2 files changed, 137 insertions, 2 deletions

diff --git a/src/LuaEngine/LuaEngine.c b/src/LuaEngine/LuaEngine.c
index c34fd68..af30403 100644
--- a/src/LuaEngine/LuaEngine.c
+++ b/src/LuaEngine/LuaEngine.c
@@ -143,6 +143,121 @@ static char *make_chunk_name(const char *input_path, unsigned long line) {
   return chunk_name;
 }
 
+typedef struct {
+  htmlDocPtr source;
+  EmitList *emits;
+} EmitContext;
+
+static int grow_emit_list(EmitList *emits) {
+  size_t larger_capacity;
+  EmittedPage *larger_items;
+
+  if (emits->capacity > SIZE_MAX / (2 * sizeof(*emits->items))) {
+    return -1;
+  }
+
+  larger_capacity = emits->capacity == 0 ? 4 : emits->capacity * 2;
+  larger_items =
+      realloc(emits->items, larger_capacity * sizeof(*emits->items));
+  if (larger_items == NULL) {
+    return -1;
+  }
+
+  emits->items = larger_items;
+  emits->capacity = larger_capacity;
+  return 0;
+}
+
+static int append_emit(EmitList *emits, const char *path,
+                       htmlDocPtr document) {
+  EmittedPage *emitted;
+
+  if (emits->length == emits->capacity && grow_emit_list(emits) != 0) {
+    return -1;
+  }
+
+  emitted = &emits->items[emits->length];
+  emitted->path = duplicate_string(path);
+  if (emitted->path == NULL) {
+    return -1;
+  }
+
+  emitted->document = document;
+  ++emits->length;
+  return 0;
+}
+
+void emit_list_free(EmitList *emits) {
+  size_t index;
+
+  for (index = 0; index < emits->length; ++index) {
+    free(emits->items[index].path);
+    xmlFreeDoc(emits->items[index].document);
+  }
+  free(emits->items);
+  emits->items = NULL;
+  emits->length = 0;
+  emits->capacity = 0;
+}
+
+static htmlDocPtr snapshot_document(htmlDocPtr source, lua_State *lua) {
+  htmlDocPtr copy;
+  xmlDtdPtr dtd;
+  xmlNodePtr root;
+
+  lua_getglobal(lua, "page");
+  root = lua_istable(lua, -1) ? dom_page_from_lua(lua, lua_gettop(lua)) : NULL;
+  lua_pop(lua, 1);
+  if (root == NULL) {
+    return NULL;
+  }
+
+  copy = xmlNewDoc(BAD_CAST "1.0");
+  if (copy == NULL) {
+    xmlFreeNode(root);
+    return NULL;
+  }
+  if (source->encoding != NULL) {
+    copy->encoding = xmlStrdup(source->encoding);
+  }
+
+  dtd = xmlGetIntSubset(source);
+  if (dtd != NULL) {
+    dtd = xmlCopyDtd(dtd);
+    if (dtd != NULL) {
+      xmlAddChild((xmlNodePtr)copy, (xmlNodePtr)dtd);
+      copy->intSubset = dtd;
+    }
+  }
+
+  xmlAddChild((xmlNodePtr)copy, root);
+  return copy;
+}
+
+static int page_emit(lua_State *lua) {
+  EmitContext *context;
+  const char *path;
+  htmlDocPtr document;
+
+  luaL_checktype(lua, 1, LUA_TTABLE);
+  path = luaL_checkstring(lua, 2);
+  if (path[0] == '\0') {
+    return luaL_error(lua, "emit path cannot be empty");
+  }
+  context = lua_touserdata(lua, lua_upvalueindex(1));
+
+  document = snapshot_document(context->source, lua);
+  if (document == NULL) {
+    return luaL_error(lua, "unable to snapshot the current page");
+  }
+
+  if (append_emit(context->emits, path, document) != 0) {
+    xmlFreeDoc(document);
+    return luaL_error(lua, "unable to record emitted page");
+  }
+  return 0;
+}
+
 static int run_script(lua_State *lua, const LuaScript *script,
                       const char *input_path) {
   char *source_path = NULL;
@@ -228,7 +343,9 @@ static int replace_document_root(lua_State *lua, htmlDocPtr document,
   return 0;
 }
 
-int process_html_document(htmlDocPtr document, const char *input_path) {
+int process_html_document(htmlDocPtr document, const char *input_path,
+                          EmitList *emits) {
+  EmitContext context = {document, emits};
   xmlNodePtr root = xmlDocGetRootElement(document);
   ScriptList scripts = {0};
   lua_State *lua;
@@ -262,6 +379,11 @@ int process_html_document(htmlDocPtr document, const char *input_path) {
   directory_walker_register(lua, input_path);
   dom_push_page(lua, root);
   lua_setglobal(lua, "page");
+  lua_getglobal(lua, "page");
+  lua_pushlightuserdata(lua, &context);
+  lua_pushcclosure(lua, page_emit, 1);
+  lua_setfield(lua, -2, "emit");
+  lua_pop(lua, 1);
 
   result = run_scripts(lua, &scripts, input_path);
   if (result == 0) {
diff --git a/src/LuaEngine/LuaEngine.h b/src/LuaEngine/LuaEngine.h
index bd035b9..2a5eea4 100644
--- a/src/LuaEngine/LuaEngine.h
+++ b/src/LuaEngine/LuaEngine.h
@@ -3,6 +3,19 @@
 
 #include <libxml/HTMLparser.h>
 
-int process_html_document(htmlDocPtr document, const char *input_path);
+typedef struct {
+  char *path;
+  htmlDocPtr document;
+} EmittedPage;
+
+typedef struct {
+  EmittedPage *items;
+  size_t length;
+  size_t capacity;
+} EmitList;
+
+int process_html_document(htmlDocPtr document, const char *input_path,
+                          EmitList *emits);
+void emit_list_free(EmitList *emits);
 
 #endif