//! Create, read, destroy import definitions (function, global, memory
//! and table) on an instance.

use crate::{
    error::{update_last_error, CApiError},
    export::{wasmer_import_export_kind, wasmer_import_export_value},
    module::wasmer_module_t,
    value::wasmer_value_tag,
    wasmer_byte_array, wasmer_result_t,
};
use libc::{c_uint, uint32_t};
use std::{ffi::c_void, ptr, slice, sync::Arc};
use wasmer_runtime::Module;
use wasmer_runtime_core::{
    export::{Context, Export, FuncPointer},
    module::ImportName,
    types::{FuncSig, Type},
};

#[repr(C)]
pub struct wasmer_import_t {
    pub module_name: wasmer_byte_array,
    pub import_name: wasmer_byte_array,
    pub tag: wasmer_import_export_kind,
    pub value: wasmer_import_export_value,
}

#[repr(C)]
#[derive(Clone)]
pub struct wasmer_import_func_t;

#[repr(C)]
#[derive(Clone)]
pub struct wasmer_import_descriptor_t;

#[repr(C)]
#[derive(Clone)]
pub struct wasmer_import_descriptors_t;

/// Gets import descriptors for the given module
///
/// The caller owns the object and should call `wasmer_import_descriptors_destroy` to free it.
#[allow(clippy::cast_ptr_alignment)]
#[no_mangle]
pub unsafe extern "C" fn wasmer_import_descriptors(
    module: *const wasmer_module_t,
    import_descriptors: *mut *mut wasmer_import_descriptors_t,
) {
    let module = &*(module as *const Module);
    let total_imports = module.info().imported_functions.len()
        + module.info().imported_tables.len()
        + module.info().imported_globals.len()
        + module.info().imported_memories.len();
    let mut descriptors: Vec<NamedImportDescriptor> = Vec::with_capacity(total_imports);

    for (
        _index,
        ImportName {
            namespace_index,
            name_index,
        },
    ) in &module.info().imported_functions
    {
        let namespace = module.info().namespace_table.get(*namespace_index);
        let name = module.info().name_table.get(*name_index);
        descriptors.push(NamedImportDescriptor {
            module: namespace.to_string(),
            name: name.to_string(),
            kind: wasmer_import_export_kind::WASM_FUNCTION,
        });
    }

    for (
        _index,
        (
            ImportName {
                namespace_index,
                name_index,
            },
            _,
        ),
    ) in &module.info().imported_tables
    {
        let namespace = module.info().namespace_table.get(*namespace_index);
        let name = module.info().name_table.get(*name_index);
        descriptors.push(NamedImportDescriptor {
            module: namespace.to_string(),
            name: name.to_string(),
            kind: wasmer_import_export_kind::WASM_TABLE,
        });
    }

    for (
        _index,
        (
            ImportName {
                namespace_index,
                name_index,
            },
            _,
        ),
    ) in &module.info().imported_globals
    {
        let namespace = module.info().namespace_table.get(*namespace_index);
        let name = module.info().name_table.get(*name_index);
        descriptors.push(NamedImportDescriptor {
            module: namespace.to_string(),
            name: name.to_string(),
            kind: wasmer_import_export_kind::WASM_GLOBAL,
        });
    }

    for (
        _index,
        (
            ImportName {
                namespace_index,
                name_index,
            },
            _,
        ),
    ) in &module.info().imported_memories
    {
        let namespace = module.info().namespace_table.get(*namespace_index);
        let name = module.info().name_table.get(*name_index);
        descriptors.push(NamedImportDescriptor {
            module: namespace.to_string(),
            name: name.to_string(),
            kind: wasmer_import_export_kind::WASM_MEMORY,
        });
    }

    let named_import_descriptors: Box<NamedImportDescriptors> =
        Box::new(NamedImportDescriptors(descriptors));
    *import_descriptors =
        Box::into_raw(named_import_descriptors) as *mut wasmer_import_descriptors_t;
}

pub struct NamedImportDescriptors(Vec<NamedImportDescriptor>);

/// Frees the memory for the given import descriptors
#[allow(clippy::cast_ptr_alignment)]
#[no_mangle]
pub extern "C" fn wasmer_import_descriptors_destroy(
    import_descriptors: *mut wasmer_import_descriptors_t,
) {
    if !import_descriptors.is_null() {
        unsafe { Box::from_raw(import_descriptors as *mut NamedImportDescriptors) };
    }
}

/// Gets the length of the import descriptors
#[allow(clippy::cast_ptr_alignment)]
#[no_mangle]
pub unsafe extern "C" fn wasmer_import_descriptors_len(
    exports: *mut wasmer_import_descriptors_t,
) -> c_uint {
    if exports.is_null() {
        return 0;
    }
    (*(exports as *mut NamedImportDescriptors)).0.len() as c_uint
}

/// Gets import descriptor by index
#[allow(clippy::cast_ptr_alignment)]
#[no_mangle]
pub unsafe extern "C" fn wasmer_import_descriptors_get(
    import_descriptors: *mut wasmer_import_descriptors_t,
    idx: c_uint,
) -> *mut wasmer_import_descriptor_t {
    if import_descriptors.is_null() {
        return ptr::null_mut();
    }
    let named_import_descriptors = &mut *(import_descriptors as *mut NamedImportDescriptors);
    &mut (*named_import_descriptors).0[idx as usize] as *mut NamedImportDescriptor
        as *mut wasmer_import_descriptor_t
}

/// Gets name for the import descriptor
#[no_mangle]
#[allow(clippy::cast_ptr_alignment)]
pub unsafe extern "C" fn wasmer_import_descriptor_name(
    import_descriptor: *mut wasmer_import_descriptor_t,
) -> wasmer_byte_array {
    let named_import_descriptor = &*(import_descriptor as *mut NamedImportDescriptor);
    wasmer_byte_array {
        bytes: named_import_descriptor.name.as_ptr(),
        bytes_len: named_import_descriptor.name.len() as u32,
    }
}

/// Gets module name for the import descriptor
#[no_mangle]
#[allow(clippy::cast_ptr_alignment)]
pub unsafe extern "C" fn wasmer_import_descriptor_module_name(
    import_descriptor: *mut wasmer_import_descriptor_t,
) -> wasmer_byte_array {
    let named_import_descriptor = &*(import_descriptor as *mut NamedImportDescriptor);
    wasmer_byte_array {
        bytes: named_import_descriptor.module.as_ptr(),
        bytes_len: named_import_descriptor.module.len() as u32,
    }
}

/// Gets export descriptor kind
#[no_mangle]
#[allow(clippy::cast_ptr_alignment)]
pub unsafe extern "C" fn wasmer_import_descriptor_kind(
    export: *mut wasmer_import_descriptor_t,
) -> wasmer_import_export_kind {
    let named_import_descriptor = &*(export as *mut NamedImportDescriptor);
    named_import_descriptor.kind.clone()
}

/// Sets the result parameter to the arity of the params of the wasmer_import_func_t
///
/// Returns `wasmer_result_t::WASMER_OK` upon success.
///
/// Returns `wasmer_result_t::WASMER_ERROR` upon failure. Use `wasmer_last_error_length`
/// and `wasmer_last_error_message` to get an error message.
#[no_mangle]
#[allow(clippy::cast_ptr_alignment)]
pub unsafe extern "C" fn wasmer_import_func_params_arity(
    func: *const wasmer_import_func_t,
    result: *mut uint32_t,
) -> wasmer_result_t {
    let export = &*(func as *const Export);
    if let Export::Function { ref signature, .. } = *export {
        *result = signature.params().len() as uint32_t;
        wasmer_result_t::WASMER_OK
    } else {
        update_last_error(CApiError {
            msg: "func ptr error in wasmer_import_func_params_arity".to_string(),
        });
        wasmer_result_t::WASMER_ERROR
    }
}

/// Creates new func
///
/// The caller owns the object and should call `wasmer_import_func_destroy` to free it.
#[no_mangle]
#[allow(clippy::cast_ptr_alignment)]
pub unsafe extern "C" fn wasmer_import_func_new(
    func: extern "C" fn(data: *mut c_void),
    params: *const wasmer_value_tag,
    params_len: c_uint,
    returns: *const wasmer_value_tag,
    returns_len: c_uint,
) -> *mut wasmer_import_func_t {
    let params: &[wasmer_value_tag] = slice::from_raw_parts(params, params_len as usize);
    let params: Vec<Type> = params.iter().cloned().map(|x| x.into()).collect();
    let returns: &[wasmer_value_tag] = slice::from_raw_parts(returns, returns_len as usize);
    let returns: Vec<Type> = returns.iter().cloned().map(|x| x.into()).collect();

    let export = Box::new(Export::Function {
        func: FuncPointer::new(func as _),
        ctx: Context::Internal,
        signature: Arc::new(FuncSig::new(params, returns)),
    });
    Box::into_raw(export) as *mut wasmer_import_func_t
}

/// Sets the params buffer to the parameter types of the given wasmer_import_func_t
///
/// Returns `wasmer_result_t::WASMER_OK` upon success.
///
/// Returns `wasmer_result_t::WASMER_ERROR` upon failure. Use `wasmer_last_error_length`
/// and `wasmer_last_error_message` to get an error message.
#[no_mangle]
#[allow(clippy::cast_ptr_alignment)]
pub unsafe extern "C" fn wasmer_import_func_params(
    func: *const wasmer_import_func_t,
    params: *mut wasmer_value_tag,
    params_len: c_uint,
) -> wasmer_result_t {
    let export = &*(func as *const Export);
    if let Export::Function { ref signature, .. } = *export {
        let params: &mut [wasmer_value_tag] =
            slice::from_raw_parts_mut(params, params_len as usize);
        for (i, item) in signature.params().iter().enumerate() {
            params[i] = item.into();
        }
        wasmer_result_t::WASMER_OK
    } else {
        update_last_error(CApiError {
            msg: "func ptr error in wasmer_import_func_params".to_string(),
        });
        wasmer_result_t::WASMER_ERROR
    }
}

/// Sets the returns buffer to the parameter types of the given wasmer_import_func_t
///
/// Returns `wasmer_result_t::WASMER_OK` upon success.
///
/// Returns `wasmer_result_t::WASMER_ERROR` upon failure. Use `wasmer_last_error_length`
/// and `wasmer_last_error_message` to get an error message.
#[no_mangle]
#[allow(clippy::cast_ptr_alignment)]
pub unsafe extern "C" fn wasmer_import_func_returns(
    func: *const wasmer_import_func_t,
    returns: *mut wasmer_value_tag,
    returns_len: c_uint,
) -> wasmer_result_t {
    let export = &*(func as *const Export);
    if let Export::Function { ref signature, .. } = *export {
        let returns: &mut [wasmer_value_tag] =
            slice::from_raw_parts_mut(returns, returns_len as usize);
        for (i, item) in signature.returns().iter().enumerate() {
            returns[i] = item.into();
        }
        wasmer_result_t::WASMER_OK
    } else {
        update_last_error(CApiError {
            msg: "func ptr error in wasmer_import_func_returns".to_string(),
        });
        wasmer_result_t::WASMER_ERROR
    }
}

/// Sets the result parameter to the arity of the returns of the wasmer_import_func_t
///
/// Returns `wasmer_result_t::WASMER_OK` upon success.
///
/// Returns `wasmer_result_t::WASMER_ERROR` upon failure. Use `wasmer_last_error_length`
/// and `wasmer_last_error_message` to get an error message.
#[no_mangle]
#[allow(clippy::cast_ptr_alignment)]
pub unsafe extern "C" fn wasmer_import_func_returns_arity(
    func: *const wasmer_import_func_t,
    result: *mut uint32_t,
) -> wasmer_result_t {
    let export = &*(func as *const Export);
    if let Export::Function { ref signature, .. } = *export {
        *result = signature.returns().len() as uint32_t;
        wasmer_result_t::WASMER_OK
    } else {
        update_last_error(CApiError {
            msg: "func ptr error in wasmer_import_func_results_arity".to_string(),
        });
        wasmer_result_t::WASMER_ERROR
    }
}

/// Frees memory for the given Func
#[allow(clippy::cast_ptr_alignment)]
#[no_mangle]
pub extern "C" fn wasmer_import_func_destroy(func: *mut wasmer_import_func_t) {
    if !func.is_null() {
        unsafe { Box::from_raw(func as *mut Export) };
    }
}

struct NamedImportDescriptor {
    module: String,
    name: String,
    kind: wasmer_import_export_kind,
}