import java.util.*;

/**
 * CWE-407 simulation tests for Strawberry Music Player defects.
 *
 * strawberry-0001: CollectionWatcher files_on_disk QStringList O(S×F + F²)
 * strawberry-0002: ScrobblerCache::Flush QList.contains/removeAll O(F×C)
 */
public class StrawberryTest {

    // ========== strawberry-0001: CollectionWatcher files_on_disk ==========

    /** BEFORE: QStringList.contains() in deleted-songs loop — O(S×F) */
    static int deletedSongsDetection_before(List<String> songsInDb, List<String> filesOnDisk) {
        int ops = 0;
        List<String> deletedSongs = new ArrayList<>();
        for (String songFile : songsInDb) {
            // QStringList::contains is O(F)
            boolean found = false;
            for (String diskFile : filesOnDisk) {
                ops++;
                if (diskFile.equals(songFile)) { found = true; break; }
            }
            if (!found) {
                deletedSongs.add(songFile);
            }
        }
        return ops;
    }

    /** AFTER: QSet<QString> for O(1) lookup — O(S) */
    static int deletedSongsDetection_after(List<String> songsInDb, Set<String> filesOnDisk) {
        int ops = 0;
        List<String> deletedSongs = new ArrayList<>();
        for (String songFile : songsInDb) {
            ops++; // O(1) hash lookup
            if (!filesOnDisk.contains(songFile)) {
                deletedSongs.add(songFile);
            }
        }
        return ops;
    }

    static boolean test_strawberry_0001() {
        int F = 5000; // files on disk
        int S = 5000; // songs in DB (most overlap)

        List<String> filesOnDisk = new ArrayList<>();
        Set<String> filesOnDiskSet = new HashSet<>();
        for (int i = 0; i < F; i++) {
            String path = "/music/track_" + i + ".mp3";
            filesOnDisk.add(path);
            filesOnDiskSet.add(path);
        }

        // Songs in DB: 90% overlap, 10% deleted
        List<String> songsInDb = new ArrayList<>();
        for (int i = 0; i < (int)(S * 0.9); i++) {
            songsInDb.add("/music/track_" + i + ".mp3");
        }
        for (int i = 0; i < (int)(S * 0.1); i++) {
            songsInDb.add("/music/deleted_" + i + ".mp3");
        }

        int opsBefore = deletedSongsDetection_before(songsInDb, filesOnDisk);
        int opsAfter = deletedSongsDetection_after(songsInDb, filesOnDiskSet);

        double ratio = (double) opsBefore / opsAfter;
        System.out.printf("  strawberry-0001 files_on_disk: before=%d after=%d ratio=%.1fx%n",
                opsBefore, opsAfter, ratio);
        return ratio > 5.0;
    }

    // ========== strawberry-0002: ScrobblerCache::Flush ==========

    /** BEFORE: QList.contains + removeAll per item — O(F×C) */
    static int scrobblerFlush_before(List<Integer> cache, List<Integer> toFlush) {
        int ops = 0;
        List<Integer> cacheCopy = new ArrayList<>(cache);
        for (int item : toFlush) {
            // contains is O(C)
            boolean found = false;
            for (int i = 0; i < cacheCopy.size(); i++) {
                ops++;
                if (cacheCopy.get(i) == item) { found = true; break; }
            }
            if (found) {
                // removeAll is O(C)
                Iterator<Integer> it = cacheCopy.iterator();
                while (it.hasNext()) {
                    ops++;
                    if (it.next() == item) it.remove();
                }
            }
        }
        return ops;
    }

    /** AFTER: build set + single-pass filter — O(F + C) */
    static int scrobblerFlush_after(List<Integer> cache, List<Integer> toFlush) {
        int ops = 0;
        Set<Integer> toRemove = new HashSet<>(toFlush);
        ops += toFlush.size(); // building the set
        List<Integer> cacheCopy = new ArrayList<>(cache);
        Iterator<Integer> it = cacheCopy.iterator();
        while (it.hasNext()) {
            ops++;
            if (toRemove.contains(it.next())) it.remove();
        }
        return ops;
    }

    static boolean test_strawberry_0002() {
        int C = 1000; // cache size
        int F = 500;  // items to flush (half the cache)

        List<Integer> cache = new ArrayList<>();
        for (int i = 0; i < C; i++) cache.add(i);

        List<Integer> toFlush = new ArrayList<>();
        for (int i = 0; i < F; i++) toFlush.add(i * 2); // flush even-numbered items

        int opsBefore = scrobblerFlush_before(cache, toFlush);
        int opsAfter = scrobblerFlush_after(cache, toFlush);

        double ratio = (double) opsBefore / opsAfter;
        System.out.printf("  strawberry-0002 scrobbler flush: before=%d after=%d ratio=%.1fx%n",
                opsBefore, opsAfter, ratio);
        return ratio > 5.0;
    }

    // ========== Main ==========

    public static void main(String[] args) {
        System.out.println("StrawberryTest: CWE-407 simulation");

        boolean pass1 = test_strawberry_0001();
        boolean pass2 = test_strawberry_0002();

        System.out.println();
        System.out.printf("  strawberry-0001: %s%n", pass1 ? "PASS" : "FAIL");
        System.out.printf("  strawberry-0002: %s%n", pass2 ? "PASS" : "FAIL");

        if (!pass1 || !pass2) {
            System.out.println("FAILED");
            System.exit(1);
        }
        System.out.println("ALL PASS");
    }
}