local protocol = require 'vim.lsp.protocol'

-- Logs to $NVIM_LOG_FILE.
--
-- TODO(justinmk): remove after https://github.com/neovim/neovim/pull/7062
local function log(loglevel, area, msg)
  vim.fn.writefile({ string.format('%s %s: %s', loglevel, area, msg) }, vim.env.NVIM_LOG_FILE, 'a')
end

local function message_parts(sep, ...)
  local parts = {}
  for i = 1, select('#', ...) do
    local arg = select(i, ...)
    if arg ~= nil then
      table.insert(parts, arg)
    end
  end
  return table.concat(parts, sep)
end

-- Assert utility methods

local function assert_eq(a, b, ...)
  if not vim.deep_equal(a, b) then
    error(
      message_parts(
        ': ',
        ...,
        'assert_eq failed',
        string.format(
          'left == %q, right == %q',
          table.concat(vim.split(vim.inspect(a), '\n'), ''),
          table.concat(vim.split(vim.inspect(b), '\n'), '')
        )
      )
    )
  end
end

local function format_message_with_content_length(encoded_message)
  return table.concat {
    'Content-Length: ',
    tostring(#encoded_message),
    '\r\n\r\n',
    encoded_message,
  }
end

local function read_message()
  local line = io.read('*l')
  local length = line:lower():match('content%-length:%s*(%d+)')
  return vim.json.decode(io.read(2 + length):sub(2))
end

local function send(payload)
  io.stdout:write(format_message_with_content_length(vim.json.encode(payload)))
end

local function respond(id, err, result)
  assert(type(id) == 'number', 'id must be a number')
  send { jsonrpc = '2.0', id = id, error = err, result = result }
end

local function notify(method, params)
  assert(type(method) == 'string', 'method must be a string')
  send { method = method, params = params or {} }
end

local function expect_notification(method, params, ...)
  local message = read_message()
  assert_eq(method, message.method, ..., 'expect_notification', 'method')
  if params then
    assert_eq(params, message.params, ..., 'expect_notification', method, 'params')
    assert_eq(
      { jsonrpc = '2.0', method = method, params = params },
      message,
      ...,
      'expect_notification',
      'message'
    )
  end
end

local function expect_request(method, handler, ...)
  local req = read_message()
  assert_eq(method, req.method, ..., 'expect_request', 'method')
  local err, result = handler(req.params)
  respond(req.id, err, result)
end

io.stderr:setvbuf('no')

local function skeleton(config)
  local on_init = assert(config.on_init)
  local body = assert(config.body)
  expect_request('initialize', function(params)
    return nil, on_init(params)
  end)
  expect_notification('initialized', {})
  body()
  expect_request('shutdown', function()
    return nil, {}
  end)
  expect_notification('exit', nil)
end

-- The actual tests.

local tests = {}

function tests.basic_init()
  skeleton {
    on_init = function(params)
      assert_eq(params.workDoneToken, '1')
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.None,
        },
      }
    end,
    body = function()
      notify('test')
    end,
  }
end

function tests.basic_init_did_change_configuration()
  skeleton({
    on_init = function(_)
      return {
        capabilities = {},
      }
    end,
    body = function()
      expect_notification('workspace/didChangeConfiguration', { settings = { dummy = 1 } })
    end,
  })
end

function tests.check_workspace_configuration()
  skeleton {
    on_init = function(_params)
      return { capabilities = {} }
    end,
    body = function()
      notify('start')
      notify('workspace/configuration', {
        items = {
          { section = 'testSetting1' },
          { section = 'testSetting2' },
          { section = 'test.Setting3' },
          { section = 'test.Setting4' },
        },
      })
      expect_notification('workspace/configuration', { true, false, 'nested', vim.NIL })
      notify('shutdown')
    end,
  }
end

function tests.prepare_rename_nil()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          renameProvider = {
            prepareProvider = true,
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/prepareRename', function()
        return nil, nil
      end)
      notify('shutdown')
    end,
  }
end

function tests.prepare_rename_placeholder()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          renameProvider = {
            prepareProvider = true,
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/prepareRename', function()
        return nil, { placeholder = 'placeholder' }
      end)
      expect_request('textDocument/rename', function(params)
        assert_eq(params.newName, 'renameto')
        return nil, nil
      end)
      notify('shutdown')
    end,
  }
end

function tests.prepare_rename_range()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          renameProvider = {
            prepareProvider = true,
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/prepareRename', function()
        return nil,
          {
            start = { line = 1, character = 8 },
            ['end'] = { line = 1, character = 12 },
          }
      end)
      expect_request('textDocument/rename', function(params)
        assert_eq(params.newName, 'renameto')
        return nil, nil
      end)
      notify('shutdown')
    end,
  }
end

function tests.prepare_rename_error()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          renameProvider = {
            prepareProvider = true,
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/prepareRename', function()
        return {}, nil
      end)
      notify('shutdown')
    end,
  }
end

function tests.basic_check_capabilities()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Full,
          codeLensProvider = false,
        },
      }
    end,
    body = function() end,
  }
end

function tests.text_document_save_did_open()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          textDocumentSync = {
            save = true,
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didClose')
      expect_notification('textDocument/didOpen')
      expect_notification('textDocument/didSave')
      notify('shutdown')
    end,
  }
end

function tests.text_document_sync_save_bool()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          textDocumentSync = {
            save = true,
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didSave', { textDocument = { uri = 'file://' } })
      notify('shutdown')
    end,
  }
end

function tests.text_document_sync_save_includeText()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          textDocumentSync = {
            save = {
              includeText = true,
            },
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didSave', {
        textDocument = {
          uri = 'file://',
        },
        text = 'help me\n',
      })
      notify('shutdown')
    end,
  }
end

function tests.capabilities_for_client_supports_method()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Full,
          completionProvider = true,
          hoverProvider = true,
          renameProvider = false,
          definitionProvider = false,
          referencesProvider = false,
          codeLensProvider = { resolveProvider = true },
        },
      }
    end,
    body = function() end,
  }
end

function tests.check_forward_request_cancelled()
  skeleton {
    on_init = function(_)
      return { capabilities = {} }
    end,
    body = function()
      expect_request('error_code_test', function()
        return { code = -32800 }, nil, { method = 'error_code_test', client_id = 1 }
      end)
      notify('finish')
    end,
  }
end

function tests.check_forward_content_modified()
  skeleton {
    on_init = function(_)
      return { capabilities = {} }
    end,
    body = function()
      expect_request('error_code_test', function()
        return { code = -32801 }, nil, { method = 'error_code_test', client_id = 1 }
      end)
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.check_forward_server_cancelled()
  skeleton {
    on_init = function()
      return { capabilities = {} }
    end,
    body = function()
      expect_request('error_code_test', function()
        return { code = -32802 }, nil, { method = 'error_code_test', client_id = 1 }
      end)
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.check_pending_request_tracked()
  skeleton {
    on_init = function(_)
      return { capabilities = {} }
    end,
    body = function()
      local msg = read_message()
      assert_eq('slow_request', msg.method)
      expect_notification('release')
      respond(msg.id, nil, {})
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.check_cancel_request_tracked()
  skeleton {
    on_init = function(_)
      return { capabilities = {} }
    end,
    body = function()
      local msg = read_message()
      assert_eq('slow_request', msg.method)
      expect_notification('$/cancelRequest', { id = msg.id })
      expect_notification('release')
      respond(msg.id, { code = -32800 }, nil)
      notify('finish')
    end,
  }
end

function tests.check_tracked_requests_cleared()
  skeleton {
    on_init = function(_)
      return { capabilities = {} }
    end,
    body = function()
      local msg = read_message()
      assert_eq('slow_request', msg.method)
      expect_notification('$/cancelRequest', { id = msg.id })
      expect_notification('release')
      respond(msg.id, nil, {})
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.basic_finish()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Full,
        },
      }
    end,
    body = function()
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.basic_check_buffer_open()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Full,
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didOpen', {
        textDocument = {
          languageId = '',
          text = table.concat({ 'testing', '123' }, '\n') .. '\n',
          uri = 'file://',
          version = 0,
        },
      })
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.basic_check_buffer_open_and_change()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Full,
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didOpen', {
        textDocument = {
          languageId = '',
          text = table.concat({ 'testing', '123' }, '\n') .. '\n',
          uri = 'file://',
          version = 0,
        },
      })
      expect_notification('textDocument/didChange', {
        textDocument = {
          uri = 'file://',
          version = 3,
        },
        contentChanges = {
          { text = table.concat({ 'testing', 'boop' }, '\n') .. '\n' },
        },
      })
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.basic_check_buffer_open_and_change_noeol()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Full,
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didOpen', {
        textDocument = {
          languageId = '',
          text = table.concat({ 'testing', '123' }, '\n'),
          uri = 'file://',
          version = 0,
        },
      })
      expect_notification('textDocument/didChange', {
        textDocument = {
          uri = 'file://',
          version = 3,
        },
        contentChanges = {
          { text = table.concat({ 'testing', 'boop' }, '\n') },
        },
      })
      expect_notification('finish')
      notify('finish')
    end,
  }
end
function tests.basic_check_buffer_open_and_change_multi()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Full,
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didOpen', {
        textDocument = {
          languageId = '',
          text = table.concat({ 'testing', '123' }, '\n') .. '\n',
          uri = 'file://',
          version = 0,
        },
      })
      expect_notification('textDocument/didChange', {
        textDocument = {
          uri = 'file://',
          version = 3,
        },
        contentChanges = {
          { text = table.concat({ 'testing', '321' }, '\n') .. '\n' },
        },
      })
      expect_notification('textDocument/didChange', {
        textDocument = {
          uri = 'file://',
          version = 4,
        },
        contentChanges = {
          { text = table.concat({ 'testing', 'boop' }, '\n') .. '\n' },
        },
      })
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.basic_check_buffer_open_and_change_multi_and_close()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Full,
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didOpen', {
        textDocument = {
          languageId = '',
          text = table.concat({ 'testing', '123' }, '\n') .. '\n',
          uri = 'file://',
          version = 0,
        },
      })
      expect_notification('textDocument/didChange', {
        textDocument = {
          uri = 'file://',
          version = 3,
        },
        contentChanges = {
          { text = table.concat({ 'testing', '321' }, '\n') .. '\n' },
        },
      })
      expect_notification('textDocument/didChange', {
        textDocument = {
          uri = 'file://',
          version = 4,
        },
        contentChanges = {
          { text = table.concat({ 'testing', 'boop' }, '\n') .. '\n' },
        },
      })
      expect_notification('textDocument/didClose', {
        textDocument = {
          uri = 'file://',
        },
      })
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.basic_check_buffer_open_and_change_incremental()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = {
            openClose = true,
            change = protocol.TextDocumentSyncKind.Incremental,
            willSave = true,
            willSaveWaitUntil = true,
            save = {
              includeText = true,
            },
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didOpen', {
        textDocument = {
          languageId = '',
          text = table.concat({ 'testing', '123' }, '\n') .. '\n',
          uri = 'file://',
          version = 0,
        },
      })
      expect_notification('textDocument/didChange', {
        textDocument = {
          uri = 'file://',
          version = 3,
        },
        contentChanges = {
          {
            range = {
              start = { line = 1, character = 3 },
              ['end'] = { line = 1, character = 3 },
            },
            rangeLength = 0,
            text = 'boop',
          },
        },
      })
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.basic_check_buffer_open_and_change_incremental_editing()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          textDocumentSync = protocol.TextDocumentSyncKind.Incremental,
        },
      }
    end,
    body = function()
      notify('start')
      expect_notification('textDocument/didOpen', {
        textDocument = {
          languageId = '',
          text = table.concat({ 'testing', '123' }, '\n'),
          uri = 'file://',
          version = 0,
        },
      })
      expect_notification('textDocument/didChange', {
        textDocument = {
          uri = 'file://',
          version = 3,
        },
        contentChanges = {
          {
            range = {
              start = { line = 0, character = 0 },
              ['end'] = { line = 1, character = 0 },
            },
            rangeLength = 4,
            text = 'testing\n\n',
          },
        },
      })
      expect_notification('finish')
      notify('finish')
    end,
  }
end

function tests.invalid_header()
  io.stdout:write('Content-length: \r\n')
end

function tests.decode_nil()
  skeleton {
    on_init = function(_)
      return { capabilities = {} }
    end,
    body = function()
      notify('start')
      notify('workspace/executeCommand', {
        arguments = { 'EXTRACT_METHOD', { metadata = { field = vim.NIL } }, 3, 0, 6123, vim.NIL },
        command = 'refactor.perform',
        title = 'EXTRACT_METHOD',
      })
      notify('finish')
    end,
  }
end

function tests.code_action_with_resolve()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          codeActionProvider = {
            resolveProvider = true,
          },
        },
      }
    end,
    body = function()
      notify('start')
      local cmd = {
        title = 'Command 1',
        command = 'dummy1',
      }
      expect_request('textDocument/codeAction', function()
        return nil, { cmd }
      end)
      expect_request('codeAction/resolve', function()
        return nil, cmd
      end)
      notify('shutdown')
    end,
  }
end

function tests.code_action_server_side_command()
  skeleton({
    on_init = function()
      return {
        capabilities = {
          codeActionProvider = {
            resolveProvider = false,
          },
          executeCommandProvider = {
            commands = { 'dummy1' },
          },
        },
      }
    end,
    body = function()
      notify('start')
      local cmd = {
        title = 'Command 1',
        command = 'dummy1',
      }
      expect_request('textDocument/codeAction', function()
        return nil, { cmd }
      end)
      expect_request('workspace/executeCommand', function()
        return nil, cmd
      end)
      notify('shutdown')
    end,
  })
end

function tests.code_action_filter()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          codeActionProvider = {
            resolveProvider = false,
          },
        },
      }
    end,
    body = function()
      notify('start')
      local action = {
        title = 'Action 1',
        command = 'command',
      }
      local preferred_action = {
        title = 'Action 2',
        isPreferred = true,
        command = 'preferred_command',
      }
      local type_annotate_action = {
        title = 'Action 3',
        kind = 'type-annotate',
        command = 'type_annotate_command',
      }
      local type_annotate_foo_action = {
        title = 'Action 4',
        kind = 'type-annotate.foo',
        command = 'type_annotate_foo_command',
      }
      expect_request('textDocument/codeAction', function()
        return nil, { action, preferred_action, type_annotate_action, type_annotate_foo_action }
      end)
      expect_request('textDocument/codeAction', function()
        return nil, { action, preferred_action, type_annotate_action, type_annotate_foo_action }
      end)
      notify('shutdown')
    end,
  }
end

function tests.clientside_commands()
  skeleton {
    on_init = function()
      return {
        capabilities = {},
      }
    end,
    body = function()
      notify('start')
      notify('shutdown')
    end,
  }
end

function tests.codelens_refresh_lock()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          codeLensProvider = { resolveProvider = true },
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/codeLens', function()
        return { code = -32002, message = 'ServerNotInitialized' }, nil
      end)
      expect_request('textDocument/codeLens', function()
        local lenses = {
          {
            range = {
              start = { line = 0, character = 0 },
              ['end'] = { line = 0, character = 3 },
            },
            command = { title = 'Lens1', command = 'Dummy' },
          },
        }
        return nil, lenses
      end)
      expect_request('textDocument/codeLens', function()
        local lenses = {
          {
            range = {
              start = { line = 0, character = 0 },
              ['end'] = { line = 0, character = 3 },
            },
            command = { title = 'Lens2', command = 'Dummy' },
          },
        }
        return nil, lenses
      end)
      notify('shutdown')
    end,
  }
end

function tests.basic_formatting()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          documentFormattingProvider = true,
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/formatting', function()
        return nil, {}
      end)
      notify('shutdown')
    end,
  }
end

function tests.range_formatting()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          documentFormattingProvider = true,
          documentRangeFormattingProvider = true,
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/rangeFormatting', function()
        return nil, {}
      end)
      notify('shutdown')
    end,
  }
end

function tests.ranges_formatting()
  skeleton {
    on_init = function()
      return {
        capabilities = {
          documentFormattingProvider = true,
          documentRangeFormattingProvider = {
            rangesSupport = true,
          },
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/rangesFormatting', function()
        return nil, {}
      end)
      notify('shutdown')
    end,
  }
end

function tests.set_defaults_all_capabilities()
  skeleton {
    on_init = function(_)
      return {
        capabilities = {
          definitionProvider = true,
          completionProvider = true,
          documentRangeFormattingProvider = true,
          hoverProvider = true,
        },
      }
    end,
    body = function()
      notify('test')
    end,
  }
end

function tests.inlay_hint()
  skeleton {
    on_init = function(params)
      local expected_capabilities = protocol.make_client_capabilities()
      assert_eq(params.capabilities, expected_capabilities)
      return {
        capabilities = {
          inlayHintProvider = true,
        },
      }
    end,
    body = function()
      notify('start')
      expect_request('textDocument/inlayHint', function()
        return nil, {}
      end)
      expect_notification('finish')
      notify('finish')
    end,
  }
end

-- Tests will be indexed by test_name
local test_name = arg[1]
local timeout = arg[2]
assert(type(test_name) == 'string', 'test_name must be specified as first arg.')

local kill_timer = assert(vim.uv.new_timer())
kill_timer:start(timeout or 1e3, 0, function()
  kill_timer:stop()
  kill_timer:close()
  log('ERROR', 'LSP', 'TIMEOUT')
  io.stderr:write('TIMEOUT')
  os.exit(100)
end)

local status, err = pcall(assert(tests[test_name], 'Test not found'))
kill_timer:stop()
kill_timer:close()
if not status then
  log('ERROR', 'LSP', tostring(err))
  io.stderr:write(err)
  vim.cmd [[101cquit]]
end