// Copyright 2013-2017, The Gtk-rs Project Developers.
// See the COPYRIGHT file at the top-level directory of this distribution.
// Licensed under the MIT license, see the LICENSE file or <http://opensource.org/licenses/MIT>

use gio_sys;
use glib;
use glib::object::IsA;
use glib::translate::*;
use glib_sys;
use gobject_sys;
use std::pin::Pin;
use std::ptr;
use Cancellable;
use File;
use FileCreateFlags;

pub trait FileExtManual: Sized {
    /// Starts an asynchronous replacement of `self` with the given
    /// `contents` of `length` bytes. `etag` will replace the document's
    /// current entity tag.
    ///
    /// When this operation has completed, `callback` will be called with
    /// `user_user` data, and the operation can be finalized with
    /// `File::replace_contents_finish`.
    ///
    /// If `cancellable` is not `None`, then the operation can be cancelled by
    /// triggering the cancellable object from another thread. If the operation
    /// was cancelled, the error `IOErrorEnum::Cancelled` will be returned.
    ///
    /// If `make_backup` is `true`, this function will attempt to
    /// make a backup of `self`.
    ///
    /// Note that no copy of `content` will be made, so it must stay valid
    /// until `callback` is called. See `File::replace_contents_bytes_async`
    /// for a `glib::Bytes` version that will automatically hold a reference to the
    /// contents (without copying) for the duration of the call.
    /// ## `contents`
    /// string of contents to replace the file with
    /// ## `length`
    /// the length of `contents` in bytes
    /// ## `etag`
    /// a new [entity tag][gfile-etag] for the `self`, or `None`
    /// ## `make_backup`
    /// `true` if a backup should be created
    /// ## `flags`
    /// a set of `FileCreateFlags`
    /// ## `cancellable`
    /// optional `Cancellable` object, `None` to ignore
    /// ## `callback`
    /// a `GAsyncReadyCallback` to call when the request is satisfied
    /// ## `user_data`
    /// the data to pass to callback function
    fn replace_contents_async<
        B: AsRef<[u8]> + Send + 'static,
        R: FnOnce(Result<(B, glib::GString), (B, glib::Error)>) + Send + 'static,
        C: IsA<Cancellable>,
    >(
        &self,
        contents: B,
        etag: Option<&str>,
        make_backup: bool,
        flags: FileCreateFlags,
        cancellable: Option<&C>,
        callback: R,
    );

    fn replace_contents_async_future<B: AsRef<[u8]> + Send + 'static>(
        &self,
        contents: B,
        etag: Option<&str>,
        make_backup: bool,
        flags: FileCreateFlags,
    ) -> Pin<
        Box<
            dyn std::future::Future<Output = Result<(B, glib::GString), (B, glib::Error)>>
                + 'static,
        >,
    >;
}

impl<O: IsA<File>> FileExtManual for O {
    fn replace_contents_async<
        B: AsRef<[u8]> + Send + 'static,
        R: FnOnce(Result<(B, glib::GString), (B, glib::Error)>) + Send + 'static,
        C: IsA<Cancellable>,
    >(
        &self,
        contents: B,
        etag: Option<&str>,
        make_backup: bool,
        flags: FileCreateFlags,
        cancellable: Option<&C>,
        callback: R,
    ) {
        let etag = etag.to_glib_none();
        let cancellable = cancellable.map(|c| c.as_ref());
        let gcancellable = cancellable.to_glib_none();
        let user_data: Box<Option<(R, B)>> = Box::new(Some((callback, contents)));
        // Need to do this after boxing as the contents pointer might change by moving into the box
        let (count, contents_ptr) = {
            let contents = &(*user_data).as_ref().unwrap().1;
            let slice = contents.as_ref();
            (slice.len(), slice.as_ptr())
        };
        unsafe extern "C" fn replace_contents_async_trampoline<
            B: AsRef<[u8]> + Send + 'static,
            R: FnOnce(Result<(B, glib::GString), (B, glib::Error)>) + Send + 'static,
        >(
            _source_object: *mut gobject_sys::GObject,
            res: *mut gio_sys::GAsyncResult,
            user_data: glib_sys::gpointer,
        ) {
            let mut user_data: Box<Option<(R, B)>> = Box::from_raw(user_data as *mut _);
            let (callback, contents) = user_data.take().unwrap();

            let mut error = ptr::null_mut();
            let mut new_etag = ptr::null_mut();
            let _ = gio_sys::g_file_replace_contents_finish(
                _source_object as *mut _,
                res,
                &mut new_etag,
                &mut error,
            );
            let result = if error.is_null() {
                Ok((contents, from_glib_full(new_etag)))
            } else {
                Err((contents, from_glib_full(error)))
            };
            callback(result);
        }
        let callback = replace_contents_async_trampoline::<B, R>;
        unsafe {
            gio_sys::g_file_replace_contents_async(
                self.as_ref().to_glib_none().0,
                mut_override(contents_ptr),
                count,
                etag.0,
                make_backup.to_glib(),
                flags.to_glib(),
                gcancellable.0,
                Some(callback),
                Box::into_raw(user_data) as *mut _,
            );
        }
    }

    fn replace_contents_async_future<B: AsRef<[u8]> + Send + 'static>(
        &self,
        contents: B,
        etag: Option<&str>,
        make_backup: bool,
        flags: FileCreateFlags,
    ) -> Pin<
        Box<
            dyn std::future::Future<Output = Result<(B, glib::GString), (B, glib::Error)>>
                + 'static,
        >,
    > {
        let etag = etag.map(glib::GString::from);
        Box::pin(crate::GioFuture::new(self, move |obj, send| {
            let cancellable = Cancellable::new();
            obj.replace_contents_async(
                contents,
                etag.as_ref().map(|s| s.as_str()),
                make_backup,
                flags,
                Some(&cancellable),
                move |res| {
                    send.resolve(res);
                },
            );

            cancellable
        }))
    }
}