#pragma once
///@file

#include "types.hh"
#include "error.hh"

#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>
#include <signal.h>

#include <functional>
#include <map>
#include <optional>

namespace nix {

struct Sink;
struct Source;

class Pid
{
    pid_t pid = -1;
    bool separatePG = false;
    int killSignal = SIGKILL;
public:
    Pid();
    Pid(pid_t pid);
    ~Pid() noexcept(false);
    void operator =(pid_t pid);
    operator pid_t();
    int kill();
    int wait();

    void setSeparatePG(bool separatePG);
    void setKillSignal(int signal);
    pid_t release();
};

/**
 * Kill all processes running under the specified uid by sending them
 * a SIGKILL.
 */
void killUser(uid_t uid);


/**
 * Fork a process that runs the given function, and return the child
 * pid to the caller.
 */
struct ProcessOptions
{
    std::string errorPrefix = "";
    bool dieWithParent = true;
    bool runExitHandlers = false;
    /**
     * use clone() with the specified flags (Linux only)
     */
    int cloneFlags = 0;
};

pid_t startProcess(std::function<void()> fun, const ProcessOptions & options = ProcessOptions());


/**
 * Run a program and return its stdout in a string (i.e., like the
 * shell backtick operator).
 */
std::string runProgram(Path program, bool searchPath = false,
    const Strings & args = Strings(),
    const std::optional<std::string> & input = {}, bool isInteractive = false);

struct RunOptions
{
    Path program;
    bool searchPath = true;
    Strings args;
    std::optional<uid_t> uid;
    std::optional<uid_t> gid;
    std::optional<Path> chdir;
    std::optional<std::map<std::string, std::string>> environment;
    std::optional<std::string> input;
    Source * standardIn = nullptr;
    Sink * standardOut = nullptr;
    bool mergeStderrToStdout = false;
    bool isInteractive = false;
};

std::pair<int, std::string> runProgram(RunOptions && options);

void runProgram2(const RunOptions & options);

class ExecError : public Error
{
public:
    int status;

    template<typename... Args>
    ExecError(int status, const Args & ... args)
        : Error(args...), status(status)
    { }
};

/**
 * Convert the exit status of a child as returned by wait() into an
 * error string.
 */
std::string statusToString(int status);

bool statusOk(int status);

}