nvim: automatically insert namespace declaration into empty PHP file

1 files changed, 89 insertions, 3 deletions

diff --git a/.config/nvim/after/ftplugin/php.lua b/.config/nvim/after/ftplugin/php.lua
index f6433f5..d6dbf6b 100644
--- a/.config/nvim/after/ftplugin/php.lua
+++ b/.config/nvim/after/ftplugin/php.lua
@@ -1,15 +1,101 @@
 vimrc.after_ftplugin('php', function(conf)
+   -- Find "composer.json" file upward from the base directory.
+   local function find_composer_json(base_dir)
+      return vim.fs.find('composer.json', {
+         path = base_dir,
+         upward = true,
+         stop = vim.loop.os_homedir(),
+         type = 'file',
+      })[1]
+   end
+
+   -- Read and decode JSON file.
+   local function load_json(file_path)
+      local ok_read, content = pcall(vim.fn.readblob, file_path)
+      if not ok_read then
+         return nil
+      end
+      local ok_decode, obj = pcall(vim.json.decode, content)
+      if not ok_decode then
+         return nil
+      end
+      return obj
+   end
+
+   -- Generate namespace declaration based on the current file name and autoload settings.
+   local function generate_namespace_declaration()
+      local current_dir = vim.fs.dirname(vim.api.nvim_buf_get_name(0))
+      local path_to_composer_json = find_composer_json(current_dir)
+      if not path_to_composer_json then
+         return nil -- failed to locate composer.json
+      end
+      local composer_json = load_json(path_to_composer_json)
+      if not composer_json then
+         return nil -- failed to load composer.json
+      end
+      local psr4 = vim.tbl_get(composer_json, 'autoload', 'psr-4')
+      if not psr4 then
+         return nil -- autoload.psr-4 section is absent
+      end
+      if vim.tbl_count(psr4) ~= 1 then
+         return nil -- psr-4 section is ambiguous
+      end
+      local psr4_namespace, psr4_dir
+      for k, v in pairs(psr4) do
+         psr4_namespace = k
+         psr4_dir = v
+      end
+      if psr4_namespace:sub(-1, -1) == '\\' then
+         psr4_namespace = psr4_namespace:sub(0, -2)
+      end
+      if psr4_dir:sub(-1, -1) == '/' then
+         psr4_dir = psr4_dir:sub(0, -2)
+      end
+      local namespace_root_dir = vim.fs.dirname(path_to_composer_json) .. '/' .. psr4_dir
+      if not vim.startswith(current_dir, namespace_root_dir) then
+         return nil
+      end
+      local current_path_suffix = current_dir:sub(#namespace_root_dir + 1)
+      local namespace = psr4_namespace .. current_path_suffix:gsub('/', '\\')
+      return ("namespace %s;"):format(namespace)
+   end
+
+   local function generate_template()
+      local lines = {
+         '<?php',
+         '',
+         'declare(strict_types=1);',
+         '',
+      }
+      local namespace_decl = generate_namespace_declaration()
+      if namespace_decl then
+         lines[#lines + 1] = namespace_decl
+         lines[#lines + 1] = ''
+      end
+      lines[#lines + 1] = ''
+      return lines
+   end
+
    -- If a buffer is empty, insert a template and position the
    -- cursor at the end of the buffer.
    --
-   -- Example:
+   -- Example 1:
    -- <?php
    --
    -- declare(strict_types=1);
    --
    -- [cursor]
+   --
+   -- Example 2 with namespace declaration:
+   -- <?php
+   --
+   -- declare(strict_types=1);
+   --
+   -- namespace Foo\Bar\Baz;
+   --
+   -- [cursor]
    if vim.fn.line('$') == 1 and vim.fn.getline(1) == '' then
-      vim.fn.setline(1, { '<?php', '', 'declare(strict_types=1);', '', '' })
-      vim.fn.cursor(6, 0)
+      vim.fn.setline(1, generate_template())
+      vim.fn.cursor('$', 0)
    end
 end)