local execute = vim.api.nvim_command
local fn = vim.fn
local fmt = string.format

local pack_path = fn.stdpath("data") .. "/site/pack"

-- ensure a given plugin from github.com/<user>/<repo> is cloned in the pack/packer/start directory
local function ensure (user, repo)
  local install_path = fmt("%s/packer/start/%s", pack_path, repo)
  if fn.empty(fn.glob(install_path)) > 0 then
    execute(fmt("!git clone https://github.com/%s/%s %s", user, repo, install_path))
    execute(fmt("packadd %s", repo))
  end
end

-- ensure the plugin manager is installed
ensure("wbthomason", "packer.nvim")

require('packer').startup(function(use)
  -- install all the plugins you need here

  -- the plugin manager can manage itself
  use {'wbthomason/packer.nvim'}

  -- lsp config for elixir-ls support
  use {'neovim/nvim-lspconfig'}

  -- cmp framework for auto-completion support
  use {'hrsh7th/nvim-cmp'}

  -- install different completion source
  use {'hrsh7th/cmp-nvim-lsp'}
  use {'hrsh7th/cmp-buffer'}
  use {'hrsh7th/cmp-path'}
  use {'hrsh7th/cmp-cmdline'}

  -- you need a snippet engine for snippet support
  -- here I'm using vsnip which can load snippets in vscode format
  use {'hrsh7th/vim-vsnip'}
  use {'hrsh7th/cmp-vsnip'}

  -- treesitter for syntax highlighting and more
  use {'nvim-treesitter/nvim-treesitter'}
end)

-- `on_attach` callback will be called after a language server
-- instance has been attached to an open buffer with matching filetype
-- here we're setting key mappings for hover documentation, goto definitions, goto references, etc
-- you may set those key mappings based on your own preference
local on_attach = function(client, bufnr)
  local opts = { noremap=true, silent=true }

  vim.api.nvim_buf_set_keymap(bufnr, 'n', 'gd', '<cmd>lua vim.lsp.buf.definition()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', 'gr', '<cmd>lua vim.lsp.buf.references()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', 'gD', '<cmd>lua vim.lsp.buf.declaration()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', 'gi', '<cmd>lua vim.lsp.buf.implementation()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', 'K', '<cmd>lua vim.lsp.buf.hover()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', '<C-k>', '<cmd>lua vim.lsp.buf.signature_help()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', '<leader>cr', '<cmd>lua vim.lsp.buf.rename()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', '<leader>ca', '<cmd>lua vim.lsp.buf.code_action()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', '<leader>cf', '<cmd>lua vim.lsp.buf.formatting()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', '<leader>cd', '<cmd>lua vim.diagnostic.open_float()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', '[d', '<cmd>lua vim.diagnostic.goto_prev()<CR>', opts)
  vim.api.nvim_buf_set_keymap(bufnr, 'n', ']d', '<cmd>lua vim.diagnostic.goto_next()<CR>', opts)
end

-- setting up the elixir language server
-- you have to manually specify the entrypoint cmd for elixir-ls
require('lspconfig').elixirls.setup {
  cmd = { "/Users/nicolasknoebber/package/elixir-ls/language_server.sh" },
  on_attach = on_attach
}