From b2065756cf9c90d493846a559587e4acec4a7851 Mon Sep 17 00:00:00 2001
From: upsilon <upsilon@langg.net>
Date: Wed, 18 Apr 2018 18:27:08 +0200
Subject: [PATCH] Add function `minetest.read_schematic`

---
 doc/lua_api.txt                 | 12 +++++
 src/script/lua_api/l_mapgen.cpp | 78 +++++++++++++++++++++++++++++++++
 src/script/lua_api/l_mapgen.h   |  3 ++
 3 files changed, 93 insertions(+)

diff --git a/doc/lua_api.txt b/doc/lua_api.txt
index 6506dc2b2..3d7d3ed3d 100644
--- a/doc/lua_api.txt
+++ b/doc/lua_api.txt
@@ -4844,6 +4844,18 @@ Schematics
           the Lua code generated will use that number of spaces as indentation
           instead of a tab character.
 
+* `minetest.read_schematic(schematic, options)`
+    * Returns a Lua table representing the schematic (see: [Schematic specifier])
+    * `schematic` is the schematic to read (see: [Schematic specifier])
+    * `options` is a table containing the following optional parameters:
+        * `write_yslice_prob`: string value:
+            * `none`: no `write_yslice_prob` table is inserted,
+            * `low`: only probabilities that are not 254 or 255 are written in
+              the `write_ylisce_prob` table,
+            * `all`: write all probabilities to the `write_yslice_prob` table.
+            * The default for this option is `all`.
+            * Any invalid value will be interpreted as `all`.
+
 HTTP Requests
 -------------
 
diff --git a/src/script/lua_api/l_mapgen.cpp b/src/script/lua_api/l_mapgen.cpp
index e7e002c16..2e0cba8dd 100644
--- a/src/script/lua_api/l_mapgen.cpp
+++ b/src/script/lua_api/l_mapgen.cpp
@@ -1754,6 +1754,83 @@ int ModApiMapgen::l_serialize_schematic(lua_State *L)
 	return 1;
 }
 
+// read_schematic(schematic, options={...})
+int ModApiMapgen::l_read_schematic(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+
+	SchematicManager *schemmgr = getServer(L)->getEmergeManager()->schemmgr;
+
+	//// Read options
+	std::string write_yslice = getstringfield_default(L, 2, "write_yslice_prob", "all");
+
+	//// Get schematic
+	bool was_loaded = false;
+	Schematic *schem = (Schematic *)get_objdef(L, 1, schemmgr);
+	if (!schem) {
+		schem = load_schematic(L, 1, NULL, NULL);
+		was_loaded = true;
+	}
+	if (!schem) {
+		errorstream << "read_schematic: failed to get schematic" << std::endl;
+		return 0;
+	}
+	lua_pop(L, 2);
+
+	//// Create the Lua table
+	u32 numnodes = schem->size.X * schem->size.Y * schem->size.Z;
+	const std::vector<std::string> &names = schem->m_nodenames;
+
+	lua_createtable(L, 0, (write_yslice == "none") ? 2 : 3);
+
+	// Create the size field
+	push_v3s16(L, schem->size);
+	lua_setfield(L, 1, "size");
+
+	// Create the yslice_prob field
+	if (write_yslice != "none") {
+		lua_createtable(L, schem->size.Y, 0);
+		for (u16 y = 0; y != schem->size.Y; ++y) {
+			u8 probability = schem->slice_probs[y] & MTSCHEM_PROB_MASK;
+			if (probability < MTSCHEM_PROB_ALWAYS || write_yslice != "low") {
+				lua_createtable(L, 0, 2);
+				lua_pushinteger(L, y);
+				lua_setfield(L, 3, "ypos");
+				lua_pushinteger(L, probability * 2);
+				lua_setfield(L, 3, "prob");
+				lua_rawseti(L, 2, y + 1);
+			}
+		}
+		lua_setfield(L, 1, "yslice_prob");
+	}
+
+	// Create the data field
+	lua_createtable(L, numnodes, 0); // data table
+	for (u32 i = 0; i < numnodes; ++i) {
+		MapNode node = schem->schemdata[i];
+		u8 probability   = node.param1 & MTSCHEM_PROB_MASK;
+		bool force_place = node.param1 & MTSCHEM_FORCE_PLACE;
+		lua_createtable(L, 0, force_place ? 4 : 3);
+		lua_pushstring(L, names[schem->schemdata[i].getContent()].c_str());
+		lua_setfield(L, 3, "name");
+		lua_pushinteger(L, probability * 2);
+		lua_setfield(L, 3, "prob");
+		lua_pushinteger(L, node.param2);
+		lua_setfield(L, 3, "param2");
+		if (force_place) {
+			lua_pushboolean(L, 1);
+			lua_setfield(L, 3, "force_place");
+		}
+		lua_rawseti(L, 2, i + 1);
+	}
+	lua_setfield(L, 1, "data");
+
+	if (was_loaded)
+		delete schem;
+
+	return 1;
+}
+
 
 void ModApiMapgen::Initialize(lua_State *L, int top)
 {
@@ -1793,4 +1870,5 @@ void ModApiMapgen::Initialize(lua_State *L, int top)
 	API_FCT(place_schematic);
 	API_FCT(place_schematic_on_vmanip);
 	API_FCT(serialize_schematic);
+	API_FCT(read_schematic);
 }
diff --git a/src/script/lua_api/l_mapgen.h b/src/script/lua_api/l_mapgen.h
index 1339791f3..4a6a9ccf4 100644
--- a/src/script/lua_api/l_mapgen.h
+++ b/src/script/lua_api/l_mapgen.h
@@ -131,6 +131,9 @@ private:
 	// serialize_schematic(schematic, format, options={...})
 	static int l_serialize_schematic(lua_State *L);
 
+	// read_schematic(schematic, options={...})
+	static int l_read_schematic(lua_State *L);
+
 public:
 	static void Initialize(lua_State *L, int top);
 
-- 
2.25.1