pub mod errors;
pub mod libcalls;
pub mod relocation;
pub mod utils;

use wasmer_clif_backend::CraneliftCompiler;
use wasmer_runtime::{
    backend::Compiler,
    module::Module,
    import::Imports,
    instance::Instance,
};
use cranelift_codegen::{
    isa,
    settings::{self, Configurable},
};
use std::panic;
use std::str::FromStr;
use std::sync::Arc;
use target_lexicon;
use wasmparser;
use wasmparser::WasmDecoder;

pub use self::errors::{Error, ErrorKind};

use wasmer_emscripten::{allocate_cstr_on_stack, allocate_on_stack, is_emscripten_module};

pub struct ResultObject {
    /// A webassembly::Module object representing the compiled WebAssembly module.
    /// This Module can be instantiated again
    pub module: Arc<Module>,
    /// A webassembly::Instance object that contains all the Exported WebAssembly
    /// functions.
    pub instance: Box<Instance>,
}


pub struct InstanceOptions {
    // Shall we mock automatically the imported functions if they don't exist?
    pub mock_missing_imports: bool,
    pub mock_missing_globals: bool,
    pub mock_missing_tables: bool,
    pub abi: InstanceABI,
    pub show_progressbar: bool,
//    pub isa: Box<isa::TargetIsa>, TODO isa
}

#[derive(PartialEq)]
pub enum InstanceABI {
    Emscripten,
    None,
}

/// The webassembly::instantiate() function allows you to compile and
/// instantiate WebAssembly code
/// Params:
/// * `buffer_source`: A `Vec<u8>` containing the
///   binary code of the .wasm module you want to compile.
/// * `import_object`: An object containing the values to be imported
///   into the newly-created Instance, such as functions or
///   webassembly::Memory objects. There must be one matching property
///   for each declared import of the compiled module or else a
///   webassembly::LinkError is thrown.
/// Errors:
/// If the operation fails, the Result rejects with a
/// webassembly::CompileError, webassembly::LinkError, or
/// webassembly::RuntimeError, depending on the cause of the failure.
pub fn instantiate(
    buffer_source: &[u8],
    import_object: &Imports,
    options: Option<InstanceOptions>,
) -> Result<ResultObject, ErrorKind> {
    debug!("webassembly - creating instance");

    //let instance = Instance::new(&module, import_object, options)?;
    unimplemented!()
//    let instance = wasmer_runtime::instantiate(buffer_source, &CraneliftCompiler::new(), import_object)
//        .map_err(|e| ErrorKind::CompileError(e))?;
//
//    let isa = get_isa();
    //    let abi = if is_emscripten_module(&instance.module) {
    //        InstanceABI::Emscripten
    //    } else {
    //        InstanceABI::None
    //    };
    //
    //    let options = options.unwrap_or_else(|| InstanceOptions {
    //        mock_missing_imports: false,
    //        mock_missing_globals: false,
    //        mock_missing_tables: false,
    //        abi,
    //        show_progressbar: false,
    //        isa,
    //    });

//    debug!("webassembly - instance created");
//    Ok(ResultObject {
//        module: Arc::clone(&instance.module),
//        instance,
//    })
}

/// The webassembly::instantiate_streaming() function compiles and instantiates
/// a WebAssembly module directly from a streamed underlying source.
/// This is the most efficient, optimized way to load wasm code.
pub fn instantiate_streaming(
    _buffer_source: Vec<u8>,
    _import_object: Imports,
) -> Result<ResultObject, ErrorKind> {
    unimplemented!();
}

/// The webassembly::compile() function compiles a webassembly::Module
/// from WebAssembly binary code.  This function is useful if it
/// is necessary to a compile a module before it can be instantiated
/// (otherwise, the webassembly::instantiate() function should be used).
/// Params:
/// * `buffer_source`: A `Vec<u8>` containing the
///   binary code of the .wasm module you want to compile.
/// Errors:
/// If the operation fails, the Result rejects with a
/// webassembly::CompileError.
pub fn compile(buffer_source: &[u8]) -> Result<Arc<Module>, ErrorKind> {
    let compiler = &CraneliftCompiler {};
    let module = compiler
        .compile(buffer_source)
        .map_err(|e| ErrorKind::CompileError(e))?;

    Ok(Arc::new(module))
}

/// The webassembly::validate() function validates a given typed
/// array of WebAssembly binary code, returning whether the bytes
/// form a valid wasm module (true) or not (false).
/// Params:
/// * `buffer_source`: A `&[u8]` containing the
///   binary code of the .wasm module you want to compile.
pub fn validate(buffer_source: &[u8]) -> bool {
    validate_or_error(buffer_source).is_ok()
}

pub fn validate_or_error(bytes: &[u8]) -> Result<(), ErrorKind> {
    let mut parser = wasmparser::ValidatingParser::new(bytes, None);
    loop {
        let state = parser.read();
        match *state {
            wasmparser::ParserState::EndWasm => return Ok(()),
            wasmparser::ParserState::Error(err) => {
                return Err(ErrorKind::CompileError(format!(
                    "Validation error: {}",
                    err.message
                )));
            }
            _ => (),
        }
    }
}

pub fn get_isa() -> Box<isa::TargetIsa> {
    let flags = {
        let mut builder = settings::builder();
        builder.set("opt_level", "best").unwrap();

        if cfg!(not(test)) {
            builder.set("enable_verifier", "false").unwrap();
        }

        let flags = settings::Flags::new(builder);
        debug_assert_eq!(flags.opt_level(), settings::OptLevel::Best);
        flags
    };
    isa::lookup(triple!("x86_64")).unwrap().finish(flags)
}

fn store_module_arguments(path: &str, args: Vec<&str>, instance: &mut Instance) -> (u32, u32) {
    let argc = args.len() + 1;

    let (argv_offset, argv_slice): (_, &mut [u32]) =
        unsafe { allocate_on_stack(((argc + 1) * 4) as u32, instance) };
    assert!(!argv_slice.is_empty());

    argv_slice[0] = unsafe { allocate_cstr_on_stack(path, instance).0 };

    for (slot, arg) in argv_slice[1..argc].iter_mut().zip(args.iter()) {
        *slot = unsafe { allocate_cstr_on_stack(&arg, instance).0 };
    }

    argv_slice[argc] = 0;

    (argc as u32, argv_offset)
}

// fn get_module_arguments(options: &Run, instance: &mut webassembly::Instance) -> (u32, u32) {
//     // Application Arguments
//     let mut arg_values: Vec<String> = Vec::new();
//     let mut arg_addrs: Vec<*const u8> = Vec::new();
//     let arg_length = options.args.len() + 1;

//     arg_values.reserve_exact(arg_length);
//     arg_addrs.reserve_exact(arg_length);

//     // Push name of wasm file
//     arg_values.push(format!("{}\0", options.path.to_str().unwrap()));
//     arg_addrs.push(arg_values[0].as_ptr());

//     // Push additional arguments
//     for (i, arg) in options.args.iter().enumerate() {
//         arg_values.push(format!("{}\0", arg));
//         arg_addrs.push(arg_values[i + 1].as_ptr());
//     }

//     // Get argument count and pointer to addresses
//     let argv = arg_addrs.as_ptr() as *mut *mut i8;
//     let argc = arg_length as u32;

//     // Copy the the arguments into the wasm memory and get offset
//     let argv_offset =  unsafe {
//         copy_cstr_array_into_wasm(argc, argv, instance)
//     };

//     debug!("argc = {:?}", argc);
//     debug!("argv = {:?}", arg_addrs);

//     (argc, argv_offset)
// }

pub fn start_instance(
    module: Arc<Module>,
    instance: &mut Instance,
    path: &str,
    args: Vec<&str>,
) -> Result<(), String> {
    let main_name = if is_emscripten_module(&instance.module) {
        "_main"
    } else {
        "main"
    };

    // TODO handle args
    instance.call(main_name, &[]).map(|o| ())
    // TODO atinit and atexit for emscripten

    //    if let Some(ref emscripten_data) = &instance.emscripten_data {
    //        emscripten_data.atinit(module, instance)?;
    //
    //        let func_index = match module.exports.get("_main") {
    //            Some(&Export::Function(index)) => index,
    //            _ => panic!("_main emscripten function not found"),
    //        };
    //
    //        let sig_index = module.get_func_type(func_index);
    //        let signature = module.get_signature(sig_index);
    //        let num_params = signature.params.len();
    //        let result = match num_params {
    //            2 => {
    //                let main: extern "C" fn(u32, u32, &Instance) =
    //                    get_instance_function!(instance, func_index);
    //                let (argc, argv) = store_module_arguments(path, args, instance);
    //                call_protected!(main(argc, argv, &instance))
    //            }
    //            0 => {
    //                let main: extern "C" fn(&Instance) = get_instance_function!(instance, func_index);
    //                call_protected!(main(&instance))
    //            }
    //            _ => panic!(
    //                "The emscripten main function has received an incorrect number of params {}",
    //                num_params
    //            ),
    //        }
    //        .map_err(|err| format!("{}", err));
    //
    //        emscripten_data.atexit(module, instance)?;
    //
    //        result
    //    } else {
    //        let func_index =
    //            instance
    //                .start_func
    //                .unwrap_or_else(|| match module.info.exports.get("main") {
    //                    Some(&Export::Function(index)) => index,
    //                    _ => panic!("Main function not found"),
    //                });
    //        let main: extern "C" fn(&Instance) = get_instance_function!(instance, func_index);
    //        call_protected!(main(&instance)).map_err(|err| format!("{}", err))
    //    }
}