use std::net::{IpAddr, Ipv4Addr};

use mlua::prelude::*;

const DEFAULT_IP_ADDRESS: IpAddr = IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1));

const WEB_SOCKET_UPDGRADE_REQUEST_HANDLER: &str = r#"
return {
    status = 426,
    body = "Upgrade Required",
    headers = {
        Upgrade = "websocket",
    },
}
"#;

#[derive(Debug, Clone)]
pub struct ServeConfig {
    pub address: IpAddr,
    pub handle_request: LuaFunction,
    pub handle_web_socket: Option<LuaFunction>,
}

impl FromLua for ServeConfig {
    fn from_lua(value: LuaValue, lua: &Lua) -> LuaResult<Self> {
        if let LuaValue::Function(f) = &value {
            // Single function = request handler, rest is default
            Ok(ServeConfig {
                handle_request: f.clone(),
                handle_web_socket: None,
                address: DEFAULT_IP_ADDRESS,
            })
        } else if let LuaValue::Table(t) = &value {
            // Table means custom options
            let address: Option<LuaString> = t.get("address")?;
            let handle_request: Option<LuaFunction> = t.get("handleRequest")?;
            let handle_web_socket: Option<LuaFunction> = t.get("handleWebSocket")?;
            if handle_request.is_some() || handle_web_socket.is_some() {
                let address: IpAddr = match &address {
                    Some(addr) => {
                        let addr_str = addr.to_str()?;

                        addr_str
                            .trim_start_matches("http://")
                            .trim_start_matches("https://")
                            .parse()
                            .map_err(|_e| LuaError::FromLuaConversionError {
                                from: value.type_name(),
                                to: "ServeConfig".to_string(),
                                message: Some(format!(
                                    "IP address format is incorrect - \
                                    expected an IP in the form 'http://0.0.0.0' or '0.0.0.0', \
                                    got '{addr_str}'"
                                )),
                            })?
                    }
                    None => DEFAULT_IP_ADDRESS,
                };

                Ok(Self {
                    address,
                    handle_request: handle_request.unwrap_or_else(|| {
                        lua.load(WEB_SOCKET_UPDGRADE_REQUEST_HANDLER)
                            .into_function()
                            .expect("Failed to create default http responder function")
                    }),
                    handle_web_socket,
                })
            } else {
                Err(LuaError::FromLuaConversionError {
                    from: value.type_name(),
                    to: "ServeConfig".to_string(),
                    message: Some(String::from(
                        "Invalid serve config - expected table with 'handleRequest' or 'handleWebSocket' function",
                    )),
                })
            }
        } else {
            // Anything else is invalid
            Err(LuaError::FromLuaConversionError {
                from: value.type_name(),
                to: "ServeConfig".to_string(),
                message: None,
            })
        }
    }
}