/*
 *	Hic Est Leo -- Bindings for Lua
 *
 *	(c) 2015 Martin Mares <mj@ucw.cz>
 */

%module leo
%nodefaultctor;

%{
#include "leo.h"
#include "osm.h"
#include "css.h"
#include "expr.h"

#include <lualib.h>
#include <lauxlib.h>
%}

/*** Proxy for OSM object attributes ***/

%{

struct proxy_tag {
  struct osm_object *o;
};

static void push_proxy_tag(lua_State *L, struct proxy_tag *t)
{
  SWIG_NewPointerObj(L, t, SWIGTYPE_p_proxy_tag, 0);
}

static const char *proxy_tag_index(struct proxy_tag *t, const char *key)
{
  osm_key_t k = osm_key_encode(key);
  osm_val_t v = osm_obj_find_tag(t->o, k);
  return osm_val_decode(v);
}

%}

struct proxy_tag { };

%extend proxy_tag {
  const char *index(const char *key);
};

%init %{
  // This overrides default index function generated by SWIG.
  // The tag proxy therefore cannot have any methods.
  SWIG_Lua_get_class_metatable(L, "proxy_tag");
  SWIG_Lua_add_function(L, "__index", _wrap_proxy_tag_index);
  lua_pop(L, 1);
%}

/*** Proxy for style properties ***/

%{

struct proxy_style {
  struct style_results *sr;
  layer_t layer;
};

static void push_proxy_style(lua_State *L, struct proxy_style *s)
{
  SWIG_NewPointerObj(L, s, SWIGTYPE_p_proxy_style, 0);
}

static struct style_prop *proxy_style_index(struct proxy_style *s, const char *key)
{
  prop_t k = style_prop_encode(key);
  return style_get_by_layer(s->sr, s->layer, k);
}

static void proxy_style_newindex(struct proxy_style *s, const char *key, struct style_prop *p)
{
  p->key = style_prop_encode(key);
  style_set_by_layer(s->sr, s->layer, p);
}

static void push_style_prop(lua_State *L, struct style_prop *p)
{
  if (!p)
    {
      lua_pushnil(L);
      return;
    }
  switch (p->type)
    {
    case PROP_TYPE_STRING:
      lua_pushstring(L, osm_val_decode(p->val.id));
      break;
    case PROP_TYPE_NUMBER:
      lua_pushnumber(L, (lua_Number) p->val.number);
      break;
    default:
      msg(L_WARN, "Property %s has value with no LUA representation", style_prop_decode(p->key));
      lua_pushnil(L);
    }
}

static const char *decode_style_prop(lua_State *L, int idx, struct style_prop *p)
{
  if (lua_isnil(L, idx))
    return "Cannot set property to nil. Yet.";	// FIXME

  if (lua_isnumber(L, idx))			// FIXME: numbers vs. strings
    {
      p->type = PROP_TYPE_NUMBER;
      p->val.number = lua_tonumber(L, idx);
      return NULL;
    }

  if (lua_isstring(L, idx))
    {
      p->type = PROP_TYPE_STRING;
      p->val.id = osm_val_encode(lua_tostring(L, idx));
      return NULL;
    }

  return "Invalid type of style property";
}

%}

%typemap(out) struct style_prop * { push_style_prop(L, $1); SWIG_arg++; }

%typemap(in) struct style_prop * (const char *err, struct style_prop prop) {
  err = decode_style_prop(L, $input, &prop);
  if (err)
    {
      lua_pushstring(L, err);
      SWIG_fail;
    }
  $1 = &prop;
}

struct proxy_style { };

%extend proxy_style {
  struct style_prop *index(const char *key);
  void newindex(const char *key, struct style_prop *p);
};

%init %{
  // This overrides default index function generated by SWIG.
  SWIG_Lua_get_class_metatable(L, "proxy_style");
  SWIG_Lua_add_function(L, "__index", _wrap_proxy_style_index);
  SWIG_Lua_add_function(L, "__newindex", _wrap_proxy_style_newindex);
  lua_pop(L, 1);
%}

/*** Compilation and running of expressions ***/

%{

static lua_State *lua;

void expr_init(void)
{
  lua = luaL_newstate();
  lua_State *L = lua;

  luaL_openlibs(L);
  luaopen_leo(L);

  // SWIG init code leaves data in Lua stack. Get rid of it.
  lua_pop(L, lua_gettop(L));

  lua_checkstack(L, 30);

  lua_pushliteral(L, "Leo");
  lua_newtable(L);
  lua_settable(L, LUA_REGISTRYINDEX);
}

#if 0
// Not used at the moment (FIXME)

static char *current_src;

static const char *expr_reader(lua_State *L UNUSED, void *data UNUSED, size_t *sizep)
{
  if (current_src)
    {
      char *res = current_src;
      *sizep = strlen(res);
      current_src = NULL;
      return res;
    }
  else
    {
      *sizep = 0;
      return NULL;
    }
}

#endif

void expr_compile(void *key, char *source)
{
  lua_State *L = lua;

  lua_pushliteral(L, "Leo");			// stack: "Leo"
  lua_gettable(L, LUA_REGISTRYINDEX);		// stack: leo-table
  ASSERT(lua_istable(L, -1));
  lua_pushlightuserdata(L, key);		// stack: leo-table, key

#if 0
  current_src = source;
  int err = lua_load(L, expr_reader, NULL, "@(expr)", NULL);
#else
  int err = luaL_loadbuffer(L, source, strlen(source), "@expression");
#endif
  if (err != LUA_OK)
    css_error(lua_tostring(L, -1));
  // stack: leo-table, key, function

  lua_settable(L, -3);				// stack: leo-table
  lua_pop(L, 1);				// stack: --
}

void expr_execute(void *key, struct style_results *r, layer_t layer)
{
  lua_State *L = lua;

  struct proxy_tag pt = { .o = r->obj };
  push_proxy_tag(L, &pt);			// stack: proxy
  lua_setglobal(L, "t");			// stack: --

  struct proxy_style ps = { .sr = r, .layer = layer };
  push_proxy_style(L, &ps);			// stack: proxy
  lua_setglobal(L, "s");			// stack: --

  lua_pushliteral(L, "Leo");			// stack: "Leo"
  lua_gettable(L, LUA_REGISTRYINDEX);		// stack: leo-table
  ASSERT(lua_istable(L, -1));
  lua_pushlightuserdata(L, key);		// stack: leo-table, key
  lua_gettable(L, -2);				// stack: leo-table, function
  lua_remove(L, -2);				// stack: function
  ASSERT(lua_isfunction(L, -1));

  lua_call(L, 0, 0);				// stack: --
}

%}