// Copyright (c) 2017-present PyO3 Project and Contributors

use syn;
use quote::{Tokens, ToTokens};
use method::{FnArg, FnSpec, FnType};

use utils;


pub fn gen_py_method<'a>(cls: &Box<syn::Ty>, name: &syn::Ident,
                         sig: &mut syn::MethodSig, meth_attrs: &mut Vec<syn::Attribute>) -> Tokens
{
    check_generic(name, sig);

    let doc = utils::get_doc(&meth_attrs, true);
    let spec = FnSpec::parse(name, sig, meth_attrs);

    match spec.tp {
        FnType::Fn =>
            impl_py_method_def(name, doc, &spec, &impl_wrap(cls, name, &spec, true)),
        FnType::FnNew =>
            impl_py_method_def_new(name, doc, &impl_wrap_type(cls, name, &spec)),
        FnType::FnCall =>
            impl_py_method_def_call(name, doc, &impl_wrap(cls, name, &spec, false)),
        FnType::FnClass =>
            impl_py_method_def_class(name, doc, &impl_wrap_class(cls, name, &spec)),
        FnType::FnStatic =>
            impl_py_method_def_static(name, doc, &impl_wrap_static(cls, name, &spec)),
        FnType::Getter(ref getter) =>
            impl_py_getter_def(name, doc, getter, &impl_wrap_getter(cls, name, &spec)),
        FnType::Setter(ref setter) =>
            impl_py_setter_def(name, doc, setter, &impl_wrap_setter(cls, name, &spec)),
    }
}


fn check_generic(name: &syn::Ident, sig: &syn::MethodSig) {
    if !sig.generics.ty_params.is_empty() {
        panic!("python method can not be generic: {:?}", name);
    }
}


/// Generate function wrapper (PyCFunction, PyCFunctionWithKeywords)
pub fn impl_wrap(cls: &Box<syn::Ty>, name: &syn::Ident, spec: &FnSpec, noargs: bool) -> Tokens {
    let cb = impl_call(cls, name, &spec);
    let output = &spec.output;

    if spec.args.is_empty() && noargs {
        quote! {
            unsafe extern "C" fn __wrap(
                _slf: *mut _pyo3::ffi::PyObject) -> *mut _pyo3::ffi::PyObject
            {
                const _LOCATION: &'static str = concat!(
                    stringify!(#cls), ".", stringify!(#name), "()");
                let _pool = _pyo3::GILPool::new();
                let _py = _pyo3::Python::assume_gil_acquired();
                let _slf = _py.mut_cast_from_borrowed_ptr::<#cls>(_slf);

                let _result: #output = {
                    #cb
                };
                _pyo3::callback::cb_convert(
                    _pyo3::callback::PyObjectCallbackConverter, _py, _result)
            }
        }
    } else {
        let body = impl_arg_params(&spec, cb);

        quote! {
            unsafe extern "C" fn __wrap(
                _slf: *mut _pyo3::ffi::PyObject,
                _args: *mut _pyo3::ffi::PyObject,
                _kwargs: *mut _pyo3::ffi::PyObject) -> *mut _pyo3::ffi::PyObject
            {
                use pyo3::ToPyPointer;
                const _LOCATION: &'static str = concat!(
                    stringify!(#cls), ".", stringify!(#name), "()");
                let _pool = _pyo3::GILPool::new();
                let _py = _pyo3::Python::assume_gil_acquired();
                let _slf = _py.mut_cast_from_borrowed_ptr::<#cls>(_slf);
                let _args = _py.cast_from_borrowed_ptr::<_pyo3::PyTuple>(_args);
                let _kwargs = _pyo3::argparse::get_kwargs(_py, _kwargs);

                let _result: #output = {
                    #body
                };
                _pyo3::callback::cb_convert(
                    _pyo3::callback::PyObjectCallbackConverter, _py, _result)
            }
        }
    }
}

/// Generate function wrapper for protocol method (PyCFunction, PyCFunctionWithKeywords)
pub fn impl_proto_wrap(cls: &Box<syn::Ty>, name: &syn::Ident, spec: &FnSpec) -> Tokens {
    let cb = impl_call(cls, name, &spec);
    let body = impl_arg_params(&spec, cb);

    quote! {
        #[allow(unused_mut)]
        unsafe extern "C" fn __wrap(
            _slf: *mut _pyo3::ffi::PyObject,
            _args: *mut _pyo3::ffi::PyObject,
            _kwargs: *mut _pyo3::ffi::PyObject) -> *mut _pyo3::ffi::PyObject
        {
            const _LOCATION: &'static str = concat!(stringify!(#cls),".",stringify!(#name),"()");
            let _pool = _pyo3::GILPool::new();
            let _py = _pyo3::Python::assume_gil_acquired();
            let _slf = _py.mut_cast_from_borrowed_ptr::<#cls>(_slf);
            let _args = _py.cast_from_borrowed_ptr::<_pyo3::PyTuple>(_args);
            let _kwargs = _pyo3::argparse::get_kwargs(_py, _kwargs);

            let _result = {
                #body
            };
            _pyo3::callback::cb_convert(
                _pyo3::callback::PyObjectCallbackConverter, _py, _result)
        }
    }
}

/// Generate class method wrapper (PyCFunction, PyCFunctionWithKeywords)
pub fn impl_wrap_type(cls: &Box<syn::Ty>, name: &syn::Ident, spec: &FnSpec) -> Tokens {
    let names: Vec<syn::Ident> = spec.args.iter().enumerate().map(
        |item| if item.1.py {syn::Ident::from("_py")} else {
            syn::Ident::from(format!("arg{}", item.0))}).collect();
    let cb = quote! {{
        #cls::#name(&_cls, #(#names),*)
    }};

    let body = impl_arg_params(spec, cb);
    let output = &spec.output;

    quote! {
        #[allow(unused_mut)]
        unsafe extern "C" fn __wrap(
            _cls: *mut _pyo3::ffi::PyTypeObject,
            _args: *mut _pyo3::ffi::PyObject,
            _kwargs: *mut _pyo3::ffi::PyObject) -> *mut _pyo3::ffi::PyObject
        {
            const _LOCATION: &'static str = concat!(stringify!(#cls),".",stringify!(#name),"()");
            let _pool = _pyo3::GILPool::new();
            let _py = _pyo3::Python::assume_gil_acquired();
            let _cls = _pyo3::PyType::from_type_ptr(_py, _cls);
            let _args = _py.cast_from_borrowed_ptr::<_pyo3::PyTuple>(_args);
            let _kwargs = _pyo3::argparse::get_kwargs(_py, _kwargs);

            let _result: #output = {
                #body
            };
            _pyo3::callback::cb_convert(
                _pyo3::callback::PyObjectCallbackConverter, _py, _result)
        }
    }
}

/// Generate class method wrapper (PyCFunction, PyCFunctionWithKeywords)
pub fn impl_wrap_class(cls: &Box<syn::Ty>, name: &syn::Ident, spec: &FnSpec) -> Tokens {
    let names: Vec<syn::Ident> = spec.args.iter().enumerate().map(
        |item| if item.1.py {syn::Ident::from("_py")} else {
            syn::Ident::from(format!("arg{}", item.0))}).collect();
    let cb = quote! {{
        #cls::#name(&_cls, #(#names),*)
    }};
    let body = impl_arg_params(spec, cb);
    let output = &spec.output;

    quote! {
        #[allow(unused_mut)]
        unsafe extern "C" fn __wrap(
            _cls: *mut _pyo3::ffi::PyObject,
            _args: *mut _pyo3::ffi::PyObject,
            _kwargs: *mut _pyo3::ffi::PyObject) -> *mut _pyo3::ffi::PyObject
        {
            const _LOCATION: &'static str = concat!(stringify!(#cls),".",stringify!(#name),"()");
            let _pool = _pyo3::GILPool::new();
            let _py = _pyo3::Python::assume_gil_acquired();
            let _cls = _pyo3::PyType::from_type_ptr(_py, _cls as *mut _pyo3::ffi::PyTypeObject);
            let _args = _py.cast_from_borrowed_ptr::<_pyo3::PyTuple>(_args);
            let _kwargs = _pyo3::argparse::get_kwargs(_py, _kwargs);

            let _result: #output = {
                #body
            };
            _pyo3::callback::cb_convert(
                _pyo3::callback::PyObjectCallbackConverter, _py, _result)
        }
    }
}

/// Generate static method wrapper (PyCFunction, PyCFunctionWithKeywords)
pub fn impl_wrap_static(cls: &Box<syn::Ty>, name: &syn::Ident, spec: &FnSpec) -> Tokens {
    let names: Vec<syn::Ident> = spec.args.iter().enumerate().map(
        |item| if item.1.py {syn::Ident::from("_py")} else {
            syn::Ident::from(format!("arg{}", item.0))}).collect();
    let cb = quote! {{
        #cls::#name(#(#names),*)
    }};

    let body = impl_arg_params(spec, cb);
    let output = &spec.output;

    quote! {
        #[allow(unused_mut)]
        unsafe extern "C" fn __wrap(
            _slf: *mut _pyo3::ffi::PyObject,
            _args: *mut _pyo3::ffi::PyObject,
            _kwargs: *mut _pyo3::ffi::PyObject) -> *mut _pyo3::ffi::PyObject
        {
            const _LOCATION: &'static str = concat!(stringify!(#cls),".",stringify!(#name),"()");
            let _pool = _pyo3::GILPool::new();
            let _py = _pyo3::Python::assume_gil_acquired();
            let _args = _py.cast_from_borrowed_ptr::<_pyo3::PyTuple>(_args);
            let _kwargs = _pyo3::argparse::get_kwargs(_py, _kwargs);

            let _result: #output = {
                #body
            };
            _pyo3::callback::cb_convert(
                _pyo3::callback::PyObjectCallbackConverter, _py, _result)
        }
    }
}

/// Generate functiona wrapper (PyCFunction, PyCFunctionWithKeywords)
fn impl_wrap_getter(cls: &Box<syn::Ty>, name: &syn::Ident, _spec: &FnSpec) -> Tokens {
    quote! {
        unsafe extern "C" fn __wrap(
            _slf: *mut _pyo3::ffi::PyObject, _: *mut _pyo3::c_void) -> *mut _pyo3::ffi::PyObject
        {
            use std;
            const _LOCATION: &'static str = concat!(stringify!(#cls),".",stringify!(#name),"()");

            let _pool = _pyo3::GILPool::new();
            let _py = _pyo3::Python::assume_gil_acquired();
            let _slf = _py.mut_cast_from_borrowed_ptr::<#cls>(_slf);

            match _slf.#name() {
                Ok(val) => {
                    val.into_object(_py).into_ptr()
                }
                Err(e) => {
                    e.restore(_py);
                    std::ptr::null_mut()
                }
            }
        }
    }
}

/// Generate functiona wrapper (PyCFunction, PyCFunctionWithKeywords)
fn impl_wrap_setter(cls: &Box<syn::Ty>, name: &syn::Ident, spec: &FnSpec) -> Tokens {
    if spec.args.len() < 1 {
        println!("Not enough arguments for setter {}::{}", quote!{#cls}, name);
    }
    let val_ty = spec.args[0].ty;

    quote! {
        #[allow(unused_mut)]
        unsafe extern "C" fn __wrap(
            _slf: *mut _pyo3::ffi::PyObject,
            _value: *mut _pyo3::ffi::PyObject, _: *mut _pyo3::c_void) -> _pyo3::c_int
        {
            const _LOCATION: &'static str = concat!(stringify!(#cls),".",stringify!(#name),"()");
            let _pool = _pyo3::GILPool::new();
            let _py = _pyo3::Python::assume_gil_acquired();
            let _slf = _py.mut_cast_from_borrowed_ptr::<#cls>(_slf);
            let _value = _py.cast_from_borrowed_ptr(_value);

            let _result = match <#val_ty as _pyo3::FromPyObject>::extract(_value) {
                Ok(_val) => _slf.#name(_val),
                Err(e) => Err(e)
            };
            match _result {
                Ok(_) => 0,
                Err(e) => {
                    e.restore(_py);
                    -1
                }
            }
        }
    }
}


fn impl_call(_cls: &Box<syn::Ty>, fname: &syn::Ident, spec: &FnSpec) -> Tokens {
    let names: Vec<syn::Ident> = spec.args.iter().enumerate().map(
        |item| if item.1.py {
            syn::Ident::from("_py")
        } else {
            syn::Ident::from(format!("arg{}", item.0))
        }
    ).collect();
    quote! {{
        _slf.#fname(#(#names),*)
    }}
}

pub fn impl_arg_params(spec: &FnSpec, body: Tokens) -> Tokens {
    let args: Vec<FnArg> = spec.args.iter()
        .filter(|item| !item.py).map(|item| item.clone()).collect();
    if args.is_empty() {
        return body
    }

    let mut params = Vec::new();

    for arg in spec.args.iter() {
        if arg.py {
            continue
        }
        if ! (spec.is_args(&arg.name) || spec.is_kwargs(&arg.name)) {
            let name = arg.name.as_ref();
            let kwonly = if spec.is_kw_only(&arg.name) {
                syn::Ident::from("true")
            } else {
                syn::Ident::from("false")
            };

            let opt = if let Some(_) = arg.optional {
                syn::Ident::from("true")
            } else if let Some(_) = spec.default_value(&arg.name) {
                syn::Ident::from("true")
            } else {
                syn::Ident::from("false")
            };

            params.push(
                quote! {
                    _pyo3::argparse::ParamDescription{
                        name: #name, is_optional: #opt, kw_only: #kwonly}
                }
            );
        }
    }
    let placeholders: Vec<syn::Ident> = params.iter().map(
        |_| syn::Ident::from("None")).collect();

    // generate extrat args
    let len = spec.args.len();
    let mut rargs = spec.args.clone();
    rargs.reverse();
    let mut body = body;
    for (idx, arg) in rargs.iter().enumerate() {
        body = impl_arg_param(&arg, &spec, &body, len-idx-1);
    }

    let accept_args = syn::Ident::from(
        if spec.accept_args() { "true" } else { "false" });
    let accept_kwargs = syn::Ident::from(
        if spec.accept_kwargs() { "true" } else { "false" });

    // create array of arguments, and then parse
    quote! {
        const _PARAMS: &'static [_pyo3::argparse::ParamDescription<'static>] = &[
            #(#params),*
        ];

        let mut _output = [#(#placeholders),*];
        match _pyo3::argparse::parse_args(_py, Some(_LOCATION), _PARAMS, &_args,
            _kwargs, #accept_args, #accept_kwargs, &mut _output)
        {
            Ok(_) => {
                let mut _iter = _output.iter();

                #body
            },
            Err(err) => Err(err)
        }
    }
}

fn impl_arg_param(arg: &FnArg, spec: &FnSpec, body: &Tokens, idx: usize) -> Tokens {
    if arg.py {
        return body.clone()
    }
    let ty = arg.ty;
    let name = arg.name;
    let arg_name = syn::Ident::from(format!("arg{}", idx));

    // First unwrap() asserts the iterated sequence is long enough (which should be guaranteed);
    // second unwrap() asserts the parameter was not missing (which fn
    // parse_args already checked for).

    if spec.is_args(&name) {
        quote! {
            match <#ty as _pyo3::FromPyObject>::extract(_args.as_ref())
            {
                Ok(#arg_name) => {
                    #body
                }
                Err(e) => Err(e)
            }
        }
    }
    else if spec.is_kwargs(&name) {
        quote! {{
            let #arg_name = _kwargs;
            #body
        }}
    }
    else {
        if let Some(_) = arg.optional {
            // default value
            let mut default = Tokens::new();
            if let Some(d) = spec.default_value(name) {
                let dt = quote!{ Some(#d) };
                dt.to_tokens(&mut default);
            } else {
                syn::Ident::from("None").to_tokens(&mut default);
            }

            if arg.reference {
                quote! {
                    match _iter.next().unwrap().as_ref() {
                        Some(obj) => {
                            if obj.is_none() {
                                let #arg_name = #default;
                                #body
                            } else {
                                match _pyo3::RefFromPyObject::with_extracted(
                                    obj, |#name| {
                                        let #arg_name = Some(#name);
                                        #body
                                    })
                                {
                                    Ok(v) => v,
                                    Err(e) => Err(e)
                                }
                            }
                        },
                        None => {
                            let #arg_name = #default;
                            #body
                        }
                    }
                }
            } else {
                quote! {
                    match
                        match _iter.next().unwrap().as_ref() {
                            Some(_obj) => {
                                if _obj.is_none() {
                                    Ok(#default)
                                } else {
                                    match _obj.extract() {
                                        Ok(_obj) => Ok(Some(_obj)),
                                        Err(e) => Err(e)
                                    }
                                }
                            },
                            None => Ok(#default) }
                    {
                        Ok(#arg_name) => #body,
                        Err(e) => Err(e)
                    }
                }
            }
        } else if let Some(default) = spec.default_value(name) {
            if arg.reference {
                quote! {
                    match _iter.next().unwrap().as_ref() {
                        Some(_obj) => {
                            if _obj.is_none() {
                                let #arg_name = #default;
                                #body
                            } else {
                                match _pyo3::RefFromPyObject::with_extracted(
                                    _obj, |#arg_name| {
                                        #body
                                    })
                                {
                                    Ok(v) => v,
                                    Err(e) => Err(e)
                                }
                            }
                        },
                        None => {
                            let #arg_name = #default;
                            #body
                        }
                    }
                }
            } else {
                quote! {
                    match match _iter.next().unwrap().as_ref() {
                        Some(_obj) => {
                            if _obj.is_none() {
                                Ok(#default)
                            } else {
                                match _obj.extract() {
                                    Ok(_obj) => Ok(_obj),
                                    Err(e) => Err(e),
                                }
                            }
                        },
                        None => Ok(#default)
                    } {
                        Ok(#arg_name) => #body,
                        Err(e) => Err(e)
                    }
                }
            }
        }
        else {
            if arg.reference {
                quote! {
                    match _pyo3::RefFromPyObject::with_extracted(
                        _iter.next().unwrap().as_ref().unwrap(), |#arg_name| {
                            #body
                        })
                    {
                        Ok(v) => v,
                        Err(e) => Err(e)
                    }
                }
            } else {
                quote! {
                    match _iter.next().unwrap().as_ref().unwrap().extract()
                    {
                        Ok(#arg_name) => {
                            #body
                        }
                        Err(e) => Err(e)
                    }
                }
            }
        }
    }
}

pub fn impl_py_method_def(name: &syn::Ident, doc: syn::Lit, spec: &FnSpec, wrapper: &Tokens)
                          -> Tokens
{
    if spec.args.is_empty() {
        quote! {
            _pyo3::class::PyMethodDefType::Method({
                #wrapper

                _pyo3::class::PyMethodDef {
                    ml_name: stringify!(#name),
                    ml_meth: _pyo3::class::PyMethodType::PyNoArgsFunction(__wrap),
                    ml_flags: _pyo3::ffi::METH_NOARGS,
                    ml_doc: #doc,
                }
            })
        }
    } else {
        quote! {
            _pyo3::class::PyMethodDefType::Method({
                #wrapper

                _pyo3::class::PyMethodDef {
                    ml_name: stringify!(#name),
                    ml_meth: _pyo3::class::PyMethodType::PyCFunctionWithKeywords(__wrap),
                    ml_flags: _pyo3::ffi::METH_VARARGS | _pyo3::ffi::METH_KEYWORDS,
                    ml_doc: #doc,
                }
            })
        }
    }
}

pub fn impl_py_method_def_new(name: &syn::Ident, doc: syn::Lit, wrapper: &Tokens) -> Tokens
{
    quote! {
        _pyo3::class::PyMethodDefType::New({
            #wrapper

            _pyo3::class::PyMethodDef {
                ml_name: stringify!(#name),
                ml_meth: _pyo3::class::PyMethodType::PyNewFunc(__wrap),
                ml_flags: _pyo3::ffi::METH_VARARGS | _pyo3::ffi::METH_KEYWORDS,
                ml_doc: #doc,
            }
        })
    }
}

pub fn impl_py_method_def_class(name: &syn::Ident, doc: syn::Lit, wrapper: &Tokens) -> Tokens
{
    quote! {
        _pyo3::class::PyMethodDefType::Class({
            #wrapper

            _pyo3::class::PyMethodDef {
                ml_name: stringify!(#name),
                ml_meth: _pyo3::class::PyMethodType::PyCFunctionWithKeywords(__wrap),
                ml_flags: _pyo3::ffi::METH_VARARGS | _pyo3::ffi::METH_KEYWORDS |
                _pyo3::ffi::METH_CLASS,
                ml_doc: #doc,
            }
        })
    }
}

pub fn impl_py_method_def_static(name: &syn::Ident, doc: syn::Lit, wrapper: &Tokens) -> Tokens
{
    quote! {
        _pyo3::class::PyMethodDefType::Static({
            #wrapper

            _pyo3::class::PyMethodDef {
                ml_name: stringify!(#name),
                ml_meth: _pyo3::class::PyMethodType::PyCFunctionWithKeywords(__wrap),
                ml_flags: _pyo3::ffi::METH_VARARGS | _pyo3::ffi::METH_KEYWORDS | _pyo3::ffi::METH_STATIC,
                ml_doc: #doc,
            }
        })
    }
}

pub fn impl_py_method_def_call(name: &syn::Ident, doc: syn::Lit, wrapper: &Tokens) -> Tokens
{
    quote! {
        _pyo3::class::PyMethodDefType::Call({
            #wrapper

            _pyo3::class::PyMethodDef {
                ml_name: stringify!(#name),
                ml_meth: _pyo3::class::PyMethodType::PyCFunctionWithKeywords(__wrap),
                ml_flags: _pyo3::ffi::METH_VARARGS | _pyo3::ffi::METH_KEYWORDS,
                ml_doc: #doc,
            }
        })
    }
}

fn impl_py_setter_def(name: &syn::Ident, doc: syn::Lit, setter: &Option<String>, wrapper: &Tokens)
                      -> Tokens
{
    let n = if let &Some(ref name) = setter {
        name.to_string()
    } else {
        let n = String::from(name.as_ref());
        if n.starts_with("set_") {
            n[4..].to_string()
        } else {
            n
        }
    };

    quote! {
        _pyo3::class::PyMethodDefType::Setter({
            #wrapper

            _pyo3::class::PySetterDef {
                name: #n,
                meth: __wrap,
                doc: #doc,
            }
        })
    }
}

fn impl_py_getter_def(name: &syn::Ident, doc: syn::Lit, getter: &Option<String>, wrapper: &Tokens)
                      -> Tokens
{
    let n = if let &Some(ref name) = getter {
        name.to_string()
    } else {
        let n = String::from(name.as_ref());
        if n.starts_with("get_") {
            n[4..].to_string()
        } else {
            n
        }
    };

    quote! {
        _pyo3::class::PyMethodDefType::Getter({
            #wrapper

            _pyo3::class::PyGetterDef {
                name: #n,
                meth: __wrap,
                doc: #doc,
            }
        })
    }
}