-- Native LSP and automatic completion for Neovim 0.12/0.13.
-- Requires nvim-lspconfig only for its server presets in runtimepath.
-- No nvim-cmp, cmp-nvim-lsp, lspkind, or vsnip required.

vim.opt.autocomplete = true
vim.opt.complete = 'o'
vim.opt.completeopt = { 'menu', 'menuone', 'noselect', 'popup' }
vim.opt.shortmess:append('c')

-- Keep the old LSP bindings; all are buffer-local.
local function map(buf, lhs, rhs, desc)
  vim.keymap.set('n', lhs, rhs, { buffer = buf, silent = true, desc = desc })
end

local group = vim.api.nvim_create_augroup('UserNativeLsp', { clear = true })

vim.api.nvim_create_autocmd('LspAttach', {
  group = group,
  callback = function(args)
    local bufnr = args.buf
    local client = vim.lsp.get_client_by_id(args.data.client_id)
    if not client then return end

    -- Completion requests are sent automatically while typing, without cmp.
    -- C-n/C-p move through suggestions; C-y accepts one; C-e dismisses.
    if client:supports_method('textDocument/completion') then
      vim.lsp.completion.enable(true, client.id, bufnr, { autotrigger = true })
    end

    map(bufnr, '<leader>rn', vim.lsp.buf.rename, 'LSP rename')
    map(bufnr, '<leader>ca', vim.lsp.buf.code_action, 'LSP code action')
    map(bufnr, '<M-k>', vim.lsp.buf.hover, 'LSP hover')
    map(bufnr, 'g0', vim.lsp.buf.document_symbol, 'Document symbols')
    map(bufnr, 'gW', vim.lsp.buf.workspace_symbol, 'Workspace symbols')
    map(bufnr, 'gd', vim.lsp.buf.definition, 'Go to definition')
    map(bufnr, 'gD', vim.lsp.buf.declaration, 'Go to declaration')
    map(bufnr, 'gi', vim.lsp.buf.implementation, 'Go to implementation')
    map(bufnr, 'gr', vim.lsp.buf.references, 'Find references')
    map(bufnr, '<C-k>', vim.lsp.buf.signature_help, 'Signature help')
    map(bufnr, 'g<Space>', vim.lsp.buf.type_definition, 'Type definition')
    map(bufnr, '[d', function() vim.diagnostic.jump({ count = -1 }) end, 'Previous diagnostic')
    map(bufnr, ']d', function() vim.diagnostic.jump({ count = 1 }) end, 'Next diagnostic')

    vim.bo[bufnr].omnifunc = 'v:lua.vim.lsp.omnifunc'
    vim.opt_local.signcolumn = 'yes'

    if client:supports_method('textDocument/documentHighlight') then
      -- Per-buffer autocommands, shared across clients to avoid duplicates.
      local hlgroup = vim.api.nvim_create_augroup('UserLspHighlight' .. bufnr, { clear = true })
      vim.api.nvim_create_autocmd({ 'CursorHold', 'CursorHoldI' }, {
        group = hlgroup, buffer = bufnr, callback = vim.lsp.buf.document_highlight,
      })
      vim.api.nvim_create_autocmd({ 'CursorMoved', 'InsertLeave' }, {
        group = hlgroup, buffer = bufnr, callback = vim.lsp.buf.clear_references,
      })
    end
  end,
})

vim.diagnostic.config({
  signs = {
    text = {
      [vim.diagnostic.severity.ERROR] = '✘',
      [vim.diagnostic.severity.WARN] = '▲',
      [vim.diagnostic.severity.INFO] = '●',
      [vim.diagnostic.severity.HINT] = '◆'
    }
  },
  underline = true,
  severity_sort = true,
})

-- nvim-lspconfig's modern lsp/*.lua presets supply cmd, filetypes and root detection.
-- Only list your desired servers and their overrides here.
local servers = {
  bashls = { filetypes = { 'bash', 'sh' } },
  clangd = { filetypes = { 'c', 'cpp', 'objc', 'objcpp', 'cuda' } },
  mlir = {},
  jqls = {},
  lua_ls = {
    settings = {
      Lua = {
        runtime = { version = 'LuaJIT' },
        workspace = { checkThirdParty = false, library = { vim.env.VIMRUNTIME } },
      },
    },
  },
  ocamllsp = {},
  perlpls = {},
  rust_analyzer = {},
  verible = {},
  vimls = {},
  zls = {},
  texlab = {},
  hls = { settings = { haskell = { plugin = { semanticTokens = { globalOn = true } } } } },
  pylsp = { settings = { pylsp = { plugins = { pycodestyle = { enabled = false } } } } },
}

for name, overrides in pairs(servers) do
  vim.lsp.config(name, overrides)
  vim.lsp.enable(name)
end

vim.keymap.set('i', '<Tab>', function()
  if vim.fn.pumvisible() == 1 then
    return '<C-y>'
  end
  return '<Tab>'
end, { expr = true, desc = 'Accept completion or insert Tab' })

local fallbacks = {
  Pmenu         = 'NormalFloat',
  PmenuSel      = 'Visual',
  PmenuKind     = 'Type',
  PmenuKindSel  = 'Type',
  PmenuExtra    = 'Comment',
  PmenuExtraSel = 'Comment',
  PmenuMatch    = 'Identifier',
  PmenuMatchSel = 'Identifier',
  PmenuBorder   = 'FloatBorder',
}

local function apply_fallbacks()
  for group, target in pairs(fallbacks) do
    local hl = vim.api.nvim_get_hl(0, { name = group, link = true })

    if vim.tbl_isempty(hl) or hl.link == 'Pmenu' then
      vim.api.nvim_set_hl(0, group, { link = target })
    end
  end
end

vim.api.nvim_create_autocmd('ColorScheme', {
  callback = apply_fallbacks,
})

apply_fallbacks()

vim.opt.pumheight = 12
vim.opt.pummaxwidth = 70
vim.opt.pumblend = 0