diff --git a/src/index.ts b/src/index.ts
index 81c4377..8c0508d 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,50 +1,89 @@
 // TODO file handle?
-export const parse = function(input: string) {
-  var lines = input.split(/\r*\n/); //allow Windows newlines
-  console.log('Got input, '+lines.length+' lines');
-  var out = {
-    tags: {},
-    files: []
+import { FileHandle, open } from 'fs/promises'; 
+// const file = await fsPromise.open('./words.txt', 'r');
+const TOC_PREFIX_TAG = '## '
+const TOC_PREFIX_COMMENT = '#'
+const TOC_TAG_SEPARATOR = ':'
+const TOC_LINE_MAX_LENGTH = 1024
+
+export type TOC = {/*interface: number, title: string, titleLocalized: Record<string,string>, xTags: Record<string, string>,*/ allTags: Record<string, string>,files: string[]}
+
+export const parse = async function(file: FileHandle, strict = true) {
+  const result: TOC = {
+    // interface: 0,
+    // title: '',
+    // titleLocalized: {},
+    // xTags: {},
+    allTags: {},
+    files: [],
   };
-  lines.forEach(function(line) {
-    if (line.length > 1024) {
-      //WoW only reads the first 1024 lines
-      console.log('Line is longer than 1024 characters, trunicating to be like WoW');
-      line = line.substr(0, 1024);
+  for await (const line of file.readLines()) {
+    if (strict && line.length > TOC_LINE_MAX_LENGTH) {
+      throw new Error('Line is longer than TOC_LINE_MAX_LENGTH characters, WoW will truncate!');
     }
 
-    if (line.substr(0, 2) === '##') { //## Title: Recount
-      console.log('Line is tag: '+line);
-      var tag = line.substr(2, line.indexOf(':')).trim().replace(':', '');
-      var value = line.substr(line.indexOf(':')+1, line.length).trim();
-      console.log('`'+tag+'` : `'+value+'`');
-      out.tags[tag] = value;
-    } else if (line.substr(0, 1) === '#') { //#bug not feature
-      console.log('Line is comment: '+line);
-    } else { // recount.lua
-      //file loading
-      console.log('Line is file: '+line);
-      if (line.trim() !== '') {
-        out.files.push(line.trim());
+    if (line.slice(0, TOC_PREFIX_TAG.length) === TOC_PREFIX_TAG) {
+      const tagData = line.slice(TOC_PREFIX_TAG.length+1).split(TOC_TAG_SEPARATOR)
+      if(tagData.length !== 2){
+        throw new Error(`Tag could not be parsed: ${tagData}`)
       }
-    }
-  });
-  return out;
+
+      const tagName = tagData[0].trim()
+      const tagValue = tagData[1].trim()
+      if(strict && result.allTags[tagName]){
+        throw new Error(`Duplicate value: ${tagName}`)
+      }
+
+      result.allTags[tagName] = tagValue;
+
+      // specific tags
+      /*switch(tagName.toLowerCase()){
+        case 'interface': 
+          result.interface = Number(tagValue)
+          break;
+        case 'title':
+          result.title
+          break;
+      }*/
+
+      // 
+    } else if (line.slice(0, 1) !== TOC_PREFIX_COMMENT && !line.trim()) {
+      result.files.push(line.trimEnd()));
+    } 
+  }
+  return result;
 };
 
-export const stringify = function(input) {
-  if (typeof input !== 'object') {
-    throw new TypeError('wowtoc.stringify input must be an object, got '+typeof input);
-  }
+/*
+https://wowpedia.fandom.com/wiki/TOC_format
+## Interface: 100007
+## Title: Waiting for Godot
+## Title-frFR: En attendant Godot
+## Notes: This word is |cFFFF0000red|r
+## IconTexture: Interface\Icons\TEMP
+## IconAtlas: TaskPOI-Icon
+// ## AddonCompartmentFunc: MyAddon_OnAddonCompartmentClick
+// ## AddonCompartmentFuncOnEnter: MyAddon_OnAddonCompartmentEnter
+// ## AddonCompartmentFuncOnLeave: MyAddon_OnAddonCompartmentLeave
+## LoadOnDemand: 1
+## Dependencies: someAddOn, someOtherAddOn
+## OptionalDeps: someAddOn, someOtherAddOn
+## LoadWith: someAddOn, someOtherAddOn
+// ## LoadManagers: someAddOn, someOtherAddOn
+## DefaultState: disabled
+## SavedVariables: MyAddOnNameFoo, MyAddOnNameBar
+## SavedVariablesPerCharacter: MyAddOnNameAnotherVariable
+## Author
+## Version
+## X-_____
 
-  var out = [];
-  for(var tag in input.tags) {
-    if(input.tags.hasOwnProperty(tag)) {
-      out.push('## '+tag+': '+input.tags[tag]);
-    }
+*/
+
+export const stringify = function(toc: TOC) {
+  var result: string[] = [];
+  for(const tag in toc.allTags) {
+    result.push(`${TOC_PREFIX_TAG}${tag}${TOC_TAG_SEPARATOR} ${toc.allTags[tag]}`)
   }
-  (input.files || []).forEach(function(file) {
-    out.push(file);
-  });
-  return out.join('\n');
-};
\ No newline at end of file
+  result.concat(toc.files)
+  return result.join('\n');
+};