feat: add Javap command to decompile classpath files

ftplugin/java.lua

@@ -4,3 +4,47 @@ nvim_jdtls.start_or_attach({
 	root_dir = vim.fs.dirname(vim.fs.find({'.gradlew', '.git', 'mvnw'}, {upward = true})[1]),
 })
 require('keybinds'):set_lsp_keys({buffer = 0})
+
+-- Allow decompiling classes coming from the language server too
+vim.api.nvim_create_user_command(
+	'Javap',
+	function(args)
+		local fname = vim.api.nvim_buf_get_name(0)
+		if vim.startswith(fname, "jdt://") then
+			local _, _, classpath_raw, classname_raw = string.find(fname, "jdt://.+?=%a+/(.+).jar=/.+,test=/(.+)%.class.*")
+			local classpath = classpath_raw:gsub("%%5C", "") .. '.jar'
+			local classname = classname_raw:gsub("%%3C", ""):gsub("%(", ".")
+			vim.fn.jobstart(
+				{'javap', '-c', '--class-path', classpath, classname},
+				{
+					width = 1024,
+					stdout_buffered = true,
+					on_stdout = function(_, data, _)
+						local buf = vim.api.nvim_create_buf(false, true)
+						vim.api.nvim_buf_set_text(buf, 0, 0, 0, 0, data)
+						vim.api.nvim_buf_set_option(buf, 'ft', 'asm')
+						if args.bang then
+							local width = vim.fn.winwidth(0)
+							local height = vim.fn.winheight(0)
+							vim.api.nvim_open_win(buf, true, {
+								relative='win',
+								row = 5,
+								col = 10,
+								width=width - 20,
+								height=height - 10,
+								border="single",
+								zindex=100, -- TODO hardcoded?
+							})
+						else
+							vim.api.nvim_win_set_buf(0, buf)
+							vim.api.nvim_win_set_cursor(buf, { 1, 0 })
+						end
+					end
+				}
+			)
+		else
+			require('jdtls').javap()
+		end
+	end,
+	{ bang=true }
+)