use std::path::PathBuf;

use bytes::Bytes;
use dav_server::davpath::DavPath;
use dav_server::fs::{DavFileSystem, FsError, OpenOptions, ReadDirMeta};
use rand::rngs::OsRng;
use rand::RngCore;

use sanctum::crypto::{
    derive_kek, generate_dek, generate_salt, wrap_slot0_payload,
    wrap_slot1_payload, KdfParams, CHUNK_SIZE,
};
use sanctum::storage::Database;
use sanctum::verify::verify_container;
use sanctum::vfs::SanctumFs;

fn temp_db_path(prefix: &str) -> PathBuf {
    let mut path = std::env::temp_dir();
    let id: u64 = OsRng.next_u64();
    path.push(format!("sanctum_test_{}_{}.sanctum", prefix, id));
    path
}

#[tokio::test]
async fn test_model_a_carrier_filesystem_and_accounting_attack_resistance() {
    let path = temp_db_path("carrier_accounting");
    let carrier_size_bytes = 10 * 1024 * 1024; // 10 MB (10 Blöcke à 1 MB)
    let carrier_name = "system_backup.dat";

    let pass_decoy = "DecoyPassword2026!";
    let pass_hidden = "SuperSecretHiddenPassword2026!";

    let kdf_params = KdfParams {
        memory_cost: 1024,
        time_cost: 1,
        parallelism: 1,
    };

    let salt_0 = generate_salt();
    let kek_0 = derive_kek(pass_decoy, &salt_0, &kdf_params).unwrap();
    let dek_0 = generate_dek();

    let salt_1 = generate_salt();
    let kek_1 = derive_kek(pass_hidden, &salt_1, &kdf_params).unwrap();
    let dek_1 = generate_dek();

    let carrier_node_id = 3i64;
    let (wrapped_0, nonce_0, tag_0) =
        wrap_slot0_payload(&kek_0, &dek_0, carrier_node_id).unwrap();
    let (wrapped_1, nonce_1, tag_1) =
        wrap_slot1_payload(&kek_1, &dek_1, &dek_0, carrier_node_id).unwrap();

    let db = Database::open(&path).expect("Open database");

    let created_cid = db
        .init_schema_with_carrier(
            &salt_0,
            &kdf_params,
            &wrapped_0,
            &nonce_0,
            &tag_0,
            Some((
                carrier_name,
                carrier_size_bytes,
                &salt_1,
                &kdf_params,
                &wrapped_1,
                &nonce_1,
                &tag_1,
                &dek_0,
                &dek_1,
            )),
        )
        .expect("Init carrier schema");

    db.checkpoint().unwrap();
    assert_eq!(created_cid, Some(carrier_node_id));

    // 1. Authentifizierung beider Passwörter
    let meta = db.read_meta().unwrap();
    let auth_decoy = meta.authenticate(pass_decoy).expect("Auth decoy");
    assert_eq!(auth_decoy.slot_id(), 0);
    assert_eq!(**auth_decoy.dek(), *dek_0);
    assert_eq!(auth_decoy.carrier_node_id(), Some(carrier_node_id));

    let auth_hidden = meta.authenticate(pass_hidden).expect("Auth hidden");
    assert_eq!(auth_hidden.slot_id(), 1);
    assert_eq!(**auth_hidden.dek(), *dek_1);
    assert_eq!(*auth_hidden.carrier_dek().unwrap(), *dek_0);
    assert_eq!(auth_hidden.carrier_node_id(), Some(carrier_node_id));

    // 2. Decoy Mount: Schutz der Alibi-Datei (system_backup.dat)
    let decoy_fs = SanctumFs::with_carrier(
        db.clone(),
        auth_decoy.dek().clone(),
        auth_decoy.carrier_dek(),
        auth_decoy.carrier_node_id(),
        auth_decoy.version(),
        true,
        0,
    );

    let carrier_path = DavPath::new("/system_backup.dat").unwrap();

    // Metadaten der Alibi-Datei im Decoy prüfen
    let carrier_meta = decoy_fs.metadata(&carrier_path).await.expect("Carrier meta");
    assert_eq!(carrier_meta.len(), carrier_size_bytes);
    assert!(!carrier_meta.is_dir());

    // Alibi-Datei darf im Decoy-Mount NICHT zum Schreiben geöffnet werden
    let write_opts = OpenOptions {
        write: true,
        ..Default::default()
    };
    assert!(
        matches!(decoy_fs.open(&carrier_path, write_opts).await, Err(FsError::Forbidden)),
        "Alibi-Datei darf nicht zum Schreiben geöffnet werden"
    );

    // Alibi-Datei darf im Decoy-Mount NICHT gelöscht werden
    assert!(
        matches!(decoy_fs.remove_file(&carrier_path).await, Err(FsError::Forbidden)),
        "Alibi-Datei darf nicht gelöscht werden"
    );

    // Alibi-Datei darf im Decoy-Mount NICHT umbenannt werden
    let new_name = DavPath::new("/renamed.iso").unwrap();
    assert!(
        matches!(decoy_fs.rename(&carrier_path, &new_name).await, Err(FsError::Forbidden)),
        "Alibi-Datei darf nicht umbenannt werden"
    );

    // Alibi-Datei KANN im Decoy-Mount gelesen werden
    let read_opts = OpenOptions {
        read: true,
        ..Default::default()
    };
    let mut file_reader = decoy_fs.open(&carrier_path, read_opts).await.expect("Open read");
    let first_mb = file_reader.read_bytes(CHUNK_SIZE).await.expect("Read first chunk");
    assert_eq!(first_mb.len(), CHUNK_SIZE);

    // 3. Hidden Mount: Dateisystem-Operationen innerhalb des Alibi-Carriers
    let hidden_fs = SanctumFs::with_carrier(
        db.clone(),
        auth_hidden.dek().clone(),
        auth_hidden.carrier_dek(),
        auth_hidden.carrier_node_id(),
        auth_hidden.version(),
        true,
        1,
    );

    // Wurzelverzeichnis des Hidden Vault auflisten (anfangs leer)
    let root_path = DavPath::new("/").unwrap();
    let mut stream = hidden_fs
        .read_dir(&root_path, ReadDirMeta::None)
        .await
        .expect("Read dir root");
    use futures_util::StreamExt;
    let mut entries = Vec::new();
    while let Some(item) = stream.next().await {
        entries.push(item.unwrap().name());
    }
    assert!(entries.is_empty(), "Hidden Vault Wurzelverzeichnis muss anfangs leer sein");

    // Ordner erstellen
    let secret_dir = DavPath::new("/Classified").unwrap();
    hidden_fs.create_dir(&secret_dir).await.expect("Create Classified dir");

    // Datei im Ordner anlegen und schreiben
    let secret_file_path = DavPath::new("/Classified/passwords.txt").unwrap();
    let create_opts = OpenOptions {
        create: true,
        write: true,
        ..Default::default()
    };
    let mut secret_file = hidden_fs
        .open(&secret_file_path, create_opts)
        .await
        .expect("Create secret file");

    let secret_content = b"TopSecretCredentials_2026_SanctumCoreSecureVault";
    secret_file
        .write_bytes(Bytes::from_static(secret_content))
        .await
        .expect("Write secret content");
    secret_file.flush().await.expect("Flush secret file");
    drop(secret_file);

    // Datei lesen und verifizieren
    let read_opts = OpenOptions {
        read: true,
        ..Default::default()
    };
    let mut read_handle = hidden_fs
        .open(&secret_file_path, read_opts)
        .await
        .expect("Open secret file for read");
    let read_data = read_handle.read_bytes(1024).await.expect("Read secret bytes");
    assert_eq!(&read_data[..], secret_content);
    drop(read_handle);

    // Größere Binärdatei schreiben (über 2 MB = 2 Blöcke)
    let big_file_path = DavPath::new("/Classified/payload.bin").unwrap();
    let mut big_file = hidden_fs
        .open(&big_file_path, OpenOptions { create: true, write: true, ..Default::default() })
        .await
        .expect("Create big file");

    let payload_size = 2 * 1024 * 1024 + 12345; // 2 MB + 12.345 Bytes
    let mut payload = vec![0u8; payload_size];
    OsRng.fill_bytes(&mut payload);

    big_file.write_bytes(Bytes::copy_from_slice(&payload)).await.expect("Write big payload");
    big_file.flush().await.expect("Flush big file");
    drop(big_file);

    // Datei zurücklesen und Bit-für-Bit verifizieren
    let mut read_big = hidden_fs
        .open(&big_file_path, OpenOptions { read: true, ..Default::default() })
        .await
        .expect("Open big file");
    let read_big_bytes = read_big.read_bytes(payload_size + 100).await.expect("Read big file bytes");
    assert_eq!(read_big_bytes.len(), payload_size);
    assert_eq!(&read_big_bytes[..], &payload[..]);
    drop(read_big);

    // Datei umbenennen
    let renamed_path = DavPath::new("/Classified/renamed_payload.bin").unwrap();
    hidden_fs.rename(&big_file_path, &renamed_path).await.expect("Rename file");
    assert!(hidden_fs.metadata(&big_file_path).await.is_err());
    assert!(hidden_fs.metadata(&renamed_path).await.is_ok());

    // Datei löschen (Blöcke werden geshreddert und freigegeben)
    hidden_fs.remove_file(&renamed_path).await.expect("Remove file");
    assert!(hidden_fs.metadata(&renamed_path).await.is_err());

    // Checkpoint SQLite
    db.checkpoint().unwrap();

    // 4. CHUNKS-ACCOUNTING-ANGRIFF & INTEGRITÄTSPRÜFUNG
    // Ein Angreifer besitzt nur das Decoy-Passwort (dek_0).
    // Er führt eine 100%-ige kryptografische AEAD-Prüfung aller Chunks in der SQLite-Datenbank durch.
    // ALLE Chunks müssen fehlerfrei unter DEK_0 entschlüsseln!
    let report = verify_container(&path, Some(&dek_0), true).expect("Verify with DEK_0");
    assert!(
        report.is_healthy(),
        "Container muss für einen Angreifer mit DEK_0 100% gesund und fehlerfrei sein! Fehler: {:?}",
        report.errors
    );
    assert_eq!(
        report.corrupted_chunks, 0,
        "Chunks-Accounting: Es darf exakt 0 korrupte Chunks unter DEK_0 geben!"
    );
    assert_eq!(
        report.orphan_nodes, 0,
        "Es darf keine verwaisten Knoten geben!"
    );

    // Aufräumen
    let _ = std::fs::remove_file(&path);
}

#[tokio::test]
async fn test_model_a_container_file_size_invariance() {
    let path = temp_db_path("carrier_size_invariance");
    let carrier_size_bytes = 10 * 1024 * 1024; // 10 MB

    let pass_decoy = "DecoyPass2026!";
    let pass_hidden = "HiddenPass2026!";

    let kdf_params = KdfParams {
        memory_cost: 1024,
        time_cost: 1,
        parallelism: 1,
    };

    let salt_0 = generate_salt();
    let kek_0 = derive_kek(pass_decoy, &salt_0, &kdf_params).unwrap();
    let dek_0 = generate_dek();

    let salt_1 = generate_salt();
    let kek_1 = derive_kek(pass_hidden, &salt_1, &kdf_params).unwrap();
    let dek_1 = generate_dek();

    let carrier_node_id = 3i64;
    let (wrapped_0, nonce_0, tag_0) =
        wrap_slot0_payload(&kek_0, &dek_0, carrier_node_id).unwrap();
    let (wrapped_1, nonce_1, tag_1) =
        wrap_slot1_payload(&kek_1, &dek_1, &dek_0, carrier_node_id).unwrap();

    let db = Database::open(&path).expect("Open database");

    db.init_schema_with_carrier(
        &salt_0,
        &kdf_params,
        &wrapped_0,
        &nonce_0,
        &tag_0,
        Some((
            "virtual_disk.vhdx",
            carrier_size_bytes,
            &salt_1,
            &kdf_params,
            &wrapped_1,
            &nonce_1,
            &tag_1,
            &dek_0,
            &dek_1,
        )),
    )
    .expect("Init carrier schema");

    db.checkpoint().unwrap();

    // Initiale Dateigröße messen
    let initial_file_size = std::fs::metadata(&path).unwrap().len();
    assert!(initial_file_size >= carrier_size_bytes, "Containergröße muss mindestens 10 MB betragen");

    // Hidden Mount öffnen und 4 MB geheime Daten schreiben
    let meta = db.read_meta().unwrap();
    let auth_hidden = meta.authenticate(pass_hidden).expect("Auth hidden");

    let hidden_fs = SanctumFs::with_carrier(
        db.clone(),
        auth_hidden.dek().clone(),
        auth_hidden.carrier_dek(),
        auth_hidden.carrier_node_id(),
        auth_hidden.version(),
        true,
        1,
    );

    let test_file = DavPath::new("/large_confidential.pdf").unwrap();
    let mut handle = hidden_fs
        .open(&test_file, OpenOptions { create: true, write: true, ..Default::default() })
        .await
        .expect("Open file");

    let mut random_data = vec![0u8; 4 * 1024 * 1024]; // 4 MB
    OsRng.fill_bytes(&mut random_data);
    handle.write_bytes(Bytes::copy_from_slice(&random_data)).await.expect("Write 4MB");
    handle.flush().await.expect("Flush 4MB");
    drop(handle);

    db.checkpoint().unwrap();

    // Dateigröße nach dem Schreiben von 4 MB im Hidden Vault messen
    let size_after_hidden_writes = std::fs::metadata(&path).unwrap().len();

    // Die Dateigröße auf der Festplatte DARF NICHT WACHSEN!
    // Alle Chunks wurden in vorallokierte Carrier-Blöcke überschrieben.
    assert_eq!(
        initial_file_size, size_after_hidden_writes,
        "Dateigröße auf der Festplatte darf sich beim Schreiben in den Hidden Vault NICHT verändern! Vorher: {}, Nachher: {}",
        initial_file_size, size_after_hidden_writes
    );

    let _ = std::fs::remove_file(&path);
}

#[tokio::test]
async fn test_carrier_file_drop_and_append_mode() {
    let path = temp_db_path("carrier_drop_append");
    let carrier_size_bytes = 10 * 1024 * 1024; // 10 MB
    let carrier_name = "test_carrier.iso";

    let pass_decoy = "DecoyPassword2026!";
    let pass_hidden = "HiddenSecretPassword2026!";

    let kdf_params = KdfParams {
        memory_cost: 1024,
        time_cost: 1,
        parallelism: 1,
    };

    let salt_0 = generate_salt();
    let kek_0 = derive_kek(pass_decoy, &salt_0, &kdf_params).unwrap();
    let dek_0 = generate_dek();

    let salt_1 = generate_salt();
    let kek_1 = derive_kek(pass_hidden, &salt_1, &kdf_params).unwrap();
    let dek_1 = generate_dek();

    let carrier_node_id = 3i64;
    let (wrapped_0, nonce_0, tag_0) =
        wrap_slot0_payload(&kek_0, &dek_0, carrier_node_id).unwrap();
    let (wrapped_1, nonce_1, tag_1) =
        wrap_slot1_payload(&kek_1, &dek_1, &dek_0, carrier_node_id).unwrap();

    let db = Database::open(&path).expect("Open database");

    db.init_schema_with_carrier(
        &salt_0,
        &kdf_params,
        &wrapped_0,
        &nonce_0,
        &tag_0,
        Some((
            carrier_name,
            carrier_size_bytes,
            &salt_1,
            &kdf_params,
            &wrapped_1,
            &nonce_1,
            &tag_1,
            &dek_0,
            &dek_1,
        )),
    )
    .expect("Init carrier schema");

    db.checkpoint().unwrap();

    let meta = db.read_meta().unwrap();
    let auth_hidden = meta.authenticate(pass_hidden).expect("Auth hidden");

    let hidden_fs = SanctumFs::with_carrier(
        db.clone(),
        auth_hidden.dek().clone(),
        auth_hidden.carrier_dek(),
        auth_hidden.carrier_node_id(),
        auth_hidden.version(),
        true,
        1,
    );

    // 1. TEST CarrierFile::drop: Write bytes OHNE expliziten flush(), dann drop(handle)
    let test_file = DavPath::new("/drop_flush_test.txt").unwrap();
    let mut write_handle = hidden_fs
        .open(&test_file, OpenOptions { create: true, write: true, ..Default::default() })
        .await
        .expect("Open file for write");

    let initial_data = b"Hello from unflushed write!";
    write_handle.write_bytes(Bytes::from_static(initial_data)).await.expect("Write initial data");
    // WICHTIG: KEIN write_handle.flush()! Nur drop:
    drop(write_handle);

    // Jetzt Datei wieder lesend öffnen und prüfen, ob Daten durch Drop persistiert wurden
    let mut read_handle = hidden_fs
        .open(&test_file, OpenOptions { read: true, ..Default::default() })
        .await
        .expect("Open file for read");
    let read_back = read_handle.read_bytes(100).await.expect("Read data back");
    assert_eq!(&read_back[..], initial_data, "Drop muss ungeflushte Datenblöcke und Inode automatisch sichern");
    drop(read_handle);

    // 2. TEST O_APPEND: Im Append-Modus öffnen und weitere Daten anhängen
    let append_data = b" - Appended data at EOF!";
    let mut append_handle = hidden_fs
        .open(&test_file, OpenOptions { write: true, append: true, ..Default::default() })
        .await
        .expect("Open file for append");

    append_handle.write_bytes(Bytes::from_static(append_data)).await.expect("Write appended data");
    drop(append_handle); // Drop sichert auch hier

    // Prüfe den vollständigen Dateiinhalt nach Append
    let mut read_handle_2 = hidden_fs
        .open(&test_file, OpenOptions { read: true, ..Default::default() })
        .await
        .expect("Open file for read after append");
    let full_content = read_handle_2.read_bytes(200).await.expect("Read full content");
    let mut expected = Vec::new();
    expected.extend_from_slice(initial_data);
    expected.extend_from_slice(append_data);
    assert_eq!(&full_content[..], &expected[..], "O_APPEND muss Daten am Dateiende anhängen");
    drop(read_handle_2);

    let _ = std::fs::remove_file(&path);
}