#include "cache.h"
#include "blob.h"
#include "dir.h"
#include "streaming.h"
#include "submodule.h"

static void create_directories(const char *path, int path_len,
                               const struct checkout *state)
{
        char *buf = xmallocz(path_len);
        int len = 0;

        while (len < path_len) {
                do {
                        buf[len] = path[len];
                        len++;
                } while (len < path_len && path[len] != '/');
                if (len >= path_len)
                        break;
                buf[len] = 0;

                /*
                 * For 'checkout-index --prefix=<dir>', <dir> is
                 * allowed to be a symlink to an existing directory,
                 * and we set 'state->base_dir_len' below, such that
                 * we test the path components of the prefix with the
                 * stat() function instead of the lstat() function.
                 */
                if (has_dirs_only_path(buf, len, state->base_dir_len))
                        continue; /* ok, it is already a directory. */

                /*
                 * If this mkdir() would fail, it could be that there
                 * is already a symlink or something else exists
                 * there, therefore we then try to unlink it and try
                 * one more time to create the directory.
                 */
                if (mkdir(buf, 0777)) {
                        if (errno == EEXIST && state->force &&
                            !unlink_or_warn(buf) && !mkdir(buf, 0777))
                                continue;
                        die_errno("cannot create directory at '%s'", buf);
                }
        }
        free(buf);
}

static void remove_subtree(struct strbuf *path)
{
        DIR *dir = opendir(path->buf);
        struct dirent *de;
        int origlen = path->len;

        if (!dir)
                die_errno("cannot opendir '%s'", path->buf);
        while ((de = readdir(dir)) != NULL) {
                struct stat st;

                if (is_dot_or_dotdot(de->d_name))
                        continue;

                strbuf_addch(path, '/');
                strbuf_addstr(path, de->d_name);
                if (lstat(path->buf, &st))
                        die_errno("cannot lstat '%s'", path->buf);
                if (S_ISDIR(st.st_mode))
                        remove_subtree(path);
                else if (unlink(path->buf))
                        die_errno("cannot unlink '%s'", path->buf);
                strbuf_setlen(path, origlen);
        }
        closedir(dir);
        if (rmdir(path->buf))
                die_errno("cannot rmdir '%s'", path->buf);
}

static int create_file(const char *path, unsigned int mode)
{
        mode = (mode & 0100) ? 0777 : 0666;
        return open(path, O_WRONLY | O_CREAT | O_EXCL, mode);
}

static void *read_blob_entry(const struct cache_entry *ce, unsigned long *size)
{
        enum object_type type;
        void *new = read_sha1_file(ce->oid.hash, &type, size);

        if (new) {
                if (type == OBJ_BLOB)
                        return new;
                free(new);
        }
        return NULL;
}

static int open_output_fd(char *path, const struct cache_entry *ce, int to_tempfile)
{
        int symlink = (ce->ce_mode & S_IFMT) != S_IFREG;
        if (to_tempfile) {
                xsnprintf(path, TEMPORARY_FILENAME_LENGTH, "%s",
                          symlink ? ".merge_link_XXXXXX" : ".merge_file_XXXXXX");
                return mkstemp(path);
        } else {
                return create_file(path, !symlink ? ce->ce_mode : 0666);
        }
}

static int fstat_output(int fd, const struct checkout *state, struct stat *st)
{
        /* use fstat() only when path == ce->name */
        if (fstat_is_reliable() &&
            state->refresh_cache && !state->base_dir_len) {
                fstat(fd, st);
                return 1;
        }
        return 0;
}

static int streaming_write_entry(const struct cache_entry *ce, char *path,
                                 struct stream_filter *filter,
                                 const struct checkout *state, int to_tempfile,
                                 int *fstat_done, struct stat *statbuf)
{
        int result = 0;
        int fd;

        fd = open_output_fd(path, ce, to_tempfile);
        if (fd < 0)
                return -1;

        result |= stream_blob_to_fd(fd, &ce->oid, filter, 1);
        *fstat_done = fstat_output(fd, state, statbuf);
        result |= close(fd);

        if (result)
                unlink(path);
        return result;
}

static int write_entry(struct cache_entry *ce,
                       char *path, const struct checkout *state, int to_tempfile)
{
        unsigned int ce_mode_s_ifmt = ce->ce_mode & S_IFMT;
        int fd, ret, fstat_done = 0;
        char *new;
        struct strbuf buf = STRBUF_INIT;
        unsigned long size;
        size_t wrote, newsize = 0;
        struct stat st;
        const struct submodule *sub;

        if (ce_mode_s_ifmt == S_IFREG) {
                struct stream_filter *filter = get_stream_filter(ce->name,
                                                                 ce->oid.hash);
                if (filter &&
                    !streaming_write_entry(ce, path, filter,
                                           state, to_tempfile,
                                           &fstat_done, &st))
                        goto finish;
        }

        switch (ce_mode_s_ifmt) {
        case S_IFREG:
        case S_IFLNK:
                new = read_blob_entry(ce, &size);
                if (!new)
                        return error("unable to read sha1 file of %s (%s)",
                                path, oid_to_hex(&ce->oid));

                if (ce_mode_s_ifmt == S_IFLNK && has_symlinks && !to_tempfile) {
                        ret = symlink(new, path);
                        free(new);
                        if (ret)
                                return error_errno("unable to create symlink %s",
                                                   path);
                        break;
                }

                /*
                 * Convert from git internal format to working tree format
                 */
                if (ce_mode_s_ifmt == S_IFREG &&
                    convert_to_working_tree(ce->name, new, size, &buf)) {
                        free(new);
                        new = strbuf_detach(&buf, &newsize);
                        size = newsize;
                }

                fd = open_output_fd(path, ce, to_tempfile);
                if (fd < 0) {
                        free(new);
                        return error_errno("unable to create file %s", path);
                }

                wrote = write_in_full(fd, new, size);
                if (!to_tempfile)
                        fstat_done = fstat_output(fd, state, &st);
                close(fd);
                free(new);
                if (wrote != size)
                        return error("unable to write file %s", path);
                break;
        case S_IFGITLINK:
                if (to_tempfile)
                        return error("cannot create temporary submodule %s", path);
                if (mkdir(path, 0777) < 0)
                        return error("cannot create submodule directory %s", path);
                sub = submodule_from_ce(ce);
                if (sub)
                        return submodule_move_head(ce->name,
                                NULL, oid_to_hex(&ce->oid), SUBMODULE_MOVE_HEAD_FORCE);
                break;
        default:
                return error("unknown file mode for %s in index", path);
        }

finish:
        if (state->refresh_cache) {
                assert(state->istate);
                if (!fstat_done)
                        lstat(ce->name, &st);
                fill_stat_cache_info(ce, &st);
                ce->ce_flags |= CE_UPDATE_IN_BASE;
                state->istate->cache_changed |= CE_ENTRY_CHANGED;
        }
        return 0;
}

/*
 * This is like 'lstat()', except it refuses to follow symlinks
 * in the path, after skipping "skiplen".
 */
static int check_path(const char *path, int len, struct stat *st, int skiplen)
{
        const char *slash = path + len;

        while (path < slash && *slash != '/')
                slash--;
        if (!has_dirs_only_path(path, slash - path, skiplen)) {
                errno = ENOENT;
                return -1;
        }
        return lstat(path, st);
}

/*
 * Write the contents from ce out to the working tree.
 *
 * When topath[] is not NULL, instead of writing to the working tree
 * file named by ce, a temporary file is created by this function and
 * its name is returned in topath[], which must be able to hold at
 * least TEMPORARY_FILENAME_LENGTH bytes long.
 */
int checkout_entry(struct cache_entry *ce,
                   const struct checkout *state, char *topath)
{
        static struct strbuf path = STRBUF_INIT;
        struct stat st;

        if (topath)
                return write_entry(ce, topath, state, 1);

        strbuf_reset(&path);
        strbuf_add(&path, state->base_dir, state->base_dir_len);
        strbuf_add(&path, ce->name, ce_namelen(ce));

        if (!check_path(path.buf, path.len, &st, state->base_dir_len)) {
                const struct submodule *sub;
                unsigned changed = ce_match_stat(ce, &st, CE_MATCH_IGNORE_VALID|CE_MATCH_IGNORE_SKIP_WORKTREE);
                /*
                 * Needs to be checked before !changed returns early,
                 * as the possibly empty directory was not changed
                 */
                sub = submodule_from_ce(ce);
                if (sub) {
                        int err;
                        if (!is_submodule_populated_gently(ce->name, &err)) {
                                struct stat sb;
                                if (lstat(ce->name, &sb))
                                        die(_("could not stat file '%s'"), ce->name);
                                if (!(st.st_mode & S_IFDIR))
                                        unlink_or_warn(ce->name);

                                return submodule_move_head(ce->name,
                                        NULL, oid_to_hex(&ce->oid),
                                        SUBMODULE_MOVE_HEAD_FORCE);
                        } else
                                return submodule_move_head(ce->name,
                                        "HEAD", oid_to_hex(&ce->oid),
                                        SUBMODULE_MOVE_HEAD_FORCE);
                }

                if (!changed)
                        return 0;
                if (!state->force) {
                        if (!state->quiet)
                                fprintf(stderr,
                                        "%s already exists, no checkout\n",
                                        path.buf);
                        return -1;
                }

                /*
                 * 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)
                 */
                if (S_ISDIR(st.st_mode)) {
                        /* If it is a gitlink, leave it alone! */
                        if (S_ISGITLINK(ce->ce_mode))
                                return 0;
                        if (!state->force)
                                return error("%s is a directory", path.buf);
                        remove_subtree(&path);
                } else if (unlink(path.buf))
                        return error_errno("unable to unlink old '%s'", path.buf);
        } else if (state->not_new)
                return 0;

        create_directories(path.buf, path.len, state);
        return write_entry(ce, path.buf, state, 0);
}