use std::ffi::CString;
use std::mem::{align_of, forget};

use wasmer::{FunctionEnv, FunctionEnvMut, Imports, StoreMut};

use crate::script_implementations::wasm::extern_ref::ExternRef;
use crate::script_implementations::wasm::script_resolver::WebAssemblyEnv;
use crate::static_data::EffectParameter;
use crate::StringKey;

/// Dynamic data registration
mod dynamic_data;
/// Static data registration
mod static_data;

/// Register a single function.
macro_rules! register_func_with_env {
    ($imports: ident, $store: ident, $func: ident, $env: expr) => {
        $imports.define(
            "env",
            stringify!($func),
            wasmer::Function::new_typed_with_env($store, $env, $func),
        );
    };
}

/// Utility macro to register a bunch of WASM functions easily.
macro_rules! register {
    (
        $(
            fn $name:ident($($par:ident: $par_type:ty),*$(,)?) $(-> $return:ty)? $block:block
        )*
        $(
            manual $manual_name:ident
        )?
    ) => {

        $(
            fn $name(
                $(
                $par: $par_type,
                )*
            ) $(-> $return)* $block
        )*

        pub(crate) fn register(imports: &mut wasmer::Imports,
            store: &mut wasmer::StoreMut,
            env: &wasmer::FunctionEnv<crate::script_implementations::wasm::script_resolver::WebAssemblyEnv>) {
            $(
                crate::script_implementations::wasm::export_registry::register_func_with_env!(imports, store, $name, env);
            )*
            $( $manual_name(imports, store, env) )*
        }
    };
}

pub(crate) use register;
pub(crate) use register_func_with_env;

/// Register the functions we expose to WASM.
pub(crate) fn register_webassembly_funcs(
    imports: &mut Imports,
    store: &mut StoreMut,
    env: &FunctionEnv<WebAssemblyEnv>,
) {
    register_func_with_env!(imports, store, _print, env);
    register_func_with_env!(imports, store, _error, env);
    register_func_with_env!(imports, store, _vec_extern_ref_get_value, env);

    static_data::register(imports, store, env);
    dynamic_data::register(imports, store, env);

    register_func_with_env!(imports, store, string_key_get_hash, env);
    register_func_with_env!(imports, store, string_key_get_str, env);
    register_func_with_env!(imports, store, effect_parameter_get_type, env);
    register_func_with_env!(imports, store, effect_parameter_as_bool, env);
    register_func_with_env!(imports, store, effect_parameter_as_int, env);
    register_func_with_env!(imports, store, effect_parameter_as_float, env);
    register_func_with_env!(imports, store, effect_parameter_as_string, env);
}

/// Logging function for WASM.
fn _print(env: FunctionEnvMut<WebAssemblyEnv>, p: u32, len: u32) {
    unsafe {
        let mem: *mut u8 = env.data().data().memory().offset(p as isize);
        let s = String::from_raw_parts(mem, len as usize, len as usize);
        println!("{}", s);
        forget(s);
    }
}

/// Triggers when WASM panics.
#[track_caller]
fn _error(
    env: FunctionEnvMut<WebAssemblyEnv>,
    message: u32,
    message_len: u32,
    file: u32,
    file_len: u32,
    line: u32,
    position: u32,
) {
    unsafe {
        let mem: *mut u8 = env.data().data().memory().offset(message as isize);
        let message_str = String::from_raw_parts(mem, message_len as usize, message_len as usize);
        let mem: *mut u8 = env.data().data().memory().offset(file as isize);
        let file_str = String::from_raw_parts(mem, file_len as usize, file_len as usize);
        panic!(
            "Error: {} in file {}, line: {}:{}",
            message_str, file_str, line, position
        );
    }
}

/// Get a single item from an earlier passed VecExternRef
fn _vec_extern_ref_get_value(env: FunctionEnvMut<WebAssemblyEnv>, reference: u32, index: u32) -> u32 {
    env.data().data().get_extern_vec_ref_extern_ref(reference, index)
}

/// Gets the hash value of a StringKey.
fn string_key_get_hash(env: FunctionEnvMut<WebAssemblyEnv>, string_key: ExternRef<StringKey>) -> u32 {
    string_key.value_func(&env).unwrap().hash()
}

/// Get a null-terminated C string from a StringKey. Note that this involves a copy into WASM
/// memory, so this is relatively heavy.
fn string_key_get_str(env: FunctionEnvMut<WebAssemblyEnv>, string_key: ExternRef<StringKey>) -> u32 {
    let string_key = string_key.value_func(&env).unwrap().str();
    let wasm_string_ptr = env
        .data()
        .data()
        .allocate_mem((string_key.len() + 1) as u32, align_of::<CString>() as u32);
    let mut wasm_string: Vec<u8> =
        unsafe { Vec::from_raw_parts(wasm_string_ptr.0, string_key.len() + 1, string_key.len() + 1) };
    wasm_string.resize(string_key.len() + 1, 0);
    string_key.as_bytes().clone_into(&mut wasm_string);
    wasm_string.insert(string_key.len(), 0_u8);
    forget(wasm_string);
    wasm_string_ptr.1
}

/// Gets the type of an EffectParameter
fn effect_parameter_get_type(env: FunctionEnvMut<WebAssemblyEnv>, parameter: ExternRef<EffectParameter>) -> u8 {
    let v = parameter.value_func(&env).unwrap();
    match v {
        EffectParameter::Bool(_) => 1,
        EffectParameter::Int(_) => 2,
        EffectParameter::Float(_) => 3,
        EffectParameter::String(_) => 4,
    }
}

/// Gets the inner bool data of an EffectParameter. Panics if it's not a bool.
fn effect_parameter_as_bool(env: FunctionEnvMut<WebAssemblyEnv>, parameter: ExternRef<EffectParameter>) -> u8 {
    let v = parameter.value_func(&env).unwrap();
    match v {
        EffectParameter::Bool(b) => {
            if *b {
                1
            } else {
                0
            }
        }
        _ => panic!("Unexpected parameter type!"),
    }
}

/// Gets the inner int data of an EffectParameter. Panics if it's not an int.
fn effect_parameter_as_int(env: FunctionEnvMut<WebAssemblyEnv>, parameter: ExternRef<EffectParameter>) -> i64 {
    let v = parameter.value_func(&env).unwrap();
    match v {
        EffectParameter::Int(i) => *i,
        _ => panic!("Unexpected parameter type!"),
    }
}

/// Gets the inner float data of an EffectParameter. Panics if it's not a float.
fn effect_parameter_as_float(env: FunctionEnvMut<WebAssemblyEnv>, parameter: ExternRef<EffectParameter>) -> f32 {
    let v = parameter.value_func(&env).unwrap();
    match v {
        EffectParameter::Float(f) => *f,
        _ => panic!("Unexpected parameter type!"),
    }
}

/// Gets the inner string data of an EffectParameter. Panics if it's not a string.
fn effect_parameter_as_string(
    env: FunctionEnvMut<WebAssemblyEnv>,
    parameter: ExternRef<EffectParameter>,
) -> ExternRef<StringKey> {
    let v = parameter.value_func(&env).unwrap();
    match v {
        EffectParameter::String(s) => ExternRef::func_new(&env, s),
        _ => panic!("Unexpected parameter type!"),
    }
}