#![allow(non_snake_case)]

use std::marker::PhantomData;

mod bindings;
use bindings::*;

#[derive(Debug, Clone)]
pub enum SupportedFsvVersion {
    V1_40_14, // 1.40.14
    V1_40_13, // 1.40.13
}

impl SupportedFsvVersion {
    fn as_str(&self) -> &'static str {
        match self {
            Self::V1_40_14 => "1.40.14",
            Self::V1_40_13 => "1.40.13",
        }
    }
}

#[derive(thiserror::Error, Debug)]
pub enum Error {
    #[error(transparent)]
    LibLoading(#[from] libloading::Error),
    #[error("Symbol missing: {0}")]
    SymbolMissing(&'static str),
}

/// Macro to generate a function that implements a call to an external function in BINDINGS
macro_rules! ssv_function {
    ($binding:ty, $func_name:ident, {$($arg_name:ident: $arg_type:ty),*}) => {
        /// # Safety
        /// This function is unsafe because it calls an external function through FFI.
        /// The caller must ensure that the provided arguments are valid and that the
        /// external function is safe to call.
        pub unsafe fn $func_name(&self, $($arg_name: $arg_type),*) -> Result<u16, Error> {
            let symbol_name = match stringify!($binding)
                .split(&[' ', ':'])
                .last() {
                    Some(name) => name,
                    None => return Err(Error::SymbolMissing(stringify!($binding))),
                };
            let func_struct: libloading::Symbol<'_, $binding> =
                unsafe { self.library.get(symbol_name.as_bytes())? };
            let func = match *func_struct {
                Some(func) => func,
                None => return Err(Error::SymbolMissing(stringify!($binding))),
            };
            Ok(func($($arg_name),*))
        }
    };
}

/// `sealed::Sealed` trait is used to prevent external crates from implementing the LibVersion trait.
mod sealed { pub trait Sealed {}}

/// Wrapper around the SESAM-VITALE library
/// This struct is responsible for loading the library and providing an interface to call its functions.
/// The library is loaded at creation and kept in memory until the struct is dropped.
pub trait SSVLibraryCommon {
    fn new(path: &str) -> Result<Self, Error> where Self: Sized;
}

pub trait SSVLibraryVersion: sealed::Sealed {}

pub struct V1_40_13 {}
impl sealed::Sealed for V1_40_13 {}
impl SSVLibraryVersion for V1_40_13 {}

pub struct V1_40_14 {}
impl sealed::Sealed for V1_40_14 {}
impl SSVLibraryVersion for V1_40_14 {}

pub struct SSVLibrary<Version: SSVLibraryVersion> {
    _version: PhantomData<Version>,
    library: libloading::Library,
}

impl<Version: SSVLibraryVersion> SSVLibraryCommon for SSVLibrary<Version> {
    fn new(path: &str) -> Result<Self, Error> {
        let library = unsafe { libloading::Library::new(path)?};
        Ok(Self {
            _version: PhantomData,
            library
        })
    }
}

impl SSVLibrary<V1_40_14> {
    pub fn library(&self) -> &libloading::Library {
        &self.library
    }

    ssv_function!(BINDINGS_V1_40_14::SSV_InitLIB2, ssv_init_lib2, {
        pcFichierSesam: *const i8
    });

    ssv_function!(BINDINGS_V1_40_14::SSV_LireConfig, ssv_lire_config, {
        pZDataOut: *mut *mut libc::c_void,
        psTailleDataOut: *mut usize
    });

    ssv_function!(BINDINGS_V1_40_14::SSV_LireCartePS, ssv_lire_carte_ps, {
        NomRessourcePS: *const i8,
        NomRessourceLecteur: *const i8,
        CodePorteurPS: *const i8,
        pZDataOut: *mut *mut libc::c_void,
        pTailleZone: *mut usize
    });
}

impl SSVLibrary<V1_40_13> {
    ssv_function!(BINDINGS_V1_40_13::SSV_InitLIB2, ssv_init_lib2, {
        pcFichierSesam: *const i8
    });

    ssv_function!(BINDINGS_V1_40_13::SSV_LireConfig, ssv_lire_config, {
        pZDataOut: *mut *mut libc::c_void,
        psTailleDataOut: *mut usize
    });

    ssv_function!(BINDINGS_V1_40_13::SSV_LireCartePS, ssv_lire_carte_ps, {
        NomRessourcePS: *const i8,
        NomRessourceLecteur: *const i8,
        CodePorteurPS: *const i8,
        pZDataOut: *mut *mut libc::c_void,
        pTailleZone: *mut usize
    });
}

pub fn get_library_path(version: &SupportedFsvVersion) -> String {
    let root_path = get_library_root_path();
    let library_name = get_library_name();
    let version = version.as_str();
    format!("{root_path}/{version}/lib/{library_name}")
}

pub fn sesam_ini_path(version: &SupportedFsvVersion) -> String {
    let root_path = get_sesam_ini_root_path();
    let version = version.as_str();
    format!("{root_path}/{version}/conf/sesam.ini")
}

fn get_library_name() -> &'static str {
    // TODO : Use libloading::library_filename to get platform-specific filename ?
    "libssvlux64.so"
}

fn get_library_root_path() -> &'static str {
    "/opt/santesocial/fsv"
}

fn get_sesam_ini_root_path() -> &'static str {
    "/etc/opt/santesocial/fsv"
}

#[cfg(test)]
mod test {
    use std::{ffi::CString, ptr};

    use super::*;

    #[test]
    fn test_initlib2() {
        let lib_path = &get_library_path(&SupportedFsvVersion::V1_40_13);
        let ssv_library = SSVLibrary::<V1_40_13>::new(lib_path).expect("SSVLibrary::new failed");

        let sesam_ini_str =
            CString::new(sesam_ini_path(&SupportedFsvVersion::V1_40_13)).expect("CString::new failed");
        let result = unsafe { ssv_library.ssv_init_lib2(sesam_ini_str.as_ptr()) }.unwrap();
        assert_eq!(result, 0);
    }

    #[test]
    fn test_lire_config_and_carte_ps() {
        let lib_path = &get_library_path(&SupportedFsvVersion::V1_40_13);
        let ssv_library = SSVLibrary::<V1_40_13>::new(lib_path).expect("SSVLibrary::new failed");

        let sesam_ini_str =
            CString::new(sesam_ini_path(&SupportedFsvVersion::V1_40_13)).expect("CString::new failed");
        let result = unsafe { ssv_library.ssv_init_lib2(sesam_ini_str.as_ptr()) }.unwrap();
        assert_eq!(result, 0);

        let mut buffer_ptr: *mut libc::c_void = ptr::null_mut();
        let mut size: libc::size_t = 0;
        let result = unsafe { ssv_library.ssv_lire_config(&mut buffer_ptr, &mut size) }.unwrap();
        assert_eq!(result, 0);
        unsafe { libc::free(buffer_ptr) };

        let nom_ressource_ps =
            CString::new("Gemalto PC Twin Reader (645D94C3) 00 00").expect("CString::new failed");
        let nom_ressource_lecteur =
            CString::new("Gemalto PC Twin Reader (645D94C3) 00 00").expect("CString::new failed");
        let code_porteur_ps = CString::new("1234").expect("CString::new failed");
        let mut buffer_ptr: *mut libc::c_void = ptr::null_mut();
        let mut size: libc::size_t = 0;
        let result = unsafe {
            ssv_library.ssv_lire_carte_ps(
                nom_ressource_ps.as_ptr(),
                nom_ressource_lecteur.as_ptr(),
                code_porteur_ps.as_ptr(),
                &mut buffer_ptr,
                &mut size,
            )
        }
        .unwrap();
        assert_eq!(result, 0);
        unsafe { libc::free(buffer_ptr) };
    }
}