/*
 * Copyright (c) 2018 Atmosphère-NX
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
#include <switch.h>

#include <algorithm>
#include <functional>
#include <mutex>

#include <stratosphere/waitablemanager.hpp>

void WaitableManager::add_waitable(IWaitable *waitable) {
    std::scoped_lock lk{this->lock};
    this->to_add_waitables.push_back(waitable);
    waitable->set_manager(this);
    this->has_new_items = true;
}

void WaitableManager::process_internal(bool break_on_timeout) {
    std::vector<Handle> handles;
    
    int handle_index = 0;
    Result rc;
    
    while (1) {
        /* Add new items, if relevant. */
        if (this->has_new_items) {
            std::scoped_lock lk{this->lock};
            this->waitables.insert(this->waitables.end(), this->to_add_waitables.begin(), this->to_add_waitables.end());
            this->to_add_waitables.clear();
            this->has_new_items = false;
        }
                
        /* Sort waitables by priority. */
        std::sort(this->waitables.begin(), this->waitables.end(), IWaitable::compare);
        
        /* Copy out handles. */
        handles.resize(this->waitables.size());
        std::transform(this->waitables.begin(), this->waitables.end(), handles.begin(), [](IWaitable *w) { return w->get_handle(); });
        
        
        rc = svcWaitSynchronization(&handle_index, handles.data(), this->waitables.size(), this->timeout);
        if (R_SUCCEEDED(rc)) {
            /* Handle a signaled waitable. */
            /* TODO: What timeout should be passed here? */
                        
            rc = this->waitables[handle_index]->handle_signaled(0);
            
            std::for_each(waitables.begin(), waitables.begin() + handle_index, std::mem_fn(&IWaitable::update_priority));
        } else if (rc == 0xEA01) {
            /* Timeout. */
            std::for_each(waitables.begin(), waitables.end(), std::mem_fn(&IWaitable::update_priority));
            if (break_on_timeout) {
                return;
            }
        } else if (rc != 0xF601) {
            /* TODO: Panic. When can this happen? */
        }
        
        if (rc == 0xF601) {
            /* handles[handle_index] was closed! */
            
            /* Close the handle. */
            svcCloseHandle(handles[handle_index]);
            
            IWaitable  *to_delete = this->waitables[handle_index];
            
            /* If relevant, remove from waitables. */
            this->waitables.erase(this->waitables.begin() + handle_index);
            
            /* Delete it. */
            delete to_delete;
                        
            std::for_each(waitables.begin(), waitables.begin() + handle_index, std::mem_fn(&IWaitable::update_priority));
        }
        
        /* Do deferred callback for each waitable. */
        for (auto & waitable : this->waitables) {
            if (waitable->get_deferred()) {
                waitable->handle_deferred();
            }
        }
    }
}

void WaitableManager::process() {
    WaitableManager::process_internal(false);
}

void WaitableManager::process_until_timeout() {
    WaitableManager::process_internal(true);
}