commit e2d177b480ad315b6e43689d0ae8e46d6c39d673
Author: Price Hiller <price@orion-technologies.io>
Date:   Mon Apr 15 06:31:43 2024 -0500

    feat: initial commit

diff --git a/.editorconfig b/.editorconfig
new file mode 100644
index 0000000..9a6cc75
--- /dev/null
+++ b/.editorconfig
@@ -0,0 +1,3 @@
+[*.lua]
+indent_style = space
+indent_size = 2
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..415c879
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,43 @@
+# Compiled Lua sources
+luac.out
+
+# luarocks build files
+*.src.rock
+*.zip
+*.tar.gz
+
+# Object files
+*.o
+*.os
+*.ko
+*.obj
+*.elf
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Libraries
+*.lib
+*.a
+*.la
+*.lo
+*.def
+*.exp
+
+# Shared objects (inc. Windows DLLs)
+*.dll
+*.so
+*.so.*
+*.dylib
+
+# Executables
+*.exe
+*.out
+*.app
+*.i*86
+*.x86_64
+*.hex
+
+# Directory containing testing dependencies downloaded during test run
+.deps/
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..49802b7
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+The MIT Licence
+
+Copyright (c) 2024 Price Hiller
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..ef7ccc6
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,8 @@
+clean:
+	nvim --headless --clean -n -c "lua vim.fn.delete('./tests/.deps', 'rf')" +q
+test:
+	nvim --headless --clean -u tests/test.lua "$(FILE)"
+lint:
+	stylua --check lua/ tests/
+format:
+	stylua lua/ tests/
diff --git a/README.md b/README.md
new file mode 100644
index 0000000..19946a5
--- /dev/null
+++ b/README.md
@@ -0,0 +1,34 @@
+# Virt-Indent.nvim
+
+Add virtual indentation to align content under headlines to their headings.
+
+## Markdown Showcase
+
+_Before:_
+![Before](./assets/before.png)
+
+_After:_
+![After](./assets/after.png)
+
+## Quick Start
+
+### Requirements
+
+- Neovim 0.10.0 or later
+
+### Installation
+
+- [**lazy.nvim**](https://github.com/folke/lazy.nvim)
+  ```lua
+  {
+    "PriceHiller/Virt-Indent.nvim",
+    ft = { "org", "markdown" },
+  }
+  ```
+
+## Credits
+
+This plugin is a module extracted from [nvim-orgmode](https://github.com/nvim-orgmode/orgmode/), specifically its [`virtual-indent`](https://github.com/nvim-orgmode/orgmode/blob/master/lua/orgmode/ui/virtual_indent.lua) module and adds additional support for more filetypes beyond org files.
+
+- [@danilshvalov](https://github.com/danilshvalov), the original creator of some of this code. I ultimately took the existing code he wrote and carried a PR with my own additions to completion and integration into nvim-orgmode.
+- [@kristijanhusak](https://github.com/kristijanhusak), the creator/maintainer of nvim-orgmode. He has done an amazing amount of work on that plugin and much of what was done in this plugin would not have come into being without him.
diff --git a/assets/after.png b/assets/after.png
new file mode 100644
index 0000000..67a4645
Binary files /dev/null and b/assets/after.png differ
diff --git a/assets/before.png b/assets/before.png
new file mode 100644
index 0000000..df42b38
Binary files /dev/null and b/assets/before.png differ
diff --git a/ftplugin/markdown.lua b/ftplugin/markdown.lua
new file mode 100644
index 0000000..b8801b4
--- /dev/null
+++ b/ftplugin/markdown.lua
@@ -0,0 +1 @@
+require("vindent").ftplugin_setup()
diff --git a/ftplugin/org.lua b/ftplugin/org.lua
new file mode 100644
index 0000000..b8801b4
--- /dev/null
+++ b/ftplugin/org.lua
@@ -0,0 +1 @@
+require("vindent").ftplugin_setup()
diff --git a/lua/vindent/indent.lua b/lua/vindent/indent.lua
new file mode 100644
index 0000000..497cc8b
--- /dev/null
+++ b/lua/vindent/indent.lua
@@ -0,0 +1,178 @@
+---@class VirtualIndent
+---@field private _ns_id number extmarks namespace id
+---@field private _bufnr integer Buffer VirtualIndent is attached to
+---@field private _attached boolean Whether or not VirtualIndent is attached for its buffer
+---@field private _bufnrs table<integer, VirtualIndent> Buffers with VirtualIndent attached
+---@field private _watcher_running boolean Whether or not VirtualIndent is reacting to `vim.b.org_indent_mode`
+---@field private _tree_utils table<string, function> Treesitter utilities for the given filetype
+---@field private _fallback_pattern string Pattern to search for if treesitter parser fails
+local VirtualIndent = {
+  _ns_id = vim.api.nvim_create_namespace "VirtIndent",
+  _bufnrs = {},
+}
+VirtualIndent.__index = VirtualIndent
+
+--- Creates a new instance of VirtualIndent for a given buffer or returns the existing instance if
+--- one exists
+---@param bufnr? integer Buffer to use for VirtualIndent when attached
+---@return VirtualIndent?
+function VirtualIndent:new(bufnr)
+  -- TODO: Improve organization of this, ideally should be a separate module that returns these.
+  local ft_settings = {
+    markdown = {
+      utils = require "vindent.treesitter.markdown",
+      fallback_pattern = "^%#+",
+    },
+    org = {
+      utils = require "vindent.treesitter.org",
+      fallback_pattern = "^%*+",
+    },
+  }
+
+  local filetype = vim.api.nvim_get_option_value("filetype", { buf = bufnr }) or ""
+  local ft_setting = ft_settings[filetype]
+  if not ft_setting then
+    return
+  end
+
+  bufnr = bufnr or vim.api.nvim_get_current_buf()
+  if self._bufnrs[bufnr] then
+    return self._bufnrs[bufnr]
+  end
+
+  local this = setmetatable({
+    _bufnr = bufnr,
+    _watcher_running = false,
+    _attached = false,
+    _fallback_pattern = ft_setting.fallback_pattern,
+    _tree_utils = ft_setting.utils,
+  }, self)
+  self._bufnrs[bufnr] = this
+  return this
+end
+
+function VirtualIndent:_delete_old_extmarks(start_line, end_line)
+  local ok, old_extmarks = pcall(
+    vim.api.nvim_buf_get_extmarks,
+    self._bufnr,
+    self._ns_id,
+    { start_line, 0 },
+    { end_line, 0 },
+    { type = "virt_text" }
+  )
+  if not ok then
+    old_extmarks = {}
+  end
+  for _, ext in ipairs(old_extmarks) do
+    vim.api.nvim_buf_del_extmark(self._bufnr, self._ns_id, ext[1])
+  end
+end
+
+function VirtualIndent:_get_indent_size(line, ts_has_errors, ts_fallback_pat)
+  -- If tree has errors, we can't rely on treesitter to get the correct indentation
+  -- Fallback to searching closest headline by checking each previous line
+  if ts_has_errors then
+    local linenr = line
+    while linenr > 0 do
+      local _, level = vim.fn.getline(linenr):find(ts_fallback_pat)
+      if level then
+        -- If the current line is a headline we should return no virtual indentation, otherwise
+        -- return virtual indentation
+        return (linenr == line and 0 or level + 1)
+      end
+      linenr = linenr - 1
+    end
+  end
+
+  local headline = self._tree_utils.closest_headline_node { line + 1, 1 }
+
+  if headline then
+    local headline_line = headline:start()
+
+    if headline_line ~= line then
+      return self._tree_utils.headline_level(headline) + 1
+    end
+  end
+
+  return 0
+end
+
+---@param start_line number start line number to set the indentation, 0-based inclusive
+---@param end_line number end line number to set the indentation, 0-based inclusive
+---@param ignore_ts? boolean whether or not to skip the treesitter start & end lookup
+function VirtualIndent:set_indent(start_line, end_line, ignore_ts)
+  ignore_ts = ignore_ts or false
+  local headline = self._tree_utils.closest_headline_node { start_line + 1, 1 }
+  if headline and not ignore_ts then
+    local parent = headline:parent()
+    if parent then
+      start_line = math.min(parent:start(), start_line)
+      end_line = math.max(parent:end_(), end_line)
+    end
+  end
+  if start_line > 0 then
+    start_line = start_line - 1
+  end
+
+  local node_at_cursor = vim.treesitter.get_node()
+  local ts_has_errors = false
+  if node_at_cursor then
+    ts_has_errors = node_at_cursor:tree():root():has_error()
+  end
+
+  self:_delete_old_extmarks(start_line, end_line)
+  for line = start_line, end_line do
+    local indent = self:_get_indent_size(line, ts_has_errors, self._fallback_pattern)
+
+    if indent > 0 then
+      -- NOTE: `ephemeral = true` is not implemented for `inline` virt_text_pos :(
+      pcall(vim.api.nvim_buf_set_extmark, self._bufnr, self._ns_id, line, 0, {
+        -- HACK: The 'space' character below is not a space, it is actually a "Braille Pattern Blank"
+        -- character, U+2800. This avoids issues with how `indentexpr` is calculated by not using
+        -- spaces (which the `indentexpr` is looking for).
+        virt_text = { { string.rep("⠀", indent), "VirtIndent" } },
+        virt_text_pos = "inline",
+        right_gravity = false,
+        priority = 110,
+      })
+    end
+  end
+end
+
+--- Enables virtual indentation in registered buffer
+function VirtualIndent:attach()
+  if self._attached then
+    return
+  end
+  self:set_indent(0, vim.api.nvim_buf_line_count(self._bufnr) - 1, true)
+
+  vim.api.nvim_buf_attach(self._bufnr, false, {
+    on_lines = function(_, _, _, start_line, _, end_line)
+      if not self._attached then
+        return true
+      end
+
+      vim.schedule(function()
+        self:set_indent(start_line, end_line)
+      end)
+    end,
+    on_reload = function()
+      self:set_indent(0, vim.api.nvim_buf_line_count(self._bufnr) - 1, true)
+    end,
+    on_detach = function(_, bufnr)
+      self:detach()
+      self._bufnrs[bufnr] = nil
+    end,
+  })
+  self._attached = true
+end
+
+function VirtualIndent:detach()
+  if not self._attached then
+    return
+  end
+  self:_delete_old_extmarks(0, vim.api.nvim_buf_line_count(self._bufnr) - 1)
+  self._attached = false
+end
+
+return VirtualIndent
diff --git a/lua/vindent/init.lua b/lua/vindent/init.lua
new file mode 100644
index 0000000..107452b
--- /dev/null
+++ b/lua/vindent/init.lua
@@ -0,0 +1,23 @@
+local M = {}
+
+function M.ftplugin_setup()
+  if vim.b.did_ftplugin then
+    return
+  end
+  vim.b.did_ftplugin = true
+
+  vim.b.vindent_enabled = true
+  local vindent = require("vindent.indent"):new()
+  if vindent then
+    vindent:attach()
+  end
+end
+
+---Gets the current VirtualIndent instance
+---@param buf? number Buffer number or 0 for current buffer
+---@return VirtualIndent? The VirtualIndent instance if it exists
+function M.get_buf_vindent(buf)
+  return require("vindent.indent"):new(buf)
+end
+
+return M
diff --git a/lua/vindent/treesitter/markdown.lua b/lua/vindent/treesitter/markdown.lua
new file mode 100644
index 0000000..c384cc7
--- /dev/null
+++ b/lua/vindent/treesitter/markdown.lua
@@ -0,0 +1,53 @@
+local M = {}
+
+function M.find_headline(node)
+  if node:type() == "atx_heading" then
+    return node
+  end
+
+  if node:type() == "section" then
+    -- The headline is always the first child of a section
+    local child = node:child "atx_heading"
+    if child then
+      return child
+    end
+  end
+
+  if node:parent() then
+    return M.find_headline(node:parent())
+  end
+
+  return nil
+end
+
+function M.headline_level(headline)
+  local heading_content = headline:field "heading_content"
+  if not heading_content or #heading_content == 0 then
+    return 0
+  end
+  local _, level = heading_content[1]:start()
+  return level - 1
+end
+
+function M.get_node_at_cursor(cursor)
+  if not cursor then
+    return vim.treesitter.get_node()
+  end
+
+  return vim.treesitter.get_node {
+    bufnr = 0,
+    pos = { cursor[1] - 1, cursor[2] },
+  }
+end
+
+function M.closest_headline_node(cursor)
+  local node = M.get_node_at_cursor(cursor)
+
+  if not node then
+    return nil
+  end
+
+  return M.find_headline(node)
+end
+
+return M
diff --git a/lua/vindent/treesitter/org.lua b/lua/vindent/treesitter/org.lua
new file mode 100644
index 0000000..b5c6fa5
--- /dev/null
+++ b/lua/vindent/treesitter/org.lua
@@ -0,0 +1,46 @@
+local M = {}
+
+function M.find_headline(node)
+  if node:type() == "headline" then
+    return node
+  end
+
+  if node:type() == "section" then
+    -- The headline is always the first child of a section
+    return node:child("headline")[1]
+  end
+
+  if node:parent() then
+    return M.find_headline(node:parent())
+  end
+
+  return nil
+end
+
+function M.get_node_at_cursor(cursor)
+  if not cursor then
+    return vim.treesitter.get_node()
+  end
+
+  return vim.treesitter.get_node {
+    bufnr = 0,
+    pos = { cursor[1] - 1, cursor[2] },
+  }
+end
+
+function M.headline_level(headline)
+  local _, level = headline:field("stars")[1]:end_()
+  return level + 1
+end
+
+function M.closest_headline_node(cursor)
+  local node = M.get_node_at_cursor(cursor)
+
+  if not node then
+    return nil
+  end
+
+  return M.find_headline(node)
+end
+
+return M
diff --git a/stylua.toml b/stylua.toml
new file mode 100644
index 0000000..5b6fff8
--- /dev/null
+++ b/stylua.toml
@@ -0,0 +1,4 @@
+line_endings = "Unix"
+indent_type = "Spaces"
+indent_width = 2
+no_call_parentheses = true
diff --git a/tests/minimal_init.lua b/tests/minimal_init.lua
new file mode 100644
index 0000000..157c55f
--- /dev/null
+++ b/tests/minimal_init.lua
@@ -0,0 +1,92 @@
+local M = {}
+
+---@class OrgMinPlugin A plugin to download and register on the package path
+---@alias OrgPluginName string The plugin name, will be used as part of the git clone destination
+---@alias OrgPluginUrl string The git url at which a plugin is located, can be a path. See https://git-scm.com/book/en/v2/Git-on-the-Server-The-Protocols for details
+---@alias OrgMinPlugins table<OrgPluginName, OrgPluginUrl>
+
+-- Gets the current directory of this file
+local base_root_path = vim.fn.fnamemodify(debug.getinfo(1, "S").source:sub(2), ":p:h")
+---Gets the root directory of the minimal init and if path is specified appends the given path to the root allowing for
+---subdirectories within the current cwd
+---@param path string? The additional path to append to the root, not required
+---@return string root The root path suffixed with the path provided or an empty suffix if none was given
+function M.root(path)
+  return base_root_path .. "/.deps/" .. (path or "")
+end
+
+---Downloads a plugin from a given url and registers it on the 'runtimepath'
+---@param plugin_name OrgPluginName
+---@param plugin_url OrgPluginUrl
+function M.load_plugin(plugin_name, plugin_url)
+  local package_root = M.root "plugins/"
+  local install_destination = package_root .. plugin_name
+  vim.opt.runtimepath:append(install_destination)
+
+  if not vim.loop.fs_stat(package_root) then
+    vim.fn.mkdir(package_root, "p")
+  end
+
+  -- If the plugin install path already exists, we don't need to clone it again.
+  if not vim.loop.fs_stat(install_destination) then
+    print(string.format('>> Downloading plugin "%s" to "%s"', plugin_name, install_destination))
+    vim.fn.system {
+      "git",
+      "clone",
+      "--depth=1",
+      plugin_url,
+      install_destination,
+    }
+    if vim.v.shell_error > 0 then
+      error(
+        string.format('>> Failed to clone plugin: "%s" to "%s"!', plugin_name, install_destination),
+        vim.log.levels.ERROR
+      )
+    end
+  end
+end
+
+---Do the initial setup. Downloads plugins, ensures the minimal init does not pollute the filesystem by keeping
+---everything self contained to the CWD of the minimal init file. Run prior to running tests, reproducing issues, etc.
+---@param plugins? OrgMinPlugins
+function M.setup(plugins)
+  vim.opt.packpath = {} -- Empty the package path so we use only the plugins specified
+  vim.opt.runtimepath:append(M.root ".min") -- Ensure the runtime detects the root min dir
+
+  -- Install required plugins
+  if plugins ~= nil then
+    for plugin_name, plugin_url in pairs(plugins) do
+      M.load_plugin(plugin_name, plugin_url)
+    end
+  end
+
+  vim.env.XDG_CONFIG_HOME = M.root "xdg/config"
+  vim.env.XDG_DATA_HOME = M.root "xdg/data"
+  vim.env.XDG_STATE_HOME = M.root "xdg/state"
+  vim.env.XDG_CACHE_HOME = M.root "xdg/cache"
+
+  local std_paths = {
+    "cache",
+    "data",
+    "config",
+  }
+
+  for _, std_path in pairs(std_paths) do
+    vim.fn.mkdir(vim.fn.stdpath(std_path), "p")
+  end
+
+  -- NOTE: Cleanup the xdg cache on exit so new runs of the minimal init doesn't share any previous state, e.g. shada
+  vim.api.nvim_create_autocmd("VimLeave", {
+    callback = function()
+      vim.fn.delete(M.root "xdg", "rf")
+    end,
+  })
+end
+
+M.setup {
+  plenary = "https://github.com/nvim-lua/plenary.nvim.git",
+  treesitter = "https://github.com/nvim-treesitter/nvim-treesitter",
+}
+
+-- WARN: Do all plugin setup, test runs, reproductions, etc. AFTER calling setup with a list of plugins!
+-- Basically, do all that stuff AFTER this line.
diff --git a/tests/test.lua b/tests/test.lua
new file mode 100644
index 0000000..9a51689
--- /dev/null
+++ b/tests/test.lua
@@ -0,0 +1,14 @@
+require "tests.minimal_init"
+---@type string
+local test_file = vim.v.argv[#vim.v.argv]
+if test_file == "" or not test_file:find("tests/plenary/", nil, true) then
+  test_file = "tests/tests"
+  print("Running all tests at " .. test_file)
+else
+  print("Individual Test File/Directory provided: " .. test_file)
+end
+
+require("plenary.test_harness").test_directory(test_file, {
+  minimal_init = "tests/minimal_init.lua",
+  sequential = true,
+})