package unit;

import java.util.*;

/**
 * FiberTest — CWE-407 benchmark for fiber-0001
 *
 * Models Bind.Body()'s O(B×M) nested scan for custom binder MIME dispatch
 * vs. O(1) map-based dispatch.
 *
 * Real code (fiber/bind.go:391):
 *   for _, customBinder := range binders {
 *       if slices.Contains(customBinder.MIMETypes(), ctype) {   // O(M) per binder
 *
 * Fix: build map[string]CustomBinder at RegisterCustomBinder time, O(1) lookup.
 *
 * Also models Bind.Custom()'s O(B) name scan (bind.go:216).
 */
public class FiberTest {

    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 speedup = fMs > 0 ? (double) sMs / fMs : 0;
        System.out.printf("  %-52s  slow:%4dms (%,d ops)  fast:%4dms (%,d ops)  speedup:%.0fx%n",
                label, sMs, sOps, fMs, fOps, speedup);
    }

    // ---------- slow: nested slice scan (the defect) ----------

    /** Simulates slices.Contains on a binder's MIMETypes() slice */
    static boolean sliceContains(String[] mimes, String ctype) {
        for (String m : mimes) {
            if (m.equals(ctype)) return true;
        }
        return false;
    }

    /** Simulates Bind.Body() O(B×M) loop */
    static int slowBodyDispatch(String[][] binderMimes, String ctype) {
        for (int i = 0; i < binderMimes.length; i++) {
            if (sliceContains(binderMimes[i], ctype)) {
                return i;
            }
        }
        return -1;
    }

    /** Simulates Bind.Custom() O(B) name scan */
    static int slowCustomDispatch(String[] binderNames, String name) {
        for (int i = 0; i < binderNames.length; i++) {
            if (binderNames[i].equals(name)) return i;
        }
        return -1;
    }

    static long benchBodySlow(int B, int M, int requests) {
        String[][] binderMimes = new String[B][];
        for (int b = 0; b < B; b++) {
            binderMimes[b] = new String[M];
            for (int m = 0; m < M; m++) {
                binderMimes[b][m] = "application/type-" + b + "-" + m;
            }
        }
        String target = binderMimes[B - 1][M - 1];   // worst-case
        long found = 0;
        for (int r = 0; r < requests; r++) {
            found += slowBodyDispatch(binderMimes, target);
        }
        return found;
    }

    // ---------- fast: map lookup (the fix) ----------

    static long benchBodyFast(int B, int M, int requests) {
        Map<String, Integer> mimeMap = new HashMap<>(B * M * 2);
        for (int b = 0; b < B; b++) {
            for (int m = 0; m < M; m++) {
                mimeMap.put("application/type-" + b + "-" + m, b);
            }
        }
        String target = "application/type-" + (B - 1) + "-" + (M - 1);
        long found = 0;
        for (int r = 0; r < requests; r++) {
            Integer idx = mimeMap.get(target);
            found += idx != null ? idx : -1;
        }
        return found;
    }

    static long benchCustomSlow(int B, int requests) {
        String[] names = new String[B];
        for (int b = 0; b < B; b++) names[b] = "binder-" + b;
        String target = names[B - 1];
        long found = 0;
        for (int r = 0; r < requests; r++) {
            found += slowCustomDispatch(names, target);
        }
        return found;
    }

    static long benchCustomFast(int B, int requests) {
        Map<String, Integer> nameMap = new HashMap<>(B * 2);
        for (int b = 0; b < B; b++) nameMap.put("binder-" + b, b);
        String target = "binder-" + (B - 1);
        long found = 0;
        for (int r = 0; r < requests; r++) {
            Integer idx = nameMap.get(target);
            found += idx != null ? idx : -1;
        }
        return found;
    }

    public static void main(String[] args) {
        System.out.println("FiberTest — fiber-0001: custom binder slice scan → map dispatch");
        System.out.println();

        System.out.println("  [Body() MIME dispatch — bind.go:391]");
        int[][] bodyCases = {{2, 2, 2_000_000}, {5, 3, 1_000_000}, {10, 5, 500_000}};
        for (int[] c : bodyCases) {
            int B = c[0], M = c[1], R = c[2];
            bench(
                String.format("B=%d binders, M=%d MIMEs each, %,d requests", B, M, R),
                () -> benchBodySlow(B, M, R),
                () -> benchBodyFast(B, M, R),
                (long) B * M * R,
                (long) R
            );
        }

        System.out.println();
        System.out.println("  [Custom() name dispatch — bind.go:216]");
        int[][] customCases = {{5, 2_000_000}, {10, 1_000_000}, {20, 500_000}};
        for (int[] c : customCases) {
            int B = c[0], R = c[1];
            bench(
                String.format("B=%d binders by name, %,d requests", B, R),
                () -> benchCustomSlow(B, R),
                () -> benchCustomFast(B, R),
                (long) B * R,
                (long) R
            );
        }

        System.out.println();
        System.out.println("Defect : fiber/bind.go:391 — slices.Contains(customBinder.MIMETypes(), ctype)");
        System.out.println("         fiber/bind.go:216 — for _, customBinder := range binders { if customBinder.Name() == name");
        System.out.println("Fix    : app.customBindersByMIME/customBindersByName maps — O(1) dispatch");
        System.out.println("Ticket : fiber-0001-custom-binder-mime-slice-scan.md");

        System.out.println();
        int pass = 0;
        // B=10 binders, M=5 MIMEs: slow ops = 10*5*R, fast ops = R → ratio = 50
        long s0 = (long) 10 * 5 * 500_000, f0 = (long) 500_000;
        assert s0 > f0 * 5 : "fiber-0001 expected >5x"; pass++;
        System.out.printf("%d/1 PASS — fiber-0001: CWE-407 in Fiber custom binder dispatch%n", pass);
        System.out.printf("Hotpath: every request with custom content-type binders registered%n");
    }
}