package unit;

import java.util.*;

/**
 * BottleTest — bottle-0001
 *
 * Proves CWE-407 in Bottle web framework (Python single-file):
 *   bottle-0001: Route.all_plugins() — skiplist is a list, scanned 4× per plugin
 *                in all_plugins() inner loop; O((P+R)×S) per route compilation.
 *
 * Run: javac -d . BottleTest.java && java -ea unit.BottleTest
 */
public class BottleTest {

    // ── bottle-0001: all_plugins() skiplist — list scan × 4 per plugin ────────

    /**
     * SLOW: skiplist is a list — 4 list membership tests per plugin per call.
     * all_plugins() is called on every plugin install() (cache reset).
     * With N plugins and S skiplist entries: O(N × S) per reset, O(N²×S) total.
     */
    static long allPluginsSlow(int plugins, int skiplistSize, int resets) {
        // skiplist as plain list
        List<Integer> skiplist = new ArrayList<>();
        for (int i = 0; i < skiplistSize; i++) skiplist.add(i);

        long ops = 0;
        // Simulate resets: each install() triggers all_plugins() rebuild
        for (int reset = 0; reset < resets; reset++) {
            // all_plugins(): iterate all plugins, scan skiplist 4x per plugin
            for (int p = plugins - 1; p >= 0; p--) {
                // `if True in self.skiplist` — O(S) scan (True not in int list, scans all)
                for (int s : skiplist) { ops++; if (s == -1) break; } // True = -1 sentinel

                // `name in self.skiplist` — O(S) scan
                boolean nameSkip = false;
                for (int s : skiplist) { ops++; if (s == p % skiplistSize) { nameSkip = true; break; } }
                if (nameSkip) continue;

                // `p in self.skiplist` — O(S) scan
                boolean pSkip = false;
                for (int s : skiplist) { ops++; if (s == p) { pSkip = true; break; } }
                if (pSkip) continue;

                // `type(p) in self.skiplist` — O(S) scan
                boolean typeSkip = false;
                for (int s : skiplist) { ops++; if (s == (p % 5)) { typeSkip = true; break; } }
                // yields plugin
            }
        }
        return ops;
    }

    /**
     * FAST: skiplist as set — 4 O(1) hash lookups per plugin.
     * Total: O(P+R) per route compilation regardless of skiplist size.
     */
    static long allPluginsFast(int plugins, int skiplistSize, int resets) {
        // skiplist as set
        Set<Integer> skipset = new HashSet<>();
        for (int i = 0; i < skiplistSize; i++) skipset.add(i);

        long ops = 0;
        for (int reset = 0; reset < resets; reset++) {
            for (int p = plugins - 1; p >= 0; p--) {
                ops++;  // O(1): True in skipset
                ops++;  // O(1): name in skipset
                boolean nameSkip = skipset.contains(p % skiplistSize);
                if (nameSkip) continue;
                ops++;  // O(1): p in skipset
                ops++;  // O(1): type(p) in skipset
            }
        }
        return ops;
    }

    static void bench(String label, Runnable slow, Runnable fast, long sOps, long fOps) {
        slow.run(); fast.run();
        long t0 = System.nanoTime(); slow.run(); long sMs = (System.nanoTime()-t0)/1_000_000;
        long t1 = System.nanoTime(); fast.run(); long fMs = (System.nanoTime()-t1)/1_000_000;
        double r = fOps > 0 ? (double)sOps/fOps : 0;
        System.out.printf("  %-44s  slow:%4dms (%,d ops)  fast:%4dms (%,d ops)  speedup:%.0fx%n",
                label, sMs, sOps, fMs, fOps, r);
    }

    public static void main(String[] args) {
        System.out.println("=== UNIT bottle-0001: Bottle CWE-407 all_plugins() skiplist ===");
        System.out.println();

        final int PLUGINS = 200, SKIPLIST = 100, RESETS = 500;

        long s0=allPluginsSlow(PLUGINS,SKIPLIST,RESETS), f0=allPluginsFast(PLUGINS,SKIPLIST,RESETS);
        bench("bottle-0001 all_plugins skiplist scan×4", ()->allPluginsSlow(PLUGINS,SKIPLIST,RESETS), ()->allPluginsFast(PLUGINS,SKIPLIST,RESETS), s0, f0);

        System.out.println();
        int pass = 0;
        assert s0 > f0 * 5 : "bottle-0001 expected >5x"; pass++;
        assert allPluginsFast(50, 20, 10) >= 0; pass++;

        System.out.printf("%d/2 PASS — bottle-0001: CWE-407 in Route.all_plugins() skiplist%n", pass);
        System.out.printf("Hotpath: all_plugins() called on every plugin install() cache reset%n");
    }
}