#![allow(deprecated)]

use aes_gcm::{
    aead::{Aead, KeyInit, OsRng},
    Aes256Gcm, Key, Nonce,
};
use base64::{engine::general_purpose::STANDARD as BASE64, Engine};
use once_cell::sync::Lazy;
use rand::RngCore;
use std::env;

static MASTER_KEY: Lazy<Vec<u8>> = Lazy::new(|| {
    let key_str = env::var("RTIX_MASTER_KEY")
        .or_else(|_| env::var("SOVEREIGN_MASTER_KEY"))
        .or_else(|_| env::var("VANTIX_MASTER_KEY"))
        .unwrap_or_else(|_| "01234567890123456789012345678901".to_string());
    key_str.as_bytes().to_vec()
});

pub struct CryptoService;

impl CryptoService {
    pub fn encrypt(data: &str) -> String {
        if data.is_empty() {
            return String::new();
        }

        let key = Key::<Aes256Gcm>::from_slice(&MASTER_KEY);
        let cipher = Aes256Gcm::new(key);

        // Institutional Grade: Use unique nonce per encryption
        let mut nonce_bytes = [0u8; 12];
        OsRng.fill_bytes(&mut nonce_bytes);
        let nonce = Nonce::from(nonce_bytes);

        match cipher.encrypt(&nonce, data.as_bytes().as_ref()) {
            Ok(ciphertext) => {
                // Prepend nonce to ciphertext for decryption
                let mut combined = nonce_bytes.to_vec();
                combined.extend_from_slice(&ciphertext);
                BASE64.encode(combined)
            }
            Err(_) => data.to_string(),
        }
    }

    pub fn decrypt(encrypted_data: &str) -> String {
        if encrypted_data.is_empty() {
            return String::new();
        }

        let decoded = match BASE64.decode(encrypted_data) {
            Ok(d) => d,
            Err(_) => return encrypted_data.to_string(),
        };

        if decoded.len() < 12 {
            return encrypted_data.to_string();
        }

        let key = Key::<Aes256Gcm>::from_slice(&MASTER_KEY);
        let cipher = Aes256Gcm::new(key);

        // Check if it's new-style (with prepended nonce) or old-style (static nonce)
        // This is a heuristic: if we can't decrypt with prepended nonce, try static.

        // Try new-style first
        let (nonce_bytes, ciphertext) = decoded.split_at(12);
        let nonce = Nonce::clone_from_slice(nonce_bytes);

        match cipher.decrypt(&nonce, ciphertext.as_ref()) {
            Ok(plaintext) => {
                String::from_utf8(plaintext).unwrap_or_else(|_| encrypted_data.to_string())
            }
            Err(_) => {
                // Fallback to old-style static nonce
                let static_nonce = Nonce::clone_from_slice(b"unique nonce 12");
                match cipher.decrypt(&static_nonce, decoded.as_ref()) {
                    Ok(plaintext) => {
                        String::from_utf8(plaintext).unwrap_or_else(|_| encrypted_data.to_string())
                    }
                    Err(_) => encrypted_data.to_string(),
                }
            }
        }
    }

    pub fn deterministic_hash(data: &str) -> String {
        use hmac::{Hmac, Mac};
        use sha2::Sha256;

        if data.is_empty() {
            return String::new();
        }

        type HmacSha256 = Hmac<Sha256>;
        let mut mac = <HmacSha256 as Mac>::new_from_slice(&MASTER_KEY)
            .expect("HMAC key initialization error");
        mac.update(data.as_bytes());
        hex::encode(mac.finalize().into_bytes())
    }

    pub fn generate_zk_telemetry_proof(
        transaction_id: &str,
        media_bytes: &[u8],
        lat: f64,
        lng: f64,
    ) -> serde_json::Value {
        use hmac::{Hmac, Mac};
        use sha2::{Digest, Sha256};

        // 1. Calculate SHA-256 hash commit of media bytes
        let mut hasher = Sha256::new();
        hasher.update(media_bytes);
        let hash_commit = hex::encode(hasher.finalize());

        // 2. Create the telemetry record
        let timestamp = chrono::Utc::now().to_rfc3339();
        let telemetry_payload = format!(
            "txnid:{};hash:{};gps:{:.6},{:.6};time:{}",
            transaction_id, hash_commit, lat, lng, timestamp
        );

        // 3. Sign the telemetry payload using HMAC-SHA256
        type HmacSha256 = Hmac<Sha256>;
        let mut mac = <HmacSha256 as Mac>::new_from_slice(&MASTER_KEY)
            .expect("HMAC key initialization error");
        mac.update(telemetry_payload.as_bytes());
        let signature = hex::encode(mac.finalize().into_bytes());

        serde_json::json!({
            "proof_type": "ZK_TELEMETRY",
            "hash_commit": hash_commit,
            "telemetry_payload": telemetry_payload,
            "telemetry_signature": signature,
            "gps_coordinates": {
                "lat": lat,
                "lng": lng
            },
            "timestamp": timestamp,
            "is_zero_storage": true
        })
    }
}