/*
 * Copyright (c) 2013 Matthew Stevens
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

// Modifications copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT License.

static_assert(__has_feature(objc_arc), "Objective-C ARC must be enabled");

#import <Foundation/Foundation.h>
#import <XCTest/XCTest.h>
#import <gtest/gtest.h>
#import <objc/runtime.h>

using testing::TestCase;
using testing::TestInfo;
using testing::TestPartResult;
using testing::UnitTest;

static NSString* const GoogleTestDisabledPrefix = @"DISABLED_";

/**
 * Class prefix used for generated Objective-C class names.
 *
 * If a class name generated for a Google Test case conflicts with an existing
 * class the value of this variable can be changed to add a class prefix.
 */
static NSString* const GeneratedClassPrefix = @"";

/**
 * Map of test keys to Google Test filter strings.
 *
 * Some names allowed by Google Test would result in illegal Objective-C
 * identifiers and in such cases the generated class and method names are
 * adjusted to handle this. This map is used to obtain the original Google Test
 * filter string associated with a generated Objective-C test method.
 */
static NSDictionary* GoogleTestFilterMap;

/**
 * A Google Test listener that reports failures to XCTest.
 */
class XCTestListener : public testing::EmptyTestEventListener {
 public:
  XCTestListener(XCTestCase* testCase) : _testCase(testCase) {}

  void OnTestPartResult(const TestPartResult& test_part_result) {
    if (test_part_result.passed() || test_part_result.skipped())
      return;

    int lineNumber = test_part_result.line_number();
    const char* fileName = test_part_result.file_name();
    NSString* path = fileName ? [@(fileName) stringByStandardizingPath] : nil;
    NSString* description = @(test_part_result.message());
    [_testCase recordFailureWithDescription:description
                                     inFile:path
                                     atLine:(lineNumber >= 0 ? (NSUInteger)lineNumber : 0)
                                   expected:YES];
  }

 private:
  XCTestCase* _testCase;
};

/**
 * Registers an XCTestCase subclass for each Google Test case.
 *
 * Generating these classes allows Google Test cases to be represented as peers
 * of standard XCTest suites and supports filtering of test runs to specific
 * Google Test cases or individual tests via Xcode.
 */
@interface GoogleTestLoader : NSObject
@end

/**
 * Base class for the generated classes for Google Test cases.
 */
@interface GoogleTestCase : XCTestCase
@end

@implementation GoogleTestCase

/**
 * Associates generated Google Test classes with the test bundle.
 *
 * This affects how the generated test cases are represented in reports. By
 * associating the generated classes with a test bundle the Google Test cases
 * appear to be part of the same test bundle that this source file is compiled
 * into. Without this association they appear to be part of a bundle
 * representing the directory of an internal Xcode tool that runs the tests.
 */
+ (NSBundle*)bundleForClass {
  return [NSBundle bundleForClass:[GoogleTestLoader class]];
}

/**
 * Implementation of +[XCTestCase testInvocations] that returns an array of test
 * invocations for each test method in the class.
 *
 * This differs from the standard implementation of testInvocations, which only
 * adds methods with a prefix of "test".
 */
+ (NSArray*)testInvocations {
  NSMutableArray* invocations = [NSMutableArray array];

  unsigned int methodCount = 0;
  Method* methods = class_copyMethodList([self class], &methodCount);

  for (unsigned int i = 0; i < methodCount; i++) {
    SEL sel = method_getName(methods[i]);
    NSMethodSignature* sig = [self instanceMethodSignatureForSelector:sel];
    NSInvocation* invocation = [NSInvocation invocationWithMethodSignature:sig];
    [invocation setSelector:sel];
    [invocations addObject:invocation];
  }

  free(methods);

  return invocations;
}

@end

/**
 * Runs a single test.
 */
static void RunTest(id self, SEL _cmd) {
  XCTestListener* listener = new XCTestListener(self);
  UnitTest* googleTest = UnitTest::GetInstance();
  googleTest->listeners().Append(listener);

  NSString* testKey = [NSString stringWithFormat:@"%@.%@", [self class], NSStringFromSelector(_cmd)];
  NSString* testFilter = GoogleTestFilterMap[testKey];
  XCTAssertNotNil(testFilter, @"No test filter found for test %@", testKey);

  testing::GTEST_FLAG(filter) = [testFilter UTF8String];
  (void)RUN_ALL_TESTS();

  delete googleTest->listeners().Release(listener);

  int totalTestsRun = googleTest->successful_test_count() +
                      googleTest->failed_test_count() + googleTest->skipped_test_count();
  XCTAssertEqual(totalTestsRun, 1, @"Expected to run a single test for filter \"%@\"", testFilter);
}

@implementation GoogleTestLoader

/**
 * Performs registration of classes for Google Test cases after our bundle has
 * finished loading.
 *
 * This registration needs to occur before XCTest queries the runtime for test
 * subclasses, but after C++ static initializers have run so that all Google
 * Test cases have been registered. This is accomplished by synchronously
 * observing the NSBundleDidLoadNotification for our own bundle.
 */
+ (void)load {
  NSBundle* bundle = [NSBundle bundleForClass:self];
  [[NSNotificationCenter defaultCenter] addObserverForName:NSBundleDidLoadNotification
                                                    object:bundle
                                                     queue:nil
                                                usingBlock:^(NSNotification* notification) {
                                                  [self registerTestClasses];
                                                }];
}

+ (void)registerTestClasses {
  // Pass the command-line arguments to Google Test to support the --gtest options
  NSArray* arguments = [[NSProcessInfo processInfo] arguments];

  int i = 0;
  int argc = (int)[arguments count];
  const char** argv = (const char**)calloc((unsigned int)argc + 1, sizeof(const char*));
  for (NSString* arg in arguments) {
    argv[i++] = [arg UTF8String];
  }

  testing::InitGoogleTest(&argc, (char**)argv);
  UnitTest* googleTest = UnitTest::GetInstance();
  testing::TestEventListeners& listeners = googleTest->listeners();
  delete listeners.Release(listeners.default_result_printer());
  free(argv);

  BOOL runDisabledTests = testing::GTEST_FLAG(also_run_disabled_tests);
  NSMutableDictionary* testFilterMap = [NSMutableDictionary dictionary];
  NSCharacterSet* decimalDigitCharacterSet = [NSCharacterSet decimalDigitCharacterSet];

  for (int testCaseIndex = 0; testCaseIndex < googleTest->total_test_case_count(); testCaseIndex++) {
    const TestCase* testCase = googleTest->GetTestCase(testCaseIndex);
    NSString* testCaseName = @(testCase->name());

    // For typed tests '/' is used to separate the parts of the test case name.
    NSArray* testCaseNameComponents = [testCaseName componentsSeparatedByString:@"/"];

    if (runDisabledTests == NO) {
      BOOL testCaseDisabled = NO;

      for (NSString* component in testCaseNameComponents) {
        if ([component hasPrefix:GoogleTestDisabledPrefix]) {
          testCaseDisabled = YES;
          break;
        }
      }

      if (testCaseDisabled) {
        continue;
      }
    }

    // Join the test case name components with '_' rather than '/' to create
    // a valid class name.
    NSString* className = [GeneratedClassPrefix stringByAppendingString:[testCaseNameComponents componentsJoinedByString:@"_"]];

    Class testClass = objc_allocateClassPair([GoogleTestCase class], [className UTF8String], 0);
    NSAssert1(testClass, @"Failed to register Google Test class \"%@\", this class may already exist. The value of GeneratedClassPrefix can be changed to avoid this.", className);
    BOOL hasMethods = NO;

    for (int testIndex = 0; testIndex < testCase->total_test_count(); testIndex++) {
      const TestInfo* testInfo = testCase->GetTestInfo(testIndex);
      NSString* testName = @(testInfo->name());
      if (runDisabledTests == NO && [testName hasPrefix:GoogleTestDisabledPrefix]) {
        continue;
      }

      // Google Test allows test names starting with a digit, prefix these with an
      // underscore to create a valid method name.
      NSString* methodName = testName;
      if ([methodName length] > 0 && [decimalDigitCharacterSet characterIsMember:[methodName characterAtIndex:0]]) {
        methodName = [@"_" stringByAppendingString:methodName];
      }

      NSString* testKey = [NSString stringWithFormat:@"%@.%@", className, methodName];
      NSString* testFilter = [NSString stringWithFormat:@"%@.%@", testCaseName, testName];
      testFilterMap[testKey] = testFilter;

      SEL selector = sel_registerName([methodName UTF8String]);
      BOOL added = class_addMethod(testClass, selector, (IMP)RunTest, "v@:");
      NSAssert1(added, @"Failed to add Goole Test method \"%@\", this method may already exist in the class.", methodName);
      hasMethods = YES;
    }

    if (hasMethods) {
      objc_registerClassPair(testClass);
    } else {
      objc_disposeClassPair(testClass);
    }
  }

  GoogleTestFilterMap = testFilterMap;
}

@end
