use std::fs::{self, File};
use std::io::Write;
use std::path::Path;

use sanctum::crypto::{
    derive_kek, generate_dek, generate_salt, wrap_dek, KdfParams, CHUNK_SIZE, FORMAT_VERSION,
};
use sanctum::storage::Database;
use sanctum::sync::{run_sync, SyncDirection, SyncOptions};

fn create_test_container(path: &Path) -> (Database, [u8; 32]) {
    if path.exists() {
        let _ = fs::remove_file(path);
    }
    let db = Database::open(path).expect("Open database");
    let salt = generate_salt();
    let kdf_params = KdfParams {
        memory_cost: 1024,
        time_cost: 1,
        parallelism: 1,
    };
    let kek = derive_kek("sync_password", &salt, &kdf_params).unwrap();
    let dek = generate_dek();
    let (wrapped_dek, header_nonce, header_tag) = wrap_dek(&kek, &dek).unwrap();
    db.init_schema(&salt, &kdf_params, &wrapped_dek, &header_nonce, &header_tag).unwrap();
    (db, *dek)
}

#[test]
fn test_sync_push_and_pull_basic() {
    let temp_root = std::env::temp_dir().join(format!("sanctum_sync_test_{}", rand::random::<u64>()));
    let container_path = temp_root.join("test.sanctum");
    let source_dir = temp_root.join("source");
    let target_dir = temp_root.join("restored");

    fs::create_dir_all(&source_dir).unwrap();
    fs::create_dir_all(source_dir.join("sub")).unwrap();

    // Testdateien anlegen
    fs::write(source_dir.join("file1.txt"), b"Hello Sanctum Sync!").unwrap();
    fs::write(source_dir.join("sub").join("file2.bin"), vec![0x42u8; 100_000]).unwrap();

    let (db, dek) = create_test_container(&container_path);

    // 1. Push
    let mut opts = SyncOptions::default();
    opts.direction = SyncDirection::Push;
    opts.quiet = true;

    let stats = run_sync(
        &db,
        0,
        &dek,
        FORMAT_VERSION,
        source_dir.to_str().unwrap(),
        "/Backup",
        &opts,
    ).expect("Sync push");

    assert_eq!(stats.files_scanned, 2);
    assert_eq!(stats.files_transferred, 2);
    assert_eq!(stats.files_skipped, 0);

    // 2. Erneuter Push (Fast check / Delta): Muss 0 übertragen, 2 überspringen
    let stats_delta = run_sync(
        &db,
        0,
        &dek,
        FORMAT_VERSION,
        source_dir.to_str().unwrap(),
        "/Backup",
        &opts,
    ).expect("Sync push delta");

    assert_eq!(stats_delta.files_transferred, 0);
    assert_eq!(stats_delta.files_skipped, 2);

    // 3. Dry-Run mit neuer Datei
    fs::write(source_dir.join("new_file.txt"), b"Brand new file").unwrap();
    let mut dry_opts = opts.clone();
    dry_opts.dry_run = true;

    let stats_dry = run_sync(
        &db,
        0,
        &dek,
        FORMAT_VERSION,
        source_dir.to_str().unwrap(),
        "/Backup",
        &dry_opts,
    ).expect("Sync push dry-run");

    assert_eq!(stats_dry.files_transferred, 1);
    assert_eq!(stats_dry.files_skipped, 2);

    // Verifizieren, dass new_file.txt im Tresor tatsächlich NICHT existiert
    let node = db.resolve_path_in_vault("/Backup/new_file.txt", 0, &dek).unwrap();
    assert!(node.is_none());

    // 4. Pull
    let mut pull_opts = SyncOptions::default();
    pull_opts.direction = SyncDirection::Pull;
    pull_opts.quiet = true;

    let stats_pull = run_sync(
        &db,
        0,
        &dek,
        FORMAT_VERSION,
        "/Backup",
        target_dir.to_str().unwrap(),
        &pull_opts,
    ).expect("Sync pull");

    assert_eq!(stats_pull.files_transferred, 2);

    // Inhalt vergleichen
    let c1 = fs::read(target_dir.join("file1.txt")).unwrap();
    assert_eq!(c1, b"Hello Sanctum Sync!");
    let c2 = fs::read(target_dir.join("sub").join("file2.bin")).unwrap();
    assert_eq!(c2, vec![0x42u8; 100_000]);

    // Aufräumen
    let _ = fs::remove_dir_all(&temp_root);
}

#[test]
fn test_sync_multi_megabyte_large_file() {
    let temp_root = std::env::temp_dir().join(format!("sanctum_sync_large_{}", rand::random::<u64>()));
    let container_path = temp_root.join("test_large.sanctum");
    let source_dir = temp_root.join("source");
    let target_dir = temp_root.join("restored");

    fs::create_dir_all(&source_dir).unwrap();

    // 3.5 MB große Datei erzeugen (geht über 4 Chunks: 0, 1, 2, 3)
    let large_file_path = source_dir.join("large_payload.bin");
    let mut large_file = File::create(&large_file_path).unwrap();
    let chunk_sample = vec![0xA5u8; CHUNK_SIZE];
    for _ in 0..3 {
        large_file.write_all(&chunk_sample).unwrap();
    }
    large_file.write_all(&vec![0x5Au8; 512 * 1024]).unwrap(); // 3.5 MB
    large_file.flush().unwrap();
    drop(large_file);

    let (db, dek) = create_test_container(&container_path);

    // Push
    let mut opts = SyncOptions::default();
    opts.direction = SyncDirection::Push;
    opts.quiet = true;

    let stats = run_sync(
        &db,
        0,
        &dek,
        FORMAT_VERSION,
        source_dir.to_str().unwrap(),
        "/LargeTest",
        &opts,
    ).expect("Sync push large");

    assert_eq!(stats.files_transferred, 1);
    assert_eq!(stats.bytes_transferred, 3 * (CHUNK_SIZE as u64) + 512 * 1024);

    // Pull
    let mut pull_opts = SyncOptions::default();
    pull_opts.direction = SyncDirection::Pull;
    pull_opts.quiet = true;

    run_sync(
        &db,
        0,
        &dek,
        FORMAT_VERSION,
        "/LargeTest",
        target_dir.to_str().unwrap(),
        &pull_opts,
    ).expect("Sync pull large");

    let restored = fs::read(target_dir.join("large_payload.bin")).unwrap();
    let original = fs::read(&large_file_path).unwrap();
    assert_eq!(restored.len(), original.len());
    assert_eq!(restored, original);

    let _ = fs::remove_dir_all(&temp_root);
}

#[test]
fn test_sync_delete_and_exclude_flags() {
    let temp_root = std::env::temp_dir().join(format!("sanctum_sync_flags_{}", rand::random::<u64>()));
    let container_path = temp_root.join("test_flags.sanctum");
    let source_dir = temp_root.join("source");

    fs::create_dir_all(&source_dir).unwrap();
    fs::write(source_dir.join("keep.txt"), b"Keep this").unwrap();
    fs::write(source_dir.join("remove_me.txt"), b"Will be deleted later").unwrap();
    fs::write(source_dir.join("ignore.tmp"), b"Temporary file").unwrap();

    let (db, dek) = create_test_container(&container_path);

    let mut opts = SyncOptions::default();
    opts.direction = SyncDirection::Push;
    opts.exclude_patterns = vec!["*.tmp".to_string()];
    opts.quiet = true;

    // 1. Initialer Push mit Exclude
    let stats = run_sync(
        &db,
        0,
        &dek,
        FORMAT_VERSION,
        source_dir.to_str().unwrap(),
        "/Files",
        &opts,
    ).unwrap();

    assert_eq!(stats.files_transferred, 2); // keep.txt und remove_me.txt
    assert!(db.resolve_path_in_vault("/Files/ignore.tmp", 0, &dek).unwrap().is_none());

    // 2. Lokale Datei löschen und Sync mit --delete ausführen
    fs::remove_file(source_dir.join("remove_me.txt")).unwrap();
    opts.delete = true;

    let stats_del = run_sync(
        &db,
        0,
        &dek,
        FORMAT_VERSION,
        source_dir.to_str().unwrap(),
        "/Files",
        &opts,
    ).unwrap();

    assert_eq!(stats_del.files_deleted, 1);
    assert!(db.resolve_path_in_vault("/Files/remove_me.txt", 0, &dek).unwrap().is_none());
    assert!(db.resolve_path_in_vault("/Files/keep.txt", 0, &dek).unwrap().is_some());

    let _ = fs::remove_dir_all(&temp_root);
}