/*
 * Converts filenames from decomposed unicode into precomposed unicode.
 * Used on MacOS X.
 */

#define PRECOMPOSE_UNICODE_C

#include "cache.h"
#include "utf8.h"
#include "precompose_utf8.h"

typedef char *iconv_ibp;
static const char *repo_encoding = "UTF-8";
static const char *path_encoding = "UTF-8-MAC";

static size_t has_non_ascii(const char *s, size_t maxlen, size_t *strlen_c)
{
        const uint8_t *ptr = (const uint8_t *)s;
        size_t strlen_chars = 0;
        size_t ret = 0;

        if (!ptr || !*ptr)
                return 0;

        while (*ptr && maxlen) {
                if (*ptr & 0x80)
                        ret++;
                strlen_chars++;
                ptr++;
                maxlen--;
        }
        if (strlen_c)
                *strlen_c = strlen_chars;

        return ret;
}


void probe_utf8_pathname_composition(void)
{
        struct strbuf path = STRBUF_INIT;
        static const char *auml_nfc = "\xc3\xa4";
        static const char *auml_nfd = "\x61\xcc\x88";
        int output_fd;
        if (precomposed_unicode != -1)
                return; /* We found it defined in the global config, respect it */
        git_path_buf(&path, "%s", auml_nfc);
        output_fd = open(path.buf, O_CREAT|O_EXCL|O_RDWR, 0600);
        if (output_fd >= 0) {
                close(output_fd);
                git_path_buf(&path, "%s", auml_nfd);
                precomposed_unicode = access(path.buf, R_OK) ? 0 : 1;
                git_config_set("core.precomposeunicode", precomposed_unicode ? "true" : "false");
                git_path_buf(&path, "%s", auml_nfc);
                if (unlink(path.buf))
                        die_errno(_("failed to unlink '%s'"), path.buf);
        }
        strbuf_release(&path);
}


void precompose_argv(int argc, const char **argv)
{
        int i = 0;
        const char *oldarg;
        char *newarg;
        iconv_t ic_precompose;

        if (precomposed_unicode != 1)
                return;

        ic_precompose = iconv_open(repo_encoding, path_encoding);
        if (ic_precompose == (iconv_t) -1)
                return;

        while (i < argc) {
                size_t namelen;
                oldarg = argv[i];
                if (has_non_ascii(oldarg, (size_t)-1, &namelen)) {
                        newarg = reencode_string_iconv(oldarg, namelen, ic_precompose, NULL);
                        if (newarg)
                                argv[i] = newarg;
                }
                i++;
        }
        iconv_close(ic_precompose);
}


PREC_DIR *precompose_utf8_opendir(const char *dirname)
{
        PREC_DIR *prec_dir = xmalloc(sizeof(PREC_DIR));
        prec_dir->dirent_nfc = xmalloc(sizeof(dirent_prec_psx));
        prec_dir->dirent_nfc->max_name_len = sizeof(prec_dir->dirent_nfc->d_name);

        prec_dir->dirp = opendir(dirname);
        if (!prec_dir->dirp) {
                free(prec_dir->dirent_nfc);
                free(prec_dir);
                return NULL;
        } else {
                int ret_errno = errno;
                prec_dir->ic_precompose = iconv_open(repo_encoding, path_encoding);
                /* if iconv_open() fails, die() in readdir() if needed */
                errno = ret_errno;
        }

        return prec_dir;
}

struct dirent_prec_psx *precompose_utf8_readdir(PREC_DIR *prec_dir)
{
        struct dirent *res;
        res = readdir(prec_dir->dirp);
        if (res) {
                size_t namelenz = strlen(res->d_name) + 1; /* \0 */
                size_t new_maxlen = namelenz;

                int ret_errno = errno;

                if (new_maxlen > prec_dir->dirent_nfc->max_name_len) {
                        size_t new_len = sizeof(dirent_prec_psx) + new_maxlen -
                                sizeof(prec_dir->dirent_nfc->d_name);

                        prec_dir->dirent_nfc = xrealloc(prec_dir->dirent_nfc, new_len);
                        prec_dir->dirent_nfc->max_name_len = new_maxlen;
                }

                prec_dir->dirent_nfc->d_ino  = res->d_ino;
                prec_dir->dirent_nfc->d_type = res->d_type;

                if ((precomposed_unicode == 1) && has_non_ascii(res->d_name, (size_t)-1, NULL)) {
                        if (prec_dir->ic_precompose == (iconv_t)-1) {
                                die("iconv_open(%s,%s) failed, but needed:\n"
                                                "    precomposed unicode is not supported.\n"
                                                "    If you want to use decomposed unicode, run\n"
                                                "    \"git config core.precomposeunicode false\"\n",
                                                repo_encoding, path_encoding);
                        } else {
                                iconv_ibp       cp = (iconv_ibp)res->d_name;
                                size_t inleft = namelenz;
                                char *outpos = &prec_dir->dirent_nfc->d_name[0];
                                size_t outsz = prec_dir->dirent_nfc->max_name_len;
                                errno = 0;
                                iconv(prec_dir->ic_precompose, &cp, &inleft, &outpos, &outsz);
                                if (errno || inleft) {
                                        /*
                                         * iconv() failed and errno could be E2BIG, EILSEQ, EINVAL, EBADF
                                         * MacOS X avoids illegal byte sequemces.
                                         * If they occur on a mounted drive (e.g. NFS) it is not worth to
                                         * die() for that, but rather let the user see the original name
                                        */
                                        namelenz = 0; /* trigger strlcpy */
                                }
                        }
                } else
                        namelenz = 0;

                if (!namelenz)
                        strlcpy(prec_dir->dirent_nfc->d_name, res->d_name,
                                                        prec_dir->dirent_nfc->max_name_len);

                errno = ret_errno;
                return prec_dir->dirent_nfc;
        }
        return NULL;
}


int precompose_utf8_closedir(PREC_DIR *prec_dir)
{
        int ret_value;
        int ret_errno;
        ret_value = closedir(prec_dir->dirp);
        ret_errno = errno;
        if (prec_dir->ic_precompose != (iconv_t)-1)
                iconv_close(prec_dir->ic_precompose);
        free(prec_dir->dirent_nfc);
        free(prec_dir);
        errno = ret_errno;
        return ret_value;
}