use anyhow::{Context, Result};
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::fs;
use std::path::Path;

// Structure to define individual authorized clients
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ClientDefinition {
    pub name: String,        // Friendly name for the client
    pub ip_address: String,  // Allowed IP address
    pub port: Option<u16>,   // Optional specific port (if None, any port is allowed)
    pub group_ids: Vec<String>, // Multicast groups this client is allowed to access (empty = all)
}

// Definition of a multicast group
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct MulticastGroup {
    pub address: String,     // Multicast address
    #[serde(skip_serializing_if = "Option::is_none")]
    pub port: Option<u16>,   // Single port (used if port_range is None)
    #[serde(skip_serializing_if = "Option::is_none")]
    pub port_range: Option<(u16, u16)>, // Optional port range (start, end)
}

impl MulticastGroup {
    // Helper method to get all ports that should be used
    pub fn get_ports(&self) -> Vec<u16> {
        if let Some(range) = self.port_range {
            // If a range is specified, return all ports in the range
            (range.0..=range.1).collect()
        } else if let Some(port) = self.port {
            // If only a single port is specified, return just that port
            vec![port]
        } else {
            // Default to empty vec if neither is specified (should be validated elsewhere)
            vec![]
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ServerConfig {
    pub secret: String,
    pub listen_ip: String,
    pub listen_port: u16,
    pub multicast_groups: HashMap<String, MulticastGroup>,
    pub authorized_clients: Vec<ClientDefinition>,
    #[serde(default)]
    pub simple_auth: bool,
    #[serde(default)]
    pub allow_external_clients: bool,  // Flag to allow clients from outside the local network
}

impl Default for ServerConfig {
    fn default() -> Self {
        let mut groups = HashMap::new();
        groups.insert("default".to_string(), MulticastGroup {
            address: "224.0.0.1".to_string(),
            port: Some(5000),
            port_range: None,
        });
        groups.insert("ssdp".to_string(), MulticastGroup {
            address: "239.255.255.250".to_string(),
            port: Some(1900),
            port_range: None,
        });
        // Example with port range
        groups.insert("range_example".to_string(), MulticastGroup {
            address: "239.192.55.2".to_string(),
            port: None,
            port_range: Some((1680, 1685)),
        });
        
        Self {
            secret: "changeme".to_string(),
            listen_ip: "0.0.0.0".to_string(),
            listen_port: 8989,
            multicast_groups: groups,
            authorized_clients: vec![
                ClientDefinition {
                    name: "localhost".to_string(),
                    ip_address: "127.0.0.1".to_string(),
                    port: None,
                    group_ids: vec![],  // Empty means all groups
                },
                ClientDefinition {
                    name: "example-client".to_string(),
                    ip_address: "192.168.1.100".to_string(),
                    port: Some(12345),
                    group_ids: vec!["default".to_string()], // Only the default group
                }
            ],
            simple_auth: false,  // Default to standard auth mode
            allow_external_clients: false,  // Default to disallow external clients
        }
    }
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ClientConfig {
    pub secret: String,
    pub server: String,
    pub port: u16,
    pub multicast_group_ids: Vec<String>,
    pub test_mode: bool,
    #[serde(default)]
    pub nat_traversal: bool,  // Flag to enable NAT traversal features
    #[serde(default = "default_reconnect_delay")]
    pub reconnect_delay_secs: u64,
}

fn default_reconnect_delay() -> u64 {
    5
}

impl Default for ClientConfig {
    fn default() -> Self {
        Self {
            secret: "changeme".to_string(),
            server: "127.0.0.1".to_string(),
            port: 8989,
            multicast_group_ids: vec![], // Empty means subscribe to all groups
            test_mode: false,
            nat_traversal: false,
            reconnect_delay_secs: 5,
        }
    }
}

// Load server configuration from a file
pub fn load_server_config<P: AsRef<Path>>(path: P) -> Result<ServerConfig> {
    let config_str = fs::read_to_string(path)
        .context("Failed to read server configuration file")?;
    let config: ServerConfig = toml::from_str(&config_str)
        .context("Failed to parse server configuration")?;
    Ok(config)
}

// Save server configuration to a file
pub fn save_server_config<P: AsRef<Path>>(config: &ServerConfig, path: P) -> Result<()> {
    let toml_str = toml::to_string_pretty(config)
        .context("Failed to serialize server configuration")?;
    fs::write(path, toml_str)
        .context("Failed to write server configuration file")?;
    Ok(())
}

// Load client configuration from a file
pub fn load_client_config<P: AsRef<Path>>(path: P) -> Result<ClientConfig> {
    let config_str = fs::read_to_string(path)
        .context("Failed to read client configuration file")?;
    let config: ClientConfig = toml::from_str(&config_str)
        .context("Failed to parse client configuration")?;
    Ok(config)
}

// Save client configuration to a file
pub fn save_client_config<P: AsRef<Path>>(config: &ClientConfig, path: P) -> Result<()> {
    let toml_str = toml::to_string_pretty(config)
        .context("Failed to serialize client configuration")?;
    fs::write(path, toml_str)
        .context("Failed to write client configuration file")?;
    Ok(())
}

// Generate default configuration files if they don't exist
pub fn ensure_default_configs() -> Result<()> {
    let server_config_path = "server_config.toml";
    if !Path::new(server_config_path).exists() {
        let default_config = ServerConfig::default();
        save_server_config(&default_config, server_config_path)?;
        println!("Created default server configuration at {}", server_config_path);
    }

    let client_config_path = "client_config.toml";
    if !Path::new(client_config_path).exists() {
        let default_config = ClientConfig::default();
        save_client_config(&default_config, client_config_path)?;
        println!("Created default client configuration at {}", client_config_path);
    }

    Ok(())
}

// Check if a client is authorized for specified groups
pub fn get_client_authorized_groups(
    config: &ServerConfig, 
    ip: &str, 
    port: u16
) -> Option<Vec<String>> {
    // If simple_auth is enabled, all clients that know the secret get access to all groups
    if config.simple_auth {
        return Some(vec![]);  // Empty vector means all groups
    }

    // Otherwise use the standard group authorization check
    for client in &config.authorized_clients {
        if client.ip_address == ip {
            // If port is None or matches the client's port
            if client.port.is_none() || client.port == Some(port) {
                // Return the group IDs or empty vector (meaning all groups)
                return Some(client.group_ids.clone());
            }
        }
    }
    
    None  // Not authorized
}

// Get client name if authorized
pub fn get_client_name(config: &ServerConfig, ip: &str, port: u16) -> Option<String> {
    for client in &config.authorized_clients {
        if client.ip_address == ip {
            // If port is None, any port from this IP is allowed
            if client.port.is_none() || client.port == Some(port) {
                return Some(client.name.clone());
            }
        }
    }

    None
}

// Check if a client's IP address and port are authorized
pub fn is_client_authorized(config: &ServerConfig, ip: &str, port: u16) -> bool {
    // If simple_auth is enabled, all clients that know the secret are authorized
    if config.simple_auth {
        return true;
    }

    // Otherwise use the standard client authorization check
    for client in &config.authorized_clients {
        if client.ip_address == ip {
            // If port is None, any port from this IP is allowed
            if client.port.is_none() || client.port == Some(port) {
                return true;
            }
        }
    }

    false
}