Add initial Lua scripting support

This is preliminary. There are still tons of issues, and any aspect
of scripting may change in the future. I decided to merge this
(preliminary) work now because it makes it easier to develop it, not
because it's done. lua.rst is clear enough about it (plus some
sarcasm).

This requires linking to Lua. Lua has no official pkg-config file, but
there are distribution specific .pc files, all with different names.
Adding a non-pkg-config based configure test was considered, but we'd
rather not.

One major complication is that libquvi links against Lua too, and if
the Lua version is different from mpv's, you will get a crash as soon
as libquvi uses Lua. (libquvi by design always runs when a file is
opened.) I would consider this the problem of distros and whoever
builds mpv, but to make things easier for users, we add a terrible
runtime test to the configure script, which probes whether libquvi
will crash. This is disabled when cross-compiling, but in that case
we hope the user knows what he is doing.

.gitignore

@@ -18,6 +18,7 @@
 /demux/ebml_defs.c
 /demux/ebml_types.h
 /sub/osd_font.h
+/mpvcore/lua/*.inc
 /DOCS/man/*/mpv.1
 /DOCS/man/*/mpv.aux
 /DOCS/man/*/mpv.log

DOCS/man/en/lua.rst

@@ -0,0 +1,18 @@
+LUA SCRIPTING
+=============
+
+mpv can load Lua scripts. These scripts can be used to control mpv in a similar
+way to slave mode. mpv provides the builtin module ``mp`` (can be loaded
+with ``require 'mpv'``), which provides functions to send commands to the
+mpv core and to retrieve information about playback state, user settings,
+file information, and so on.
+
+.. admonition:: Warning
+
+    Lua scripting is work in progress, and it's in a very early stage. When
+    writing scripts, rely only on the features and functions documented here.
+    Everything else is subject to change.
+
+.. admonition:: Warning
+
+    Nothing is finished and documented yet.

DOCS/man/en/mpv.rst

@@ -441,6 +441,8 @@ OPTIONS
 
 .. include:: input.rst
 
+.. include:: lua.rst
+
 .. include:: changes.rst
 
 ENVIRONMENT VARIABLES

DOCS/man/en/options.rst

@@ -1258,6 +1258,10 @@
     looping. If several files are specified on command line, the entire playlist
     is looped.
 
+``--lua=<filename>``
+    Load a Lua script. You can load multiple scripts by separating them with
+    commas (``,``).
+
 ``--mc=<seconds/frame>``
     Maximum A-V sync correction per frame (in seconds)
 

Makefile

@@ -123,6 +123,8 @@ SOURCES-$(WAYLAND)              += video/out/vo_wayland.c video/out/wayland_comm
 SOURCES-$(VF_LAVFI)             += video/filter/vf_lavfi.c
 SOURCES-$(AF_LAVFI)             += audio/filter/af_lavfi.c
 
+SOURCES-$(LUA)                  += mpvcore/mp_lua.c
+
 ifeq ($(HAVE_AVUTIL_REFCOUNTING),no)
     SOURCES-yes                 += video/decode/lavc_dr1.c
 endif
@@ -397,6 +399,14 @@ sub/osd_libass.c: sub/osd_font.h
 sub/osd_font.h: TOOLS/file2string.pl sub/osd_font.otf
 	./$^ >$@
 
+mpvcore/mp_lua.c: mpvcore/lua/defaults.inc
+mpvcore/lua/defaults.inc: TOOLS/file2string.pl mpvcore/lua/defaults.lua
+	./$^ >$@
+
+mpvcore/mp_lua.c: mpvcore/lua/assdraw.inc
+mpvcore/lua/assdraw.inc: TOOLS/file2string.pl mpvcore/lua/assdraw.lua
+	./$^ >$@
+
 # ./configure must be rerun if it changed
 config.mak: configure
 	@echo "############################################################"
@@ -495,6 +505,8 @@ clean:
 	-$(RM) video/out/gl_video_shaders.h
 	-$(RM) video/out/x11_icon.inc
 	-$(RM) sub/osd_font.h
+	-$(RM) mpvcore/lua/defaults.inc
+	-$(RM) mpvcore/lua/assdraw.inc
 
 distclean: clean
 	-$(RM) config.log config.mak config.h TAGS tags

configure

@@ -293,6 +293,9 @@ Installation directories:
 
 Optional features:
   --disable-encoding     disable encoding functionality [enable]
+  --disable-lua          disable Lua scripting support [autodetect]
+  --lua=LUA              select Lua package which should be autodetected
+                         Choices: 51 51deb 52 52deb luajit
   --disable-libguess     disable libguess [autodetect]
   --enable-terminfo      use terminfo database for key codes [autodetect]
   --enable-termcap       use termcap database for key codes [autodetect]
@@ -485,6 +488,7 @@ _pthreads=auto
 _ass=auto
 _libass_osd=auto
 _rpath=no
+lua=auto
 libpostproc=auto
 libavfilter=auto
 vf_lavfi=auto
@@ -679,6 +683,9 @@ for ac_option do
   --disable-libavresample) _disable_avresample=yes ;;
   --enable-libavresample) _disable_avresample=no   ;;
 
+  --enable-lua)         lua=yes         ;;
+  --disable-lua)        lua=no          ;;
+  --lua=*)              lua_pkg=$(echo $ac_option | cut -d '=' -f 2) ;;
   --enable-lirc)        _lirc=yes       ;;
   --disable-lirc)       _lirc=no        ;;
   --enable-lircc)       _lircc=yes      ;;
@@ -2982,6 +2989,111 @@ fi
 echores "$_pvr"
 
 
+# Note: Lua has no official .pc file, so there are different OS-specific ones.
+# Also, we support luajit, which is compatible to 5.1.
+# The situation is further complicated by distros supporting multiple Lua
+# versions, without ensuring libraries linking to conflicting Lua libs don't
+# cause issues. This is a real problem with libquvi.
+
+cat > $TMPC << EOF
+#include <stdlib.h>
+#include <lua.h>
+#include <lualib.h>
+#include <lauxlib.h>
+EOF
+# abuse $TMPH file as second temp file
+cat > $TMPH << EOF
+void test_lua(void) {
+    lua_State *L = luaL_newstate();
+    lua_pushstring(L, "test");
+    lua_setglobal(L, "test");
+}
+void test_other(void) {
+EOF
+
+# test all other Lua using packages (hack that gives us time)
+if test "$_libquvi4" = yes ; then
+
+echo "#include <quvi/quvi.h>" >> $TMPC
+cat >> $TMPH << EOF
+    quvi_t q;
+    if (quvi_init(&q) == QUVI_OK)
+        quvi_supported(q, "http://nope");
+EOF
+
+fi
+
+if test "$_libquvi9" = yes ; then
+
+echo "#include <quvi.h>" >> $TMPC
+cat >> $TMPH << EOF
+    quvi_t q = quvi_new();
+    if (quvi_ok(q))
+        quvi_supports(q, "http://nope", QUVI_SUPPORTS_MODE_OFFLINE, QUVI_SUPPORTS_TYPE_MEDIA);
+EOF
+
+fi
+
+cat >> $TMPH << EOF
+}
+int main(void) {
+    test_lua();
+    test_other();
+    return 0;
+}
+EOF
+
+cat $TMPH >> $TMPC
+
+test_lua() {
+    # changed by pkg_config_add
+    old_extra_cflags="$extra_cflags"
+    old_libs_mplayer="$libs_mplayer"
+    echocheck "Lua $2 ($1)"
+    if test "$lua" = yes ; then
+        echores "no"
+        return 1
+    fi
+    if test "x$lua_pkg" != "x" && test "$lua_pkg" != "$1" ; then
+        echores "no"
+        return 1
+    fi
+    if pkg_config_add "$2" ; then
+        if test $_cross_compile = no ; then
+            if cc_check && tmp_run ; then
+                echo > /dev/null # idiot NOP
+            else
+                extra_cflags="$old_extra_cflags"
+                libs_mplayer="$old_libs_mplayer"
+                echores "no - does not run"
+                return 1
+            fi
+        fi
+        lua=yes
+    fi
+    echores "$lua"
+    test "$lua" = yes
+    return $?
+}
+
+if test "$lua" = auto ; then
+
+lua=no
+test_lua 51 "lua >= 5.1.0 lua < 5.2.0"
+test_lua 51deb "lua5.1 >= 5.1.0" # debian
+test_lua luajit "luajit >= 2.0.0"
+# assume all our dependencies (libquvi in particular) link with 5.1
+test_lua 52 "lua >= 5.2.0"
+test_lua 52deb "lua5.2 >= 5.2.0" # debian
+
+fi
+
+if test "$lua" = yes ; then
+    def_lua='#define CONFIG_LUA 1'
+else
+    def_lua='#undef CONFIG_LUA'
+fi
+
 echocheck "encoding"
 if test "$_encoding" = yes ; then
     def_encoding="#define CONFIG_ENCODING 1"
@@ -3155,6 +3267,7 @@ DUMMY_OSD = $_dummy_osd
 LIBBLURAY = $_bluray
 LIBBS2B = $_libbs2b
 LCMS2 = $_lcms2
+LUA = $lua
 LIBPOSTPROC = $libpostproc
 LIBAVDEVICE = $libavdevice
 LIBAVFILTER = $libavfilter
@@ -3341,6 +3454,7 @@ $def_libquvi9
 $def_libguess
 
 $def_lcms2
+$def_lua
 
 
 /* libvo options */

mpvcore/command.c

@@ -68,6 +68,8 @@
 
 #include "mpvcore/mp_core.h"
 
+#include "mp_lua.h"
+
 static int edit_filters(struct MPContext *mpctx, enum stream_type mediatype,
                         const char *cmd, const char *arg);
 static int set_filters(struct MPContext *mpctx, enum stream_type mediatype,
@@ -1913,6 +1915,11 @@ static const m_option_t mp_properties[] = {
     {0},
 };
 
+const struct m_option *mp_get_property_list(void)
+{
+    return mp_properties;
+}
+
 int mp_property_do(const char *name, int action, void *val,
                    struct MPContext *ctx)
 {
@@ -2729,6 +2736,15 @@ void run_command(MPContext *mpctx, mp_cmd_t *cmd)
                          cmd->args[1].v.s, msg_osd);
         break;
 
+    case MP_CMD_SCRIPT_DISPATCH:
+        if (mpctx->lua_ctx) {
+#ifdef CONFIG_LUA
+            mp_lua_script_dispatch(mpctx, cmd->args[0].v.s, cmd->args[1].v.i,
+                            cmd->key_up_follows ? "keyup_follows" : "press");
+#endif
+        }
+        break;
+
     case MP_CMD_COMMAND_LIST: {
         for (struct mp_cmd *sub = cmd->args[0].v.p; sub; sub = sub->queue_next)
             run_command(mpctx, sub);
@@ -2755,3 +2771,59 @@ void run_command(MPContext *mpctx, mp_cmd_t *cmd)
         break;
     }
 }
+
+struct command_ctx {
+    int events;
+};
+
+void command_init(struct MPContext *mpctx)
+{
+    mpctx->command_ctx = talloc_zero(mpctx, struct command_ctx);
+}
+
+// Notify that a property might have changed.
+void mp_notify_property(struct MPContext *mpctx, const char *property)
+{
+    mp_notify(mpctx, MP_EVENT_PROPERTY, (void *)property);
+}
+
+void mp_notify(struct MPContext *mpctx, enum mp_event event, void *arg)
+{
+    struct command_ctx *ctx = mpctx->command_ctx;
+    ctx->events |= 1u << event;
+}
+
+static void handle_script_event(struct MPContext *mpctx, const char *name,
+                                const char *arg)
+{
+#ifdef CONFIG_LUA
+    mp_lua_event(mpctx, name, arg);
+#endif
+}
+
+void mp_flush_events(struct MPContext *mpctx)
+{
+    struct command_ctx *ctx = mpctx->command_ctx;
+
+    ctx->events |= (1u << MP_EVENT_TICK);
+
+    for (int n = 0; n < 16; n++) {
+        enum mp_event event = n;
+        unsigned mask = 1 << event;
+        if (ctx->events & mask) {
+            // The event handler could set event flags again; in this case let
+            // the next mp_flush_events() call handle it to avoid infinite loops.
+            ctx->events &= ~mask;
+            const char *name = NULL;
+            switch (event) {
+            case MP_EVENT_TICK:             name = "tick"; break;
+            case MP_EVENT_TRACKS_CHANGED:   name = "track-layout"; break;
+            case MP_EVENT_START_FILE:       name = "start"; break;
+            case MP_EVENT_END_FILE:         name = "end"; break;
+            default: ;
+            }
+            if (name)
+                handle_script_event(mpctx, name, "");
+        }
+    }
+}

mpvcore/command.h

@@ -22,6 +22,8 @@
 struct MPContext;
 struct mp_cmd;
 
+void command_init(struct MPContext *mpctx);
+
 void mp_get_osd_mouse_pos(struct MPContext *mpctx, float *x, float *y);
 
 void run_command(struct MPContext *mpctx, struct mp_cmd *cmd);
@@ -30,4 +32,20 @@ void property_print_help(void);
 int mp_property_do(const char* name, int action, void* val,
                    struct MPContext *mpctx);
 
+const struct m_option *mp_get_property_list(void);
+
+enum mp_event {
+    MP_EVENT_NONE,
+    MP_EVENT_TICK,
+    MP_EVENT_PROPERTY,          // char*, property that is changed
+    MP_EVENT_TRACKS_CHANGED,
+    MP_EVENT_START_FILE,
+    MP_EVENT_END_FILE,
+};
+
+void mp_notify(struct MPContext *mpctx, enum mp_event event, void *arg);
+void mp_notify_property(struct MPContext *mpctx, const char *property);
+
+void mp_flush_events(struct MPContext *mpctx);
+
 #endif /* MPLAYER_COMMAND_H */

mpvcore/input/input.c

@@ -229,6 +229,8 @@ static const mp_cmd_t mp_cmds[] = {
 
   { MP_CMD_VO_CMDLINE, "vo_cmdline", { ARG_STRING } },
 
+  { MP_CMD_SCRIPT_DISPATCH, "script_dispatch", { ARG_STRING, ARG_INT } },
+
   {0}
 };
 
@@ -528,6 +530,7 @@ struct input_ctx {
     // Autorepeat stuff
     short ar_state;
     int64_t last_ar;
+
     // Autorepeat config
     unsigned int ar_delay;
     unsigned int ar_rate;
@@ -1455,6 +1458,8 @@ static void remove_key_down(struct input_ctx *ictx, int code)
 static bool key_updown_ok(enum mp_command_type cmd)
 {
     switch (cmd) {
+    case MP_CMD_SCRIPT_DISPATCH:
+        return true;
     default:
         return false;
     }

mpvcore/input/input.h

@@ -85,6 +85,9 @@ enum mp_command_type {
     /// Video output commands
     MP_CMD_VO_CMDLINE,
 
+    /// Internal for Lua scripts
+    MP_CMD_SCRIPT_DISPATCH,
+
     // Internal
     MP_CMD_COMMAND_LIST, // list of sub-commands in args[0].v.p
 };