/*
 * Copyright © Canonical Ltd.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 or 3 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that 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/>.
 */

#ifndef MIR_GRAPHICS_GBM_LINUX_VIRTUAL_TERMINAL_H_
#define MIR_GRAPHICS_GBM_LINUX_VIRTUAL_TERMINAL_H_

#include <mir/console_services.h>

#include <memory>
#include <linux/vt.h>
#include <termios.h>
#include <unistd.h>
#include <future>
#include <vector>

namespace mir
{
class EmergencyCleanupRegistry;

namespace graphics
{
class DisplayReport;
}

class VTFileOperations
{
public:
    virtual ~VTFileOperations() = default;

    virtual int open(char const* pathname, int flags) = 0;
    virtual int close(int fd) = 0;
    virtual int ioctl(int d, unsigned long int request, int val) = 0;
    virtual int ioctl(int d, unsigned long int request, void* p_val) = 0;
    virtual int tcsetattr(int d, int acts, const struct termios *tcattr) = 0;
    virtual int tcgetattr(int d, struct termios *tcattr) = 0;

protected:
    VTFileOperations() = default;
    VTFileOperations(VTFileOperations const&) = delete;
    VTFileOperations& operator=(VTFileOperations const&) = delete;
};

class PosixProcessOperations
{
public:
    virtual ~PosixProcessOperations() = default;

    virtual pid_t getpid() const = 0;
    virtual pid_t getppid() const = 0;
    virtual pid_t getpgid(pid_t process) const = 0;
    virtual pid_t getsid(pid_t process) const = 0;

    virtual int setpgid(pid_t process, pid_t group) = 0;
    virtual pid_t setsid() = 0;

protected:
    PosixProcessOperations() = default;
    PosixProcessOperations(PosixProcessOperations const&) = delete;
    PosixProcessOperations& operator=(PosixProcessOperations const&) = delete;
};

class LinuxVirtualTerminal : public ConsoleServices
{
public:
    LinuxVirtualTerminal(
        std::shared_ptr<VTFileOperations> const& fops,
        std::unique_ptr<PosixProcessOperations> pops,
        int vt_number,
        EmergencyCleanupRegistry& emergency_cleanup,
        std::shared_ptr<graphics::DisplayReport> const& report);
    ~LinuxVirtualTerminal() noexcept(true);

    void register_switch_handlers(
        graphics::EventHandlerRegister& handlers,
        std::function<bool()> const& switch_away,
        std::function<bool()> const& switch_back) override;
    void restore() override;
    std::unique_ptr<VTSwitcher> create_vt_switcher() override;
    std::future<std::unique_ptr<mir::Device>> acquire_device(
        int major, int minor,
        std::unique_ptr<mir::Device::Observer> observer) override;

    class Device;
    class DeviceList;
private:
    std::shared_ptr<DeviceList> const active_devices;

    class FDWrapper
    {
    public:
        FDWrapper(std::shared_ptr<VTFileOperations> const& fops, int fd)
            : fops{fops}, fd_{fd}
        {
        }
        ~FDWrapper() { if (fd_ >= 0) fops->close(fd_); }
        int fd() const { return fd_; }
    private:
        std::shared_ptr<VTFileOperations> const fops;
        int const fd_;
    };

    int find_active_vt_number();
    int open_vt(int vt_number);


    std::shared_ptr<VTFileOperations> const fops;
    std::unique_ptr<PosixProcessOperations> const pops;
    std::shared_ptr<graphics::DisplayReport> const report;
    // prev_active_vt must be declared before vt_fd: open_vt() (called during
    // vt_fd construction) writes to it, so it must already be initialised.
    int prev_active_vt{0};
    FDWrapper const vt_fd;
    int prev_kd_mode;
    struct vt_mode prev_vt_mode;
    int prev_tty_mode;
    struct termios prev_tcattr;
    bool active;
};

}

#endif /* MIR_GRAPHICS_GBM_LINUX_VIRTUAL_TERMINAL_H_ */
