feat(luasnip): add custom snippet

Add a custom snippet for markdown to insert a YAML metadata block
This is a highly targeted snippet as it works for my blog template only.

There is some work to do on neatening this snippet up

luasnip/markdown.lua

@@ -0,0 +1,109 @@
+-- Markdown snippets
+
+-- We manually create these as the LSP doesn't understand 
+-- if they are loaded properly.
+local ls = require('luasnip')
+local lsf = require('luasnip.extras.fmt')
+local s = ls.snippet
+local t = ls.text_node
+local i = ls.insert_node
+local c = ls.choice_node
+local sn = ls.snippet_node
+local fmt = lsf.fmt
+local fmta = lsf.fmta
+local currentUser
+
+
+if vim.fn.has('linux') == 1 then
+	--- Get the current users full name
+	---@return string @The users full name OR NAME
+	currentUser = function ()
+		local status, res = require('sherlock5512.scriptutils').shellexec("getent passwd $USER | cut -d: -f5 | cut -d, -f1")
+		if status.ok then
+			-- We know there will only be stdout if the command runs successfully
+			---@diagnostic disable-next-line: return-type-mismatch, need-check-nil
+			return res:match("^[\r\n]*(.-)[\r\n]*$")
+		end
+			return "NAME"
+	end
+elseif vim.fn.has('mac') == 1 then
+	--- Get the current users full name
+	---@return string @The users full name OR NAME
+	currentUser = function ()
+		local status, res = require('sherlock5512.scriptutils').shellexec("id -F")
+		if status.ok then
+			-- We know there will only be stdout if the command runs successfully
+			---@diagnostic disable-next-line: return-type-mismatch, need-check-nil
+			return res:match("^[\r\n]*(.-)[\r\n]*$")
+		end
+		return "NAME"
+	end
+else
+	--- Get the current users full name
+	---@return string @The users full name OR NAME
+	currentUser = function ()
+		return "NAME"
+	end
+end
+
+--- @module 'luasnip'
+--- @type LuaSnip.Snippet[]
+return {
+	s(
+		{ trig = '\\yaml', dscr = 'YAML frontmatter block'}, {
+			t {'---',''}, -- end with empty block to force a newline
+			t {'author: "' },
+			i(1, currentUser()),
+			t {'"',''},
+			t {'title: "'},
+			i(2),
+			t {'"', ''},
+			t {'date: '},
+			i(3),
+			t {'',''},
+			t {'description: "'},
+			i(4),
+			t {'"', ''},
+			c(5,
+				{
+					t '', 
+					sn(nil,{
+						t {"keywords: [ "},
+						i(1),
+						t { ' ]', '' },
+					})
+				}
+			),
+			t {"lang: "},
+			i(6, 'en-gb'),
+			t {'', ''},
+			c(7, {
+				sn(nil, {
+					t {'math: true', ''},
+					i(1),
+					c(2, {
+						t {'mathjax: true', ''},
+						t {'mathjax: false', ''}
+					}),
+				}),
+				t {'math: false', ''},
+			}),
+			c(8, {
+				t {'needs-syntax-highlighting: true', ''},
+				t {'needs-syntax-highlighting: false', ''},
+			}),
+			c(9, {
+				t {'allow-comments: true', ''},
+				t {'allow-comments: false', ''},
+			}),
+			c(10, {
+				t '',
+				sn(nil, {
+					t {'style: "', ''},
+					i(1),
+					t {'','"', ''}
+				})
+			}),
+			t {'---',''}
+		})
+}