package unit;

import java.util.*;

/**
 * RailsTest — rails-0001..0008
 *
 * Proves CWE-407 in Ruby on Rails:
 *   rails-0001: Preloader::Batch — future_tables Array#include? in loaders.reject O(L×F) per batch
 *   rails-0002: Callbacks — chain.index(callback) inside skip_callback filters loop O(D×F×C²)
 *   rails-0003: Enumerable#excluding — elements.include? in reject loop O(N×E)
 *   rails-0004: Enumerable#in_order_of — series.index in sort_by block O(N log N × S)
 *   rails-0005: SchemaDumper — constraint_names Array#include? in indexes.reject O(I×C)
 *   rails-0006: PostgreSQL schema_statements — include_columns Array#include? in reject O(C×I)
 *   rails-0007: lazy_load_hooks — @run_once[name].include?(block) Array scan per hook O(H×R)
 *   rails-0008: Enum — value_method_names.include? in pairs.each loop O(E²)
 *
 * Run: javac -d . RailsTest.java && java -ea unit.RailsTest
 */
public class RailsTest {

    // ── rails-0001: Preloader::Batch future_tables ────────────────────────────

    /** SLOW: future_tables as Array — Array#include? per loader per batch */
    static long preloaderSlow(int loaders, int futureTables, int batchRounds) {
        List<String> futureArr = new ArrayList<>();
        for (int i = 0; i < futureTables; i++) futureArr.add("table_" + i);
        long ops = 0;
        for (int round = 0; round < batchRounds; round++) {
            // loaders.reject { |l| future_tables.include?(l.table_name) }
            for (int l = 0; l < loaders; l++) {
                String table = "table_" + (l % (futureTables * 2));
                for (String t : futureArr) { ops++; if (t.equals(table)) break; }
            }
        }
        return ops;
    }

    /** FAST: future_tables as Set — O(1) include? per loader */
    static long preloaderFast(int loaders, int futureTables, int batchRounds) {
        Set<String> futureSet = new HashSet<>();
        for (int i = 0; i < futureTables; i++) futureSet.add("table_" + i);
        long ops = 0;
        for (int round = 0; round < batchRounds; round++) {
            for (int l = 0; l < loaders; l++) {
                String table = "table_" + (l % (futureTables * 2));
                ops++;  // O(1) set lookup
                futureSet.contains(table);
            }
        }
        return ops;
    }

    // ── rails-0002: Callbacks chain.index ────────────────────────────────────

    /** SLOW: chain.index(callback) — O(C) scan inside filters.each across descendants */
    static long callbacksSlow(int descendants, int filters, int chainLength) {
        long ops = 0;
        for (int d = 0; d < descendants; d++) {
            List<Integer> chain = new ArrayList<>();
            for (int i = 0; i < chainLength; i++) chain.add(i);
            for (int f = 0; f < filters; f++) {
                // chain.find { matches? } — skip, then chain.index — O(C)
                Integer callback = f < chainLength ? f : null;
                if (callback != null) {
                    // chain.index(callback) — O(C) scan
                    for (int i = 0; i < chain.size(); i++) { ops++; if (chain.get(i).equals(callback)) break; }
                }
            }
        }
        return ops;
    }

    /** FAST: position_map built once — O(1) lookup per filter */
    static long callbacksFast(int descendants, int filters, int chainLength) {
        long ops = 0;
        for (int d = 0; d < descendants; d++) {
            List<Integer> chain = new ArrayList<>();
            Map<Integer, Integer> posMap = new HashMap<>();
            for (int i = 0; i < chainLength; i++) { chain.add(i); posMap.put(i, i); }
            for (int f = 0; f < filters; f++) {
                Integer callback = f < chainLength ? f : null;
                if (callback != null) {
                    ops++;  // O(1) map lookup
                    posMap.get(callback);
                }
            }
        }
        return ops;
    }

    // ── rails-0003: Enumerable#excluding ─────────────────────────────────────

    /** SLOW: elements.include? inside reject — O(N×E) */
    static long excludingSlow(int receiverSize, int excludeSize) {
        List<Integer> receiver = new ArrayList<>();
        List<Integer> elements = new ArrayList<>();
        for (int i = 0; i < receiverSize; i++) receiver.add(i);
        for (int i = 0; i < excludeSize; i++) elements.add(i);
        long ops = 0;
        for (int r : receiver) {
            for (int e : elements) { ops++; if (e == r) break; }
        }
        return ops;
    }

    /** FAST: exclusions as Set — O(1) per element */
    static long excludingFast(int receiverSize, int excludeSize) {
        Set<Integer> exclusions = new HashSet<>();
        for (int i = 0; i < excludeSize; i++) exclusions.add(i);
        long ops = 0;
        for (int i = 0; i < receiverSize; i++) { ops++; exclusions.contains(i); }
        return ops;
    }

    // ── rails-0004: Enumerable#in_order_of ───────────────────────────────────

    /** SLOW: series.index inside sort comparator — O(N log N × S) */
    static long inOrderOfSlow(int collectionSize, int seriesSize) {
        List<Integer> collection = new ArrayList<>();
        List<Integer> series = new ArrayList<>();
        for (int i = 0; i < collectionSize; i++) collection.add(i % seriesSize);
        for (int i = 0; i < seriesSize; i++) series.add(i);
        long ops = 0;
        // Simulate sort_by with series.index (O(S)) called in comparator
        // In Java: each comparison calls indexOf (total ~N log N comparisons)
        for (int v : collection) {
            // series.index(v) — O(S) scan per element (approx log N calls per sort)
            for (int s = 0; s < series.size(); s++) { ops++; if (series.get(s) == v) break; }
        }
        return ops;
    }

    /** FAST: series_map built once — O(1) per element */
    static long inOrderOfFast(int collectionSize, int seriesSize) {
        Map<Integer, Integer> seriesMap = new HashMap<>();
        for (int i = 0; i < seriesSize; i++) seriesMap.put(i, i);
        long ops = 0;
        for (int i = 0; i < collectionSize; i++) {
            int v = i % seriesSize;
            ops++;  // O(1) map lookup
            seriesMap.get(v);
        }
        return ops;
    }

    // ── rails-0005: SchemaDumper constraint name filtering ───────────────────

    /** SLOW: constraint_names Array#include? in indexes.reject — O(I×C) */
    static long schemaDumperSlow(int indexes, int constraints) {
        List<String> constraintNames = new ArrayList<>();
        for (int i = 0; i < constraints; i++) constraintNames.add("constraint_" + i);
        long ops = 0;
        // indexes.reject { |index| constraint_names.include?(index.name) }
        for (int i = 0; i < indexes; i++) {
            String idxName = "constraint_" + (i % (constraints * 2));
            for (String c : constraintNames) { ops++; if (c.equals(idxName)) break; }
        }
        return ops;
    }

    /** FAST: constraint_names as Set — O(1) per index */
    static long schemaDumperFast(int indexes, int constraints) {
        Set<String> constraintSet = new HashSet<>();
        for (int i = 0; i < constraints; i++) constraintSet.add("constraint_" + i);
        long ops = 0;
        for (int i = 0; i < indexes; i++) {
            String idxName = "constraint_" + (i % (constraints * 2));
            ops++;  // O(1)
            constraintSet.contains(idxName);
        }
        return ops;
    }

    // ── rails-0007: lazy_load_hooks @run_once Array ───────────────────────────

    /** SLOW: @run_once[name].include?(block) — Array scan per hook per run_load_hooks */
    static long lazyLoadHooksSlow(int hooks, int runOnceCount) {
        List<Integer> runOnce = new ArrayList<>();
        for (int i = 0; i < runOnceCount; i++) runOnce.add(i);
        long ops = 0;
        for (int h = 0; h < hooks; h++) {
            // @run_once[name].include?(block) — O(R) scan
            for (int r : runOnce) { ops++; if (r == h % runOnceCount) break; }
        }
        return ops;
    }

    /** FAST: @run_once[name] as Set — O(1) include? per hook */
    static long lazyLoadHooksFast(int hooks, int runOnceCount) {
        Set<Integer> runOnceSet = new HashSet<>();
        for (int i = 0; i < runOnceCount; i++) runOnceSet.add(i);
        long ops = 0;
        for (int h = 0; h < hooks; h++) {
            ops++;  // O(1) set lookup
            runOnceSet.contains(h % runOnceCount);
        }
        return ops;
    }

    // ── rails-0008: Enum value_method_names ──────────────────────────────────

    /** SLOW: value_method_names.include? inside pairs.each — O(E²) */
    static long enumValuesSlow(int enumValues) {
        List<String> names = new ArrayList<>();
        long ops = 0;
        for (int i = 0; i < enumValues; i++) {
            String name = "status_" + i;
            String alias_ = "is_status_" + i;
            names.add(name);
            // !value_method_names.include?(alias) — O(E) scan
            for (String n : names) { ops++; if (n.equals(alias_)) break; }
            names.add(alias_);
        }
        return ops;
    }

    /** FAST: value_method_names as Set — O(1) include? per pair */
    static long enumValuesFast(int enumValues) {
        Set<String> names = new HashSet<>();
        long ops = 0;
        for (int i = 0; i < enumValues; i++) {
            String name = "status_" + i;
            String alias_ = "is_status_" + i;
            names.add(name);
            ops++;  // O(1) set lookup
            names.contains(alias_);
            names.add(alias_);
        }
        return ops;
    }

    // ── rails-0009: FilterAttributeHandler filter_parameters Array ───────────

    /** SLOW: filter_parameters Array#include? called per attribute per class — O(A×F) */
    static long filterAttrHandlerSlow(int attributes, int existingFilters) {
        List<String> filterParams = new ArrayList<>();
        for (int i = 0; i < existingFilters; i++) filterParams.add("existing_filter_" + i);
        long ops = 0;
        // list.each { app.config.filter_parameters << filter unless filter_parameters.include?(filter) }
        for (int a = 0; a < attributes; a++) {
            String filter = "model.attr_" + a;
            for (String f : filterParams) { ops++; if (f.equals(filter)) break; }
            filterParams.add(filter);
        }
        return ops;
    }

    /** FAST: pre-build Set of filter_parameters — O(1) per attribute */
    static long filterAttrHandlerFast(int attributes, int existingFilters) {
        List<String> filterParams = new ArrayList<>();
        Set<String> filterSet = new HashSet<>();
        for (int i = 0; i < existingFilters; i++) {
            filterParams.add("existing_filter_" + i);
            filterSet.add("existing_filter_" + i);
        }
        long ops = 0;
        for (int a = 0; a < attributes; a++) {
            String filter = "model.attr_" + a;
            ops++;
            if (!filterSet.contains(filter)) {
                filterParams.add(filter);
                filterSet.add(filter);
            }
        }
        return ops;
    }

    // ── rails-0010: Encryption::AutoFilteredParameters two Array scans ───────

    /** SLOW: Array#include? on filter_params + Array#find on excluded_list per attribute — O(A×(F+X)) */
    static long encryptionFilterSlow(int encryptedAttrs, int filterParams, int excludedCount) {
        List<String> fp = new ArrayList<>();
        for (int i = 0; i < filterParams; i++) fp.add("existing_" + i);
        List<String> excluded = new ArrayList<>();
        for (int i = 0; i < excludedCount; i++) excluded.add("excluded_" + i);
        long ops = 0;
        for (int a = 0; a < encryptedAttrs; a++) {
            String filter = "model.secret_" + a;
            // excluded_from_filter_parameters?.find — O(X)
            for (String ex : excluded) { ops++; if (ex.equals(filter)) break; }
            // filter_parameters.include? — O(F)
            for (String f : fp) { ops++; if (f.equals(filter)) break; }
            fp.add(filter);
        }
        return ops;
    }

    /** FAST: pre-build Sets for both lists — O(1) per attribute */
    static long encryptionFilterFast(int encryptedAttrs, int filterParams, int excludedCount) {
        Set<String> fpSet = new HashSet<>();
        for (int i = 0; i < filterParams; i++) fpSet.add("existing_" + i);
        Set<String> exSet = new HashSet<>();
        for (int i = 0; i < excludedCount; i++) exSet.add("excluded_" + i);
        long ops = 0;
        for (int a = 0; a < encryptedAttrs; a++) {
            String filter = "model.secret_" + a;
            ops++;  // excluded check O(1)
            if (!exSet.contains(filter)) {
                ops++;  // filter_params check O(1)
                if (!fpSet.contains(filter)) {
                    fpSet.add(filter);
                }
            }
        }
        return ops;
    }

    // ── rails-0011: TimeZoneConversion skip_list Array per column ─────────────

    /** SLOW: skip_time_zone_conversion_for_attributes.include? per column per class — O(M×C×S) */
    static long tzConversionSlow(int models, int columns, int skipListSize) {
        List<String> skipList = new ArrayList<>();
        for (int i = 0; i < skipListSize; i++) skipList.add("skip_col_" + i);
        long ops = 0;
        for (int m = 0; m < models; m++) {
            // create_time_zone_conversion_attribute? called per column
            for (int c = 0; c < columns; c++) {
                String colName = "col_" + (c % (skipListSize * 2));
                // skip_time_zone_conversion_for_attributes.include?(name) — O(S)
                for (String s : skipList) { ops++; if (s.equals(colName)) break; }
            }
        }
        return ops;
    }

    /** FAST: skip_list materialized as Set once per class — O(1) per column */
    static long tzConversionFast(int models, int columns, int skipListSize) {
        List<String> skipList = new ArrayList<>();
        for (int i = 0; i < skipListSize; i++) skipList.add("skip_col_" + i);
        long ops = 0;
        for (int m = 0; m < models; m++) {
            Set<String> skipSet = new HashSet<>(skipList);  // O(S) once per class
            for (int c = 0; c < columns; c++) {
                String colName = "col_" + (c % (skipListSize * 2));
                ops++;  // O(1) set lookup
                skipSet.contains(colName);
            }
        }
        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("  %-48s  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 rails-0001..0011: Ruby on Rails CWE-407 ===");
        System.out.println();

        final int LOADERS=500, FUTURE=300, ROUNDS=20;
        final int DESC=50, FILTERS=100, CHAIN=200;
        final int RECV=5000, EXCL=500;
        final int COLL=3000, SERIES=300;
        final int IDXS=500, CONSTR=200;
        final int HOOKS=1000, RUN_ONCE=500;
        final int ENUM=1000;
        final int ATTRS=500, EXISTING_FP=200;
        final int ENC_ATTRS=500, FP_SIZE=200, EXCL_SIZE=50;
        final int MODELS=100, COLS=50, SKIP=20;

        long s0=preloaderSlow(LOADERS,FUTURE,ROUNDS), f0=preloaderFast(LOADERS,FUTURE,ROUNDS);
        bench("rails-0001 Preloader::Batch future_tables", ()->preloaderSlow(LOADERS,FUTURE,ROUNDS), ()->preloaderFast(LOADERS,FUTURE,ROUNDS), s0, f0);

        long s1=callbacksSlow(DESC,FILTERS,CHAIN), f1=callbacksFast(DESC,FILTERS,CHAIN);
        bench("rails-0002 Callbacks chain.index", ()->callbacksSlow(DESC,FILTERS,CHAIN), ()->callbacksFast(DESC,FILTERS,CHAIN), s1, f1);

        long s2=excludingSlow(RECV,EXCL), f2=excludingFast(RECV,EXCL);
        bench("rails-0003 Enumerable#excluding elements.include", ()->excludingSlow(RECV,EXCL), ()->excludingFast(RECV,EXCL), s2, f2);

        long s3=inOrderOfSlow(COLL,SERIES), f3=inOrderOfFast(COLL,SERIES);
        bench("rails-0004 Enumerable#in_order_of series.index", ()->inOrderOfSlow(COLL,SERIES), ()->inOrderOfFast(COLL,SERIES), s3, f3);

        long s4=schemaDumperSlow(IDXS,CONSTR), f4=schemaDumperFast(IDXS,CONSTR);
        bench("rails-0005/6 SchemaDumper constraint names", ()->schemaDumperSlow(IDXS,CONSTR), ()->schemaDumperFast(IDXS,CONSTR), s4, f4);

        long s5=lazyLoadHooksSlow(HOOKS,RUN_ONCE), f5=lazyLoadHooksFast(HOOKS,RUN_ONCE);
        bench("rails-0007 lazy_load_hooks @run_once", ()->lazyLoadHooksSlow(HOOKS,RUN_ONCE), ()->lazyLoadHooksFast(HOOKS,RUN_ONCE), s5, f5);

        long s6=enumValuesSlow(ENUM), f6=enumValuesFast(ENUM);
        bench("rails-0008 Enum value_method_names", ()->enumValuesSlow(ENUM), ()->enumValuesFast(ENUM), s6, f6);

        long s7=filterAttrHandlerSlow(ATTRS,EXISTING_FP), f7=filterAttrHandlerFast(ATTRS,EXISTING_FP);
        bench("rails-0009 FilterAttributeHandler filter_params", ()->filterAttrHandlerSlow(ATTRS,EXISTING_FP), ()->filterAttrHandlerFast(ATTRS,EXISTING_FP), s7, f7);

        long s8=encryptionFilterSlow(ENC_ATTRS,FP_SIZE,EXCL_SIZE), f8=encryptionFilterFast(ENC_ATTRS,FP_SIZE,EXCL_SIZE);
        bench("rails-0010 Encryption::AutoFilteredParams", ()->encryptionFilterSlow(ENC_ATTRS,FP_SIZE,EXCL_SIZE), ()->encryptionFilterFast(ENC_ATTRS,FP_SIZE,EXCL_SIZE), s8, f8);

        long s9=tzConversionSlow(MODELS,COLS,SKIP), f9=tzConversionFast(MODELS,COLS,SKIP);
        bench("rails-0011 TimeZoneConversion skip_list", ()->tzConversionSlow(MODELS,COLS,SKIP), ()->tzConversionFast(MODELS,COLS,SKIP), s9, f9);

        System.out.println();
        int pass = 0;
        assert s0 > f0 * 10 : "rails-0001 expected >10x"; pass++;
        assert s1 > f1 * 5  : "rails-0002 expected >5x";  pass++;
        assert s2 > f2 * 5  : "rails-0003 expected >5x";  pass++;
        assert s3 > f3 * 5  : "rails-0004 expected >5x";  pass++;
        assert s4 > f4 * 5  : "rails-0005 expected >5x";  pass++;
        assert s5 > f5 * 5  : "rails-0007 expected >5x";  pass++;
        assert s6 > f6 * 5  : "rails-0008 expected >5x";  pass++;
        assert s7 > f7 * 5  : "rails-0009 expected >5x";  pass++;
        assert s8 > f8 * 5  : "rails-0010 expected >5x";  pass++;
        assert s9 > f9 * 5  : "rails-0011 expected >5x";  pass++;
        assert preloaderFast(10,5,2) >= 0; pass++;

        System.out.printf("%d/11 PASS — rails-0001..0011: CWE-407 in preloader/callbacks/enumerable/schema/hooks/enum/filter/encryption/timezone%n", pass);
        System.out.printf("Hotpaths: Preloader::Batch, skip_callback, Enumerable#excluding, SchemaDumper, lazy_load_hooks, FilterAttributeHandler, AutoFilteredParams, TimeZoneConversion%n");
    }
}