ci: Add release with changelog workflow

Author: kristijanhusak

docs/changelog.org

@@ -0,0 +1,2 @@
+* Changelog
+

scripts/generate_changelog.lua

@@ -0,0 +1,57 @@
+local function populate_section(content, name, list)
+  if #list == 0 then
+    return
+  end
+  content[#content + 1] = '*** ' .. name
+  vim.list_extend(
+    content,
+    vim.tbl_map(function(item)
+      return '- ' .. item
+    end, list)
+  )
+  content[#content + 1] = ''
+end
+local function generate_changelog()
+  local latest_tag = vim.fn.system('git describe --tags `git rev-list --tags --max-count=1`'):gsub('\n', '')
+  local commits = vim.fn.systemlist('git log ' .. latest_tag .. "..master --pretty=format:'%s'")
+  local fixes = {}
+  local features = {}
+  local breaking_changes = {}
+
+  for _, commit in ipairs(commits) do
+    local type = commit:match('^(.-):')
+    if type then
+      type = type
+      local message = vim.trim(commit:sub(#type + 2))
+      if vim.endswith(type, '!') then
+        table.insert(breaking_changes, message)
+      elseif vim.startswith(type, 'fix') then
+        table.insert(fixes, message)
+      elseif vim.startswith(type, 'feat') or vim.startswith(type, 'feature') then
+        table.insert(features, message)
+      end
+    end
+  end
+  local new_tag = arg[1]
+  local changelog = vim.fn.readfile('./docs/changelog.org')
+  local start = { unpack(changelog, 1, 2) }
+  local remaining = { unpack(changelog, 3) }
+
+  local new_content = {
+    '** ' .. new_tag,
+    '- Date: [[' .. os.date('%Y-%m-%d') .. ']]',
+    ('- [[https://github.com/nvim-orgmode/orgmode/compare/%s...%s][Compare]]'):format(latest_tag, new_tag),
+    ('- [[https://github.com/nvim-orgmode/orgmode/releases/tag/%s][Link to release]]'):format(latest_tag),
+    '',
+  }
+  populate_section(new_content, 'Breaking changes', breaking_changes)
+  populate_section(new_content, 'Features', features)
+  populate_section(new_content, 'Bug fixes', fixes)
+
+  local new_changelog = vim.list_extend(start, new_content)
+  new_changelog = vim.list_extend(new_changelog, remaining)
+
+  vim.fn.writefile(new_changelog, './docs/changelog.org')
+end
+
+generate_changelog()