UndoManager = require 'undo-manager'
Buffer = require 'text-buffer'
Range = require 'range'

describe "UndoManager", ->
  [buffer, undoManager] = []

  beforeEach ->
    buffer = new Buffer(require.resolve('fixtures/sample.js'))
    undoManager = buffer.undoManager

  afterEach ->
    buffer.destroy()

  describe ".undo()", ->
    it "undoes the last change", ->
      buffer.change(new Range([0, 5], [0, 9]), '')
      buffer.insert([0, 6], 'h')
      buffer.insert([0, 10], 'y')
      expect(buffer.lineForRow(0)).toContain 'qshorty'

      undoManager.undo()
      expect(buffer.lineForRow(0)).toContain 'qshort'
      expect(buffer.lineForRow(0)).not.toContain 'qshorty'

      undoManager.undo()
      expect(buffer.lineForRow(0)).toContain 'qsort'

      undoManager.undo()
      expect(buffer.lineForRow(0)).toContain 'quicksort'

    it "does not throw an exception when there is nothing to undo", ->
      undoManager.undo()

  describe ".redo()", ->
    beforeEach ->
      buffer.change(new Range([0, 5], [0, 9]), '')
      buffer.insert([0, 6], 'h')
      buffer.insert([0, 10], 'y')
      undoManager.undo()
      undoManager.undo()
      expect(buffer.lineForRow(0)).toContain 'qsort'

    it "redoes the last undone change", ->
      undoManager.redo()
      expect(buffer.lineForRow(0)).toContain 'qshort'

      undoManager.redo()
      expect(buffer.lineForRow(0)).toContain 'qshorty'

      undoManager.undo()
      expect(buffer.lineForRow(0)).toContain 'qshort'

    it "does not throw an exception when there is nothing to redo", ->
      undoManager.redo()
      undoManager.redo()
      undoManager.redo()

    it "discards the redo history when there is a new change following an undo", ->
      buffer.insert([0, 6], 'p')
      expect(buffer.getText()).toContain 'qsport'

      undoManager.redo()
      expect(buffer.getText()).toContain 'qsport'

  describe "transaction methods", ->
    describe "transact()", ->
      beforeEach ->
        buffer.setText('')

      it "starts a transaction that can be committed later", ->
        buffer.append('1')
        undoManager.transact()
        buffer.append('2')
        buffer.append('3')
        undoManager.commit()
        buffer.append('4')

        expect(buffer.getText()).toBe '1234'
        undoManager.undo()
        expect(buffer.getText()).toBe '123'
        undoManager.undo()
        expect(buffer.getText()).toBe '1'
        undoManager.redo()
        expect(buffer.getText()).toBe '123'

      it "starts a transaction that can be aborted later", ->
        buffer.append('1')
        buffer.append('2')

        undoManager.transact()

        buffer.append('3')
        buffer.append('4')
        expect(buffer.getText()).toBe '1234'

        undoManager.abort()
        expect(buffer.getText()).toBe '12'

        undoManager.undo()
        expect(buffer.getText()).toBe '1'

        undoManager.redo()
        expect(buffer.getText()).toBe '12'

        undoManager.redo()
        expect(buffer.getText()).toBe '12'

    describe "commit", ->
      it "throws an exception if there is no current transaction", ->
        expect(-> buffer.commit()).toThrow()

      it "does not record empty transactions", ->
        buffer.insert([0,0], "foo")
        undoManager.transact()
        undoManager.commit()
        undoManager.undo()
        expect(buffer.lineForRow(0)).not.toContain("foo")

    describe "abort", ->
      it "does not affect the undo stack when the current transaction is empty", ->
        buffer.setText('')
        buffer.append('1')
        buffer.transact()
        buffer.abort()
        expect(buffer.getText()).toBe '1'
        buffer.undo()
        expect(buffer.getText()).toBe ''

      it "throws an exception if there is no current transaction", ->
        expect(-> buffer.abort()).toThrow()

  describe "exception handling", ->
    describe "when a `do` operation throws an exception", ->
      it "clears the stack", ->
        spyOn(console, 'error')
        buffer.setText("word")
        buffer.insert([0,0], "1")
        expect(->
          undoManager.pushOperation(do: -> throw new Error("I'm a bad do operation"))
        ).toThrow("I'm a bad do operation")

        undoManager.undo()
        expect(buffer.lineForRow(0)).toBe "1word"

    describe "when an `undo` operation throws an exception", ->
      it "clears the stack", ->
        spyOn(console, 'error')
        buffer.setText("word")
        buffer.insert([0,0], "1")
        undoManager.pushOperation(undo: -> throw new Error("I'm a bad undo operation"))
        expect(-> undoManager.undo()).toThrow("I'm a bad undo operation")
        expect(buffer.lineForRow(0)).toBe "1word"

    describe "when an `redo` operation throws an exception", ->
      it "clears the stack", ->
        spyOn(console, 'error')
        buffer.setText("word")
        buffer.insert([0,0], "1")
        undoManager.pushOperation(redo: -> throw new Error("I'm a bad redo operation"))
        undoManager.undo()
        expect(-> undoManager.redo()).toThrow("I'm a bad redo operation")
        expect(buffer.lineForRow(0)).toBe "1word"