// Copyright 2016 Avraham Weinstock
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#[macro_use]
extern crate objc;

use objc::runtime::{Class, Object};
use objc_foundation::{
    INSArray, INSObject, INSString, NSArray, NSDictionary, NSObject, NSString,
};
use objc_id::{Id, Owned};
use std::{error::Error, mem::transmute};

pub struct Clipboard {
    pasteboard: Id<Object>,
}

// required to bring NSPasteboard into the path of the class-resolver
#[link(name = "AppKit", kind = "framework")]
extern "C" {}

impl Clipboard {
    pub fn new() -> Result<Clipboard, Box<dyn Error>> {
        let cls =
            Class::get("NSPasteboard").ok_or("Class::get(\"NSPasteboard\")")?;
        let pasteboard: *mut Object =
            unsafe { msg_send![cls, generalPasteboard] };
        if pasteboard.is_null() {
            return Err("NSPasteboard#generalPasteboard returned null".into());
        }
        let pasteboard: Id<Object> = unsafe { Id::from_ptr(pasteboard) };
        Ok(Clipboard { pasteboard })
    }

    pub fn read(&self) -> Result<String, Box<dyn Error>> {
        let string_class: Id<NSObject> = {
            let cls: Id<Class> = unsafe { Id::from_ptr(class("NSString")) };
            unsafe { transmute(cls) }
        };
        let classes: Id<NSArray<NSObject, Owned>> =
            NSArray::from_vec(vec![string_class]);
        let options: Id<NSDictionary<NSObject, NSObject>> = NSDictionary::new();
        let string_array: Id<NSArray<NSString>> = unsafe {
            let obj: *mut NSArray<NSString> = msg_send![self.pasteboard, readObjectsForClasses:&*classes options:&*options];
            if obj.is_null() {
                return Err(
                    "pasteboard#readObjectsForClasses:options: returned null"
                        .into(),
                );
            }
            Id::from_ptr(obj)
        };
        if string_array.count() == 0 {
            Err("pasteboard#readObjectsForClasses:options: returned empty"
                .into())
        } else {
            Ok(string_array[0].as_str().to_owned())
        }
    }

    pub fn write(&mut self, data: String) -> Result<(), Box<dyn Error>> {
        let string_array = NSArray::from_vec(vec![NSString::from_str(&data)]);
        let _: usize = unsafe { msg_send![self.pasteboard, clearContents] };
        let success: bool =
            unsafe { msg_send![self.pasteboard, writeObjects: string_array] };
        return if success {
            Ok(())
        } else {
            Err("NSPasteboard#writeObjects: returned false".into())
        };
    }
}

// this is a convenience function that both cocoa-rs and
//  glutin define, which seems to depend on the fact that
//  Option::None has the same representation as a null pointer
#[inline]
pub fn class(name: &str) -> *mut Class {
    unsafe { transmute(Class::get(name)) }
}