-- Test suite for testing interactions with the incremental sync algorithms powering the LSP client
local helpers = require('test.functional.helpers')(after_each)

local meths = helpers.meths
local clear = helpers.clear
local eq = helpers.eq
local exec_lua = helpers.exec_lua
local feed = helpers.feed

before_each(function ()
  clear()
  exec_lua [[
    local evname = ...
    local sync = require('vim.lsp.sync')
    local events = {}
    local buffer_cache = {}

    -- local format_line_ending = {
    --   ["unix"] = '\n',
    --   ["dos"] = '\r\n',
    --   ["mac"] = '\r',
    -- }

    -- local line_ending = format_line_ending[vim.api.nvim_buf_get_option(0, 'fileformat')]


    function test_register(bufnr, id, offset_encoding, line_ending)
      local curr_lines
      local prev_lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, true)

      local function callback(_, bufnr, changedtick, firstline, lastline, new_lastline)
        if test_unreg == id then
          return true
        end

        local curr_lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, true)
        local incremental_change = sync.compute_diff(
          prev_lines, curr_lines, firstline, lastline, new_lastline, offset_encoding, line_ending)

        table.insert(events, incremental_change)
        prev_lines = curr_lines
      end
      local opts = {on_lines=callback, on_detach=callback, on_reload=callback}
      vim.api.nvim_buf_attach(bufnr, false, opts)
    end

    function get_events()
      local ret_events = events
      events = {}
      return ret_events
    end
  ]]
end)

local function test_edit(prev_buffer, edit_operations, expected_text_changes, offset_encoding, line_ending)
  offset_encoding = offset_encoding or 'utf-16'
  line_ending = line_ending or '\n'

  meths.buf_set_lines(0, 0, -1, true, prev_buffer)
  exec_lua("return test_register(...)", 0, "test1", offset_encoding, line_ending)

  for _, edit in ipairs(edit_operations) do
    feed(edit)
  end
  eq(expected_text_changes, exec_lua("return get_events(...)" ))
  exec_lua("test_unreg = 'test1'")

end

describe('incremental synchronization', function()
  describe('single line edit', function()
    it('inserting a character in an empty buffer', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 0
            },
            ['end'] = {
              character = 0,
              line = 0
            }
          },
          rangeLength = 0,
          text = 'a'
        }
      }
      test_edit({""}, {"ia"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('inserting a character in the middle of a the first line', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 1,
              line = 0
            },
            ['end'] = {
              character = 1,
              line = 0
            }
          },
          rangeLength = 0,
          text = 'a'
        }
      }
      test_edit({"ab"}, {"lia"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('deleting the only character in a buffer', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 0
            },
            ['end'] = {
              character = 1,
              line = 0
            }
          },
          rangeLength = 1,
          text = ''
        }
      }
      test_edit({"a"}, {"x"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('deleting a character in the middle of the line', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 1,
              line = 0
            },
            ['end'] = {
              character = 2,
              line = 0
            }
          },
          rangeLength = 1,
          text = ''
        }
      }
      test_edit({"abc"}, {"lx"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('replacing a character', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 0
            },
            ['end'] = {
              character = 1,
              line = 0
            }
          },
          rangeLength = 1,
          text = 'b'
        }
      }
      test_edit({"a"}, {"rb"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('deleting a line', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 0
            },
            ['end'] = {
              character = 0,
              line = 1
            }
          },
          rangeLength = 12,
          text = ''
        }
      }
      test_edit({"hello world"}, {"dd"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('deleting an empty line', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 1
            },
            ['end'] = {
              character = 0,
              line = 2
            }
          },
          rangeLength = 1,
          text = ''
        }
      }
      test_edit({"hello world", ""}, {"jdd"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('adding a line', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 1
            },
            ['end'] = {
              character = 0,
              line = 1
            }
          },
          rangeLength = 0,
          text = 'hello world\n'
        }
      }
      test_edit({"hello world"}, {"yyp"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('adding an empty line', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 1
            },
            ['end'] = {
              character = 0,
              line = 1
            }
          },
          rangeLength = 0,
          text = '\n'
        }
      }
      test_edit({"hello world"}, {"o"}, expected_text_changes, 'utf-16', '\n')
    end)
  end)
  describe('multi line edit', function()
    it('deletion and insertion', function()
      local expected_text_changes = {
        -- delete "_fsda" from end of line 1
        {
          range = {
            ['start'] = {
              character = 4,
              line = 1
            },
            ['end'] = {
              character = 9,
              line = 1
            }
          },
          rangeLength = 5,
          text = ''
        },
        -- delete "hello world\n" from line 2
        {
          range = {
            ['start'] = {
              character = 0,
              line = 2
            },
            ['end'] = {
              character = 0,
              line = 3
            }
          },
          rangeLength = 12,
          text = ''
        },
        -- delete "1234" from beginning of line 2
        {
          range = {
            ['start'] = {
              character = 0,
              line = 2
            },
            ['end'] = {
              character = 4,
              line = 2
            }
          },
          rangeLength = 4,
          text = ''
        },
        -- add " asdf" to end of line 1
        {
          range = {
            ['start'] = {
              character = 4,
              line = 1
            },
            ['end'] = {
              character = 4,
              line = 1
            }
          },
          rangeLength = 0,
          text = ' asdf'
        },
        -- delete " asdf\n" from line 2
        {
          range = {
            ['start'] = {
              character = 0,
              line = 2
            },
            ['end'] = {
              character = 0,
              line = 3
            }
          },
          rangeLength = 6,
          text = ''
        },
        -- undo entire deletion
        {
          range = {
            ['start'] = {
              character = 4,
              line = 1
            },
            ['end'] = {
              character = 9,
              line = 1
            }
          },
          rangeLength = 5,
          text = "_fdsa\nhello world\n1234 asdf"
        },
        -- redo entire deletion
        {
          range = {
            ['start'] = {
              character = 4,
              line = 1
            },
            ['end'] = {
              character = 9,
              line = 3
            }
          },
          rangeLength = 27,
          text = ' asdf'
        },
      }
      local original_lines = {
        "\\begin{document}",
        "test_fdsa",
        "hello world",
        "1234 asdf",
        "\\end{document}"
      }
      test_edit(original_lines, {"jf_vejjbhhdu<C-R>"}, expected_text_changes, 'utf-16', '\n')
    end)
  end)

  describe('multi-operation edits', function()
    it('mult-line substitution', function()
      local expected_text_changes = {
        {
          range = {
             ["end"] = {
               character = 11,
               line = 2 },
             ["start"] = {
               character = 10,
               line = 2 } },
          rangeLength = 1,
          text = '',
        },{
          range = {
            ["end"] = {
              character = 10,
              line = 2 },
            start = {
              character = 10,
              line = 2 } },
          rangeLength = 0,
          text = '2',
        },{
          range = {
            ["end"] = {
              character = 11,
              line = 3 },
            ["start"] = {
              character = 10,
              line = 3 } },
          rangeLength = 1,
          text = ''
        },{
          range = {
            ['end'] = {
              character = 10,
              line = 3 },
            ['start'] = {
              character = 10,
              line = 3 } },
          rangeLength = 0,
          text = '3' },
        {
          range = {
            ['end'] = {
              character = 0,
              line = 3 },
            ['start'] = {
              character = 12,
              line = 2 } },
          rangeLength = 1,
          text = '\n'
        }
      }
      local original_lines = {
        "\\begin{document}",
        "\\section*{1}",
        "\\section*{1}",
        "\\section*{1}",
        "\\end{document}"
      }
      test_edit(original_lines, {"3gg$h<C-V>jg<C-A>"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('join and undo', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 11,
              line = 0
            },
            ['end'] = {
              character = 11,
              line = 0
            }
          },
          rangeLength = 0,
          text = ' test3'
        },{
          range = {
            ['start'] = {
              character = 0,
              line = 1
            },
            ['end'] = {
              character = 0,
              line = 2
            }
          },
          rangeLength = 6,
          text = ''
        },{
          range = {
            ['start'] = {
              character = 11,
              line = 0
            },
            ['end'] = {
              character = 17,
              line = 0
            }
          },
          rangeLength = 6,
          text = '\ntest3'
        },
      }
      test_edit({"test1 test2", "test3"}, {"J", "u"}, expected_text_changes, 'utf-16', '\n')
    end)
  end)

  describe('multi-byte edits', function()
    it('deleting a multibyte character', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 0
            },
            ['end'] = {
              character = 2,
              line = 0
            }
          },
          rangeLength = 2,
          text = ''
        }
      }
      test_edit({"🔥"}, {"x"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('replacing a multibyte character with matching prefix', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 1
            },
            ['end'] = {
              character = 1,
              line = 1
            }
          },
          rangeLength = 1,
          text = '⟩'
        }
      }
      -- ⟨ is e29fa8, ⟩ is e29fa9
      local original_lines = {
        "\\begin{document}",
        "⟨",
        "\\end{document}",
      }
      test_edit(original_lines, {"jr⟩"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('replacing a multibyte character with matching suffix', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 1
            },
            ['end'] = {
              character = 1,
              line = 1
            }
          },
          rangeLength = 1,
          text = 'ḟ'
        }
      }
      -- ฟ is e0b89f, ḟ is e1b89f
      local original_lines = {
        "\\begin{document}",
        "ฟ",
        "\\end{document}",
      }
      test_edit(original_lines, {"jrḟ"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('inserting before a multibyte character', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 1
            },
            ['end'] = {
              character = 0,
              line = 1
            }
          },
          rangeLength = 0,
          text = ' '
        }
      }
      local original_lines = {
        "\\begin{document}",
        "→",
        "\\end{document}",
      }
      test_edit(original_lines, {"ji "}, expected_text_changes, 'utf-16', '\n')
    end)
    it('deleting a multibyte character from a long line', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 85,
              line = 1
            },
            ['end'] = {
              character = 86,
              line = 1
            }
          },
          rangeLength = 1,
          text = ''
        }
      }
      local original_lines = {
        "\\begin{document}",
        "→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→→",
        "\\end{document}",
      }
      test_edit(original_lines, {"jx"}, expected_text_changes, 'utf-16', '\n')
    end)
    it('deleting multiple lines containing multibyte characters', function()
      local expected_text_changes = {
        {
          range = {
            ['start'] = {
              character = 0,
              line = 1
            },
            ['end'] = {
              character = 0,
              line = 3
            }
          },
          --utf 16 len of 🔥 is 2
          rangeLength = 8,
          text = ''
        }
      }
      test_edit({"a🔥", "b🔥", "c🔥", "d🔥"}, {"j2dd"}, expected_text_changes, 'utf-16', '\n')
    end)
  end)
end)

-- TODO(mjlbach): Add additional tests
-- deleting single lone line
-- 2 lines -> 2 line delete -> undo -> redo
-- describe('future tests', function()
--   -- This test is currently wrong, ask bjorn why dd on an empty line triggers on_lines
--   it('deleting an empty line', function()
--     local expected_text_changes = {{ }}
--     test_edit({""}, {"ggdd"}, expected_text_changes, 'utf-16', '\n')
--   end)
-- end)
