#include "PTYMultiplexer.h"
#include "MasterPTY.h"
#include <Kernel/Process.h>
#include <LibC/errno_numbers.h>

static const unsigned s_max_pty_pairs = 8;
static PTYMultiplexer* s_the;

PTYMultiplexer& PTYMultiplexer::the()
{
    ASSERT(s_the);
    return *s_the;
}

PTYMultiplexer::PTYMultiplexer()
    : CharacterDevice(5, 2)
    , m_lock("PTYMultiplexer")
{
    s_the = this;
    m_freelist.ensure_capacity(s_max_pty_pairs);
    for (int i = s_max_pty_pairs; i > 0; --i)
        m_freelist.unchecked_append(i - 1);
}

PTYMultiplexer::~PTYMultiplexer()
{
}

RetainPtr<FileDescriptor> PTYMultiplexer::open(int& error, int options)
{
    LOCKER(m_lock);
    if (m_freelist.is_empty()) {
        error = -EBUSY;
        return nullptr;
    }
    auto master_index = m_freelist.take_last();
    auto master = adopt(*new MasterPTY(master_index));
    dbgprintf("PTYMultiplexer::open: Vending master %u\n", master->index());
    return VFS::the().open(move(master), error, options);
}

void PTYMultiplexer::notify_master_destroyed(Badge<MasterPTY>, unsigned index)
{
    LOCKER(m_lock);
    m_freelist.append(index);
    dbgprintf("PTYMultiplexer: %u added to freelist\n", index);
}