/*
 * Check-out files from the "current cache directory"
 *
 * Copyright (C) 2005 Linus Torvalds
 *
 * Careful: order of argument flags does matter. For example,
 *
 *      checkout-cache -a -f file.c
 *
 * Will first check out all files listed in the cache (but not
 * overwrite any old ones), and then force-checkout "file.c" a
 * second time (ie that one _will_ overwrite any old contents
 * with the same filename).
 *
 * Also, just doing "checkout-cache" does nothing. You probably
 * meant "checkout-cache -a". And if you want to force it, you
 * want "checkout-cache -f -a".
 *
 * Intuitiveness is not the goal here. Repeatability is. The
 * reason for the "no arguments means no work" thing is that
 * from scripts you are supposed to be able to do things like
 *
 *      find . -name '*.h' -print0 | xargs -0 checkout-cache -f --
 *
 * which will force all existing *.h files to be replaced with
 * their cached copies. If an empty command line implied "all",
 * then this would force-refresh everything in the cache, which
 * was not the point.
 *
 * Oh, and the "--" is just a good idea when you know the rest
 * will be filenames. Just so that you wouldn't have a filename
 * of "-a" causing problems (not possible in the above example,
 * but get used to it in scripting!).
 */
#include <sys/types.h>
#include <dirent.h>
#include "cache.h"

static int force = 0, quiet = 0, not_new = 0;

static void create_directories(const char *path)
{
        int len = strlen(path);
        char *buf = xmalloc(len + 1);
        const char *slash = path;

        while ((slash = strchr(slash+1, '/')) != NULL) {
                len = slash - path;
                memcpy(buf, path, len);
                buf[len] = 0;
                if (mkdir(buf, 0755)) {
                        if (errno == EEXIST) {
                                struct stat st;
                                if (!lstat(buf, &st) && S_ISDIR(st.st_mode))
                                        continue; /* ok */
                                if (force && !unlink(buf) && !mkdir(buf, 0755))
                                        continue;
                        }
                        die("cannot create directory at %s", buf);
                }
        }
        free(buf);
}

static void remove_subtree(const char *path)
{
        DIR *dir = opendir(path);
        struct dirent *de;
        char pathbuf[PATH_MAX];
        char *name;
        
        if (!dir)
                die("cannot opendir %s", path);
        strcpy(pathbuf, path);
        name = pathbuf + strlen(path);
        *name++ = '/';
        while ((de = readdir(dir)) != NULL) {
                struct stat st;
                if ((de->d_name[0] == '.') &&
                    ((de->d_name[1] == 0) ||
                     ((de->d_name[1] == '.') && de->d_name[2] == 0)))
                        continue;
                strcpy(name, de->d_name);
                if (lstat(pathbuf, &st))
                        die("cannot lstat %s", pathbuf);
                if (S_ISDIR(st.st_mode))
                        remove_subtree(pathbuf);
                else if (unlink(pathbuf))
                        die("cannot unlink %s", pathbuf);
        }
        closedir(dir);
        if (rmdir(path))
                die("cannot rmdir %s", path);
}

static int create_file(const char *path, unsigned int mode)
{
        int fd;

        mode = (mode & 0100) ? 0777 : 0666;
        create_directories(path);
        fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
        if (fd < 0) {
                if (errno == EISDIR && force) {
                        remove_subtree(path);
                        fd = open(path, O_WRONLY | O_TRUNC | O_CREAT, mode);
                }
        }
        return fd;
}

static int write_entry(struct cache_entry *ce, const char *path)
{
        int fd;
        void *new;
        unsigned long size;
        long wrote;
        char type[20];
        char target[1024];

        new = read_sha1_file(ce->sha1, type, &size);
        if (!new || strcmp(type, "blob")) {
                if (new)
                        free(new);
                return error("checkout-cache: unable to read sha1 file of %s (%s)",
                        path, sha1_to_hex(ce->sha1));
        }
        switch (ntohl(ce->ce_mode) & S_IFMT) {
        case S_IFREG:
                fd = create_file(path, ntohl(ce->ce_mode));
                if (fd < 0) {
                        free(new);
                        return error("checkout-cache: unable to create file %s (%s)",
                                path, strerror(errno));
                }
                wrote = write(fd, new, size);
                close(fd);
                free(new);
                if (wrote != size)
                        return error("checkout-cache: unable to write file %s", path);
                break;
        case S_IFLNK:
                memcpy(target, new, size);
                target[size] = '\0';
                create_directories(path);
                if (symlink(target, path)) {
                        free(new);
                        return error("checkout-cache: unable to create symlink %s (%s)",
                                path, strerror(errno));
                }
                free(new);
                break;
        default:
                free(new);
                return error("checkout-cache: unknown file mode for %s", path);
        }
        return 0;
}

static int checkout_entry(struct cache_entry *ce, const char *base_dir)
{
        struct stat st;
        static char path[MAXPATHLEN+1];
        int len = strlen(base_dir);

        memcpy(path, base_dir, len);
        strcpy(path + len, ce->name);

        if (!lstat(path, &st)) {
                unsigned changed = cache_match_stat(ce, &st);
                if (!changed)
                        return 0;
                if (!force) {
                        if (!quiet)
                                fprintf(stderr, "checkout-cache: %s already exists\n", path);
                        return 0;
                }

                /*
                 * We unlink the old file, to get the new one with the
                 * right permissions (including umask, which is nasty
                 * to emulate by hand - much easier to let the system
                 * just do the right thing)
                 */
                unlink(path);
        } else if (not_new) 
                return 0;
        return write_entry(ce, path);
}

static int checkout_file(const char *name, const char *base_dir)
{
        int pos = cache_name_pos(name, strlen(name));
        if (pos < 0) {
                if (!quiet) {
                        pos = -pos - 1;
                        fprintf(stderr,
                                "checkout-cache: %s is %s.\n",
                                name,
                                (pos < active_nr &&
                                 !strcmp(active_cache[pos]->name, name)) ?
                                "unmerged" : "not in the cache");
                }
                return -1;
        }
        return checkout_entry(active_cache[pos], base_dir);
}

static int checkout_all(const char *base_dir)
{
        int i;

        for (i = 0; i < active_nr ; i++) {
                struct cache_entry *ce = active_cache[i];
                if (ce_stage(ce))
                        continue;
                if (checkout_entry(ce, base_dir) < 0)
                        return -1;
        }
        return 0;
}

int main(int argc, char **argv)
{
        int i, force_filename = 0;
        const char *base_dir = "";

        if (read_cache() < 0) {
                die("invalid cache");
        }

        for (i = 1; i < argc; i++) {
                const char *arg = argv[i];
                if (!force_filename) {
                        if (!strcmp(arg, "-a")) {
                                checkout_all(base_dir);
                                continue;
                        }
                        if (!strcmp(arg, "--")) {
                                force_filename = 1;
                                continue;
                        }
                        if (!strcmp(arg, "-f")) {
                                force = 1;
                                continue;
                        }
                        if (!strcmp(arg, "-q")) {
                                quiet = 1;
                                continue;
                        }
                        if (!strcmp(arg, "-n")) {
                                not_new = 1;
                                continue;
                        }
                        if (!memcmp(arg, "--prefix=", 9)) {
                                base_dir = arg+9;
                                continue;
                        }
                }
                checkout_file(arg, base_dir);
        }
        return 0;
}