Multiline comment and suggestion (#66)

This MR adds the ability to leave multi-line comments and suggested changes to an MR. The features are only supported for `diffview` because we plan to deprecate `delta` as a reviewer soon.

lua/gitlab/reviewer/diffview.lua

@@ -1,22 +1,23 @@
 -- This Module contains all of the code specific to the Diffview reviewer.
-local state           = require("gitlab.state")
+local u = require("gitlab.utils")
+local state = require("gitlab.state")
 local async_ok, async = pcall(require, "diffview.async")
 
-local M               = {
+local M = {
   bufnr = nil,
-  tabnr = nil
+  tabnr = nil,
 }
 
 -- Public Functions
 -- These functions are exposed externally and are used
 -- when the reviewer is consumed by other code. They must follow the specification
 -- outlined in the reviewer/init.lua file
-M.open                = function()
+M.open = function()
   vim.api.nvim_command(string.format("DiffviewOpen %s", state.INFO.target_branch))
   M.tabnr = vim.api.nvim_get_current_tabpage()
 end
 
-M.jump                = function(file_name, new_line, old_line)
+M.jump = function(file_name, new_line, old_line)
   if M.tabnr == nil then
     vim.notify("Can't jump to Diffvew. Is it open?", vim.log.levels.ERROR)
     return
@@ -49,12 +50,25 @@ M.jump                = function(file_name, new_line, old_line)
   end
 end
 
-M.get_location        = function()
-  if M.tabnr == nil then return nil, nil, "Diffview reviewer must be initialized first" end
+---Get the location of a line within the diffview. If range is specified, then also the location
+---of the lines in range.
+---@param range LineRange | nil Line range to get location for
+---@return ReviewerInfo | nil nil is returned only if error was encountered
+M.get_location = function(range)
+  if M.tabnr == nil then
+    vim.notify("Diffview reviewer must be initialized first")
+    return
+  end
   local bufnr = vim.api.nvim_get_current_buf()
+  local current_line = vim.api.nvim_win_get_cursor(0)[1]
+
   -- check if we are in the diffview tab
   local tabnr = vim.api.nvim_get_current_tabpage()
-  if tabnr ~= M.tabnr then return nil, nil, "Line location can only be determined within reviewer window" end
+  if tabnr ~= M.tabnr then
+    vim.notify("Line location can only be determined within reviewer window")
+    return
+  end
+
   -- check if we are in the diffview buffer
   local view = require("diffview.lib").get_current_view()
   if view == nil then
@@ -62,18 +76,81 @@ M.get_location        = function()
     return
   end
   local layout = view.cur_layout
-  local file_name = nil
-  local current_line_changes = nil
+  local result = {}
+  local type
+  local is_new
   if layout.a.file.bufnr == bufnr then
-    file_name = layout.a.file.path
-    current_line_changes = { new_line = nil, old_line = vim.api.nvim_win_get_cursor(0)[1] }
-    return file_name, current_line_changes
+    result.file_name = layout.a.file.path
+    result.old_line = current_line
+    type = "old"
+    is_new = false
   elseif layout.b.file.bufnr == bufnr then
-    file_name = layout.b.file.path
-    current_line_changes = { new_line = vim.api.nvim_win_get_cursor(0)[1], old_line = nil }
-    return file_name, current_line_changes
+    result.file_name = layout.b.file.path
+    result.new_line = current_line
+    type = "new"
+    is_new = true
+  else
+    vim.notify("Line location can only be determined within reviewer window")
+    return
   end
-  return nil, nil, "Line location can only be determined within reviewer window"
+
+  local hunks = u.parse_hunk_headers(result.file_name, state.INFO.target_branch)
+  if hunks == nil then
+    vim.notify("Could not parse hunks", vim.log.levels.ERROR)
+    return
+  end
+
+  local current_line_info
+  if is_new then
+    current_line_info = u.get_lines_from_hunks(hunks, result.new_line, is_new)
+  else
+    current_line_info = u.get_lines_from_hunks(hunks, result.old_line, is_new)
+  end
+
+  -- If single line comment is outside of changed lines then we need to specify both new line and old line
+  -- otherwise the API returns error.
+  -- https://docs.gitlab.com/ee/api/discussions.html#create-a-new-thread-in-the-merge-request-diff
+  if not current_line_info.in_hunk then
+    result.old_line = current_line_info.old_line
+    result.new_line = current_line_info.new_line
+  end
+
+  if range == nil then
+    return result
+  end
+
+  result.range_info = { start = {}, ["end"] = {} }
+  if current_line == range.start_line then
+    result.range_info.start.old_line = current_line_info.old_line
+    result.range_info.start.new_line = current_line_info.new_line
+    result.range_info.start.type = type
+  else
+    local start_line_info = u.get_lines_from_hunks(hunks, range.start_line, is_new)
+    result.range_info.start.old_line = start_line_info.old_line
+    result.range_info.start.new_line = start_line_info.new_line
+    result.range_info.start.type = type
+  end
+
+  if current_line == range.end_line then
+    result.range_info["end"].old_line = current_line_info.old_line
+    result.range_info["end"].new_line = current_line_info.new_line
+    result.range_info["end"].type = type
+  else
+    local end_line_info = u.get_lines_from_hunks(hunks, range.end_line, is_new)
+    result.range_info["end"].old_line = end_line_info.old_line
+    result.range_info["end"].new_line = end_line_info.new_line
+    result.range_info["end"].type = type
+  end
+
+  return result
+end
+
+---Return content between start_line and end_line
+---@param start_line integer
+---@param end_line integer
+---@return string[]
+M.get_lines = function(start_line, end_line)
+  return vim.api.nvim_buf_get_lines(0, start_line - 1, end_line, false)
 end
 
 return M