p>
 */
public final class SpiSystemProperties {

    private SpiSystemProperties() {
        throw new AssertionError("No instances.");
    }

    /**
     * Reads all string system properties with the given prefix.
     *
     * <p>
     * The returned map is a snapshot of {@link System#getProperties()} at the time
     * of invocation. Values are returned as-is (no trimming/normalization) to keep
     * behavior explicit.
     * </p>
     * 
     * @param prefix property prefix including trailing dot, e.g.
     *               {@code "zeroecho.pki.store."}
     * @return map of subKey -&gt; value (never {@code null})
     */
    public static Map<String, String> readPrefixed(String prefix) {
        Objects.requireNonNull(prefix, "prefix");

        Map<String, String> out = new HashMap<>();
        Properties props = System.getProperties();
        for (Map.Entry<Object, Object> e : props.entrySet()) {
            Object k = e.getKey();
            Object v = e.getValue();
            if (!(k instanceof String) || !(v instanceof String)) {
                continue;
            }
            String key = (String) k;
            if (!key.startsWith(prefix)) {
                continue;
            }
            String subKey = key.substring(prefix.length());
            if (subKey.isBlank()) {
                continue;
            }
            out.put(subKey, (String) v);
        }
        return out;
    }
}
