refactor(nvim): extract follow engine into dotfiles.follow module

1 files changed, 8 insertions, 172 deletions

diff --git a/.config/nvim/plugin/50-follow.lua b/.config/nvim/plugin/50-follow.lua
index 6784ad6..1e48cd5 100644
--- a/.config/nvim/plugin/50-follow.lua
+++ b/.config/nvim/plugin/50-follow.lua
@@ -1,183 +1,19 @@
--- Following file names and URL inside Neovim
+-- Following file names and URLs inside Neovim. The engine lives in
+-- `lua/dotfiles/follow.lua`; per-scheme behavior is registered by the feature
+-- that owns it — see 50-notes.lua (`notes://` and `[[wiki-links]]`) and
+-- 50-nvim-help.lua (`nvim-help://`).
 
-local function get_visual_selection()
-	return table.concat(vim.fn.getregion(vim.fn.getpos("v"), vim.fn.getpos("."), { type = vim.fn.mode() }), "\n")
-end
-
--- Returns a suitable target for `vim.cmd.edit()` by looking for a Markdown link under the cursor.
--- Returns `nil` if no target was found, if the current buffer `'filetype'` is not `markdown`.
-local function get_markdown_link_target()
-	local function get_link_node(node)
-		local function type_is_link(type)
-			return type == "full_reference_link" or type == "inline_link" or type == "shortcut_link"
-		end
-		if type_is_link(node:type()) then
-			return node
-		elseif node:parent() ~= nil and type_is_link(node:parent():type()) then
-			return node:parent()
-		end
-		return nil
-	end
-
-	local function follow_link_label(label)
-		-- Escape Lua pattern magic chars so the label is matched literally.
-		local escaped = label:gsub("[%(%)%.%%%+%-%*%?%[%]%^%$]", "%%%1")
-		-- Reference labels are case-insensitive in CommonMark, so match each letter against either case.
-		local insensitive = escaped:gsub("%a", function(c)
-			return "[" .. c:upper() .. c:lower() .. "]"
-		end)
-		local label_pattern = "^%[" .. insensitive .. "%]: (.*)"
-		for _, line in ipairs(vim.api.nvim_buf_get_lines(0, 0, -1, true)) do
-			local match = line:match(label_pattern)
-			if match ~= nil then
-				return match
-			end
-		end
-		vim.notify("No link destination found for link label [" .. label .. "]", vim.log.levels.ERROR)
-		return nil
-	end
-
-	if vim.o.filetype == "markdown" and vim.treesitter.get_parser(0) ~= nil then
-		-- `ignore_injections = false` because the `link_destination`|`link_label` types are injected by `markdown_inline`
-		local node = vim.treesitter.get_node({ ignore_injections = false })
-		if node == nil then
-			vim.notify("No node found under cursor", vim.log.levels.ERROR)
-			return nil
-		end
-		local link_node = get_link_node(node)
-		if link_node == nil then
-			return nil
-		end
-		for child in link_node:iter_children() do
-			local text = vim.treesitter.get_node_text(child, 0)
-			if child:type() == "link_destination" then
-				return text
-			elseif
-				child:type() == "link_label" or (link_node:type() == "shortcut_link" and child:type() == "link_text")
-			then
-				-- shortcut_link text don't include the `[]` unlike link_label
-				if link_node:type() ~= "shortcut_link" then
-					text = text:sub(2, -2)
-				end
-				return follow_link_label(text)
-			end
-		end
-		vim.notify("No link destination/label found in link_node children", vim.log.levels.ERROR)
-		return nil
-	end
-	return nil
-end
+local follow = require("dotfiles.follow")
 
 -- Add `'` to the list of characters included in `<cfile>` because `'` is a valid URI character
 vim.opt.isfname:append("'")
 
--- Returns a suitable target for `vim.cmd.edit()`.
--- In normal mode, looks for a filename/link under the cursor.
--- In selection mode, use the visual selection as-is.
-local function get_target()
-	if vim.fn.mode() == "n" then
-		return get_markdown_link_target() or vim.fn.expand("<cfile>")
-	else
-		return get_visual_selection()
-	end
-end
-
--- Edit the file/URL under the cursor or in visual selection.
--- target: URL or absolute file name
--- edit-type: edit|split|vsplit
-local function edit_target(target, edit_cmd)
-	local scheme, uri = string.match(target, "^(%a[%w%+%-%.]+)://(.*)")
-	if scheme ~= nil then -- if the target is a URL (and not a file name)
-		uri = vim.uri_decode(uri)
-		target = scheme .. "://" .. uri
-	end
-	if scheme == "notes" then
-		target = vim.g.notes_dir .. "/" .. target
-	elseif scheme == "nvim-help" then
-		local tagfiles = {}
-		for _, path in pairs(vim.opt.runtimepath:get()) do
-			table.insert(tagfiles, path .. "/doc/tags")
-		end
-		vim.opt_local.tags = tagfiles
-		local matches = vim.fn.taglist(uri)
-		if #matches == 0 then
-			vim.notify("No help page found for " .. target, vim.log.levels.WARN)
-			return
-		end
-		target = matches[1].filename
-	end
-	vim.cmd(edit_cmd .. " " .. vim.fn.fnameescape(target))
-	if scheme == "nvim-help" then
-		vim.opt_local.bufhidden = "wipe"
-		vim.opt_local.buftype = "nofile"
-		vim.opt_local.swapfile = false
-		vim.opt_local.readonly = true
-	end
-end
-
--- Returns the inner text of a `[[wiki-link]]` under the cursor, or `nil`.
-local function get_wikilink_target()
-	local line = vim.api.nvim_get_current_line()
-	local col = vim.api.nvim_win_get_cursor(0)[2] + 1
-	local init = 1
-	while true do
-		local s, e, inner = line:find("%[%[(.-)%]%]", init)
-		if s == nil then
-			return nil
-		end
-		if col >= s and col <= e then
-			return inner
-		end
-		init = e + 1
-	end
-end
-
--- Follow a `[[note]]` / `[[note#Heading]]` / `[[dir/]]` wiki-link relative to the
--- notes dir, creating parent directories (and the note itself on save) as needed.
-local function follow_wikilink(inner, edit_cmd)
-	local name, heading = inner:match("^(.-)#(.*)$")
-	if name == nil then
-		name = inner
-	end
-	local target = vim.g.notes_dir .. "/" .. name
-	if name:sub(-1) == "/" then -- directory link: create and open it
-		vim.fn.mkdir(target, "p")
-		vim.cmd(edit_cmd .. " " .. vim.fn.fnameescape(target))
-		return
-	end
-	if not name:match("%.%w+$") then -- default to a Markdown note
-		target = target .. ".md"
-	end
-	vim.fn.mkdir(vim.fs.dirname(target), "p")
-	vim.cmd(edit_cmd .. " " .. vim.fn.fnameescape(target))
-	if heading ~= nil and heading ~= "" then
-		vim.fn.cursor(1, 1)
-		-- `\V` matches the heading literally; `\v` brackets the heading markers.
-		local pat = [[\v^#+\s+\V]] .. vim.fn.escape(heading, [[\]]) .. [[\v\s*$]]
-		if vim.fn.search(pat, "cW") == 0 then
-			vim.notify("No heading '" .. heading .. "' in " .. name, vim.log.levels.WARN)
-		end
-	end
-end
-
--- Follow a wiki-link if the cursor is on one, else fall back to URL/file following.
-local function follow(edit_cmd)
-	if vim.fn.mode() == "n" and vim.bo.filetype == "markdown" then
-		local inner = get_wikilink_target()
-		if inner ~= nil then
-			follow_wikilink(inner, edit_cmd)
-			return
-		end
-	end
-	edit_target(get_target(), edit_cmd)
-end
-
 vim.keymap.set({ "n", "x" }, "<Leader>gg", function()
-	follow("edit")
+	follow.follow("edit")
 end, { desc = "Edit URL/file in current window" })
 vim.keymap.set({ "n", "x" }, "<Leader>gs", function()
-	follow("split")
+	follow.follow("split")
 end, { desc = "Edit URL/file in split window" })
 vim.keymap.set({ "n", "x" }, "<Leader>gv", function()
-	follow("vsplit")
+	follow.follow("vsplit")
 end, { desc = "Edit URL/file in vertically split window" })