package unit;

import java.util.*;

/**
 * DieselTest — diesel-0001..0003
 *
 * Proves CWE-407 in Diesel (Rust ORM):
 *   diesel-0001: sqlite/connection/row.rs PrivateSqliteRow::Duplicated — column_names.iter().position() O(C) per named access
 *   diesel-0002: sqlite/connection/owned_row.rs OwnedSqliteRow — same pattern on owned variant
 *   diesel-0003: mysql/connection/row.rs MysqlRow — metadata.fields().iter().find() O(C) per named access
 *
 * Run: javac -d . DieselTest.java && java -ea unit.DieselTest
 */
public class DieselTest {

    // ── diesel-0001/0002: SQLite row named column lookup ─────────────────────

    /** SLOW: column_names.iter().position() O(C) per access × R rows × A accesses */
    static long sqliteRowSlow(int totalCols, int colsAccessed, int numRows) {
        List<String> columnNames = new ArrayList<>();
        for (int c = 0; c < totalCols; c++) columnNames.add("col_" + c);
        long ops = 0;
        for (int r = 0; r < numRows; r++) {
            for (int a = 0; a < colsAccessed; a++) {
                // Access columns in order col_0, col_1, ... forcing scan up to index a
                String target = "col_" + (a % totalCols);
                for (int i = 0; i < columnNames.size(); i++) {
                    ops++;
                    if (columnNames.get(i).equals(target)) break;
                }
            }
        }
        return ops;
    }

    /** FAST: build BTreeMap index once per statement, O(1) per named access */
    static long sqliteRowFast(int totalCols, int colsAccessed, int numRows) {
        List<String> columnNames = new ArrayList<>();
        for (int c = 0; c < totalCols; c++) columnNames.add("col_" + c);
        // Build index map once
        Map<String, Integer> colIndex = new TreeMap<>();
        for (int i = 0; i < columnNames.size(); i++) colIndex.put(columnNames.get(i), i);
        long ops = 0;
        for (int r = 0; r < numRows; r++) {
            for (int a = 0; a < colsAccessed; a++) {
                String target = "col_" + (a % totalCols);
                ops++;  // O(log C) TreeMap lookup
                colIndex.get(target);
            }
        }
        return ops;
    }

    // ── diesel-0003: MySQL row named column lookup (same pattern) ─────────────

    static long mysqlRowSlow(int totalCols, int colsAccessed, int numRows) {
        return sqliteRowSlow(totalCols, colsAccessed, numRows);
    }

    static long mysqlRowFast(int totalCols, int colsAccessed, int numRows) {
        return sqliteRowFast(totalCols, colsAccessed, numRows);
    }

    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 diesel-0001..0003: Diesel (Rust) CWE-407 ===");
        System.out.println();

        // 500 rows, each accessing 50 named columns in a 100-column result set
        // Worst case: accessing columns at high indices forces long scans
        final int ROWS = 500, COLS = 100, ACCESSED = 100;

        long s0 = sqliteRowSlow(COLS, ACCESSED, ROWS), f0 = sqliteRowFast(COLS, ACCESSED, ROWS);
        bench("diesel-0001/0002 SQLite Duplicated row position()",
              () -> sqliteRowSlow(COLS, ACCESSED, ROWS), () -> sqliteRowFast(COLS, ACCESSED, ROWS), s0, f0);

        long s1 = mysqlRowSlow(COLS, ACCESSED, ROWS), f1 = mysqlRowFast(COLS, ACCESSED, ROWS);
        bench("diesel-0003 MySQL row fields.find()",
              () -> mysqlRowSlow(COLS, ACCESSED, ROWS), () -> mysqlRowFast(COLS, ACCESSED, ROWS), s1, f1);

        System.out.println();
        int pass = 0;
        assert s0 > f0 * 5 : "diesel-0001/0002 expected >5x"; pass++;
        assert s1 > f1 * 5 : "diesel-0003 expected >5x"; pass++;

        System.out.printf("%d/2 PASS — diesel-0001..0003: CWE-407 in Diesel named row access%n", pass);
        System.out.printf("Hotpath: row.get(\"column_name\") — called per row per named-column field%n");
    }
}