use std::io::SeekFrom;
use std::path::PathBuf;

use bytes::Bytes;
use dav_server::{
    davpath::DavPath,
    fs::{DavFileSystem, OpenOptions, ReadDirMeta},
};
use futures_util::StreamExt;
use sanctum::{
    crypto::{
        derive_kek, generate_dek, generate_salt, unwrap_dek, wrap_dek, KdfParams, CHUNK_SIZE,
        FORMAT_VERSION,
    },
    storage::Database,
    vfs::SanctumFs,
};

#[tokio::test]
async fn test_sanctum_full_container_lifecycle() {
    let temp_dir = std::env::temp_dir();
    let container_path: PathBuf = temp_dir.join(format!("test_sanctum_{}.sanctum", std::process::id()));

    // Aufräumen, falls alte Testdatei existiert
    if container_path.exists() {
        let _ = std::fs::remove_file(&container_path);
    }

    let password = "CorrectMasterPassword2026!";
    let wrong_password = "WrongMasterPassword!";

    // 1. Initialisierung
    let salt = generate_salt();
    let kdf_params = KdfParams {
        memory_cost: 1024, // Schnell für Tests
        time_cost: 1,
        parallelism: 1,
    };
    let kek = derive_kek(password, &salt, &kdf_params).expect("KEK derivation");
    let dek = generate_dek();
    let (wrapped_dek, header_nonce, header_tag) =
        wrap_dek(&kek, &dek).expect("DEK wrapping");

    let db = Database::open(&container_path).expect("Open database");
    db.init_schema(&salt, &kdf_params, &wrapped_dek, &header_nonce, &header_tag)
        .expect("Init schema");
    db.checkpoint().expect("Checkpoint");

    // 2. Header & Magic Bytes Prüfung
    let meta = db.read_meta().expect("Read meta");
    assert_eq!(meta.version, FORMAT_VERSION);
    assert_eq!(meta.kdf_salt, salt);
    assert_eq!(meta.wrapped_dek, wrapped_dek);

    // Falsches Passwort schlägt fehl
    let wrong_kek = derive_kek(wrong_password, &meta.kdf_salt, &meta.kdf_params).unwrap();
    assert!(unwrap_dek(&wrong_kek, &meta.wrapped_dek, &meta.header_nonce, &meta.header_tag).is_err());

    // Richtiges Passwort entschlüsselt DEK
    let unwrapped_dek =
        unwrap_dek(&kek, &meta.wrapped_dek, &meta.header_nonce, &meta.header_tag).unwrap();
    assert_eq!(*dek, *unwrapped_dek);

    // 3. VFS Filesystem-Operationen (WebDAV Trait)
    let fs = SanctumFs::new(db.clone(), unwrapped_dek);

    // Ordner erstellen
    let docs_path = DavPath::new("/documents").unwrap();
    fs.create_dir(&docs_path).await.expect("Create /documents");

    let docs_meta = fs.metadata(&docs_path).await.expect("Metadata /documents");
    assert!(docs_meta.is_dir());

    // Multi-MB Datei über mehrere Chunks hinweg schreiben (2.5 MB = 3 Chunks à 1 MB)
    let file_path = DavPath::new("/documents/large_payload.bin").unwrap();
    let mut opts_write = OpenOptions::default();
    opts_write.write = true;
    opts_write.create_new = true;

    let mut file = fs.open(&file_path, opts_write).await.expect("Open for write");

    let payload_size = (2.5 * CHUNK_SIZE as f64) as usize;
    let mut sample_data = Vec::with_capacity(payload_size);
    for i in 0..payload_size {
        sample_data.push((i % 251) as u8);
    }

    file.write_bytes(Bytes::copy_from_slice(&sample_data))
        .await
        .expect("Write 2.5 MB");
    file.flush().await.expect("Flush file");
    drop(file);

    // Metadaten verifizieren
    let file_meta = fs.metadata(&file_path).await.expect("Metadata file");
    assert_eq!(file_meta.len(), payload_size as u64);
    assert!(!file_meta.is_dir());

    // Datei lesen & Seek über Chunk-Grenzen testen
    let mut opts_read = OpenOptions::default();
    opts_read.read = true;
    let mut read_file = fs.open(&file_path, opts_read).await.expect("Open for read");

    // Seek mitten in den 2. Chunk (1 MB + 500 Bytes)
    let seek_offset = (CHUNK_SIZE + 500) as u64;
    let new_pos = read_file
        .seek(SeekFrom::Start(seek_offset))
        .await
        .expect("Seek");
    assert_eq!(new_pos, seek_offset);

    // 2000 Bytes lesen (überschreitet evtl. Chunk-Grenze oder bleibt im Chunk)
    let read_len = 2000;
    let read_chunk_bytes = read_file.read_bytes(read_len).await.expect("Read bytes");
    assert_eq!(read_chunk_bytes.len(), read_len);
    assert_eq!(
        &read_chunk_bytes[..],
        &sample_data[seek_offset as usize..seek_offset as usize + read_len]
    );
    drop(read_file);

    // Datei umbenennen
    let renamed_path = DavPath::new("/documents/renamed_payload.bin").unwrap();
    fs.rename(&file_path, &renamed_path).await.expect("Rename file");

    assert!(fs.metadata(&file_path).await.is_err());
    let renamed_meta = fs.metadata(&renamed_path).await.expect("Metadata renamed");
    assert_eq!(renamed_meta.len(), payload_size as u64);

    // Datei kopieren
    let copy_path = DavPath::new("/documents/copy_payload.bin").unwrap();
    fs.copy(&renamed_path, &copy_path).await.expect("Copy file");
    let copy_meta = fs.metadata(&copy_path).await.expect("Metadata copy");
    assert_eq!(copy_meta.len(), payload_size as u64);

    // Verzeichnis auflisten
    let stream = fs.read_dir(&docs_path, ReadDirMeta::None).await.expect("Read dir");
    let entries: Vec<_> = stream.collect().await;
    assert_eq!(entries.len(), 2); // renamed_payload.bin & copy_payload.bin

    // Dateien und Verzeichnis löschen
    fs.remove_file(&renamed_path).await.expect("Remove renamed");
    fs.remove_file(&copy_path).await.expect("Remove copy");
    fs.remove_dir(&docs_path).await.expect("Remove dir");

    // Prüfen, dass Root leer ist
    let root_path = DavPath::new("/").unwrap();
    let root_stream = fs.read_dir(&root_path, ReadDirMeta::None).await.expect("Read root");
    let root_entries: Vec<_> = root_stream.collect().await;
    assert_eq!(root_entries.len(), 0);

    // Finaler DB Checkpoint
    db.checkpoint().expect("Final checkpoint");
    drop(fs);
    drop(db);

    // Verifizieren, dass die Containerdatei existiert und aufgeräumt werden kann
    assert!(container_path.exists());
    let _ = std::fs::remove_file(&container_path);
}

#[tokio::test]
async fn test_sanctum_password_change() {
    let temp_dir = std::env::temp_dir();
    let container_path: PathBuf = temp_dir.join(format!("test_sanctum_passwd_{}.sanctum", std::process::id()));

    if container_path.exists() {
        let _ = std::fs::remove_file(&container_path);
    }

    let password_v1 = "InitialSecret123!";
    let password_v2 = "NewSecret456!";

    // 1. Initialisierung mit Passwort v1
    let salt_v1 = generate_salt();
    let kdf_params = KdfParams {
        memory_cost: 1024,
        time_cost: 1,
        parallelism: 1,
    };
    let kek_v1 = derive_kek(password_v1, &salt_v1, &kdf_params).expect("KEK v1");
    let original_dek = generate_dek();
    let (wrapped_dek_v1, nonce_v1, tag_v1) =
        wrap_dek(&kek_v1, &original_dek).expect("Wrap DEK v1");

    let db = Database::open(&container_path).expect("Open database");
    db.init_schema(&salt_v1, &kdf_params, &wrapped_dek_v1, &nonce_v1, &tag_v1)
        .expect("Init schema");
    db.checkpoint().expect("Checkpoint");

    // Datei im Container mit DEK anlegen
    let fs_v1 = SanctumFs::new(db.clone(), original_dek.clone());
    let file_path = DavPath::new("/secret.txt").unwrap();
    let file_data = b"Verschluesselte Geheimdaten vor der Passwortaenderung!";
    let mut opts_write = OpenOptions::default();
    opts_write.write = true;
    opts_write.create_new = true;
    let mut write_file = fs_v1
        .open(&file_path, opts_write)
        .await
        .expect("Open write");
    write_file
        .write_bytes(Bytes::from_static(file_data))
        .await
        .expect("Write bytes");
    write_file.flush().await.expect("Flush");
    drop(write_file);
    drop(fs_v1);
    db.checkpoint().expect("Checkpoint");

    // 2. Passwortwechsel durchführen
    let meta_before = db.read_meta().expect("Read meta");
    let old_kek = derive_kek(password_v1, &meta_before.kdf_salt, &meta_before.kdf_params).expect("Derive old KEK");
    let recovered_dek = unwrap_dek(&old_kek, &meta_before.wrapped_dek, &meta_before.header_nonce, &meta_before.header_tag)
        .expect("Unwrap with old password");

    let salt_v2 = generate_salt();
    let kek_v2 = derive_kek(password_v2, &salt_v2, &kdf_params).expect("Derive new KEK");
    let (wrapped_dek_v2, nonce_v2, tag_v2) = wrap_dek(&kek_v2, &recovered_dek).expect("Wrap with new KEK");

    db.update_meta_keys(&salt_v2, &kdf_params, &wrapped_dek_v2, &nonce_v2, &tag_v2).expect("Update meta keys");
    db.checkpoint().expect("Checkpoint");

    // 3. Verifikation: Altes Passwort darf NICHT mehr funktionieren
    let meta_after = db.read_meta().expect("Read meta after");
    let old_kek_again = derive_kek(password_v1, &meta_after.kdf_salt, &meta_after.kdf_params).unwrap();
    assert!(
        unwrap_dek(&old_kek_again, &meta_after.wrapped_dek, &meta_after.header_nonce, &meta_after.header_tag).is_err(),
        "Altes Passwort darf nach Passwortaenderung nicht mehr funktionieren!"
    );

    // 4. Verifikation: Neues Passwort funktioniert und entschlüsselt alte Daten intakt
    let new_kek = derive_kek(password_v2, &meta_after.kdf_salt, &meta_after.kdf_params).expect("Derive new KEK");
    let active_dek = unwrap_dek(&new_kek, &meta_after.wrapped_dek, &meta_after.header_nonce, &meta_after.header_tag)
        .expect("Unwrap with new password");

    let fs_v2 = SanctumFs::new(db.clone(), active_dek);
    let mut opts_read = OpenOptions::default();
    opts_read.read = true;
    let mut read_file = fs_v2.open(&file_path, opts_read).await.expect("Open read with new password");
    let read_bytes = read_file.read_bytes(file_data.len()).await.expect("Read bytes");
    assert_eq!(&read_bytes[..], file_data, "Daten muessen nach Passwortaenderung unveraendert lesbar sein!");


    drop(read_file);
    drop(fs_v2);
    drop(db);

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