use base64::{engine::general_purpose, Engine as _};

use super::{utils, UriBuilder};
use crate::services::uri_generator::{error::UriGeneratorError, ClientConfigData};

pub struct ShadowsocksUriBuilder;

impl ShadowsocksUriBuilder {
    pub fn new() -> Self {
        Self
    }

    /// Map Xray cipher type to Shadowsocks method name
    fn map_xray_cipher_to_shadowsocks_method(&self, cipher: &str) -> &str {
        match cipher {
            // AES GCM variants
            "AES_256_GCM" | "aes-256-gcm" => "aes-256-gcm",
            "AES_128_GCM" | "aes-128-gcm" => "aes-128-gcm",

            // ChaCha20 variants
            "CHACHA20_POLY1305" | "chacha20-ietf-poly1305" | "chacha20-poly1305" => {
                "chacha20-ietf-poly1305"
            }

            // AES CFB variants
            "AES_256_CFB" | "aes-256-cfb" => "aes-256-cfb",
            "AES_128_CFB" | "aes-128-cfb" => "aes-128-cfb",

            // Legacy ciphers
            "RC4_MD5" | "rc4-md5" => "rc4-md5",
            "AES_256_CTR" | "aes-256-ctr" => "aes-256-ctr",
            "AES_128_CTR" | "aes-128-ctr" => "aes-128-ctr",

            // Default to most secure and widely supported
            _ => "aes-256-gcm",
        }
    }
}

impl UriBuilder for ShadowsocksUriBuilder {
    fn build_uri(&self, config: &ClientConfigData) -> Result<String, UriGeneratorError> {
        self.validate_config(config)?;

        // Get cipher type from base_settings and map to Shadowsocks method
        let cipher = config
            .base_settings
            .get("cipherType")
            .and_then(|c| c.as_str())
            .or_else(|| config.base_settings.get("method").and_then(|m| m.as_str()))
            .unwrap_or("AES_256_GCM");

        let method = self.map_xray_cipher_to_shadowsocks_method(cipher);

        // Shadowsocks SIP002 format: ss://base64(method:password)@hostname:port#remark
        // Use xray_user_id as password (following Marzban approach)
        let credentials = format!("{}:{}", method, config.xray_user_id);
        let encoded_credentials = general_purpose::STANDARD.encode(credentials.as_bytes());

        // Generate alias for the URI
        let alias = utils::generate_alias(&config.server_name, &config.template_name);

        // Build simple SIP002 URI (no plugin parameters for standard Shadowsocks)
        let uri = format!(
            "ss://{}@{}:{}#{}",
            encoded_credentials,
            config.hostname,
            config.port,
            utils::url_encode(&alias)
        );

        Ok(uri)
    }

    fn validate_config(&self, config: &ClientConfigData) -> Result<(), UriGeneratorError> {
        // Basic validation
        if config.hostname.is_empty() {
            return Err(UriGeneratorError::MissingRequiredField(
                "hostname".to_string(),
            ));
        }
        if config.port <= 0 || config.port > 65535 {
            return Err(UriGeneratorError::InvalidConfiguration(
                "Invalid port number".to_string(),
            ));
        }
        if config.xray_user_id.is_empty() {
            return Err(UriGeneratorError::MissingRequiredField(
                "xray_user_id".to_string(),
            ));
        }

        // Shadowsocks uses xray_user_id as password, already validated above

        Ok(())
    }
}

impl Default for ShadowsocksUriBuilder {
    fn default() -> Self {
        Self::new()
    }
}