#include "cache.h"
#include "dir.h"

static int inside_git_dir = -1;
static int inside_work_tree = -1;

const char *prefix_path(const char *prefix, int len, const char *path)
{
        const char *orig = path;
        for (;;) {
                char c;
                if (*path != '.')
                        break;
                c = path[1];
                /* "." */
                if (!c) {
                        path++;
                        break;
                }
                /* "./" */
                if (c == '/') {
                        path += 2;
                        continue;
                }
                if (c != '.')
                        break;
                c = path[2];
                if (!c)
                        path += 2;
                else if (c == '/')
                        path += 3;
                else
                        break;
                /* ".." and "../" */
                /* Remove last component of the prefix */
                do {
                        if (!len)
                                die("'%s' is outside repository", orig);
                        len--;
                } while (len && prefix[len-1] != '/');
                continue;
        }
        if (len) {
                int speclen = strlen(path);
                char *n = xmalloc(speclen + len + 1);

                memcpy(n, prefix, len);
                memcpy(n + len, path, speclen+1);
                path = n;
        }
        return path;
}

/*
 * Unlike prefix_path, this should be used if the named file does
 * not have to interact with index entry; i.e. name of a random file
 * on the filesystem.
 */
const char *prefix_filename(const char *pfx, int pfx_len, const char *arg)
{
        static char path[PATH_MAX];
        if (!pfx || !*pfx || arg[0] == '/')
                return arg;
        memcpy(path, pfx, pfx_len);
        strcpy(path + pfx_len, arg);
        return path;
}

/*
 * Verify a filename that we got as an argument for a pathspec
 * entry. Note that a filename that begins with "-" never verifies
 * as true, because even if such a filename were to exist, we want
 * it to be preceded by the "--" marker (or we want the user to
 * use a format like "./-filename")
 */
void verify_filename(const char *prefix, const char *arg)
{
        const char *name;
        struct stat st;

        if (*arg == '-')
                die("bad flag '%s' used after filename", arg);
        name = prefix ? prefix_filename(prefix, strlen(prefix), arg) : arg;
        if (!lstat(name, &st))
                return;
        if (errno == ENOENT)
                die("ambiguous argument '%s': unknown revision or path not in the working tree.\n"
                    "Use '--' to separate paths from revisions", arg);
        die("'%s': %s", arg, strerror(errno));
}

/*
 * Opposite of the above: the command line did not have -- marker
 * and we parsed the arg as a refname.  It should not be interpretable
 * as a filename.
 */
void verify_non_filename(const char *prefix, const char *arg)
{
        const char *name;
        struct stat st;

        if (!is_inside_work_tree() || is_inside_git_dir())
                return;
        if (*arg == '-')
                return; /* flag */
        name = prefix ? prefix_filename(prefix, strlen(prefix), arg) : arg;
        if (!lstat(name, &st))
                die("ambiguous argument '%s': both revision and filename\n"
                    "Use '--' to separate filenames from revisions", arg);
        if (errno != ENOENT && errno != ENOTDIR)
                die("'%s': %s", arg, strerror(errno));
}

const char **get_pathspec(const char *prefix, const char **pathspec)
{
        const char *entry = *pathspec;
        const char **p;
        int prefixlen;

        if (!prefix && !entry)
                return NULL;

        if (!entry) {
                static const char *spec[2];
                spec[0] = prefix;
                spec[1] = NULL;
                return spec;
        }

        /* Otherwise we have to re-write the entries.. */
        p = pathspec;
        prefixlen = prefix ? strlen(prefix) : 0;
        do {
                *p = prefix_path(prefix, prefixlen, entry);
        } while ((entry = *++p) != NULL);
        return (const char **) pathspec;
}

/*
 * Test if it looks like we're at a git directory.
 * We want to see:
 *
 *  - either a objects/ directory _or_ the proper
 *    GIT_OBJECT_DIRECTORY environment variable
 *  - a refs/ directory
 *  - either a HEAD symlink or a HEAD file that is formatted as
 *    a proper "ref:", or a regular file HEAD that has a properly
 *    formatted sha1 object name.
 */
static int is_git_directory(const char *suspect)
{
        char path[PATH_MAX];
        size_t len = strlen(suspect);

        strcpy(path, suspect);
        if (getenv(DB_ENVIRONMENT)) {
                if (access(getenv(DB_ENVIRONMENT), X_OK))
                        return 0;
        }
        else {
                strcpy(path + len, "/objects");
                if (access(path, X_OK))
                        return 0;
        }

        strcpy(path + len, "/refs");
        if (access(path, X_OK))
                return 0;

        strcpy(path + len, "/HEAD");
        if (validate_headref(path))
                return 0;

        return 1;
}

int is_inside_git_dir(void)
{
        if (inside_git_dir < 0)
                inside_git_dir = is_inside_dir(get_git_dir());
        return inside_git_dir;
}

int is_inside_work_tree(void)
{
        if (inside_work_tree < 0)
                inside_work_tree = is_inside_dir(get_git_work_tree());
        return inside_work_tree;
}

/*
 * set_work_tree() is only ever called if you set GIT_DIR explicitely.
 * The old behaviour (which we retain here) is to set the work tree root
 * to the cwd, unless overridden by the config, the command line, or
 * GIT_WORK_TREE.
 */
static const char *set_work_tree(const char *dir)
{
        char buffer[PATH_MAX + 1];

        if (!getcwd(buffer, sizeof(buffer)))
                die ("Could not get the current working directory");
        git_work_tree_cfg = xstrdup(buffer);
        inside_work_tree = 1;

        return NULL;
}

/*
 * We cannot decide in this function whether we are in the work tree or
 * not, since the config can only be read _after_ this function was called.
 */
const char *setup_git_directory_gently(int *nongit_ok)
{
        const char *work_tree_env = getenv(GIT_WORK_TREE_ENVIRONMENT);
        static char cwd[PATH_MAX+1];
        const char *gitdirenv;
        int len, offset;

        /*
         * If GIT_DIR is set explicitly, we're not going
         * to do any discovery, but we still do repository
         * validation.
         */
        gitdirenv = getenv(GIT_DIR_ENVIRONMENT);
        if (gitdirenv) {
                if (PATH_MAX - 40 < strlen(gitdirenv))
                        die("'$%s' too big", GIT_DIR_ENVIRONMENT);
                if (is_git_directory(gitdirenv)) {
                        static char buffer[1024 + 1];
                        const char *retval;

                        if (!work_tree_env)
                                return set_work_tree(gitdirenv);
                        retval = get_relative_cwd(buffer, sizeof(buffer) - 1,
                                        get_git_work_tree());
                        if (!retval || !*retval)
                                return NULL;
                        set_git_dir(make_absolute_path(gitdirenv));
                        if (chdir(work_tree_env) < 0)
                                die ("Could not chdir to %s", work_tree_env);
                        strcat(buffer, "/");
                        return retval;
                }
                if (nongit_ok) {
                        *nongit_ok = 1;
                        return NULL;
                }
                die("Not a git repository: '%s'", gitdirenv);
        }

        if (!getcwd(cwd, sizeof(cwd)-1))
                die("Unable to read current working directory");

        /*
         * Test in the following order (relative to the cwd):
         * - .git/
         * - ./ (bare)
         * - ../.git/
         * - ../ (bare)
         * - ../../.git/
         *   etc.
         */
        offset = len = strlen(cwd);
        for (;;) {
                if (is_git_directory(DEFAULT_GIT_DIR_ENVIRONMENT))
                        break;
                if (is_git_directory(".")) {
                        inside_git_dir = 1;
                        if (!work_tree_env)
                                inside_work_tree = 0;
                        setenv(GIT_DIR_ENVIRONMENT, ".", 1);
                        return NULL;
                }
                chdir("..");
                do {
                        if (!offset) {
                                if (nongit_ok) {
                                        if (chdir(cwd))
                                                die("Cannot come back to cwd");
                                        *nongit_ok = 1;
                                        return NULL;
                                }
                                die("Not a git repository");
                        }
                } while (cwd[--offset] != '/');
        }

        inside_git_dir = 0;
        if (!work_tree_env)
                inside_work_tree = 1;
        git_work_tree_cfg = xstrndup(cwd, offset);
        if (offset == len)
                return NULL;

        /* Make "offset" point to past the '/', and add a '/' at the end */
        offset++;
        cwd[len++] = '/';
        cwd[len] = 0;
        return cwd + offset;
}

int git_config_perm(const char *var, const char *value)
{
        if (value) {
                int i;
                if (!strcmp(value, "umask"))
                        return PERM_UMASK;
                if (!strcmp(value, "group"))
                        return PERM_GROUP;
                if (!strcmp(value, "all") ||
                    !strcmp(value, "world") ||
                    !strcmp(value, "everybody"))
                        return PERM_EVERYBODY;
                i = atoi(value);
                if (i > 1)
                        return i;
        }
        return git_config_bool(var, value);
}

int check_repository_format_version(const char *var, const char *value)
{
        if (strcmp(var, "core.repositoryformatversion") == 0)
                repository_format_version = git_config_int(var, value);
        else if (strcmp(var, "core.sharedrepository") == 0)
                shared_repository = git_config_perm(var, value);
        else if (strcmp(var, "core.bare") == 0) {
                is_bare_repository_cfg = git_config_bool(var, value);
                if (is_bare_repository_cfg == 1)
                        inside_work_tree = -1;
        } else if (strcmp(var, "core.worktree") == 0) {
                if (git_work_tree_cfg)
                        free(git_work_tree_cfg);
                git_work_tree_cfg = xstrdup(value);
                inside_work_tree = -1;
        }
        return 0;
}

int check_repository_format(void)
{
        git_config(check_repository_format_version);
        if (GIT_REPO_VERSION < repository_format_version)
                die ("Expected git repo version <= %d, found %d",
                     GIT_REPO_VERSION, repository_format_version);
        return 0;
}

const char *setup_git_directory(void)
{
        const char *retval = setup_git_directory_gently(NULL);
        check_repository_format();

        /* If the work tree is not the default one, recompute prefix */
        if (inside_work_tree < 0) {
                static char buffer[PATH_MAX + 1];
                char *rel;
                if (retval && chdir(retval))
                        die ("Could not jump back into original cwd");
                rel = get_relative_cwd(buffer, PATH_MAX, get_git_work_tree());
                return rel && *rel ? strcat(rel, "/") : NULL;
        }

        return retval;
}