/*
 * Copyright (C) the libgit2 contributors. All rights reserved.
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */
#include "path_w32.h"
#include "utf-conv.h"
#include "path.h"
#include "findfile.h"
#define REG_MSYSGIT_INSTALL_LOCAL L"SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Git_is1"
#ifndef _WIN64
#define REG_MSYSGIT_INSTALL REG_MSYSGIT_INSTALL_LOCAL
#else
#define REG_MSYSGIT_INSTALL L"SOFTWARE\\Wow6432Node\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\Git_is1"
#endif
typedef struct {
        git_win32_path path;
        DWORD len;
} _findfile_path;
static int git_win32__expand_path(_findfile_path *dest, const wchar_t *src)
{
        dest->len = ExpandEnvironmentStringsW(src, dest->path, ARRAY_SIZE(dest->path));
        if (!dest->len || dest->len > ARRAY_SIZE(dest->path))
                return -1;
        return 0;
}
static int win32_path_to_8(git_buf *dest, const wchar_t *src)
{
        git_win32_utf8_path utf8_path;
        if (git_win32_path_to_utf8(utf8_path, src) < 0) {
                giterr_set(GITERR_OS, "Unable to convert path to UTF-8");
                return -1;
        }
        /* Convert backslashes to forward slashes */
        git_path_mkposix(utf8_path);
        return git_buf_sets(dest, utf8_path);
}
static wchar_t* win32_walkpath(wchar_t *path, wchar_t *buf, size_t buflen)
{
        wchar_t term, *base = path;
        assert(path && buf && buflen);
        term = (*path == L'"') ? *path++ : L';';
        for (buflen--; *path && *path != term && buflen; buflen--)
                *buf++ = *path++;
        *buf = L'\0'; /* reserved a byte via initial subtract */
        while (*path == term || *path == L';')
                path++;
        return (path != base) ? path : NULL;
}
static int win32_find_git_in_path(git_buf *buf, const wchar_t *gitexe, const wchar_t *subdir)
{
        wchar_t *env = _wgetenv(L"PATH"), lastch;
        _findfile_path root;
        size_t gitexe_len = wcslen(gitexe);
        if (!env)
                return -1;
        while ((env = win32_walkpath(env, root.path, MAX_PATH-1)) && *root.path) {
                root.len = (DWORD)wcslen(root.path);
                lastch = root.path[root.len - 1];
                /* ensure trailing slash (MAX_PATH-1 to walkpath guarantees space) */
                if (lastch != L'/' && lastch != L'\\') {
                        root.path[root.len++] = L'\\';
                        root.path[root.len]   = L'\0';
                }
                if (root.len + gitexe_len >= MAX_PATH)
                        continue;
                wcscpy(&root.path[root.len], gitexe);
                if (_waccess(root.path, F_OK) == 0 && root.len > 5) {
                        /* replace "bin\\" or "cmd\\" with subdir */
                        wcscpy(&root.path[root.len - 4], subdir);
                        win32_path_to_8(buf, root.path);
                        return 0;
                }
        }
        return GIT_ENOTFOUND;
}
static int win32_find_git_in_registry(
        git_buf *buf, const HKEY hive, const wchar_t *key, const wchar_t *subdir)
{
        HKEY hKey;
        int error = GIT_ENOTFOUND;
        assert(buf);
        if (!RegOpenKeyExW(hive, key, 0, KEY_READ, &hKey)) {
                DWORD dwType, cbData;
                git_win32_path path;
                /* Ensure that the buffer is big enough to have the suffix attached
                 * after we receive the result. */
                cbData = (DWORD)(sizeof(path) - wcslen(subdir) * sizeof(wchar_t));
                /* InstallLocation points to the root of the git directory */
                if (!RegQueryValueExW(hKey, L"InstallLocation", NULL, &dwType, (LPBYTE)path, &cbData) &&
                        dwType == REG_SZ) {
                        /* Append the suffix */
                        wcscat(path, subdir);
                        /* Convert to UTF-8, with forward slashes, and output the path
                         * to the provided buffer */
                        if (!win32_path_to_8(buf, path))
                                error = 0;
                }
                RegCloseKey(hKey);
        }
        return error;
}
static int win32_find_existing_dirs(
        git_buf *out, const wchar_t *tmpl[])
{
        _findfile_path path16;
        git_buf buf = GIT_BUF_INIT;
        git_buf_clear(out);
        for (; *tmpl != NULL; tmpl++) {
                if (!git_win32__expand_path(&path16, *tmpl) &&
                        path16.path[0] != L'%' &&
                        !_waccess(path16.path, F_OK))
                {
                        win32_path_to_8(&buf, path16.path);
                        if (buf.size)
                                git_buf_join(out, GIT_PATH_LIST_SEPARATOR, out->ptr, buf.ptr);
                }
        }
        git_buf_free(&buf);
        return (git_buf_oom(out) ? -1 : 0);
}
int git_win32__find_system_dirs(git_buf *out, const wchar_t *subdir)
{
        git_buf buf = GIT_BUF_INIT;
        /* directories where git.exe & git.cmd are found */
        if (!win32_find_git_in_path(&buf, L"git.exe", subdir) && buf.size)
                git_buf_set(out, buf.ptr, buf.size);
        else
                git_buf_clear(out);
        if (!win32_find_git_in_path(&buf, L"git.cmd", subdir) && buf.size)
                git_buf_join(out, GIT_PATH_LIST_SEPARATOR, out->ptr, buf.ptr);
        /* directories where git is installed according to registry */
        if (!win32_find_git_in_registry(
                        &buf, HKEY_CURRENT_USER, REG_MSYSGIT_INSTALL_LOCAL, subdir) && buf.size)
                git_buf_join(out, GIT_PATH_LIST_SEPARATOR, out->ptr, buf.ptr);
        if (!win32_find_git_in_registry(
                        &buf, HKEY_LOCAL_MACHINE, REG_MSYSGIT_INSTALL, subdir) && buf.size)
                git_buf_join(out, GIT_PATH_LIST_SEPARATOR, out->ptr, buf.ptr);
        git_buf_free(&buf);
        return (git_buf_oom(out) ? -1 : 0);
}
int git_win32__find_global_dirs(git_buf *out)
{
        static const wchar_t *global_tmpls[4] = {
                L"%HOME%\\",
                L"%HOMEDRIVE%%HOMEPATH%\\",
                L"%USERPROFILE%\\",
                NULL,
        };
        return win32_find_existing_dirs(out, global_tmpls);
}
int git_win32__find_xdg_dirs(git_buf *out)
{
        static const wchar_t *global_tmpls[7] = {
                L"%XDG_CONFIG_HOME%\\git",
                L"%APPDATA%\\git",
                L"%LOCALAPPDATA%\\git",
                L"%HOME%\\.config\\git",
                L"%HOMEDRIVE%%HOMEPATH%\\.config\\git",
                L"%USERPROFILE%\\.config\\git",
                NULL,
        };
        return win32_find_existing_dirs(out, global_tmpls);
}
int git_win32__find_programdata_dirs(git_buf *out)
{
        static const wchar_t *programdata_tmpls[2] = {
                L"%PROGRAMDATA%\\Git",
                NULL,
        };
        return win32_find_existing_dirs(out, programdata_tmpls);
}