#
#
# add_dir "tests/automate_lua"
# 
# add_file "tests/automate_lua/__driver__.lua"
#  content [c404572e850ce7623fed9ee7013a6ec63e8fe276]
# 
# add_file "tests/automate_lua/test.lua"
#  content [9ac45e93bf665fa4ea5a90828aa6e834c1aee7a8]
# 
# patch "NEWS"
#  from [af85eefcea2e435fcdd6e04a48a4922f877e66cf]
#    to [94f333190db9922d097bcf481a0397914239cce4]
# 
# patch "automate.cc"
#  from [598a04952daffa804d60dde204967b20e17fc37a]
#    to [240c35d1563672b59f932812acc0b6bb4d4775dc]
# 
# patch "lua_hooks.cc"
#  from [0476cf2512e471ca31d9a3b185968487fbeb9e8e]
#    to [2cea55853bda5f175dc82c227ee21947236327e8]
# 
# patch "lua_hooks.hh"
#  from [eb7235af2f81fcce2921725bfd150df2ba3bfc65]
#    to [a5ac6a6139a2672c9e8d16bb97162ac849179dda]
# 
# patch "monotone.texi"
#  from [9b7b4b168714e8b980e72d95eba542ecc7234fcd]
#    to [794aeeeb1450859129acc05515a60a2dd32c793f]
# 
# patch "std_hooks.lua"
#  from [c4f02c95a5717f64d0a60251081ff5bd1a8038de]
#    to [6fa95c0269b7e1b615bf5d2dad24e32948e48350]
#
============================================================
--- tests/automate_lua/__driver__.lua	c404572e850ce7623fed9ee7013a6ec63e8fe276
+++ tests/automate_lua/__driver__.lua	c404572e850ce7623fed9ee7013a6ec63e8fe276
@@ -0,0 +1,76 @@
+
+mtn_setup()
+check(get("test.lua"))
+
+function equalRecursive(left, right)
+    if (type(left) ~= type(right)) then
+        L("type mismatch: ", type(left), " vs ", type(right), "\n")
+        return false
+    end
+
+    if (type(left) == "table") then
+        for k,v in ipairs(left) do
+            -- a not existing key is a key with its value set to nil
+            if (right[k] == nil) then
+                L("key ", k, " does not exist in right", "\n")
+                return false
+            end
+            if (not equalRecursive(left[k], right[k])) then
+                return false
+            end
+        end
+        return true
+    end
+
+    return left == right
+end
+
+function echo(retval, err, ...)
+    local args = {n=select('#', ...), ... }
+    check(mtn("automate", "lua", "--rcfile=test.lua", "echo", unpack(args, 1, args.n)), retval, true, true)
+    if (retval == 0) then
+        -- actually we're doing something here which the std_hook does itself
+        -- as well - might not be a good test...?
+        for i=1,args.n do
+            args[i] = assert(loadstring("return " .. args[i]))()
+        end
+        args.n = nil
+        canonicalize("stdout")
+        local out = readfile("stdout")
+        local echoed = assert(loadstring("return { "..out.."}"))();
+        check(equalRecursive(args, echoed))
+    else
+        canonicalize("stderr")
+        check(grep(err, "stderr"), 0, false, false)
+    end
+end
+
+-- testing simple types
+echo(0, nil, 'nil')
+echo(0, nil, '3')
+echo(0, nil, '3.4')
+echo(0, nil, 'true')
+echo(0, nil, 'false')
+-- different quoting style
+echo(0, nil, "'foo'")
+echo(0, nil, '"foo"')
+
+-- testing tables and nesting
+echo(0, nil, "{1,2,3}")
+echo(0, nil, "{true,false,{1,2,{'foo','bar'}}}")
+echo(0, nil, "{[true] = false; ['foo'] = 'bar'; 3 }")
+
+-- multiple arguments
+echo(0, nil, 'nil', '3', '3.4', "'foo'", '"foo"', 'true', 'false', "{1,2,3}")
+
+-- this is an unknown variable name which gets evaluated to nil
+echo(1, "was evaluated to nil", "unknown")
+
+-- this is an invalid argument (missing bracket)
+echo(1, "could not be evaluated", "{1,2,3")
+
+-- and finally, call a function which does not exist at all
+check(mtn("automate", "lua", "foo"), 1, false, true)
+canonicalize("stderr")
+check(grep("lua function 'foo' does not exist", "stderr"), 0, false, false)
+
============================================================
--- tests/automate_lua/test.lua	9ac45e93bf665fa4ea5a90828aa6e834c1aee7a8
+++ tests/automate_lua/test.lua	9ac45e93bf665fa4ea5a90828aa6e834c1aee7a8
@@ -0,0 +1,5 @@
+-- this very simply lua function just returns all input parameters it
+-- receives in the right order and without any modification
+function echo(...)
+    return ...
+end
============================================================
--- NEWS	af85eefcea2e435fcdd6e04a48a4922f877e66cf
+++ NEWS	94f333190db9922d097bcf481a0397914239cce4
@@ -34,6 +34,11 @@
         - New command group 'mtn conflicts *'; provides asynchronous
           conflict resolutions for merge and propagate.
 
+	- New 'automate lua' command with which lua functions, like
+          monotone hooks, can be called over automate. This is particularily
+	  useful to get user defaults, like ignorable files, branch keys and
+          passwords, which are managed through one or more monotonerc files.
+	  
         - 'merge' and 'propagate' accept user commit messages; the
           'merge rev rev' or 'propagate branch branch' message will be
           prefixed to the user message. --no-prefix removes the prefix.
============================================================
--- automate.cc	598a04952daffa804d60dde204967b20e17fc37a
+++ automate.cc	240c35d1563672b59f932812acc0b6bb4d4775dc
@@ -2276,6 +2276,51 @@ CMD_AUTOMATE(get_workspace_root, "",
   output << get_current_working_dir() << '\n';
 }
 
+// Name: lua
+// Arguments:
+//   A lua function name
+//   Zero or more function arguments
+// Changes:
+//   9.0 (added)
+// Purpose:
+//   Execute lua functions and return their results.
+// Output format:
+//   Lua parsable output.
+// Error conditions:
+//   a runtime exception is thrown if the function does not exists, the arguments cannot be parsed
+//   or the function cannot be executed for some other reason.
+
+CMD_AUTOMATE(lua, "LUA_FUNCTION [ARG1 [ARG2 [...]]]",
+             N_("Executes the given lua function and returns the result"),
+             "",
+             options::opts::none)
+{
+    N(args.size() >= 1,
+      F("wrong argument count"));
+
+    std::string func = idx(args, 0)();
+
+    N(app.lua.hook_exists(func),
+      F("lua function '%s' does not exist") % func);
+
+    std::vector<std::string> func_args;
+    if (args.size() > 1)
+      {
+        for (unsigned int i=1; i<args.size(); i++)
+        {
+          func_args.push_back(idx(args, i)());
+        }
+      }
+
+    std::string out;
+    N(app.lua.hook_hook_wrapper(func, func_args, out),
+      F("lua call '%s' failed") % func);
+
+    // the output already contains a trailing newline, so we don't add
+    // another one here
+    output << out;
+}
+
 // Local Variables:
 // mode: C++
 // fill-column: 76
============================================================
--- lua_hooks.cc	0476cf2512e471ca31d9a3b185968487fbeb9e8e
+++ lua_hooks.cc	2cea55853bda5f175dc82c227ee21947236327e8
@@ -594,6 +594,25 @@ lua_hooks::hook_get_default_command_opti
   return ll.ok() && !args.empty();
 }
 
+bool lua_hooks::hook_hook_wrapper(std::string const & func_name,
+                                  std::vector<std::string> const & args,
+                                  std::string & out)
+{
+  Lua ll(st);
+  ll.func("hook_wrapper")
+    .push_str(func_name);
+
+  for (std::vector<std::string>::const_iterator i = args.begin();
+        i != args.end(); ++i)
+    {
+      ll.push_str(*i);
+    }
+
+  ll.call(args.size() + 1, 1);
+  ll.extract_str_nolog(out);
+  return ll.ok();
+}
+
 bool
 lua_hooks::hook_use_inodeprints()
 {
============================================================
--- lua_hooks.hh	eb7235af2f81fcce2921725bfd150df2ba3bfc65
+++ lua_hooks.hh	a5ac6a6139a2672c9e8d16bb97162ac849179dda
@@ -138,6 +138,11 @@ public:
                                     bool & validated,
                                     std::string & reason);
 
+  // meta hooks
+  bool hook_hook_wrapper(std::string const & func_name,
+                         std::vector<std::string> const & args,
+                         std::string & out);
+
   // notification hooks
   bool hook_note_commit(revision_id const & new_id,
                         revision_data const & rdat,
============================================================
--- monotone.texi	9b7b4b168714e8b980e72d95eba542ecc7234fcd
+++ monotone.texi	794aeeeb1450859129acc05515a60a2dd32c793f
@@ -8045,7 +8045,7 @@ @section Automation
 
 @item Updated in:
 
-8.1
+9.0
 
 Added @option{--with-header} option.
 
@@ -9139,7 +9139,7 @@ @section Automation
 
 @item Added in:
 
-8.1
+9.0
 
 @item Purpose:
 
@@ -9156,6 +9156,79 @@ @section Automation
 
 @end table
 
address@hidden mtn automate lua @var{function_name} address@hidden
+
address@hidden @strong
address@hidden Arguments:
+
+A valid Lua function name and zero or more function arguments. Note that string
+arguments need to be wrapped in another pair of quotes, i.e. @code{"foo"} or
address@hidden'foo'} will not work, but @code{"'foo'"} or @code{'"foo"'} will.
+
+Complex types are also supported, anything which can be evaluated as valid
+Lua expression can be given as input, including nested tables and functions,
+like f.e. @address@hidden,true,@{['func'] = function(...) return ... end @address@hidden
+
address@hidden Added in:
+
+9.0
+
address@hidden Purpose:
+
+Call Lua functions, like monotone hooks, in the monotone context, f.e. to
+retrieve user defaults like keys, passwords, ignorable files and more.
+
address@hidden Output format:
+
+A string dump of the return value of the function, in Lua code. The Lua types
address@hidden, @code{thread}, @code{userdata} and @code{lightuserdata} are not
+serialized, but set to @code{nil} in the dump.
+
+Please note that @code{nil} values in tables are not printed since Lua does not
+distinguish between unset and not existing entries in a table like other
+programming languages do.
+
address@hidden Sample output:
+
+A single string return value:
+
address@hidden
+[1] = "Output";
address@hidden verbatim
+
+Two numeric return values:
+
address@hidden
+[1] = 3;
+[2] = 4.4;
address@hidden verbatim
+
+A nested table:
+
address@hidden
+[1] = {
+    ["bar"] = {
+        [1] = 1;
+        [2] = 2;
+        [3] = 3;
+    };
+};
address@hidden verbatim
+
+A callback function:
+
address@hidden
+[1] = nil --[[function]];
address@hidden verbatim
+
address@hidden Error conditions:
+
+This command prints an error message and exists with status 1 if the function
+does not exist, one or more function arguments could not be evaluated or the
+function could not be called for another reason.
+
address@hidden table
+
 @end ftable
 
 @page
@@ -10186,6 +10259,21 @@ @subsection Validation Hooks
 
 @end ftable
 
address@hidden Meta Hooks
+
+Monotone allows the execution of arbitrary Lua hooks and functions through a
+special generalized "meta hook". See @command{automate lua} for more information.
+
address@hidden @code
address@hidden hook_wrapper (@var{func_name}, @var{...})
+
+This hook is explicitely called on every execution of @command{automate lua}.
+It takes a function name and zero or more string function arguments which are
+internally evaluated into Lua code. It returns a dump of the return value of
+the called function in Lua code on success.
+
address@hidden ftable
+
 @page
 @node   Additional Lua Functions,  , Hooks, Hook Reference
 @section Additional Lua Functions
============================================================
--- std_hooks.lua	c4f02c95a5717f64d0a60251081ff5bd1a8038de
+++ std_hooks.lua	6fa95c0269b7e1b615bf5d2dad24e32948e48350
@@ -1157,7 +1157,54 @@ end
    return default_args
 end
 
+hook_wrapper_dump                = {}
+hook_wrapper_dump.depth          = 0
+hook_wrapper_dump._string        = function(s) return string.format("%q", s) end
+hook_wrapper_dump._number        = function(n) return tostring(n) end
+hook_wrapper_dump._boolean       = function(b) if (b) then return "true" end return "false" end
+hook_wrapper_dump._userdata      = function(u) return "nil --[[userdata]]" end
+-- if we really need to return / serialize functions we could do it
+-- like address@hidden did here: http://lua-users.org/wiki/TablePersistence
+hook_wrapper_dump._function      = function(f) return "nil --[[function]]" end
+hook_wrapper_dump._nil           = function(n) return "nil" end
+hook_wrapper_dump._thread        = function(t) return "nil --[[thread]]" end
+hook_wrapper_dump._lightuserdata = function(l) return "nil --[[lightuserdata]]" end
 
+hook_wrapper_dump._table = function(t)
+    local buf = ''
+    if (hook_wrapper_dump.depth > 0) then
+        buf = buf .. '{\n'
+    end
+    hook_wrapper_dump.depth = hook_wrapper_dump.depth + 1;
+    for k,v in pairs(t) do
+        buf = buf..string.format('%s[%s] = %s;\n',
+              string.rep("\t", hook_wrapper_dump.depth - 1),
+              hook_wrapper_dump["_" .. type(k)](k),
+              hook_wrapper_dump["_" .. type(v)](v))
+    end
+    hook_wrapper_dump.depth = hook_wrapper_dump.depth - 1;
+    if (hook_wrapper_dump.depth > 0) then
+        buf = buf .. string.rep("\t", hook_wrapper_dump.depth - 1) .. '}'
+    end
+    return buf
+end
+
+function hook_wrapper(func_name, ...)
+    -- we have to ensure that nil arguments are restored properly for the
+    -- function call, see http://lua-users.org/wiki/StoringNilsInTables
+    local args = { n=select('#', ...), ... }
+    for i=1,args.n do
+        local val = assert(loadstring("return " .. args[i]),
+                         "argument "..args[i].." could not be evaluated")()
+        assert(val ~= nil or args[i] == "nil",
+               "argument "..args[i].." was evaluated to nil")
+        args[i] = val
+    end
+    local res = { _G[func_name](unpack(args, 1, args.n)) }
+    return hook_wrapper_dump._table(res)
+end
+
+
 function get_remote_unix_socket_command(host)
     return "socat"
 end