/*
    This file is part of the KDE project, module kdesu.
    SPDX-FileCopyrightText: 1999, 2000 Geert Jansen <jansen@kde.org>

    SPDX-License-Identifier: GPL-2.0-only
*/

#ifndef KDESUPTYPROCESS_H
#define KDESUPTYPROCESS_H

#include <memory>
#include <sys/types.h>

#include <QByteArray>
#include <QList>
#include <QString>
#include <QStringList>

#include <kdesu/kdesu_export.h>

#include <KPty>

namespace KDESu
{
class PtyProcessPrivate;

/** \class PtyProcess ptyprocess.h KDESu/PtyProcess
 * Synchronous communication with tty programs.
 *
 * PtyProcess provides synchronous communication with tty based programs.
 * The communications channel used is a pseudo tty (as opposed to a pipe)
 * This means that programs which require a terminal will work.
 */

class KDESU_EXPORT PtyProcess
{
public:
    /** Error return values for checkPidExited() */
    enum checkPidStatus {
        Error = -1, /**< No child */
        NotExited = -2, /**< Child hasn't exited */
        Killed = -3, /**< Child terminated by signal */
    };

    PtyProcess();
    virtual ~PtyProcess();

    /**
     * Forks off and execute a command. The command's standard in and output
     * are connected to the pseudo tty. They are accessible with readLine
     * and writeLine.
     * @param command The command to execute.
     * @param args The arguments to the command.
     * @return 0 on success, -1 on error. errno might give more information then.
     */
    int exec(const QByteArray &command, const QList<QByteArray> &args);

    /**
     * Reads a line from the program's standard out. Depending on the @em block
     * parameter, this call blocks until something was read.
     * Note that in some situations this function will return less than a full
     * line of output, but never more. Newline characters are stripped.
     * @param block Block until a full line is read?
     * @return The output string.
     */
    QByteArray readLine(bool block = true);

    /**
     * Read all available output from the program's standard out.
     * @param block If no output is in the buffer, should the function block
     * (else it will return an empty QByteArray)?
     * @return The output.
     */
    QByteArray readAll(bool block = true);

    /**
     * Writes a line of text to the program's standard in.
     * @param line The text to write.
     * @param addNewline Adds a '\n' to the line.
     */
    void writeLine(const QByteArray &line, bool addNewline = true);

    /**
     * Puts back a line of input.
     * @param line The line to put back.
     * @param addNewline Adds a '\n' to the line.
     */
    void unreadLine(const QByteArray &line, bool addNewline = true);

    /**
     * Sets the exit string. If a line of program output matches this,
     * waitForChild() will terminate the program and return.
     */
    void setExitString(const QByteArray &exit);

    /**
     * Waits for the child to exit. See also setExitString.
     */
    int waitForChild();

    /**
     * Waits until the pty has cleared the ECHO flag. This is useful
     * when programs write a password prompt before they disable ECHO.
     * Disabling it might flush any input that was written.
     */
    int waitSlave();

    /**
     * Enables/disables local echo on the pseudo tty.
     */
    int enableLocalEcho(bool enable = true);

    /**
     * Enables/disables terminal output. Relevant only to some subclasses.
     */
    void setTerminal(bool terminal);

    /**
     * Overwrites the password as soon as it is used. Relevant only to
     * some subclasses.
     */
    void setErase(bool erase);

    /**
     * Set additinal environment variables.
     */
    void setEnvironment(const QList<QByteArray> &env);

    /**
     * Returns the filedescriptor of the process.
     */
    int fd() const;

    /**
     * Returns the pid of the process.
     */
    int pid() const;

    /*
    ** This is a collection of static functions that can be
    ** used for process control inside kdesu. I'd suggest
    ** against using this publicly. There are probably
    ** nicer Qt based ways to do what you want.
    */

    /**
    ** Wait @p ms milliseconds (ie. 1/10th of a second is 100ms),
    ** using @p fd as a filedescriptor to wait on. Returns
    ** select(2)'s result, which is -1 on error, 0 on timeout,
    ** or positive if there is data on one of the selected fd's.
    **
    ** @p ms must be in the range 0..999 (i.e. the maximum wait
    ** duration is 999ms, almost one second).
    */
    static int waitMS(int fd, int ms);

    /**
    ** Basic check for the existence of @p pid.
    ** Returns true iff @p pid is an extant process,
    ** (one you could kill - see man kill(2) for signal 0).
    */
    static bool checkPid(pid_t pid);

    /**
    ** Check process exit status for process @p pid.
    ** If child @p pid has exited, return its exit status,
    ** (which may be zero).
    ** On error (no child, no exit), return -1.
    ** If child @p has not exited, return -2.
    */
    static int checkPidExited(pid_t pid);

protected:
    KDESU_NO_EXPORT explicit PtyProcess(PtyProcessPrivate &dd);

    /** Standard hack to add virtual methods in a BC way. Unused. */
    virtual void virtual_hook(int id, void *data);
    QList<QByteArray> environment() const;

    // KF6 TODO: move to PtyProcessPrivate
    bool m_erase; /**< @see setErase() */
    bool m_terminal; /**< Indicates running in a terminal, causes additional
                           newlines to be printed after output. Set to @c false
                           in constructor. @see setTerminal()  */
    int m_pid; /**< PID of child process */
    QByteArray m_command; /**< Unused */
    QByteArray m_exitString; /**< String to scan for in output that indicates child has exited. */

private:
    KDESU_NO_EXPORT int init();
    KDESU_NO_EXPORT int setupTTY();

protected:
    std::unique_ptr<PtyProcessPrivate> const d_ptr;

private:
    Q_DECLARE_PRIVATE(PtyProcess)
};

}

#endif // KDESUPTYPROCESS_H