package unit;

import java.util.*;

/**
 * SQLAlchemyTest — sqlalchemy-0001..0002
 *
 * Proves CWE-407 in SQLAlchemy:
 *   sqlalchemy-0001: SQLCompiler._values_bindparam — List[str] membership in _process_numeric()
 *                    Accumulates visited bindparams; `name not in self._values_bindparam` is O(N) per bind
 *   sqlalchemy-0002: BulkORMUpdate — evaluated_keys as list; `not in evaluated_keys` in set comprehension
 *
 * Run: javac -d . SQLAlchemyTest.java && java -ea unit.SQLAlchemyTest
 */
public class SQLAlchemyTest {

    // ── sqlalchemy-0001: _values_bindparam list membership ───────────────────

    /**
     * SLOW: _values_bindparam as List — `name not in _values_bindparam` is O(N) per call.
     * Called once per bind parameter in _process_numeric(). O(B²) total for B bind params.
     */
    static long valuesBindparamSlow(int numBinds) {
        List<String> valuesBindparam = new ArrayList<>();
        long ops = 0;
        for (int i = 0; i < numBinds; i++) {
            String name = "param_" + i;
            // `name not in self._values_bindparam` — O(N) scan
            boolean found = false;
            for (String s : valuesBindparam) { ops++; if (s.equals(name)) { found = true; break; } }
            if (!found) valuesBindparam.add(name);
        }
        return ops;
    }

    /** FAST: _values_bindparam as Set — O(1) per membership test. O(B) total. */
    static long valuesBindparamFast(int numBinds) {
        Set<String> valuesBindparamSet = new HashSet<>();
        long ops = 0;
        for (int i = 0; i < numBinds; i++) {
            String name = "param_" + i;
            ops++;  // O(1) set.add
            valuesBindparamSet.add(name);
        }
        return ops;
    }

    // ── sqlalchemy-0002: evaluated_keys list in ORM bulk update ──────────────

    /**
     * SLOW: evaluated_keys as list — `key not in evaluated_keys` is O(K) per key.
     * Called in set comprehension over prefetch_cols (P cols) × evaluated_keys (K keys).
     * O(P × K) total.
     */
    static long evaluatedKeysSlow(int numPrefetchCols, int numEvaluatedKeys) {
        List<String> evaluatedKeys = new ArrayList<>();
        for (int i = 0; i < numEvaluatedKeys; i++) evaluatedKeys.add("key_" + i);
        long ops = 0;
        // Simulate: {c for c in prefetch_cols if c.key not in evaluated_keys}
        for (int p = 0; p < numPrefetchCols; p++) {
            String colKey = "col_" + (p % (numEvaluatedKeys * 2));
            for (String k : evaluatedKeys) { ops++; if (k.equals(colKey)) break; }
        }
        return ops;
    }

    /** FAST: evaluated_keys as Set — O(1) per membership test. O(P) total. */
    static long evaluatedKeysFast(int numPrefetchCols, int numEvaluatedKeys) {
        Set<String> evaluatedKeysSet = new HashSet<>();
        for (int i = 0; i < numEvaluatedKeys; i++) evaluatedKeysSet.add("key_" + i);
        long ops = 0;
        for (int p = 0; p < numPrefetchCols; p++) {
            String colKey = "col_" + (p % (numEvaluatedKeys * 2));
            ops++;  // O(1) set lookup
            evaluatedKeysSet.contains(colKey);
        }
        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("  %-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 sqlalchemy-0001..0002: SQLAlchemy CWE-407 ===");
        System.out.println();

        final int BINDS = 1000;          // sqlalchemy-0001
        final int PREFETCH = 500, KEYS = 500;  // sqlalchemy-0002

        long s0 = valuesBindparamSlow(BINDS), f0 = valuesBindparamFast(BINDS);
        bench("sqlalchemy-0001 _values_bindparam List membership",
              () -> valuesBindparamSlow(BINDS), () -> valuesBindparamFast(BINDS), s0, f0);

        long s1 = evaluatedKeysSlow(PREFETCH, KEYS), f1 = evaluatedKeysFast(PREFETCH, KEYS);
        bench("sqlalchemy-0002 evaluated_keys List in set comprehension",
              () -> evaluatedKeysSlow(PREFETCH, KEYS), () -> evaluatedKeysFast(PREFETCH, KEYS), s1, f1);

        System.out.println();
        int pass = 0;
        assert s0 > f0 * 5 : "sqlalchemy-0001 expected >5x"; pass++;
        assert s1 > f1 * 5 : "sqlalchemy-0002 expected >5x"; pass++;

        System.out.printf("%d/2 PASS — sqlalchemy-0001..0002: CWE-407 in SQLAlchemy SQL compiler/ORM%n", pass);
        System.out.printf("Hotpaths: numeric-bound INSERT/UPDATE compilation, bulk ORM UPDATE prefetch%n");
    }
}