#![allow(non_camel_case_types)]

pub const FLB_ERROR: u32 = 0;
pub const FLB_OK: u32 = 1;
pub const FLB_RETRY: u32 = 2;
pub const FLB_PROXY_OUTPUT_PLUGIN: u32 = 2;
pub const FLB_PROXY_GOLANG: u32 = 11;

/// Basic plugin information
#[derive(Default)]
pub struct PluginInfo {
    /// Plugin's name
    pub name: String,
    /// Plugin's description
    pub description: String,
}

/// Fluent-bit error definitions
pub enum FLBError {
    /// The data have been processed normally.
    FLB_ERROR,
    /// A recoverable error have ocurred, the engine can try to flush the records/data later.
    FLB_RETRY,
}

/// Custom result for any plugin's operation
pub type FLBResult = Result<(), FLBError>;

impl From<FLBError> for i32 {
    fn from(error: FLBError) -> Self {
        match error {
            FLBError::FLB_ERROR => 0,
            FLBError::FLB_RETRY => 2,
        }
    }
}

/// Trait which defines the functions that should be implemented by any rust plugin
pub trait FLBPluginMethods {
    /// A plugin register method
    ///
    /// When the FLBPluginInit is triggered by Fluent Bit, a plugin context
    /// is passed and the next step is to invoke this FLBPluginRegister() function
    /// to fill the required information: name and
    /// description.
    /// # Arguments
    /// * `info` A mutable reference to a PluginInfo struct where the plugin's name and description will be filled
    /// # Returns
    /// If the operation was successful an Ok(()) is returned otherwise FLBError
    fn plugin_register(&mut self, info: &mut PluginInfo) -> FLBResult;

    /// Before the engine starts, it initialize all plugins that were requested to start
    /// Useful for initializing any data structure that would be used for this plugin during the processing
    /// # Returns
    /// If the operation was successful an Ok(()) is returned otherwise FLBError
    fn plugin_init(&mut self) -> FLBResult;

    /// Upon flush time, when Fluent Bit want's to flush it buffers, the runtime flush callback will be triggered.
    /// The callback will receive a raw buffer of msgpack data.
    /// The passed data is a bytes buffer which could be processed in anyway. A there are differents crates that would be helpful
    /// in the ecosystem, such as
    /// [`rmp`](https://crates.io/crates/rmp), [`msgpack`](https://crates.io/crates/msgpack)
    /// or you can implement a custom parser by using one of most parser libraries in the rust ecosystem.
    /// # Arguments
    /// * `data` A byte buffer with the message in a MsgPack format
    /// # Returns
    /// If the operation was successful an Ok(()) is returned otherwise FLBError
    fn plugin_flush(&mut self, data: &[u8]) -> FLBResult;

    /// When Fluent Bit will stop using the instance of the plugin, it will trigger the exit callback.
    /// # Returns
    /// If the operation was successful an Ok(()) is returned otherwise FLBError
    fn plugin_exit(&mut self) -> FLBResult;
}

/// This macro will generate the needed boilerplate for output plugins
///
/// Only one plugin instance is supported, later multi-instance plugins support would be added
#[macro_export]
macro_rules! create_boilerplate{
    ($e:expr) => {

        use libc::{c_char, c_int, c_void};
        use std::ffi::{CStr, CString, NulError};
        use std::slice;
        use std::sync::{Mutex};
        use std::cell::RefCell;
        #[macro_use]
        extern crate lazy_static;

        #[repr(C)]
        #[derive(Debug, Copy, Clone)]
        pub struct flb_plugin_proxy_def {
             type_: c_int,
             proxy: c_int,
             flags: c_int,
             name: *mut c_char,
             description: *mut c_char,
        }

        #[repr(C)]
        #[derive(Debug, Copy, Clone)]
        struct flb_api {
             output_get_property: ::std::option::Option<
                unsafe extern "C" fn(
                    arg1: *mut c_char,
                    arg2: *mut c_void,
                ) -> *mut c_char,
            >,
        }

        #[repr(C)]
        #[derive(Debug, Copy, Clone)]
        struct flb_plugin_proxy_context {
             remote_context: *mut c_void,
        }

        #[repr(C)]
        #[derive(Debug, Copy, Clone)]
        pub struct flbgo_output_plugin {
             __: *mut c_void,
             api: *mut flb_api,
             o_ins: *mut flb_output_instance,
             context: *mut flb_plugin_proxy_context,
        }

        extern "C" {
             fn output_get_property(
                key: *mut c_char,
                plugin: *mut c_void,
            ) -> *mut c_char;
        }

        #[repr(C)]
        #[derive(Debug, Copy, Clone)]
        struct flb_output_instance {
             _address: u8,
        }

        pub type FLBPluginProxyDef = flb_plugin_proxy_def;
        pub type FLBOutPlugin = flbgo_output_plugin;

       lazy_static! {
            static ref handler: Mutex<Box<FLBPluginMethods + Send>> = Mutex::new(Box::new($e));
       }

        #[no_mangle]
        pub extern fn FLBPluginRegister( ptr: *mut c_void) -> c_int {
            unsafe{
                let p = &mut *(ptr as *mut FLBPluginProxyDef);
                p.type_ = FLB_PROXY_OUTPUT_PLUGIN as c_int;
                p.proxy = FLB_PROXY_GOLANG as c_int;
                p.flags = 0;
                let mut plugin_info = PluginInfo::default();
                match handler.lock().unwrap().plugin_register(&mut plugin_info){
                    Ok(()) => {
                        match CString::new(plugin_info.name.as_bytes()) {
                            Ok(cname) => {
                                p.name = cname.into_raw() as *mut _
                            },
                            _ => return FLB_ERROR as c_int,
                        }

                        match CString::new(plugin_info.description.as_bytes()) {
                            Ok(d) => {
                                p.description = d.into_raw() as *mut _;

                            },
                            _ => return FLB_ERROR as c_int,
                        }
                    },
                    Err(e) => return i32::from(e)  as c_int,
                }
                FLB_OK as c_int
            }
        }

        #[no_mangle]
        pub extern fn FLBPluginInit(ptr: *mut c_void) -> c_int {
            match handler.lock().unwrap().plugin_exit(){
                Ok(()) => FLB_OK as c_int,
                Err(e) => return i32::from(e) as c_int,
            }
        }

        #[no_mangle]
        pub extern fn FLBPluginFlush(data: *mut c_void, length: c_int, tag: *const c_char) -> c_int {
            unsafe{
                let bytes = slice::from_raw_parts(data as *const _, length as usize);
                match handler.lock().unwrap().plugin_flush(bytes){
                    Ok(()) => FLB_OK as c_int,
                    Err(e) => return i32::from(e)  as c_int,
                }
            }
        }

        #[no_mangle]
        pub extern fn FLBPluginExit() -> c_int {
            match handler.lock().unwrap().plugin_exit(){
                Ok(()) => FLB_OK as c_int,
                Err(e) => return i32::from(e) as c_int,
            }
        }
    }
}