nodegit
diff --git a/generate/index.js b/generate/index.js
@@ -4,6 +4,7 @@ var fse = require('fs-extra');
 var glob = require('glob').sync;
 var generatedData = require('./lib/generated_data');
 var writeApiDocs = require('./lib/write_api_docs');
+var writeTsDeclarations = require('./lib/write_ts_declarations');
 var addConvenienceMethods = require('./lib/add_convenience_methods.js');
 
 var idefsPath = 'generate/nodegit/generate/output/idefs.json';
@@ -14,6 +15,7 @@ var fullData;
 
 addConvenienceMethods(baseData).then(function(fullData) {
   writeApiDocs(fullData);
+  writeTsDeclarations(fullData);
 });
 
 // Copy convenience methods in.

diff --git a/generate/lib/write_ts_declarations.js b/generate/lib/write_ts_declarations.js
@@ -0,0 +1,332 @@
+/**
+ * Consumes the API in JSON format, and produces a TypeScript declaration file.
+ * @author John Vilk <jvilk@cs.umass.edu>
+ */
+var fs = require('fs-extra');
+var Path = require('path');
+
+var writeTsDecls = function(apiData, path) {
+  var path = path || '';
+  path = ("/" + path + "/").replace(/\/+/g, '/');
+
+  /**
+   * Given a type from the API docs, produce a TypeScript type.
+   */
+  function getType(type) {
+    // Remove spaces.
+    type = type.replace(/\s/g, '');
+    // Convert [] to Array<> for generics.
+    var sqBracketIndex = type.indexOf('[');
+    if (sqBracketIndex !== -1) {
+      return "Array<" + getType(type.slice(0, sqBracketIndex)) + ">";
+    }
+
+    // If type has < in it already, translate generic argument.
+    var angleIndex = type.indexOf('<');
+    if (angleIndex !== -1) {
+      type = type.slice(0, angleIndex) + '<' + getType(type.slice(angleIndex + 1, type.indexOf('>'))) + ">";
+    }
+
+    switch (type) {
+      // Weird things. Prune items as we fix docs.
+      case 'obj':
+      case 'ConvenientHunk':
+      case 'lineStats':
+      case 'RevWalk':
+      case 'StatusFile':
+      case 'historyEntry':
+      case 'DiffList':
+        return 'any';
+      // Untyped function callbacks.
+      case 'CheckoutNotifyCb':
+      case 'CheckoutPerfdataCb':
+      case 'CheckoutProgressCb':
+      case 'DiffFileCb':
+      case 'DiffBinaryCb':
+      case 'DiffHunkCb':
+      case 'DiffLineCb':
+      case 'DiffNotifyCb':
+      case 'CredAcquireCb':
+      case 'FetchheadForeachCb':
+      case 'FilterStreamFn':
+      case 'IndexMatchedPathCb':
+      case 'NoteForeachCb':
+      case 'StashCb':
+      case 'StashApplyProgressCb':
+      case 'StatusCb':
+      case 'SubmoduleCb':
+      case 'TransferProgressCb':
+      case 'TransportCb':
+      case 'TransportCertificateCheckCb':
+        return 'Function';
+      // Primitives
+      case 'String':
+        return 'string';
+      case 'Char':
+      case 'int':
+      case 'Number':
+        return 'number';
+      case 'Void':
+        return 'void';
+      case 'bool':
+        return 'boolean';
+      case 'Array':
+        return 'Array<any>';
+      // Avoiding type collusions
+      case 'Object':
+        return 'GitObject';
+      case 'Blob':
+        return 'GitBlob';
+      // NodeJS types
+      case 'EventEmitter':
+        return 'NodeJS.EventEmitter';
+      default:
+        var dotIndex = type.indexOf('.');
+        if (dotIndex !== -1) {
+          if (type[dotIndex + 1] === '<') {
+            // Sometimes, the docs include a '.' between the type and the generic type argument.
+            return type.replace(/\./g, '');
+          } else {
+            // Remove '.' from types (e.g. Reference.Type => ReferenceType) as
+            // we make them part of the outer scope.
+            // Also, convert the owner of the type properly (e.g. Object.TYPE => GitObjectTYPE).
+            return getType(type.slice(0, dotIndex)) + type.slice(dotIndex + 1);
+          }
+        } else {
+          // Check for weird things. If there are weird things, punt with 'any'.
+          if (type.indexOf('(') !== -1 || type.indexOf(':') !== -1) {
+            return 'any';
+          }
+
+          return type;
+        }
+    }
+  }
+
+  /**
+   * Converts a block of text into a block of JSDoc. Removes empty lines.
+   */
+  function textToJSDoc(text) {
+    var lines = text.split('\n');
+    // Strip empty lines, and begin non-empty lines with " * "
+    lines = lines.filter(function(line) {
+      return line.trim() !== "";
+    }).map(function(line) {
+      return " * " + line;
+    });
+
+    return "/**\n" + lines.join("\n") + "\n */";
+  }
+
+  /**
+   * Strip illegal characters from identifiers.
+   */
+  function fixIdentifier(name) {
+    return name.replace(/[\[\]]/g, '');
+  }
+
+  /**
+   * Given a function, returns a function signature.
+   */
+  function getFunctionSignature(name, fcn, params, isStatic) {
+    var fcnSig = isStatic ? 'public static' : 'public';
+    fcnSig += " " + name + "(" +
+      params.map(function(param) {
+        var paramName = fixIdentifier(param.name);
+        // Make each param type a union type if multiple types.
+        return paramName + (param.optional ? "?" : "") + ": " + (param.types.map(function(type) { return getType(type); }).join(" | "));
+      }).join(', ') + "): ";
+    var returnType = fcn.return ? getType(fcn.return.type) : "void";
+    if (fcn.isAsync) {
+      returnType = "PromiseLike<" + returnType + ">";
+    }
+    return fcnSig + returnType + ";"
+  }
+
+  /**
+   * Returns an array of parameter permutations to a function.
+   */
+  function getParamPermutations(params) {
+    // Figure out which parameters are optional.
+    var optionalParams = []
+    var nonOptionalAfterOptional = false;
+    var i;
+    for (i = 0; i < params.length; i++) {
+      if (params[i].optional) {
+        optionalParams.push(i);
+      } else if (optionalParams.length > 0) {
+        nonOptionalAfterOptional = true;
+      }
+    }
+
+    // If no non-optional functions follow optional functions,
+    // we only need one function signature [common case].
+    if (!nonOptionalAfterOptional) {
+      return [params];
+    } else {
+      var rv = [];
+
+      // Only toggle the ones in the middle. Ignore those at the
+      // end -- they are benign.
+	    for (i = params.length - 1; i >= 0; i--) {
+        if (optionalParams[optionalParams.length - 1] === i) {
+          optionalParams.pop();
+        } else {
+          break;
+        }
+      }
+
+      var numOptionalParams = optionalParams.length;
+      var state = new Array(numOptionalParams);
+      for (i = 0; i < numOptionalParams; i++) {
+        state[i] = 0;
+      }
+      outer:
+      while(true) {
+        // 'Clone' the params object.
+        var paramVariant = JSON.parse(JSON.stringify(params));
+        // Remove 'disabled' optional params, from r2l to avoid messing with
+        // array indices.
+        for (i = numOptionalParams - 1; i >= 0; i--) {
+          var optionalIndex = optionalParams[i];
+          if (state[i]) {
+            paramVariant.splice(optionalIndex, 1);
+          } else {
+            paramVariant[optionalIndex].optional = false;
+          }
+        }
+        rv.push(paramVariant);
+
+        // Add '1' to 'state', from L2R.
+        var digit = 0;
+        while (state[digit] === 1) {
+          if ((digit + 1) < numOptionalParams) {
+            state[digit] = 0;
+            digit++;
+          } else {
+            break outer;
+          }
+        }
+        state[digit] = 1;
+      }
+      return rv.reverse();
+    }
+  }
+
+  /**
+   * Converts a function in JSON format into a TypeScript function
+   * declaration.
+   */
+  function getFunctionDeclaration(name, fcn, isStatic) {
+    var jsDoc = "";
+    if (fcn.experimental) {
+      jsDoc += "[EXPERIMENTAL] ";
+    }
+    if (fcn.description !== "") {
+      jsDoc += fcn.description + "\n";
+    }
+
+    var params = fcn.params;
+    params.map(function(param) {
+      var paramName = fixIdentifier(param.name);
+      jsDoc += "\n@param " + paramName + " ";
+      // Apparently param.description can be null, so check that it's not before looking at the contents!
+      if (param.description && param.description.trim() !== "") {
+        // Indent secondary lines of the description.
+        jsDoc += param.description.replace(/\n/g, '\n    ') + "\n";
+      }
+    });
+
+    var fcnDesc = fcn.return ? fcn.return.description.replace(/\n/g, '\n    ') : '';
+
+    if (fcnDesc.trim() !== "") {
+      jsDoc += "\n@return " + fcnDesc;
+    }
+
+    var paramPermutations = getParamPermutations(fcn.params);
+    return textToJSDoc(jsDoc) + "\n" + paramPermutations.map(function(params) { return getFunctionSignature(name, fcn, params, isStatic); }).join("\n");
+  }
+
+  /**
+   * Convert an enum into a TypeScript const enum declaration.
+   */
+  function getEnumDeclaration(className, enumName, enumData) {
+    var exportName = className + enumName;
+    var enumFields = "  " + Object.keys(enumData).sort().map(function(enumType) {
+      return enumType + " = " + enumData[enumType];
+    }).join(",\n  ");
+    return "declare enum " + exportName + " {\n" + enumFields + "\n}";
+  }
+
+  /**
+   * Indents + concatenates an array of lines.
+   */
+  function indentLines(text, indentation) {
+    return text.join("\n").replace(/^/gm, indentation);
+  }
+
+  // Array of TypeScript declarations.
+  var decls = [];
+  // Map from export name => class name
+  var nameMap = {};
+
+  Object.keys(apiData).sort().forEach(function(exportName) {
+    var className = getType(exportName);
+    var classData = apiData[exportName];
+    var classDecl = "";
+
+    // Export specially only if we have to remap the name to avoid type collisions.
+    if (className !== exportName) {
+      nameMap[exportName] = className;
+      classDecl = "declare ";
+    } else {
+      classDecl = "export ";
+    }
+    // There's no description for actual classes. Jump right into a definition.
+    classDecl += "class " + className + " {\n"
+
+    var staticMethods = Object.keys(classData.constructors).sort().map(function(name) {
+      return getFunctionDeclaration(name, classData.constructors[name], true);
+    });
+
+    var instanceMethods = Object.keys(classData.prototypes).sort().map(function(name) {
+      return getFunctionDeclaration(name, classData.prototypes[name], false);
+    });
+
+    // Fields
+    // HACK: Filter out fields that clash with declared methods. This is a bug in the doc script.
+    var fields = Object.keys(classData.fields).sort().filter(function(name) {
+      return !classData.prototypes[name];
+    }).map(function(name) {
+      // Fields do not have descriptions.
+      return "public " + fixIdentifier(name) + ": " + getType(classData.fields[name]);
+    });
+
+    // Enums (static fields)
+    var enumFields = Object.keys(classData.enums).sort().map(function(name) {
+      // Add to decl list. They are self-exporting.
+      decls.push(getEnumDeclaration(className, name, classData.enums[name]));
+
+      // Export on class, too.
+      return "public static " + name + ": typeof " + className + name + ";";
+    });
+
+    var indent = "  ";
+    classDecl += indentLines(enumFields, indent) + "\n" + indentLines(staticMethods, indent) + "\n" + indentLines(fields, indent) + "\n" + indentLines(instanceMethods, indent) + "\n" +
+        "}";
+    decls.push(classDecl);
+  });
+
+  var tsDeclFile = "// Type definitions for nodegit\n// Project: http://www.nodegit.org/\n// Definitions by: John Vilk <https://jvilk.com/>\n\n";
+
+  tsDeclFile += decls.join("\n\n");
+
+  tsDeclFile += "\n\nexport { " + Object.keys(nameMap).sort().map(function(exportName) {
+    return nameMap[exportName] + " as " + exportName;
+  }).join(", ") + " }\n";
+
+  fs.removeSync(Path.join(process.cwd(), path, 'ts'));
+  fs.outputFileSync('.' + path + 'ts/nodegit.d.ts', tsDeclFile);
+};
+
+module.exports = writeTsDecls;