import java.util.*;

/**
 * CWE-407 unit test for bun yarn lock processing defect.
 *
 * bun-0001: src/install/yarn.zig — scoped package version lookup
 *   Two sequential linear scans over version list for same package:
 *   Pass 1 (lines 777-780): find found_existing and found_new
 *   Pass 2 (lines 800-805): find package_id when found_new=true
 *   Fix: capture package_id in pass 1 → eliminate pass 2 → O(M) → O(M/2)
 */
public class BunTest {

    static class VersionInfo {
        int yarnIdx;
        String version;
        int packageId;
        VersionInfo(int y, String v, int p) { yarnIdx=y; version=v; packageId=p; }
    }

    // Two-pass scan (defect)
    static int resolveVersionTwoPass(List<VersionInfo> list, String version) {
        boolean foundNew = false;
        for (VersionInfo item : list) {                    // pass 1
            if (item.version.equals(version)) foundNew = true;
        }
        if (foundNew) {
            for (VersionInfo item : list) {                // pass 2 — redundant
                if (item.version.equals(version)) return item.packageId;
            }
        }
        return -1;
    }

    // Single-pass (fix)
    static int resolveVersionSinglePass(List<VersionInfo> list, String version) {
        for (VersionInfo item : list) {                    // single pass, capture id
            if (item.version.equals(version)) return item.packageId;
        }
        return -1;
    }

    static void testBun0001() throws Exception {
        int N = 5000;   // yarn entries
        int V = 10;     // versions per package

        // Build a scoped package list with V versions
        List<VersionInfo> versionList = new ArrayList<>();
        for (int i = 0; i < V; i++) {
            versionList.add(new VersionInfo(i, "1." + i + ".0", 100 + i));
        }
        String targetVersion = "1.5.0";

        // correctness
        int r1 = resolveVersionTwoPass(versionList, targetVersion);
        int r2 = resolveVersionSinglePass(versionList, targetVersion);
        assert r1 == r2 : "two-pass and single-pass must agree: " + r1 + " vs " + r2;

        // performance: simulate N yarn entries each needing version resolution
        long t0 = System.nanoTime();
        long sum1 = 0;
        for (int i = 0; i < N; i++) sum1 += resolveVersionTwoPass(versionList, targetVersion);
        long tTwo = System.nanoTime() - t0;

        t0 = System.nanoTime();
        long sum2 = 0;
        for (int i = 0; i < N; i++) sum2 += resolveVersionSinglePass(versionList, targetVersion);
        long tOne = System.nanoTime() - t0;

        assert sum1 == sum2 : "sums must match";
        double ratio = (double) tTwo / tOne;
        System.out.printf("bun-0001: two-pass=%.3fs single-pass=%.3fs ratio=%.1f×%n",
                tTwo / 1e9, tOne / 1e9, ratio);
        assert ratio > 1.5 : "Expected >1.5× speedup, got " + ratio;
        System.out.println("PASS bun-0001");
    }

    public static void main(String[] args) throws Exception {
        testBun0001();
        System.out.println("ALL PASS");
    }
}