import PathKit
import Spectre
@testable import Stencil
import XCTest

final class EnvironmentTests: XCTestCase {
  var environment = Environment(loader: ExampleLoader())
  var template: Template = ""

  override func setUp() {
    super.setUp()

    let errorExtension = Extension()
    errorExtension.registerFilter("throw") { (_: Any?) in
      throw TemplateSyntaxError("filter error")
    }
    errorExtension.registerSimpleTag("simpletag") { _ in
      throw TemplateSyntaxError("simpletag error")
    }
    errorExtension.registerTag("customtag") { _, token in
      ErrorNode(token: token)
    }

    environment = Environment(loader: ExampleLoader())
    environment.extensions += [errorExtension]
    template = ""
  }

  func testLoading() {
    it("can load a template from a name") {
      let template = try self.environment.loadTemplate(name: "example.html")
      try expect(template.name) == "example.html"
    }

    it("can load a template from a names") {
      let template = try self.environment.loadTemplate(names: ["first.html", "example.html"])
      try expect(template.name) == "example.html"
    }
  }

  func testRendering() {
    it("can render a template from a string") {
      let result = try self.environment.renderTemplate(string: "Hello World")
      try expect(result) == "Hello World"
    }

    it("can render a template from a file") {
      let result = try self.environment.renderTemplate(name: "example.html")
      try expect(result) == "Hello World!"
    }

    it("allows you to provide a custom template class") {
      let environment = Environment(loader: ExampleLoader(), templateClass: CustomTemplate.self)
      let result = try environment.renderTemplate(string: "Hello World")

      try expect(result) == "here"
    }
  }

  func testSyntaxError() {
    it("reports syntax error on invalid for tag syntax") {
      self.template = "Hello {% for name in %}{{ name }}, {% endfor %}!"
      try self.expectError(
        reason: "'for' statements should use the syntax: `for <x> in <y> [where <condition>]`.",
        token: "for name in"
      )
    }

    it("reports syntax error on missing endfor") {
      self.template = "{% for name in names %}{{ name }}"
      try self.expectError(reason: "`endfor` was not found.", token: "for name in names")
    }

    it("reports syntax error on unknown tag") {
      self.template = "{% for name in names %}{{ name }}{% end %}"
      try self.expectError(reason: "Unknown template tag 'end'", token: "end")
    }
  }

  func testUnknownFilter() {
    it("reports syntax error in for tag") {
      self.template = "{% for name in names|unknown %}{{ name }}{% endfor %}"
      try self.expectError(
        reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
        token: "names|unknown"
      )
    }

    it("reports syntax error in for-where tag") {
      self.template = "{% for name in names where name|unknown %}{{ name }}{% endfor %}"
      try self.expectError(
        reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
        token: "name|unknown"
      )
    }

    it("reports syntax error in if tag") {
      self.template = "{% if name|unknown %}{{ name }}{% endif %}"
      try self.expectError(
        reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
        token: "name|unknown"
      )
    }

    it("reports syntax error in elif tag") {
      self.template = "{% if name %}{{ name }}{% elif name|unknown %}{% endif %}"
      try self.expectError(
        reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
        token: "name|unknown"
      )
    }

    it("reports syntax error in ifnot tag") {
      self.template = "{% ifnot name|unknown %}{{ name }}{% endif %}"
      try self.expectError(
        reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
        token: "name|unknown"
      )
    }

    it("reports syntax error in filter tag") {
      self.template = "{% filter unknown %}Text{% endfilter %}"
      try self.expectError(
        reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
        token: "filter unknown"
      )
    }

    it("reports syntax error in variable tag") {
      self.template = "{{ name|unknown }}"
      try self.expectError(
        reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
        token: "name|unknown"
      )
    }

    it("reports error in variable tag") {
      self.template = "{{ }}"
      try self.expectError(reason: "Missing variable name", token: " ")
    }
  }

  func testRenderingError() {
    it("reports rendering error in variable filter") {
      self.template = Template(templateString: "{{ name|throw }}", environment: self.environment)
      try self.expectError(reason: "filter error", token: "name|throw")
    }

    it("reports rendering error in filter tag") {
      self.template = Template(templateString: "{% filter throw %}Test{% endfilter %}", environment: self.environment)
      try self.expectError(reason: "filter error", token: "filter throw")
    }

    it("reports rendering error in simple tag") {
      self.template = Template(templateString: "{% simpletag %}", environment: self.environment)
      try self.expectError(reason: "simpletag error", token: "simpletag")
    }

    it("reports passing argument to simple filter") {
      self.template = "{{ name|uppercase:5 }}"
      try self.expectError(reason: "Can't invoke filter with an argument", token: "name|uppercase:5")
    }

    it("reports rendering error in custom tag") {
      self.template = Template(templateString: "{% customtag %}", environment: self.environment)
      try self.expectError(reason: "Custom Error", token: "customtag")
    }

    it("reports rendering error in for body") {
      self.template = Template(templateString: """
        {% for name in names %}{% customtag %}{% endfor %}
        """, environment: self.environment)
      try self.expectError(reason: "Custom Error", token: "customtag")
    }

    it("reports rendering error in block") {
      self.template = Template(
        templateString: "{% block some %}{% customtag %}{% endblock %}",
        environment: self.environment
      )
      try self.expectError(reason: "Custom Error", token: "customtag")
    }
  }

  private func expectError(
    reason: String,
    token: String,
    file: String = #file,
    line: Int = #line,
    function: String = #function
  ) throws {
    let expectedError = expectedSyntaxError(token: token, template: template, description: reason)

    let error = try expect(
      self.environment.render(template: self.template, context: ["names": ["Bob", "Alice"], "name": "Bob"]),
      file: file,
      line: line,
      function: function
    ).toThrow() as TemplateSyntaxError
    let reporter = SimpleErrorReporter()
    try expect(
      reporter.renderError(error),
      file: file,
      line: line,
      function: function
    ) == reporter.renderError(expectedError)
  }
}

final class EnvironmentIncludeTemplateTests: XCTestCase {
  var environment = Environment(loader: ExampleLoader())
  var template: Template = ""
  var includedTemplate: Template = ""

  override func setUp() {
    super.setUp()

    let path = Path(#file as String) + ".." + "fixtures"
    let loader = FileSystemLoader(paths: [path])
    environment = Environment(loader: loader)
    template = ""
    includedTemplate = ""
  }

  func testSyntaxError() throws {
    template = Template(templateString: """
      {% include "invalid-include.html" %}
      """, environment: environment)
    includedTemplate = try environment.loadTemplate(name: "invalid-include.html")

    try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
                    token: """
                      include "invalid-include.html"
                      """,
                    includedToken: "target|unknown")
  }

  func testRuntimeError() throws {
    let filterExtension = Extension()
    filterExtension.registerFilter("unknown") {  (_: Any?) in
      throw TemplateSyntaxError("filter error")
    }
    environment.extensions += [filterExtension]

    template = Template(templateString: """
      {% include "invalid-include.html" %}
      """, environment: environment)
    includedTemplate = try environment.loadTemplate(name: "invalid-include.html")

    try expectError(reason: "filter error",
                    token: "include \"invalid-include.html\"",
                    includedToken: "target|unknown")
  }

  private func expectError(
    reason: String,
    token: String,
    includedToken: String,
    file: String = #file,
    line: Int = #line,
    function: String = #function
  ) throws {
    var expectedError = expectedSyntaxError(token: token, template: template, description: reason)
    expectedError.stackTrace = [
      expectedSyntaxError(
        token: includedToken,
        template: includedTemplate,
        description: reason
      ).token
    ].compactMap { $0 }

    let error = try expect(
      self.environment.render(template: self.template, context: ["target": "World"]),
      file: file,
      line: line,
      function: function
    ).toThrow() as TemplateSyntaxError
    let reporter = SimpleErrorReporter()
    try expect(
      reporter.renderError(error),
      file: file,
      line: line,
      function: function
    ) == reporter.renderError(expectedError)
  }
}

final class EnvironmentBaseAndChildTemplateTests: XCTestCase {
  var environment = Environment(loader: ExampleLoader())
  var childTemplate: Template = ""
  var baseTemplate: Template = ""

  override func setUp() {
    super.setUp()

    let path = Path(#file as String) + ".." + "fixtures"
    let loader = FileSystemLoader(paths: [path])
    environment = Environment(loader: loader)
    childTemplate = ""
    baseTemplate = ""
  }

  func testSyntaxErrorInBaseTemplate() throws {
    childTemplate = try environment.loadTemplate(name: "invalid-child-super.html")
    baseTemplate = try environment.loadTemplate(name: "invalid-base.html")

    try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
                    childToken: "extends \"invalid-base.html\"",
                    baseToken: "target|unknown")
  }

  func testRuntimeErrorInBaseTemplate() throws {
    let filterExtension = Extension()
    filterExtension.registerFilter("unknown") {  (_: Any?) in
      throw TemplateSyntaxError("filter error")
    }
    environment.extensions += [filterExtension]

    childTemplate = try environment.loadTemplate(name: "invalid-child-super.html")
    baseTemplate = try environment.loadTemplate(name: "invalid-base.html")

    try expectError(reason: "filter error",
                    childToken: "extends \"invalid-base.html\"",
                    baseToken: "target|unknown")
  }

  func testSyntaxErrorInChildTemplate() throws {
    childTemplate = Template(
      templateString: """
      {% extends "base.html" %}
      {% block body %}Child {{ target|unknown }}{% endblock %}
      """,
      environment: environment,
      name: nil
    )

    try expectError(reason: "Unknown filter 'unknown'. Found similar filters: 'uppercase'.",
                    childToken: "target|unknown",
                    baseToken: nil)
  }

  func testRuntimeErrorInChildTemplate() throws {
    let filterExtension = Extension()
    filterExtension.registerFilter("unknown") {  (_: Any?) in
      throw TemplateSyntaxError("filter error")
    }
    environment.extensions += [filterExtension]

    childTemplate = Template(
      templateString: """
      {% extends "base.html" %}
      {% block body %}Child {{ target|unknown }}{% endblock %}
      """,
      environment: environment,
      name: nil
    )

    try expectError(reason: "filter error",
                    childToken: "target|unknown",
                    baseToken: nil)
  }

  private func expectError(
    reason: String,
    childToken: String,
    baseToken: String?,
    file: String = #file,
    line: Int = #line,
    function: String = #function
  ) throws {
    var expectedError = expectedSyntaxError(token: childToken, template: childTemplate, description: reason)
    if let baseToken = baseToken {
      expectedError.stackTrace = [
        expectedSyntaxError(
          token: baseToken,
          template: baseTemplate,
          description: reason
        ).token
      ].compactMap { $0 }
    }
    let error = try expect(
      self.environment.render(template: self.childTemplate, context: ["target": "World"]),
      file: file,
      line: line,
      function: function
    ).toThrow() as TemplateSyntaxError
    let reporter = SimpleErrorReporter()
    try expect(
      reporter.renderError(error),
      file: file,
      line: line,
      function: function
    ) == reporter.renderError(expectedError)
  }
}

extension Expectation {
  @discardableResult
  func toThrow<T: Error>() throws -> T {
    var thrownError: Error?

    do {
      _ = try expression()
    } catch {
      thrownError = error
    }

    if let thrownError = thrownError {
      if let thrownError = thrownError as? T {
        return thrownError
      } else {
        throw failure("\(thrownError) is not \(T.self)")
      }
    } else {
      throw failure("expression did not throw an error")
    }
  }
}

extension XCTestCase {
  func expectedSyntaxError(token: String, template: Template, description: String) -> TemplateSyntaxError {
    guard let range = template.templateString.range(of: token) else {
      fatalError("Can't find '\(token)' in '\(template)'")
    }
    let lexer = Lexer(templateString: template.templateString)
    let location = lexer.rangeLocation(range)
    let sourceMap = SourceMap(filename: template.name, location: location)
    let token = Token.block(value: token, at: sourceMap)
    return TemplateSyntaxError(reason: description, token: token, stackTrace: [])
  }
}

private class ExampleLoader: Loader {
  func loadTemplate(name: String, environment: Environment) throws -> Template {
    if name == "example.html" {
      return Template(templateString: "Hello World!", environment: environment, name: name)
    }

    throw TemplateDoesNotExist(templateNames: [name], loader: self)
  }
}

private class CustomTemplate: Template {
  // swiftlint:disable discouraged_optional_collection
  override func render(_ dictionary: [String: Any]? = nil) throws -> String {
    return "here"
  }
}