#include "cache.h"
#include "exec_cmd.h"
#include "quote.h"
#define MAX_ARGS        32

extern char **environ;
static const char *argv_exec_path;
static const char *argv0_path;

const char *system_path(const char *path)
{
#ifdef RUNTIME_PREFIX
        static const char *prefix;
#else
        static const char *prefix = PREFIX;
#endif
        struct strbuf d = STRBUF_INIT;

        if (is_absolute_path(path))
                return path;

#ifdef RUNTIME_PREFIX
        assert(argv0_path);
        assert(is_absolute_path(argv0_path));

        if (!prefix) {
                const char *strip[] = {
                        GIT_EXEC_PATH,
                        BINDIR,
                        0
                };
                const char **s;

                for (s = strip; *s; s++) {
                        const char *sargv = argv0_path + strlen(argv0_path);
                        const char *ss = *s + strlen(*s);
                        while (argv0_path < sargv && *s < ss
                                && (*sargv == *ss ||
                                    (is_dir_sep(*sargv) && is_dir_sep(*ss)))) {
                                sargv--;
                                ss--;
                        }
                        if (*s == ss) {
                                struct strbuf d = STRBUF_INIT;
                                /* We also skip the trailing directory separator. */
                                assert(sargv - argv0_path - 1 >= 0);
                                strbuf_add(&d, argv0_path, sargv - argv0_path - 1);
                                prefix = strbuf_detach(&d, NULL);
                                break;
                        }
                }
        }

        if (!prefix) {
                prefix = PREFIX;
                fprintf(stderr, "RUNTIME_PREFIX requested, "
                                "but prefix computation failed.  "
                                "Using static fallback '%s'.\n", prefix);
        }
#endif

        strbuf_addf(&d, "%s/%s", prefix, path);
        path = strbuf_detach(&d, NULL);
        return path;
}

const char *git_extract_argv0_path(const char *argv0)
{
        const char *slash;

        if (!argv0 || !*argv0)
                return NULL;
        slash = argv0 + strlen(argv0);

        while (argv0 <= slash && !is_dir_sep(*slash))
                slash--;

        if (slash >= argv0) {
                argv0_path = xstrndup(argv0, slash - argv0);
                return slash + 1;
        }

        return argv0;
}

void git_set_argv_exec_path(const char *exec_path)
{
        argv_exec_path = exec_path;
}


/* Returns the highest-priority, location to look for git programs. */
const char *git_exec_path(void)
{
        const char *env;

        if (argv_exec_path)
                return argv_exec_path;

        env = getenv(EXEC_PATH_ENVIRONMENT);
        if (env && *env) {
                return env;
        }

        return system_path(GIT_EXEC_PATH);
}

static void add_path(struct strbuf *out, const char *path)
{
        if (path && *path) {
                if (is_absolute_path(path))
                        strbuf_addstr(out, path);
                else
                        strbuf_addstr(out, make_nonrelative_path(path));

                strbuf_addch(out, PATH_SEP);
        }
}

void setup_path(void)
{
        const char *old_path = getenv("PATH");
        struct strbuf new_path = STRBUF_INIT;

        add_path(&new_path, git_exec_path());
        add_path(&new_path, argv0_path);

        if (old_path)
                strbuf_addstr(&new_path, old_path);
        else
                strbuf_addstr(&new_path, "/usr/local/bin:/usr/bin:/bin");

        setenv("PATH", new_path.buf, 1);

        strbuf_release(&new_path);
}

const char **prepare_git_cmd(const char **argv)
{
        int argc;
        const char **nargv;

        for (argc = 0; argv[argc]; argc++)
                ; /* just counting */
        nargv = xmalloc(sizeof(*nargv) * (argc + 2));

        nargv[0] = "git";
        for (argc = 0; argv[argc]; argc++)
                nargv[argc + 1] = argv[argc];
        nargv[argc + 1] = NULL;
        return nargv;
}

int execv_git_cmd(const char **argv) {
        const char **nargv = prepare_git_cmd(argv);
        trace_argv_printf(nargv, "trace: exec:");

        /* execvp() can only ever return if it fails */
        execvp("git", (char **)nargv);

        trace_printf("trace: exec failed: %s\n", strerror(errno));

        free(nargv);
        return -1;
}


int execl_git_cmd(const char *cmd,...)
{
        int argc;
        const char *argv[MAX_ARGS + 1];
        const char *arg;
        va_list param;

        va_start(param, cmd);
        argv[0] = cmd;
        argc = 1;
        while (argc < MAX_ARGS) {
                arg = argv[argc++] = va_arg(param, char *);
                if (!arg)
                        break;
        }
        va_end(param);
        if (MAX_ARGS <= argc)
                return error("too many args to run %s", cmd);

        argv[argc] = NULL;
        return execv_git_cmd(argv);
}