require_relative "./helper"
require_relative "../lib/dimapa"

class DiffTest < Minitest::Test
  def setup
    @dmp = DiMaPa.new
  end

  def test_diff_common_prefix
    # Detect any common prefix.
    # Null case.
    assert_equal(0, @dmp.diff_common_prefix("abc", "xyz"))

    # Non-null case.
    assert_equal(4, @dmp.diff_common_prefix("1234abcdef", "1234xyz"))

    # Whole case.
    assert_equal(4, @dmp.diff_common_prefix("1234", "1234xyz"))
  end

  def test_diff_common_suffix
    # Detect any common suffix.
    # Null case.
    assert_equal(0, @dmp.diff_common_suffix("abc", "xyz"))

    # Non-null case.
    assert_equal(4, @dmp.diff_common_suffix("abcdef1234", "xyz1234"))

    # Whole case.
    assert_equal(4, @dmp.diff_common_suffix("1234", "xyz1234"))
  end

  def test_diff_common_overlap
    # Detect any suffix/prefix overlap.
    # Null case.
    assert_equal(0, @dmp.diff_common_overlap("", "abcd"))

    # Whole case.
    assert_equal(3, @dmp.diff_common_overlap("abc", "abcd"))

    # No overlap.
    assert_equal(0, @dmp.diff_common_overlap("123456", "abcd"))

    # Overlap.
    assert_equal(3, @dmp.diff_common_overlap("123456xxx", "xxxabcd"))

    # Unicode.
    # Some overly clever languages (C#) may treat ligatures as equal to their
    # component letters.  E.g. U+FB01 == 'fi'
    assert_equal(0, @dmp.diff_common_overlap("fi", '\ufb01i'))
  end

  def test_diff_half_match
    # Detect a halfmatch.
    @dmp.diff_timeout = 1
    # No match.
    assert_nil(@dmp.diff_half_match("1234567890", "abcdef"))

    assert_nil(@dmp.diff_half_match("12345", "23"))

    # Single Match.
    assert_equal(
      ["12", "90", "a", "z", "345678"],
      @dmp.diff_half_match("1234567890", "a345678z")
    )

    assert_equal(
      ["a", "z", "12", "90", "345678"],
      @dmp.diff_half_match("a345678z", "1234567890")
    )

    assert_equal(
      ["abc", "z", "1234", "0", "56789"],
      @dmp.diff_half_match("abc56789z", "1234567890")
    )

    assert_equal(
      ["a", "xyz", "1", "7890", "23456"],
      @dmp.diff_half_match("a23456xyz", "1234567890")
    )

    # Multiple Matches.
    assert_equal(
      ["12123", "123121", "a", "z", "1234123451234"],
      @dmp.diff_half_match("121231234123451234123121", "a1234123451234z")
    )

    assert_equal(
      ["", "-=-=-=-=-=", "x", "", "x-=-=-=-=-=-=-="],
      @dmp.diff_half_match("x-=-=-=-=-=-=-=-=-=-=-=-=", "xx-=-=-=-=-=-=-=")
    )

    assert_equal(
      ["-=-=-=-=-=", "", "", "y", "-=-=-=-=-=-=-=y"],
      @dmp.diff_half_match("-=-=-=-=-=-=-=-=-=-=-=-=y", "-=-=-=-=-=-=-=yy")
    )

    # Non-optimal halfmatch.
    # Optimal diff would be -q+x=H-i+e=lloHe+Hu=llo-Hew+y
    # not -qHillo+x=HelloHe-w+Hulloy
    assert_equal(
      ["qHillo", "w", "x", "Hulloy", "HelloHe"],
      @dmp.diff_half_match("qHilloHelloHew", "xHelloHeHulloy")
    )

    # Optimal no halfmatch.
    @dmp.diff_timeout = 0
    assert_nil(@dmp.diff_half_match("qHilloHelloHew", "xHelloHeHulloy"))
  end

  def test_diff_lines_to_chars
    # Convert lines down to characters.
    assert_equal(
      ["\x01\x02\x01", "\x02\x01\x02", ["", "alpha\n", "beta\n"]],
      @dmp.diff_lines_to_chars("alpha\nbeta\nalpha\n", "beta\nalpha\nbeta\n")
    )

    assert_equal(
      ["", "\x01\x02\x03\x03", ["", "alpha\r\n", "beta\r\n", "\r\n"]],
      @dmp.diff_lines_to_chars("", "alpha\r\nbeta\r\n\r\n\r\n")
    )

    assert_equal(
      ["\x01", "\x02", ["", "a", "b"]],
      @dmp.diff_lines_to_chars("a", "b")
    )

    # More than 256 to reveal any 8-bit limitations.
    n = 300
    line_list = (1..n).map { |x| x.to_s + "\n" }
    char_list = (1..n).map { |x| x.chr(Encoding::UTF_8) }
    assert_equal(n, line_list.length)
    lines = line_list.join
    chars = char_list.join
    assert_equal(n, chars.length)
    line_list.unshift("")
    assert_equal([chars, "", line_list], @dmp.diff_lines_to_chars(lines, ""))
  end

  def test_diff_chars_to_lines
    # Convert chars up to lines.
    diffs = [[:equal, "\x01\x02\x01"], [:insert, "\x02\x01\x02"]]
    @dmp.diff_chars_to_lines(diffs, ["", "alpha\n", "beta\n"])
    assert_equal(
      [[:equal, "alpha\nbeta\nalpha\n"], [:insert, "beta\nalpha\nbeta\n"]],
      diffs
    )

    # More than 256 to reveal any 8-bit limitations.
    n = 300
    line_list = (1..n).map { |x| x.to_s + "\n" }
    char_list = (1..n).map { |x| x.chr(Encoding::UTF_8) }
    assert_equal(n, line_list.length)
    lines = line_list.join
    chars = char_list.join
    assert_equal(n, chars.length)
    line_list.unshift("")

    diffs = [[:delete, chars]]
    @dmp.diff_chars_to_lines(diffs, line_list)
    assert_equal([[:delete, lines]], diffs)
  end

  def test_diff_cleanup_merge
    # Cleanup a messy diff.
    # Null case.
    diffs = []
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([], diffs)

    # No change case.
    diffs = [[:equal, "a"], [:delete, "b"], [:insert, "c"]]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:equal, "a"], [:delete, "b"], [:insert, "c"]], diffs)

    # Merge equalities.
    diffs = [[:equal, "a"], [:equal, "b"], [:equal, "c"]]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:equal, "abc"]], diffs)

    # Merge deletions.
    diffs = [[:delete, "a"], [:delete, "b"], [:delete, "c"]]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:delete, "abc"]], diffs)

    # Merge insertions.
    diffs = [[:insert, "a"], [:insert, "b"], [:insert, "c"]]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:insert, "abc"]], diffs)

    # Merge interweave.
    diffs = [
      [:delete, "a"], [:insert, "b"], [:delete, "c"],
      [:insert, "d"], [:equal, "e"], [:equal, "f"]
    ]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:delete, "ac"], [:insert, "bd"], [:equal, "ef"]], diffs)

    # Prefix and suffix detection.
    diffs = [[:delete, "a"], [:insert, "abc"], [:delete, "dc"]]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal(
      [[:equal, "a"], [:delete, "d"], [:insert, "b"], [:equal, "c"]],
      diffs
    )

    # Prefix and suffix detection with equalities.
    diffs = [
      [:equal, "x"], [:delete, "a"], [:insert, "abc"],
      [:delete, "dc"], [:equal, "y"]
    ]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal(
      [[:equal, "xa"], [:delete, "d"], [:insert, "b"], [:equal, "cy"]],
      diffs
    )

    # Slide edit left.
    diffs = [[:equal, "a"], [:insert, "ba"], [:equal, "c"]]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:insert, "ab"], [:equal, "ac"]], diffs)

    # Slide edit right.
    diffs = [[:equal, "c"], [:insert, "ab"], [:equal, "a"]]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:equal, "ca"], [:insert, "ba"]], diffs)

    # Slide edit left recursive.
    diffs = [
      [:equal, "a"], [:delete, "b"], [:equal, "c"],
      [:delete, "ac"], [:equal, "x"]
    ]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:delete, "abc"], [:equal, "acx"]], diffs)

    # Slide edit right recursive.
    diffs = [
      [:equal, "x"], [:delete, "ca"], [:equal, "c"],
      [:delete, "b"], [:equal, "a"]
    ]
    @dmp.diff_cleanup_merge(diffs)
    assert_equal([[:equal, "xca"], [:delete, "cba"]], diffs)
  end

  def test_diff_cleanup_semantic_lossless
    # Slide diffs to match logical boundaries.
    # Null case.
    diffs = []
    @dmp.diff_cleanup_semantic_lossless(diffs)
    assert_equal([], diffs)

    # Blank lines.
    diffs = [
      [:equal, "AAA\r\n\r\nBBB"],
      [:insert, "\r\nDDD\r\n\r\nBBB"],
      [:equal, "\r\nEEE"]
    ]
    @dmp.diff_cleanup_semantic_lossless(diffs)
    assert_equal([
      [:equal, "AAA\r\n\r\n"],
      [:insert, "BBB\r\nDDD\r\n\r\n"],
      [:equal, "BBB\r\nEEE"]
    ],
      diffs)

    # Line boundaries.
    diffs = [[:equal, "AAA\r\nBBB"], [:insert, " DDD\r\nBBB"], [:equal, " EEE"]]
    @dmp.diff_cleanup_semantic_lossless(diffs)
    assert_equal(
      [[:equal, "AAA\r\n"], [:insert, "BBB DDD\r\n"], [:equal, "BBB EEE"]],
      diffs
    )

    # Word boundaries.
    diffs = [[:equal, "The c"], [:insert, "ow and the c"], [:equal, "at."]]
    @dmp.diff_cleanup_semantic_lossless(diffs)
    assert_equal(
      [[:equal, "The "], [:insert, "cow and the "], [:equal, "cat."]],
      diffs
    )

    # Alphanumeric boundaries.
    diffs = [[:equal, "The-c"], [:insert, "ow-and-the-c"], [:equal, "at."]]
    @dmp.diff_cleanup_semantic_lossless(diffs)
    assert_equal(
      [[:equal, "The-"], [:insert, "cow-and-the-"], [:equal, "cat."]],
      diffs
    )

    # Hitting the start.
    diffs = [[:equal, "a"], [:delete, "a"], [:equal, "ax"]]
    @dmp.diff_cleanup_semantic_lossless(diffs)
    assert_equal([[:delete, "a"], [:equal, "aax"]], diffs)

    # Hitting the end.
    diffs = [[:equal, "xa"], [:delete, "a"], [:equal, "a"]]
    @dmp.diff_cleanup_semantic_lossless(diffs)
    assert_equal([[:equal, "xaa"], [:delete, "a"]], diffs)
  end

  def test_diff_cleanup_semantic
    # Cleanup semantically trivial equalities.
    # Null case.
    diffs = []
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal([], diffs)

    # No elimination #1.
    diffs = [[:delete, "ab"], [:insert, "cd"], [:equal, "12"], [:delete, "e"]]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal(
      [[:delete, "ab"], [:insert, "cd"], [:equal, "12"], [:delete, "e"]],
      diffs
    )

    # No elimination #2.
    diffs = [
      [:delete, "abc"], [:insert, "ABC"],
      [:equal, "1234"], [:delete, "wxyz"]
    ]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal(
      [[:delete, "abc"], [:insert, "ABC"], [:equal, "1234"], [:delete, "wxyz"]],
      diffs
    )

    # Simple elimination.
    diffs = [[:delete, "a"], [:equal, "b"], [:delete, "c"]]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal([[:delete, "abc"], [:insert, "b"]], diffs)

    # Backpass elimination.
    diffs = [
      [:delete, "ab"], [:equal, "cd"], [:delete, "e"],
      [:equal, "f"], [:insert, "g"]
    ]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal([[:delete, "abcdef"], [:insert, "cdfg"]], diffs)

    # Multiple eliminations.
    diffs = [
      [:insert, "1"], [:equal, "A"], [:delete, "B"],
      [:insert, "2"], [:equal, "_"], [:insert, "1"],
      [:equal, "A"], [:delete, "B"], [:insert, "2"]
    ]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal([[:delete, "AB_AB"], [:insert, "1A2_1A2"]], diffs)

    # Word boundaries.
    diffs = [[:equal, "The c"], [:delete, "ow and the c"], [:equal, "at."]]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal(
      [[:equal, "The "], [:delete, "cow and the "], [:equal, "cat."]],
      diffs
    )

    # No overlap elimination.
    diffs = [[:delete, "abcxx"], [:insert, "xxdef"]]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal([[:delete, "abcxx"], [:insert, "xxdef"]], diffs)

    # Overlap elimination.
    diffs = [[:delete, "abcxxx"], [:insert, "xxxdef"]]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal([[:delete, "abc"], [:equal, "xxx"], [:insert, "def"]], diffs)

    # Two overlap eliminations.
    diffs = [
      [:delete, "abcd1212"], [:insert, "1212efghi"], [:equal, "----"],
      [:delete, "A3"], [:insert, "3BC"]
    ]
    @dmp.diff_cleanup_semantic(diffs)
    assert_equal([
      [:delete, "abcd"], [:equal, "1212"], [:insert, "efghi"],
      [:equal, "----"], [:delete, "A"], [:equal, "3"], [:insert, "BC"]
    ],
      diffs)
  end

  def test_diff_cleanup_efficiency
    # Cleanup operationally trivial equalities.
    @dmp.diff_edit_cost = 4
    # Null case.
    diffs = []
    @dmp.diff_cleanup_efficiency(diffs)
    assert_equal([], diffs)

    # No elimination.
    diffs = [
      [:delete, "ab"], [:insert, "12"], [:equal, "wxyz"],
      [:delete, "cd"], [:insert, "34"]
    ]
    @dmp.diff_cleanup_efficiency(diffs)
    assert_equal([
      [:delete, "ab"], [:insert, "12"], [:equal, "wxyz"],
      [:delete, "cd"], [:insert, "34"]
    ],
      diffs)

    # Four-edit elimination.
    diffs = [
      [:delete, "ab"], [:insert, "12"], [:equal, "xyz"],
      [:delete, "cd"], [:insert, "34"]
    ]
    @dmp.diff_cleanup_efficiency(diffs)
    assert_equal([[:delete, "abxyzcd"], [:insert, "12xyz34"]], diffs)

    # Three-edit elimination.
    diffs = [[:insert, "12"], [:equal, "x"], [:delete, "cd"], [:insert, "34"]]
    @dmp.diff_cleanup_efficiency(diffs)
    assert_equal([[:delete, "xcd"], [:insert, "12x34"]], diffs)

    # Backpass elimination.
    diffs = [
      [:delete, "ab"], [:insert, "12"], [:equal, "xy"], [:insert, "34"],
      [:equal, "z"], [:delete, "cd"], [:insert, "56"]
    ]
    @dmp.diff_cleanup_efficiency(diffs)
    assert_equal([[:delete, "abxyzcd"], [:insert, "12xy34z56"]], diffs)

    # High cost elimination.
    @dmp.diff_edit_cost = 5
    diffs = [
      [:delete, "ab"], [:insert, "12"], [:equal, "wxyz"],
      [:delete, "cd"], [:insert, "34"]
    ]
    @dmp.diff_cleanup_efficiency(diffs)
    assert_equal([[:delete, "abwxyzcd"], [:insert, "12wxyz34"]], diffs)
    @dmp.diff_edit_cost = 4
  end

  def test_diff_pretty_html
    # Pretty print.
    diffs = [[:equal, 'a\n'], [:delete, "<B>b</B>"], [:insert, "c&d"]]
    assert_equal(
      '<span>a&para;<br></span><del style="background:#ffe6e6;">&lt;B&gt;' \
      'b&lt;/B&gt;</del><ins style="background:#e6ffe6;">c&amp;d</ins>',
      @dmp.diff_pretty_html(diffs)
    )
  end

  def test_diff_text
    # Compute the source and destination texts.
    diffs = [
      [:equal, "jump"], [:delete, "s"], [:insert, "ed"], [:equal, " over "],
      [:delete, "the"], [:insert, "a"], [:equal, " lazy"]
    ]
    assert_equal("jumps over the lazy", @dmp.diff_text1(diffs))
    assert_equal("jumped over a lazy", @dmp.diff_text2(diffs))
  end

  def test_diff_delta
    # Convert a diff into delta string.
    diffs = [
      [:equal, "jump"], [:delete, "s"], [:insert, "ed"], [:equal, " over "],
      [:delete, "the"], [:insert, "a"], [:equal, " lazy"], [:insert, "old dog"]
    ]
    text1 = @dmp.diff_text1(diffs)
    assert_equal("jumps over the lazy", text1)

    delta = @dmp.diff_to_delta(diffs)
    assert_equal("=4\t-1\t+ed\t=6\t-3\t+a\t=5\t+old dog", delta)

    # Convert delta string into a diff.
    assert_equal(diffs, @dmp.diff_from_delta(text1, delta))

    # Generates error (19 != 20).
    assert_raises ArgumentError do
      @dmp.diff_from_delta(text1 + "x", delta)
    end

    # Generates error (19 != 18)
    assert_raises ArgumentError do
      @dmp.diff_from_delta(text1[1..-1], delta)
    end

    # Test deltas with special characters.
    diffs = [
      [:equal, "\u0680 \x00 \t %"],
      [:delete, "\u0681 \x01 \n ^"],
      [:insert, "\u0682 \x02 \\ |"]
    ]
    text1 = @dmp.diff_text1(diffs)
    assert_equal("\u0680 \x00 \t %\u0681 \x01 \n ^", text1)

    delta = @dmp.diff_to_delta(diffs)
    assert_equal("=7\t-7\t+%DA%82 %02 %5C %7C", delta)

    # Convert delta string into a diff.
    assert_equal(diffs, @dmp.diff_from_delta(text1, delta))

    # Verify pool of unchanged characters.
    diffs = [[:insert, "A-Z a-z 0-9 - _ . ! ~ * \' ( )  / ? : @ & = + $ , # "]]
    text2 = @dmp.diff_text2(diffs)
    assert_equal("A-Z a-z 0-9 - _ . ! ~ * \' ( )  / ? : @ & = + $ , # ", text2)

    delta = @dmp.diff_to_delta(diffs)
    assert_equal("+A-Z a-z 0-9 - _ . ! ~ * \' ( )  / ? : @ & = + $ , # ", delta)

    # Convert delta string into a diff.
    assert_equal(diffs, @dmp.diff_from_delta("", delta))
  end

  def test_diff_x_index
    # Translate a location in text1 to text2.
    # Translation on equality.
    diffs = [[:delete, "a"], [:insert, "1234"], [:equal, "xyz"]]
    assert_equal(5, @dmp.diff_x_index(diffs, 2))

    # Translation on deletion.
    diffs = [[:equal, "a"], [:delete, "1234"], [:equal, "xyz"]]
    assert_equal(1, @dmp.diff_x_index(diffs, 3))
  end

  def test_diff_levenshtein
    # Levenshtein with trailing equality.
    diffs = [[:delete, "abc"], [:insert, "1234"], [:equal, "xyz"]]
    assert_equal(4, @dmp.diff_levenshtein(diffs))
    # Levenshtein with leading equality.
    diffs = [[:equal, "xyz"], [:delete, "abc"], [:insert, "1234"]]
    assert_equal(4, @dmp.diff_levenshtein(diffs))
    # Levenshtein with middle equality.
    diffs = [[:delete, "abc"], [:equal, "xyz"], [:insert, "1234"]]
    assert_equal(7, @dmp.diff_levenshtein(diffs))
  end

  def test_diff_bisect
    # Normal.
    a = "cat"
    b = "map"
    # Since the resulting diff hasn't been normalized, it would be ok if
    # the insertion and deletion pairs are swapped.
    # If the order changes, tweak this test as required.
    diffs = [
      [:delete, "c"], [:insert, "m"], [:equal, "a"],
      [:delete, "t"], [:insert, "p"]
    ]
    assert_equal(diffs, @dmp.diff_bisect(a, b, nil))

    # Timeout.
    assert_equal(
      [[:delete, "cat"], [:insert, "map"]],
      @dmp.diff_bisect(a, b, Time.now - 1)
    )
  end

  def test_diff_main
    # Perform a trivial diff.
    # Null case.
    assert_equal([], @dmp.diff_main("", "", false))

    # Equality.
    assert_equal([[:equal, "abc"]], @dmp.diff_main("abc", "abc", false))

    # Simple insertion.
    assert_equal(
      [[:equal, "ab"], [:insert, "123"], [:equal, "c"]],
      @dmp.diff_main("abc", "ab123c", false)
    )

    # Simple deletion.
    assert_equal(
      [[:equal, "a"], [:delete, "123"], [:equal, "bc"]],
      @dmp.diff_main("a123bc", "abc", false)
    )

    # Two insertions.
    assert_equal([
      [:equal, "a"], [:insert, "123"], [:equal, "b"],
      [:insert, "456"], [:equal, "c"]
    ],
      @dmp.diff_main("abc", "a123b456c", false))

    # Two deletions.
    assert_equal([
      [:equal, "a"], [:delete, "123"], [:equal, "b"],
      [:delete, "456"], [:equal, "c"]
    ],
      @dmp.diff_main("a123b456c", "abc", false))

    # Perform a real diff.
    # Switch off the timeout.
    @dmp.diff_timeout = 0
    # Simple cases.
    assert_equal(
      [[:delete, "a"], [:insert, "b"]],
      @dmp.diff_main("a", "b", false)
    )

    assert_equal([
      [:delete, "Apple"], [:insert, "Banana"], [:equal, "s are a"],
      [:insert, "lso"], [:equal, " fruit."]
    ],
      @dmp.diff_main("Apples are a fruit.", "Bananas are also fruit.", false))

    assert_equal([
      [:delete, "a"], [:insert, "\u0680"], [:equal, "x"],
      [:delete, "\t"], [:insert, "\0"]
    ],
      @dmp.diff_main("ax\t", "\u0680x\0", false))

    # Overlaps.
    assert_equal([
      [:delete, "1"], [:equal, "a"], [:delete, "y"],
      [:equal, "b"], [:delete, "2"], [:insert, "xab"]
    ],
      @dmp.diff_main("1ayb2", "abxab", false))

    assert_equal(
      [[:insert, "xaxcx"], [:equal, "abc"], [:delete, "y"]],
      @dmp.diff_main("abcy", "xaxcxabc", false)
    )

    assert_equal([
      [:delete, "ABCD"], [:equal, "a"], [:delete, "="], [:insert, "-"],
      [:equal, "bcd"], [:delete, "="], [:insert, "-"],
      [:equal, "efghijklmnopqrs"], [:delete, "EFGHIJKLMNOefg"]
    ],
      @dmp.diff_main(
        "ABCDa=bcd=efghijklmnopqrsEFGHIJKLMNOefg",
        "a-bcd-efghijklmnopqrs",
        false
      ))

    # Large equality.
    assert_equal(
      [
        [:insert, " "], [:equal, "a"], [:insert, "nd"],
        [:equal, " [[Pennsylvania]]"], [:delete, " and [[New"]
      ],
      @dmp.diff_main(
        "a [[Pennsylvania]] and [[New", " and [[Pennsylvania]]", false
      )
    )

    # Timeout.
    @dmp.diff_timeout = 0.1 # 100ms
    a = "`Twas brillig, and the slithy toves\nDid gyre and gimble in the " \
      "wabe:\nAll mimsy were the borogoves,\nAnd the mome raths outgrabe.\n"
    b = "I am the very model of a modern major general,\nI\'ve information " \
      "vegetable, animal, and mineral,\nI know the kings of England, and " \
      "I quote the fights historical,\nFrom Marathon to Waterloo, in " \
      "order categorical.\n"
    # Increase the text lengths by 1024 times to ensure a timeout.
    a *= 1024
    b *= 1024
    start_time = Time.now
    @dmp.diff_main(a, b)
    end_time = Time.now
    # Test that we took at least the timeout period.
    assert_equal(true, @dmp.diff_timeout <= end_time - start_time)
    # Test that we didn't take forever (be forgiving).
    # Theoretically this test could fail very occasionally if the
    # OS task swaps or locks up for a second at the wrong moment.
    assert_equal(true, @dmp.diff_timeout * 1000 * 2 > end_time - start_time)
    @dmp.diff_timeout = 0

    # Test the linemode speedup.
    # Must be long to pass the 100 char cutoff.
    # Simple line-mode.
    a = "1234567890\n1234567890\n1234567890\n1234567890\n1234567890\n" \
      "1234567890\n1234567890\n1234567890\n1234567890\n1234567890\n" \
      "1234567890\n1234567890\n1234567890\n"
    b = "abcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\n" \
      "abcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\nabcdefghij\n" \
      "abcdefghij\nabcdefghij\nabcdefghij\n"
    assert_equal(@dmp.diff_main(a, b, false), @dmp.diff_main(a, b, true))

    # Single line-mode.
    a = "123456789012345678901234567890123456789012345678901234567890" \
      "123456789012345678901234567890123456789012345678901234567890" \
      "1234567890"
    b = "abcdefghijabcdefghijabcdefghijabcdefghijabcdefghijabcdefghij" \
      "abcdefghijabcdefghijabcdefghijabcdefghijabcdefghijabcdefghijabcdefghij"
    assert_equal(@dmp.diff_main(a, b, false), @dmp.diff_main(a, b, true))

    # Overlap line-mode.
    a = "1234567890\n1234567890\n1234567890\n1234567890\n1234567890\n" \
      "1234567890\n1234567890\n1234567890\n1234567890\n1234567890\n" \
      "1234567890\n1234567890\n1234567890\n"
    b = "abcdefghij\n1234567890\n1234567890\n1234567890\nabcdefghij\n" \
      "1234567890\n1234567890\n1234567890\nabcdefghij\n1234567890\n" \
      "1234567890\n1234567890\nabcdefghij\n"

    diffs_linemode = @dmp.diff_main(a, b, false)
    diffs_textmode = @dmp.diff_main(a, b, true)

    assert_equal(
      @dmp.diff_text1(diffs_linemode),
      @dmp.diff_text1(diffs_textmode)
    )

    assert_equal(
      @dmp.diff_text2(diffs_linemode),
      @dmp.diff_text2(diffs_textmode)
    )

    # Test null inputs.
    assert_raises ArgumentError do
      @dmp.diff_main(nil, nil)
    end
  end

  def test_match_alphabet
    # Initialise the bitmasks for Bitap.
    # Unique.
    assert_equal({"a" => 4, "b" => 2, "c" => 1}, @dmp.match_alphabet("abc"))

    # Duplicates.
    assert_equal({"a" => 37, "b" => 18, "c" => 8}, @dmp.match_alphabet("abcaba"))
  end

  def test_match_bitap
    # Bitap algorithm.
    @dmp.match_distance = 100
    @dmp.match_threshold = 0.5
    # Exact matches.
    assert_equal(5, @dmp.match_bitap("abcdefghijk", "fgh", 5))

    assert_equal(5, @dmp.match_bitap("abcdefghijk", "fgh", 0))

    # Fuzzy matches.
    assert_equal(4, @dmp.match_bitap("abcdefghijk", "efxhi", 0))

    assert_equal(2, @dmp.match_bitap("abcdefghijk", "cdefxyhijk", 5))

    assert_equal(-1, @dmp.match_bitap("abcdefghijk", "bxy", 1))

    # Overflow.
    assert_equal(2, @dmp.match_bitap("123456789xx0", "3456789x0", 2))

    # Threshold test.
    @dmp.match_threshold = 0.4
    assert_equal(4, @dmp.match_bitap("abcdefghijk", "efxyhi", 1))

    @dmp.match_threshold = 0.3
    assert_equal(-1, @dmp.match_bitap("abcdefghijk", "efxyhi", 1))

    @dmp.match_threshold = 0.0
    assert_equal(1, @dmp.match_bitap("abcdefghijk", "bcdef", 1))
    @dmp.match_threshold = 0.5

    # Multiple select.
    assert_equal(0, @dmp.match_bitap("abcdexyzabcde", "abccde", 3))

    assert_equal(8, @dmp.match_bitap("abcdexyzabcde", "abccde", 5))

    # Distance test.
    @dmp.match_distance = 10 # Strict location.
    assert_equal(
      -1,
      @dmp.match_bitap("abcdefghijklmnopqrstuvwxyz", "abcdefg", 24)
    )

    assert_equal(
      0,
      @dmp.match_bitap("abcdefghijklmnopqrstuvwxyz", "abcdxxefg", 1)
    )

    @dmp.match_distance = 1000 # Loose location.
    assert_equal(
      0,
      @dmp.match_bitap("abcdefghijklmnopqrstuvwxyz", "abcdefg", 24)
    )
  end

  def test_match_main
    # Full match.
    # Shortcut matches.
    assert_equal(0, @dmp.match_main("abcdef", "abcdef", 1000))

    assert_equal(-1, @dmp.match_main("", "abcdef", 1))

    assert_equal(3, @dmp.match_main("abcdef", "", 3))

    assert_equal(3, @dmp.match_main("abcdef", "de", 3))

    # Beyond end match.
    assert_equal(3, @dmp.match_main("abcdef", "defy", 4))

    # Oversized pattern.
    assert_equal(0, @dmp.match_main("abcdef", "abcdefy", 0))

    # Complex match.
    assert_equal(
      4,
      @dmp.match_main(
        "I am the very model of a modern major general.",
        " that berry ",
        5
      )
    )

    # Test null inputs.
    assert_raises ArgumentError do
      @dmp.match_main(nil, nil, 0)
    end
  end

  # Patch tests

  def test_patch_obj
    # Patch Object.
    p = PatchObj.new
    p.start1 = 20
    p.start2 = 21
    p.length1 = 18
    p.length2 = 17
    p.diffs = [
      [:equal, "jump"],
      [:delete, "s"],
      [:insert, "ed"],
      [:equal, " over "],
      [:delete, "the"],
      [:insert, "a"],
      [:equal, "\nlaz"]
    ]
    strp = p.to_s
    assert_equal(
      "@@ -21,18 +22,17 @@\n jump\n-s\n+ed\n  over \n-the\n+a\n %0Alaz\n",
      strp
    )
  end

  def test_patch_from_text
    assert_equal([], @dmp.patch_from_text(""))

    [
      "@@ -21,18 +22,17 @@\n jump\n-s\n+ed\n  over \n-the\n+a\n %0Alaz\n",
      "@@ -1 +1 @@\n-a\n+b\n",
      "@@ -1 +1 @@\n-a\n+b\n",
      "@@ -0,0 +1,3 @@\n+abc\n"
    ].each do |strp|
      assert_equal(strp, @dmp.patch_from_text(strp).first.to_s)
    end

    # Generates error.
    assert_raises ArgumentError do
      @dmp.patch_from_text('Bad\nPatch\n')
    end
  end

  def test_patch_to_text
    [
      "@@ -21,18 +22,17 @@\n jump\n-s\n+ed\n  over \n-the\n+a\n  laz\n",
      "@@ -1,9 +1,9 @@\n-f\n+F\n oo+fooba\n@@ -7,9 +7,9 @@\n obar\n-,\n+.\n  tes\n"
    ].each do |strp|
      p = @dmp.patch_from_text(strp)
      assert_equal(strp, @dmp.patch_to_text(p))
    end
  end

  def test_patch_add_context
    @dmp.patch_margin = 4
    p = @dmp.patch_from_text("@@ -21,4 +21,10 @@\n-jump\n+somersault\n").first
    @dmp.patch_add_context(p, "The quick brown fox jumps over the lazy dog.")
    assert_equal(
      "@@ -17,12 +17,18 @@\n fox \n-jump\n+somersault\n s ov\n",
      p.to_s
    )

    # Same, but not enough trailing context.
    p = @dmp.patch_from_text("@@ -21,4 +21,10 @@\n-jump\n+somersault\n").first
    @dmp.patch_add_context(p, "The quick brown fox jumps.")
    assert_equal(
      "@@ -17,10 +17,16 @@\n fox \n-jump\n+somersault\n s.\n",
      p.to_s
    )

    # Same, but not enough leading context.
    p = @dmp.patch_from_text("@@ -3 +3,2 @@\n-e\n+at\n").first
    @dmp.patch_add_context(p, "The quick brown fox jumps.")
    assert_equal(
      "@@ -1,7 +1,8 @@\n Th\n-e\n+at\n  qui\n",
      p.to_s
    )

    # Same, but with ambiguity.
    p = @dmp.patch_from_text("@@ -3 +3,2 @@\n-e\n+at\n").first
    @dmp.patch_add_context(
      p,
      "The quick brown fox jumps.  The quick brown fox crashes."
    )

    assert_equal(
      "@@ -1,27 +1,28 @@\n Th\n-e\n+at\n  quick brown fox jumps. \n",
      p.to_s
    )
  end

  def test_patch_make
    # Null case.
    patches = @dmp.patch_make("", "")
    assert_equal("", @dmp.patch_to_text(patches))

    text1 = "The quick brown fox jumps over the lazy dog."
    text2 = "That quick brown fox jumped over a lazy dog."
    # Text2+Text1 inputs.
    expected = "@@ -1,8 +1,7 @@\n Th\n-at\n+e\n  qui\n@@ -21,17 +21,18 " \
      "@@\n jump\n-ed\n+s\n  over \n-a\n+the\n  laz\n"

    # The second patch must be "-21,17 +21,18",
    # not "-22,17 +21,18" due to rolling context
    patches = @dmp.patch_make(text2, text1)
    assert_equal(expected, @dmp.patch_to_text(patches))

    # Text1+Text2 inputs.
    expected = "@@ -1,11 +1,12 @@\n Th\n-e\n+at\n  quick b\n@@ -22,18" \
      " +22,17 @@\n jump\n-s\n+ed\n  over \n-the\n+a\n  laz\n"
    patches = @dmp.patch_make(text1, text2)
    assert_equal(expected, @dmp.patch_to_text(patches))

    # Diff input.
    diffs = @dmp.diff_main(text1, text2, false)
    patches = @dmp.patch_make(diffs)
    assert_equal(expected, @dmp.patch_to_text(patches))

    # Text1+Diff inputs.
    patches = @dmp.patch_make(text1, diffs)
    assert_equal(expected, @dmp.patch_to_text(patches))

    # Text1+Text2+Diff inputs (deprecated)
    patches = @dmp.patch_make(text1, text2, diffs)
    assert_equal(expected, @dmp.patch_to_text(patches))

    # Character encoding.
    patches = @dmp.patch_make(
      '`1234567890-=[]\\;\',./',
      '~!@#$%^&*()_+{}|:"<>?'
    )
    assert_equal(
      "@@ -1,21 +1,21 @@\n-%601234567890-=%5B%5D%5C;\',./\n+~!" \
      "@\#$%25%5E&*()_+%7B%7D%7C:%22%3C%3E?\n",
      @dmp.patch_to_text(patches)
    )

    # Character decoding.
    diffs = [
      [:delete, '`1234567890-=[]\\;\',./'],
      [:insert, '~!@#$%^&*()_+{}|:"<>?']
    ]
    assert_equal(
      diffs,
      @dmp.patch_from_text(
        "@@ -1,21 +1,21 @@\n-%601234567890-=%5B%5D%5C;\',./\n+~!" \
        "@\#$%25%5E&*()_+%7B%7D%7C:%22%3C%3E?\n"
      ).first.diffs
    )

    # Long string with repeats.
    text1 = "abcdef" * 100
    text2 = text1 + "123"
    expected = "@@ -573,28 +573,31 @@\n cdefabcdefabcdefabcdefabcdef\n+123\n"
    patches = @dmp.patch_make(text1, text2)
    assert_equal(expected, @dmp.patch_to_text(patches))

    # Test null inputs.
    assert_raises ArgumentError do
      @dmp.patch_make(nil)
    end
  end

  def test_patch_split_max
    # Assumes that dmp.Match_MaxBits is 32.
    patches = @dmp.patch_make(
      "abcdefghijklmnopqrstuvwxyz01234567890",
      "XabXcdXefXghXijXklXmnXopXqrXstXuvXwxXyzX01X23X45X67X89X0"
    )

    @dmp.patch_split_max(patches)
    assert_equal(
      "@@ -1,32 +1,46 @@\n+X\n ab\n+X\n cd\n+X\n ef\n+X\n gh\n+X\n " \
      "ij\n+X\n kl\n+X\n mn\n+X\n op\n+X\n qr\n+X\n st\n+X\n uv\n+X\n " \
      "wx\n+X\n yz\n+X\n 012345\n@@ -25,13 +39,18 @@\n zX01\n+X\n 23\n+X\n " \
      "45\n+X\n 67\n+X\n 89\n+X\n 0\n",
      @dmp.patch_to_text(patches)
    )

    patches = @dmp.patch_make(
      "abcdef1234567890123456789012345678901234567890" \
      "123456789012345678901234567890uvwxyz",
      "abcdefuvwxyz"
    )

    old_to_text = @dmp.patch_to_text(patches)
    @dmp.patch_split_max(patches)
    assert_equal(old_to_text, @dmp.patch_to_text(patches))

    patches = @dmp.patch_make(
      "1234567890123456789012345678901234567890123456789012345678901234567890",
      "abc"
    )

    @dmp.patch_split_max(patches)
    assert_equal(
      "@@ -1,32 +1,4 @@\n-1234567890123456789012345678\n 9012\n" \
      "@@ -29,32 +1,4 @@\n-9012345678901234567890123456\n 7890\n" \
      "@@ -57,14 +1,3 @@\n-78901234567890\n+abc\n",
      @dmp.patch_to_text(patches)
    )

    patches = @dmp.patch_make(
      "abcdefghij , h : 0 , t : 1 abcdefghij , h : 0 , t : 1 abcdefghij , h : 0 , t : 1",
      "abcdefghij , h : 1 , t : 1 abcdefghij , h : 1 , t : 1 abcdefghij , h : 0 , t : 1"
    )

    @dmp.patch_split_max(patches)
    assert_equal(
      "@@ -2,32 +2,32 @@\n bcdefghij , h : \n-0\n+1\n  , t : 1 abcdef\n" \
      "@@ -29,32 +29,32 @@\n bcdefghij , h : \n-0\n+1\n  , t : 1 abcdef\n",
      @dmp.patch_to_text(patches)
    )
  end

  def test_patch_add_padding
    # Both edges full.
    patches = @dmp.patch_make("", "test")
    assert_equal("@@ -0,0 +1,4 @@\n+test\n", @dmp.patch_to_text(patches))
    @dmp.patch_add_padding(patches)
    assert_equal(
      "@@ -1,8 +1,12 @@\n %01%02%03%04\n+test\n %01%02%03%04\n",
      @dmp.patch_to_text(patches)
    )

    # Both edges partial.
    patches = @dmp.patch_make("XY", "XtestY")
    assert_equal("@@ -1,2 +1,6 @@\n X\n+test\n Y\n", @dmp.patch_to_text(patches))
    @dmp.patch_add_padding(patches)
    assert_equal(
      "@@ -2,8 +2,12 @@\n %02%03%04X\n+test\n Y%01%02%03\n",
      @dmp.patch_to_text(patches)
    )

    # Both edges none.
    patches = @dmp.patch_make("XXXXYYYY", "XXXXtestYYYY")
    assert_equal(
      "@@ -1,8 +1,12 @@\n XXXX\n+test\n YYYY\n",
      @dmp.patch_to_text(patches)
    )
    @dmp.patch_add_padding(patches)
    assert_equal(
      "@@ -5,8 +5,12 @@\n XXXX\n+test\n YYYY\n",
      @dmp.patch_to_text(patches)
    )
  end

  def test_patch_apply
    @dmp.match_distance = 1000
    @dmp.match_threshold = 0.5
    @dmp.patch_delete_threshold = 0.5
    # Null case.
    patches = @dmp.patch_make("", "")
    results = @dmp.patch_apply(patches, "Hello world.")
    assert_equal(["Hello world.", []], results)

    # Exact match.
    patches = @dmp.patch_make(
      "The quick brown fox jumps over the lazy dog.",
      "That quick brown fox jumped over a lazy dog."
    )

    results = @dmp.patch_apply(
      patches,
      "The quick brown fox jumps over the lazy dog."
    )

    assert_equal(
      ["That quick brown fox jumped over a lazy dog.", [true, true]],
      results
    )

    # Partial match.
    results = @dmp.patch_apply(
      patches,
      "The quick red rabbit jumps over the tired tiger."
    )

    assert_equal(
      ["That quick red rabbit jumped over a tired tiger.", [true, true]],
      results
    )

    # Failed match.
    results = @dmp.patch_apply(
      patches,
      "I am the very model of a modern major general."
    )

    assert_equal(
      ["I am the very model of a modern major general.", [false, false]],
      results
    )

    # Big delete, small change.
    patches = @dmp.patch_make(
      "x1234567890123456789012345678901234567890123456789012345678901234567890y",
      "xabcy"
    )

    results = @dmp.patch_apply(
      patches,
      "x123456789012345678901234567890-----++++++++++-----" \
      "123456789012345678901234567890y"
    )

    assert_equal(["xabcy", [true, true]], results)

    # Big delete, big change 1.
    patches = @dmp.patch_make(
      "x1234567890123456789012345678901234567890123456789012345678901234567890y",
      "xabcy"
    )

    results = @dmp.patch_apply(
      patches,
      "x12345678901234567890---------------++++++++++---------------" \
      "12345678901234567890y"
    )

    assert_equal([
      "xabc12345678901234567890---------------++++++++++---------------" \
      "12345678901234567890y",
      [false, true]
    ],
      results)

    # Big delete, big change 2.
    @dmp.patch_delete_threshold = 0.6
    patches = @dmp.patch_make(
      "x1234567890123456789012345678901234567890123456789012345678901234567890y",
      "xabcy"
    )

    results = @dmp.patch_apply(
      patches,
      "x12345678901234567890---------------++++++++++---------------" \
      "12345678901234567890y"
    )

    assert_equal(["xabcy", [true, true]], results)
    @dmp.patch_delete_threshold = 0.5

    # Compensate for failed patch.
    @dmp.match_threshold = 0.0
    @dmp.match_distance = 0
    patches = @dmp.patch_make(
      "abcdefghijklmnopqrstuvwxyz--------------------1234567890",
      "abcXXXXXXXXXXdefghijklmnopqrstuvwxyz--------------------" \
      "1234567YYYYYYYYYY890"
    )

    results = @dmp.patch_apply(
      patches,
      "ABCDEFGHIJKLMNOPQRSTUVWXYZ--------------------1234567890"
    )

    assert_equal([
      "ABCDEFGHIJKLMNOPQRSTUVWXYZ--------------------1234567YYYYYYYYYY890",
      [false, true]
    ],
      results)
    @dmp.match_threshold = 0.5
    @dmp.match_distance = 1000

    # No side effects.
    patches = @dmp.patch_make("", "test")
    patchstr = @dmp.patch_to_text(patches)
    @dmp.patch_apply(patches, "")
    assert_equal(patchstr, @dmp.patch_to_text(patches))

    # No side effects with major delete.
    patches = @dmp.patch_make(
      "The quick brown fox jumps over the lazy dog.",
      "Woof"
    )

    patchstr = @dmp.patch_to_text(patches)
    @dmp.patch_apply(patches, "The quick brown fox jumps over the lazy dog.")
    assert_equal(patchstr, @dmp.patch_to_text(patches))

    # Edge exact match.
    patches = @dmp.patch_make("", "test")
    results = @dmp.patch_apply(patches, "")
    assert_equal(["test", [true]], results)

    # Near edge exact match.
    patches = @dmp.patch_make("XY", "XtestY")
    results = @dmp.patch_apply(patches, "XY")
    assert_equal(["XtestY", [true]], results)

    # Edge partial match.
    patches = @dmp.patch_make("y", "y123")
    results = @dmp.patch_apply(patches, "x")
    assert_equal(["x123", [true]], results)
  end
end