local function gh(repo) return 'https://github.com/' .. repo end

-- ============================================================
-- TREESITTER
-- Parser installation, syntax highlighting, folds, indentation
-- ============================================================

vim.pack.add { { src = gh 'nvim-treesitter/nvim-treesitter', version = 'main' } }

local parsers = {
  'bash', 'c', 'diff', 'html', 'lua', 'luadoc', 'markdown', 'markdown_inline', 'query', 'vim', 'vimdoc',
  'rust', 'go', 'javascript', 'typescript', 'python', 'json', 'yaml', 'toml', 'gleam', 'nim',
}
require('nvim-treesitter').install(parsers)

local function treesitter_try_attach(buf, language)
  if not vim.treesitter.language.add(language) then return end
  vim.treesitter.start(buf, language)
  local has_indent_query = vim.treesitter.query.get(language, 'indents') ~= nil
  if has_indent_query then vim.bo.indentexpr = "v:lua.require'nvim-treesitter'.indentexpr()" end
end

local available_parsers = require('nvim-treesitter').get_available()
vim.api.nvim_create_autocmd('FileType', {
  callback = function(args)
    local buf, filetype = args.buf, args.match
    local language = vim.treesitter.language.get_lang(filetype)
    if not language then return end
    local installed_parsers = require('nvim-treesitter').get_installed 'parsers'
    if vim.tbl_contains(installed_parsers, language) then
      treesitter_try_attach(buf, language)
    elseif vim.tbl_contains(available_parsers, language) then
      require('nvim-treesitter').install(language):await(function() treesitter_try_attach(buf, language) end)
    else
      treesitter_try_attach(buf, language)
    end
  end,
})