//===----------------------------------------------------------*- swift -*-===//
//
// This source file is part of the Swift Argument Parser open source project
//
// Copyright (c) 2020 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//

import ArgumentParser
import ArgumentParserToolInfo
import XCTest

@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
extension CollectionDifference.Change {
  var offset: Int {
    switch self {
    case .insert(let offset, _, _):
      return offset
    case .remove(let offset, _, _):
      return offset
    }
  }
}

@available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *)
extension CollectionDifference.Change: Comparable where ChangeElement: Equatable {
  public static func < (lhs: Self, rhs: Self) -> Bool {
    guard lhs.offset == rhs.offset else {
      return lhs.offset < rhs.offset
    }
    switch (lhs, rhs) {
    case (.remove, .insert):
      return true
    case (.insert, .remove):
      return false
    default:
      return true
    }
  }
}

// extensions to the ParsableArguments protocol to facilitate XCTestExpectation support
public protocol TestableParsableArguments: ParsableArguments {
  var didValidateExpectation: XCTestExpectation { get }
}

public extension TestableParsableArguments {
  mutating func validate() throws {
    didValidateExpectation.fulfill()
  }
}

// extensions to the ParsableCommand protocol to facilitate XCTestExpectation support
public protocol TestableParsableCommand: ParsableCommand, TestableParsableArguments {
  var didRunExpectation: XCTestExpectation { get }
}

public extension TestableParsableCommand {
  mutating func run() throws {
    didRunExpectation.fulfill()
  }
}

extension XCTestExpectation {
  public convenience init(singleExpectation description: String) {
    self.init(description: description)
    expectedFulfillmentCount = 1
    assertForOverFulfill = true
  }
}

public func AssertResultFailure<T, U: Error>(
  _ expression: @autoclosure () -> Result<T, U>,
  _ message: @autoclosure () -> String = "",
  file: StaticString = #file,
  line: UInt = #line)
{
  switch expression() {
  case .success:
    let msg = message()
    XCTFail(msg.isEmpty ? "Incorrectly succeeded" : msg, file: file, line: line)
  case .failure:
    break
  }
}

public func AssertErrorMessage<A>(_ type: A.Type, _ arguments: [String], _ errorMessage: String, file: StaticString = #file, line: UInt = #line) where A: ParsableArguments {
  do {
    _ = try A.parse(arguments)
    XCTFail("Parsing should have failed.", file: file, line: line)
  } catch {
    // We expect to hit this path, i.e. getting an error:
    XCTAssertEqual(A.message(for: error), errorMessage, file: file, line: line)
  }
}

public func AssertFullErrorMessage<A>(_ type: A.Type, _ arguments: [String], _ errorMessage: String, file: StaticString = #file, line: UInt = #line) where A: ParsableArguments {
  do {
    _ = try A.parse(arguments)
    XCTFail("Parsing should have failed.", file: (file), line: line)
  } catch {
    // We expect to hit this path, i.e. getting an error:
    XCTAssertEqual(A.fullMessage(for: error), errorMessage, file: (file), line: line)
  }
}

public func AssertParse<A>(_ type: A.Type, _ arguments: [String], file: StaticString = #file, line: UInt = #line, closure: (A) throws -> Void) where A: ParsableArguments {
  do {
    let parsed = try type.parse(arguments)
    try closure(parsed)
  } catch {
    let message = type.message(for: error)
    XCTFail("\"\(message)\" — \(error)", file: (file), line: line)
  }
}

public func AssertParseCommand<A: ParsableCommand>(_ rootCommand: ParsableCommand.Type, _ type: A.Type, _ arguments: [String], file: StaticString = #file, line: UInt = #line, closure: (A) throws -> Void) {
  do {
    let command = try rootCommand.parseAsRoot(arguments)
    guard let aCommand = command as? A else {
      XCTFail("Command is of unexpected type: \(command)", file: (file), line: line)
      return
    }
    try closure(aCommand)
  } catch {
    let message = rootCommand.message(for: error)
    XCTFail("\"\(message)\" — \(error)", file: file, line: line)
  }
}

public func AssertEqualStrings(actual: String, expected: String, file: StaticString = #file, line: UInt = #line) {
  // If the input strings are not equal, create a simple diff for debugging...
  guard actual != expected else {
    // Otherwise they are equal, early exit.
    return
  }

  // Split in the inputs into lines.
  let actualLines = actual.split(separator: "\n", omittingEmptySubsequences: false)
  let expectedLines = expected.split(separator: "\n", omittingEmptySubsequences: false)

  // If collectionDifference is available, use it to make a nicer error message.
  if #available(macOS 10.15, iOS 13.0, watchOS 6.0, tvOS 13.0, *) {
    // Compute the changes between the two strings.
    let changes = actualLines.difference(from: expectedLines).sorted()

    // Render the changes into a diff style string.
    var diff = ""
    var expectedLines = expectedLines[...]
    for change in changes {
      if expectedLines.startIndex < change.offset {
        for line in expectedLines[..<change.offset] {
          diff += "  \(line)\n"
        }
        expectedLines = expectedLines[change.offset...].dropFirst()
      }

      switch change {
      case .insert(_, let line, _):
        diff += "- \(line)\n"
      case .remove(_, let line, _):
        diff += "+ \(line)\n"
      }
    }
    for line in expectedLines {
      diff += "  \(line)\n"
    }
    XCTFail("Strings are not equal.\n\(diff)", file: file, line: line)
  } else {
    XCTAssertEqual(
      actualLines.count,
      expectedLines.count,
      "Strings have different numbers of lines.",
      file: file,
      line: line)
    for (actualLine, expectedLine) in zip(actualLines, expectedLines) {
      XCTAssertEqual(actualLine, expectedLine, file: file, line: line)
    }
  }
}

public func AssertHelp<T: ParsableArguments>(
  _ visibility: ArgumentVisibility,
  for _: T.Type,
  equals expected: String,
  file: StaticString = #file,
  line: UInt = #line
) {
  let flag: String
  let includeHidden: Bool

  switch visibility {
  case .default:
    flag = "--help"
    includeHidden = false
  case .hidden:
    flag = "--help-hidden"
    includeHidden = true
  case .private:
    XCTFail("Should not be called.", file: file, line: line)
    return
  default:
    XCTFail("Unrecognized visibility.", file: file, line: line)
    return
  }

  do {
    _ = try T.parse([flag])
    XCTFail(file: file, line: line)
  } catch {
    let helpString = T.fullMessage(for: error)
    AssertEqualStrings(actual: helpString, expected: expected, file: file, line: line)
  }

  let helpString = T.helpMessage(includeHidden: includeHidden, columns: nil)
  AssertEqualStrings(actual: helpString, expected: expected, file: file, line: line)
}

public func AssertHelp<T: ParsableCommand, U: ParsableCommand>(
  _ visibility: ArgumentVisibility,
  for _: T.Type,
  root _: U.Type,
  equals expected: String,
  file: StaticString = #file,
  line: UInt = #line
) {
  let includeHidden: Bool

  switch visibility {
  case .default:
    includeHidden = false
  case .hidden:
    includeHidden = true
  case .private:
    XCTFail("Should not be called.", file: file, line: line)
    return
  default:
    XCTFail("Unrecognized visibility.", file: file, line: line)
    return
  }

  let helpString = U.helpMessage(
    for: T.self, includeHidden: includeHidden, columns: nil)
  AssertEqualStrings(actual: helpString, expected: expected, file: file, line: line)
}

public func AssertDump<T: ParsableArguments>(
  for _: T.Type, equals expected: String,
  file: StaticString = #file, line: UInt = #line
) throws {
  do {
    _ = try T.parse(["--experimental-dump-help"])
    XCTFail(file: file, line: line)
  } catch {
    let dumpString = T.fullMessage(for: error)
    try AssertJSONEqualFromString(actual: dumpString, expected: expected, for: ToolInfoV0.self)
  }

  try AssertJSONEqualFromString(actual: T._dumpHelp(), expected: expected, for: ToolInfoV0.self)
}

public func AssertJSONEqualFromString<T: Codable & Equatable>(actual: String, expected: String, for type: T.Type) throws {
  let actualJSONData = try XCTUnwrap(actual.data(using: .utf8))
  let actualDumpJSON = try XCTUnwrap(JSONDecoder().decode(type, from: actualJSONData))

  let expectedJSONData = try XCTUnwrap(expected.data(using: .utf8))
  let expectedDumpJSON = try XCTUnwrap(JSONDecoder().decode(type, from: expectedJSONData))
  XCTAssertEqual(actualDumpJSON, expectedDumpJSON)
}

extension XCTest {
  public var debugURL: URL {
    let bundleURL = Bundle(for: type(of: self)).bundleURL
    return bundleURL.lastPathComponent.hasSuffix("xctest")
      ? bundleURL.deletingLastPathComponent()
      : bundleURL
  }
  
  public func AssertExecuteCommand(
    command: String,
    expected: String? = nil,
    exitCode: ExitCode = .success,
    file: StaticString = #file, line: UInt = #line) throws
  {
    try AssertExecuteCommand(
      command: command.split(separator: " ").map(String.init),
      expected: expected,
      exitCode: exitCode,
      file: file,
      line: line)
  }

  public func AssertExecuteCommand(
    command: [String],
    expected: String? = nil,
    exitCode: ExitCode = .success,
    file: StaticString = #file, line: UInt = #line) throws
  {
    #if os(Windows)
    throw XCTSkip("Unsupported on this platform")
    #endif

    let arguments = Array(command.dropFirst())
    let commandName = String(command.first!)
    let commandURL = debugURL.appendingPathComponent(commandName)
    guard (try? commandURL.checkResourceIsReachable()) ?? false else {
      XCTFail("No executable at '\(commandURL.standardizedFileURL.path)'.",
              file: file, line: line)
      return
    }
    
    #if !canImport(Darwin) || os(macOS)
    let process = Process()
    if #available(macOS 10.13, *) {
      process.executableURL = commandURL
    } else {
      process.launchPath = commandURL.path
    }
    process.arguments = arguments
    
    let output = Pipe()
    process.standardOutput = output
    let error = Pipe()
    process.standardError = error
    
    if #available(macOS 10.13, *) {
      guard (try? process.run()) != nil else {
        XCTFail("Couldn't run command process.", file: file, line: line)
        return
      }
    } else {
      process.launch()
    }
    process.waitUntilExit()
    
    let outputData = output.fileHandleForReading.readDataToEndOfFile()
    let outputActual = String(data: outputData, encoding: .utf8)!.trimmingCharacters(in: .whitespacesAndNewlines)
        
    let errorData = error.fileHandleForReading.readDataToEndOfFile()
    let errorActual = String(data: errorData, encoding: .utf8)!.trimmingCharacters(in: .whitespacesAndNewlines)
    
    if let expected = expected {
      AssertEqualStrings(
        actual: errorActual + outputActual,
        expected: expected,
        file: file,
        line: line)
    }

    XCTAssertEqual(process.terminationStatus, exitCode.rawValue, file: file, line: line)
    #else
    throw XCTSkip("Not supported on this platform")
    #endif
  }

  public func AssertJSONOutputEqual(
    command: String,
    expected: String,
    file: StaticString = #file, line: UInt = #line
  ) throws {
    #if os(Windows)
    throw XCTSkip("Unsupported on this platform")
    #endif

    let splitCommand = command.split(separator: " ")
    let arguments = splitCommand.dropFirst().map(String.init)

    let commandName = String(splitCommand.first!)
    let commandURL = debugURL.appendingPathComponent(commandName)
    guard (try? commandURL.checkResourceIsReachable()) ?? false else {
      XCTFail("No executable at '\(commandURL.standardizedFileURL.path)'.",
              file: file, line: line)
      return
    }

    #if !canImport(Darwin) || os(macOS)
    let process = Process()
    if #available(macOS 10.13, *) {
      process.executableURL = commandURL
    } else {
      process.launchPath = commandURL.path
    }
    process.arguments = arguments

    let output = Pipe()
    process.standardOutput = output
    let error = Pipe()
    process.standardError = error

    if #available(macOS 10.13, *) {
      guard (try? process.run()) != nil else {
        XCTFail("Couldn't run command process.", file: file, line: line)
        return
      }
    } else {
      process.launch()
    }
    process.waitUntilExit()

    let outputString = try XCTUnwrap(String(data: output.fileHandleForReading.readDataToEndOfFile(), encoding: .utf8))
    XCTAssertTrue(error.fileHandleForReading.readDataToEndOfFile().isEmpty, "Error occurred with `--experimental-dump-help`")
    try AssertJSONEqualFromString(actual: outputString, expected: expected, for: ToolInfoV0.self)
    #else
    throw XCTSkip("Not supported on this platform")
    #endif
  }

  public func AssertGenerateManual(
    multiPage: Bool,
    command: String,
    expected: String,
    file: StaticString = #file,
    line: UInt = #line
  ) throws {
    #if os(Windows)
    throw XCTSkip("Unsupported on this platform")
    #endif

    let commandURL = debugURL.appendingPathComponent(command)
    var command = [
      "generate-manual", commandURL.path,
      "--date", "1996-05-12",
      "--section", "9",
      "--authors", "Jane Appleseed",
      "--authors", "<johnappleseed@apple.com>",
      "--authors", "The Appleseeds<appleseeds@apple.com>",
      "--output-directory", "-",
    ]
    if multiPage {
      command.append("--multi-page")
    }
    try AssertExecuteCommand(
      command: command,
      expected: expected,
      exitCode: .success,
      file: file,
      line: line)
  }
}