use crate::config::Config;
use sodiumoxide::base64;
use std::sync::{Arc, RwLock};

lazy_static::lazy_static! {
    pub static ref TEMPORARY_PASSWORD:Arc<RwLock<String>> = Arc::new(RwLock::new(Config::get_auto_password(temporary_password_length())));
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum VerificationMethod {
    OnlyUseTemporaryPassword,
    OnlyUsePermanentPassword,
    UseBothPasswords,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ApproveMode {
    Both,
    Password,
    Click,
}

// Should only be called in server
pub fn update_temporary_password() {
    *TEMPORARY_PASSWORD.write().unwrap() = Config::get_auto_password(temporary_password_length());
}

// Should only be called in server
pub fn temporary_password() -> String {
    TEMPORARY_PASSWORD.read().unwrap().clone()
}

fn verification_method() -> VerificationMethod {
    let method = Config::get_option("verification-method");
    if method == "use-temporary-password" {
        VerificationMethod::OnlyUseTemporaryPassword
    } else if method == "use-permanent-password" {
        VerificationMethod::OnlyUsePermanentPassword
    } else {
        VerificationMethod::UseBothPasswords // default
    }
}

pub fn temporary_password_length() -> usize {
    let length = Config::get_option("temporary-password-length");
    if length == "8" {
        8
    } else if length == "10" {
        10
    } else {
        6 // default
    }
}

pub fn temporary_enabled() -> bool {
    verification_method() != VerificationMethod::OnlyUsePermanentPassword
}

pub fn permanent_enabled() -> bool {
    verification_method() != VerificationMethod::OnlyUseTemporaryPassword
}

pub fn has_valid_password() -> bool {
    temporary_enabled() && !temporary_password().is_empty()
        || permanent_enabled() && !Config::get_permanent_password().is_empty()
}

pub fn approve_mode() -> ApproveMode {
    let mode = Config::get_option("approve-mode");
    if mode == "password" {
        ApproveMode::Password
    } else if mode == "click" {
        ApproveMode::Click
    } else {
        ApproveMode::Both
    }
}

pub fn hide_cm() -> bool {
    approve_mode() == ApproveMode::Password
        && verification_method() == VerificationMethod::OnlyUsePermanentPassword
        && !Config::get_option("allow-hide-cm").is_empty()
}

const VERSION_LEN: usize = 2;

pub fn encrypt_str_or_original(s: &str, version: &str, max_len: usize) -> String {
    if decrypt_str_or_original(s, version).1 {
        log::error!("Duplicate encryption!");
        return s.to_owned();
    }
    if s.bytes().len() > max_len {
        return String::default();
    }
    if version == "00" {
        if let Ok(s) = encrypt(s.as_bytes(), max_len) {
            return version.to_owned() + &s;
        }
    }
    s.to_owned()
}

// String: password
// bool: whether decryption is successful
// bool: whether should store to re-encrypt when load
// note: s.len() return length in bytes, s.chars().count() return char count
//       &[..2] return the left 2 bytes, s.chars().take(2) return the left 2 chars
pub fn decrypt_str_or_original(s: &str, current_version: &str) -> (String, bool, bool) {
    if s.len() > VERSION_LEN {
        if s.starts_with("00") {
            if let Ok(v) = decrypt(s[VERSION_LEN..].as_bytes()) {
                return (
                    String::from_utf8_lossy(&v).to_string(),
                    true,
                    "00" != current_version,
                );
            }
        }
    }

    (s.to_owned(), false, !s.is_empty())
}

pub fn encrypt_vec_or_original(v: &[u8], version: &str, max_len: usize) -> Vec<u8> {
    if decrypt_vec_or_original(v, version).1 {
        log::error!("Duplicate encryption!");
        return v.to_owned();
    }
    if v.len() > max_len {
        return vec![];
    }
    if version == "00" {
        if let Ok(s) = encrypt(v, max_len) {
            let mut version = version.to_owned().into_bytes();
            version.append(&mut s.into_bytes());
            return version;
        }
    }
    v.to_owned()
}

// Vec<u8>: password
// bool: whether decryption is successful
// bool: whether should store to re-encrypt when load
pub fn decrypt_vec_or_original(v: &[u8], current_version: &str) -> (Vec<u8>, bool, bool) {
    if v.len() > VERSION_LEN {
        let version = String::from_utf8_lossy(&v[..VERSION_LEN]);
        if version == "00" {
            if let Ok(v) = decrypt(&v[VERSION_LEN..]) {
                return (v, true, version != current_version);
            }
        }
    }

    (v.to_owned(), false, !v.is_empty())
}

fn encrypt(v: &[u8], max_len: usize) -> Result<String, ()> {
    if !v.is_empty() && v.len() <= max_len {
        symmetric_crypt(v, true).map(|v| base64::encode(v, base64::Variant::Original))
    } else {
        Err(())
    }
}

fn decrypt(v: &[u8]) -> Result<Vec<u8>, ()> {
    if !v.is_empty() {
        base64::decode(v, base64::Variant::Original).and_then(|v| symmetric_crypt(&v, false))
    } else {
        Err(())
    }
}

pub fn symmetric_crypt(data: &[u8], encrypt: bool) -> Result<Vec<u8>, ()> {
    use sodiumoxide::crypto::secretbox;
    use std::convert::TryInto;

    let mut keybuf = crate::get_uuid();
    keybuf.resize(secretbox::KEYBYTES, 0);
    let key = secretbox::Key(keybuf.try_into().map_err(|_| ())?);
    let nonce = secretbox::Nonce([0; secretbox::NONCEBYTES]);

    if encrypt {
        Ok(secretbox::seal(data, &nonce, &key))
    } else {
        secretbox::open(data, &nonce, &key)
    }
}

mod test {

    #[test]
    fn test() {
        use super::*;
        use rand::{thread_rng, Rng};
        use std::time::Instant;

        let version = "00";
        let max_len = 128;

        println!("test str");
        let data = "1ü1111";
        let encrypted = encrypt_str_or_original(data, version, max_len);
        let (decrypted, succ, store) = decrypt_str_or_original(&encrypted, version);
        println!("data: {data}");
        println!("encrypted: {encrypted}");
        println!("decrypted: {decrypted}");
        assert_eq!(data, decrypted);
        assert_eq!(version, &encrypted[..2]);
        assert!(succ);
        assert!(!store);
        let (_, _, store) = decrypt_str_or_original(&encrypted, "99");
        assert!(store);
        assert!(!decrypt_str_or_original(&decrypted, version).1);
        assert_eq!(
            encrypt_str_or_original(&encrypted, version, max_len),
            encrypted
        );

        println!("test vec");
        let data: Vec<u8> = "1ü1111".as_bytes().to_vec();
        let encrypted = encrypt_vec_or_original(&data, version, max_len);
        let (decrypted, succ, store) = decrypt_vec_or_original(&encrypted, version);
        println!("data: {data:?}");
        println!("encrypted: {encrypted:?}");
        println!("decrypted: {decrypted:?}");
        assert_eq!(data, decrypted);
        assert_eq!(version.as_bytes(), &encrypted[..2]);
        assert!(!store);
        assert!(succ);
        let (_, _, store) = decrypt_vec_or_original(&encrypted, "99");
        assert!(store);
        assert!(!decrypt_vec_or_original(&decrypted, version).1);
        assert_eq!(
            encrypt_vec_or_original(&encrypted, version, max_len),
            encrypted
        );

        println!("test original");
        let data = version.to_string() + "Hello World";
        let (decrypted, succ, store) = decrypt_str_or_original(&data, version);
        assert_eq!(data, decrypted);
        assert!(store);
        assert!(!succ);
        let verbytes = version.as_bytes();
        let data: Vec<u8> = vec![verbytes[0], verbytes[1], 1, 2, 3, 4, 5, 6];
        let (decrypted, succ, store) = decrypt_vec_or_original(&data, version);
        assert_eq!(data, decrypted);
        assert!(store);
        assert!(!succ);
        let (_, succ, store) = decrypt_str_or_original("", version);
        assert!(!store);
        assert!(!succ);
        let (_, succ, store) = decrypt_vec_or_original(&[], version);
        assert!(!store);
        assert!(!succ);
        let data = "1ü1111";
        assert_eq!(decrypt_str_or_original(data, version).0, data);
        let data: Vec<u8> = "1ü1111".as_bytes().to_vec();
        assert_eq!(decrypt_vec_or_original(&data, version).0, data);

        println!("test speed");
        let test_speed = |len: usize, name: &str| {
            let mut data: Vec<u8> = vec![];
            let mut rng = thread_rng();
            for _ in 0..len {
                data.push(rng.gen_range(0..255));
            }
            let start: Instant = Instant::now();
            let encrypted = encrypt_vec_or_original(&data, version, len);
            assert_ne!(data, decrypted);
            let t1 = start.elapsed();
            let start = Instant::now();
            let (decrypted, _, _) = decrypt_vec_or_original(&encrypted, version);
            let t2 = start.elapsed();
            assert_eq!(data, decrypted);
            println!("{name}");
            println!("encrypt:{:?}, decrypt:{:?}", t1, t2);

            let start: Instant = Instant::now();
            let encrypted = base64::encode(&data, base64::Variant::Original);
            let t1 = start.elapsed();
            let start = Instant::now();
            let decrypted = base64::decode(&encrypted, base64::Variant::Original).unwrap();
            let t2 = start.elapsed();
            assert_eq!(data, decrypted);
            println!("base64, encrypt:{:?}, decrypt:{:?}", t1, t2,);
        };
        test_speed(128, "128");
        test_speed(1024, "1k");
        test_speed(1024 * 1024, "1M");
        test_speed(10 * 1024 * 1024, "10M");
        test_speed(100 * 1024 * 1024, "100M");
    }
}