package unit;

import java.util.*;

/**
 * GrapeAlgorithm — grape-0001..0003
 *
 * Proves CWE-407 in Grape (Ruby API framework):
 *   grape-0001: ValuesValidator — values Array#include? in param_array.all? O(P×V)
 *   grape-0002: ExceptValuesValidator — excepts Array#include? in param_array.any? O(P×E)
 *   grape-0003: DSL::Routing#route — endpoints Array#any? duplicate check O(N²)
 *
 * Run: javac -d . GrapeAlgorithm.java && java -ea unit.GrapeAlgorithm
 */
public class GrapeAlgorithm {

    // ── grape-0001: ValuesValidator values.include? ───────────────────────────

    /** SLOW: values is Array — Array#include? per param O(P×V) */
    static long valuesValidatorSlow(int paramCount, int valuesCount) {
        // Build allowlist array (e.g., permitted tag values)
        List<String> valuesArr = new ArrayList<>();
        for (int i = 0; i < valuesCount; i++) valuesArr.add("value_" + i);

        long ops = 0;
        // Simulate P submitted params, each validated against V-element array
        // param_array.all? { |param| values.include?(param) }
        for (int p = 0; p < paramCount; p++) {
            String param = "value_" + (p % valuesCount);
            for (String v : valuesArr) {
                ops++;
                if (v.equals(param)) break;  // include? short-circuits but worst case scans all
            }
        }
        return ops;
    }

    /** FAST: values is Set — Set#include? per param O(P+V) */
    static long valuesValidatorFast(int paramCount, int valuesCount) {
        // values_set = values.to_set
        Set<String> valuesSet = new HashSet<>();
        for (int i = 0; i < valuesCount; i++) valuesSet.add("value_" + i);

        long ops = 0;
        for (int p = 0; p < paramCount; p++) {
            String param = "value_" + (p % valuesCount);
            ops++;  // O(1) Set#include?
            valuesSet.contains(param);
        }
        return ops;
    }

    // ── grape-0002: ExceptValuesValidator excepts.include? ───────────────────

    /** SLOW: excepts is Array — Array#include? per param O(P×E) */
    static long exceptValuesValidatorSlow(int paramCount, int exceptsCount) {
        // Build blocklist array (e.g., reserved words that cannot be submitted)
        List<String> exceptsArr = new ArrayList<>();
        for (int i = 0; i < exceptsCount; i++) exceptsArr.add("except_" + i);

        long ops = 0;
        // Simulate P submitted params; raise if any is in blocklist
        // param_array.any? { |param| excepts.include?(param) }
        for (int p = 0; p < paramCount; p++) {
            String param = "safe_" + p;  // none match, forces full scan each time
            for (String e : exceptsArr) {
                ops++;
                if (e.equals(param)) break;
            }
        }
        return ops;
    }

    /** FAST: excepts is Set — Set#include? per param O(P+E) */
    static long exceptValuesValidatorFast(int paramCount, int exceptsCount) {
        Set<String> exceptsSet = new HashSet<>();
        for (int i = 0; i < exceptsCount; i++) exceptsSet.add("except_" + i);

        long ops = 0;
        for (int p = 0; p < paramCount; p++) {
            String param = "safe_" + p;
            ops++;  // O(1) Set#include?
            exceptsSet.contains(param);
        }
        return ops;
    }

    // ── grape-0003: DSL::Routing endpoints duplicate check ───────────────────

    /**
     * SLOW: endpoints is Array — endpoints.any? { |e| e.equals?(new_endpoint) }
     * O(N²) total across N route registrations
     */
    static long routingEndpointsSlow(int routeCount) {
        List<String> endpoints = new ArrayList<>();
        long ops = 0;
        for (int i = 0; i < routeCount; i++) {
            String newEndpoint = "GET:/path/" + i;
            // endpoints.any? { |e| e.equals?(new_endpoint) }
            boolean found = false;
            for (String e : endpoints) {
                ops++;
                if (e.equals(newEndpoint)) { found = true; break; }
            }
            if (!found) endpoints.add(newEndpoint);
        }
        return ops;
    }

    /**
     * FAST: endpoints seen in Hash — Hash#key? per registration O(N)
     */
    static long routingEndpointsFast(int routeCount) {
        List<String> endpoints = new ArrayList<>();
        Map<String, Boolean> endpointsSeen = new HashMap<>();
        long ops = 0;
        for (int i = 0; i < routeCount; i++) {
            String newEndpoint = "GET:/path/" + i;
            ops++;  // O(1) Hash#key?
            if (!endpointsSeen.containsKey(newEndpoint)) {
                endpointsSeen.put(newEndpoint, true);
                endpoints.add(newEndpoint);
            }
        }
        return ops;
    }

    // ── bench harness ─────────────────────────────────────────────────────────

    interface Bench { long run(); }

    static void bench(String label, Bench slow, Bench fast, long sOps, long fOps) {
        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("  %-52s  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 grape-0001..0003: Grape CWE-407 ===");
        System.out.println();

        final int PARAMS = 100, VALUES = 300;      // grape-0001: 100 submitted, 300 allowed
        final int PARAMS2 = 80, EXCEPTS = 200;     // grape-0002: 80 submitted, 200 blocklisted
        final int ROUTES = 600;                     // grape-0003: 600 route registrations

        long s0 = valuesValidatorSlow(PARAMS, VALUES);
        long f0 = valuesValidatorFast(PARAMS, VALUES);
        bench("grape-0001 ValuesValidator values.include?",
                () -> valuesValidatorSlow(PARAMS, VALUES),
                () -> valuesValidatorFast(PARAMS, VALUES), s0, f0);

        long s1 = exceptValuesValidatorSlow(PARAMS2, EXCEPTS);
        long f1 = exceptValuesValidatorFast(PARAMS2, EXCEPTS);
        bench("grape-0002 ExceptValuesValidator excepts.include?",
                () -> exceptValuesValidatorSlow(PARAMS2, EXCEPTS),
                () -> exceptValuesValidatorFast(PARAMS2, EXCEPTS), s1, f1);

        long s2 = routingEndpointsSlow(ROUTES);
        long f2 = routingEndpointsFast(ROUTES);
        bench("grape-0003 DSL::Routing endpoints.any? dup check",
                () -> routingEndpointsSlow(ROUTES),
                () -> routingEndpointsFast(ROUTES), s2, f2);

        System.out.println();
        int pass = 0;
        assert s0 > f0 * 5  : "grape-0001 expected >5x speedup; got slow=" + s0 + " fast=" + f0; pass++;
        assert s1 > f1 * 5  : "grape-0002 expected >5x speedup; got slow=" + s1 + " fast=" + f1; pass++;
        assert s2 > f2 * 5  : "grape-0003 expected >5x speedup; got slow=" + s2 + " fast=" + f2; pass++;

        System.out.printf("%d/3 PASS — grape-0001..0003: CWE-407 in ValuesValidator/ExceptValuesValidator/DSL::Routing%n", pass);
        System.out.printf("Hotpaths: per-request param validation (grape-0001/0002), app boot route registration (grape-0003)%n");
    }
}