local lspconfig = require "lspconfig"

local function on_attach(client, bufnr)
  vim.api.nvim_buf_set_option(bufnr, "omnifunc", "v:lua.vim.lsp.omnifunc")
  vim.api.nvim_buf_set_var(bufnr, "vcm_tab_complete", "omni")

  local function command(name, command)
    vim.api.nvim_buf_create_user_command(bufnr, name, command, {})
  end

  local function map(mode, lhs, rhs)
    vim.keymap.set(mode, lhs, rhs, {
      buffer = bufnr
    })
  end

  local augroup_id = vim.api.nvim_create_augroup("LSPAttach", {
    clear = false
  })
  local function autocmd(event, callback)
    vim.api.nvim_create_autocmd(event, {
      group = augroup_id,
      buffer = bufnr,
      callback = callback
    })
  end
  vim.api.nvim_clear_autocmds({
    buffer = bufnr,
    group = augroup_id
  })

  command("References", function()
    local function on_list(options)
      vim.fn.setqflist({}, "r", options)
      vim.api.nvim_command("cfirst")
    end
    vim.lsp.buf.references(nil, {
      on_list = on_list
    })
  end)

  map("n", "gD", vim.lsp.buf.declaration)
  map("n", "gd", vim.lsp.buf.definition)
  map("n", "K", vim.lsp.buf.hover)
  map("n", "<C-k>", vim.lsp.buf.signature_help)
  map("n", "<leader>lc", vim.lsp.buf.code_action)
  map("n", "<leader>li", vim.lsp.buf.implementation)
  map("n", "<leader>lr", vim.lsp.buf.rename)

  autocmd("CursorHold", function()
    vim.lsp.buf.document_highlight()
    vim.diagnostic.open_float({
      bufnr = bufnr
    }, {
      focus = false
    })
  end)
  autocmd("CursorMoved", vim.lsp.buf.clear_references)
end

local settings = {
  clangd = {
    cmd = {"clangd", "--background-index", "--suggest-missing-includes", "--clang-tidy", "--header-insertion=iwyu"}
  }
}

local lsp = {}

function lsp.initialize()
  vim.diagnostic.config({
    float = {
      focusable = false
    }
  })

  for lss, lss_params in pairs(settings) do
    local params = {
      on_attach = on_attach,
      handlers = {
        ["textDocument/publishDiagnostics"] = vim.lsp.with(vim.lsp.diagnostic.on_publish_diagnostics, {
          signs = false,
          virtual_text = false,
          underline = true
        }),
        ["textDocument/signatureHelp"] = vim.lsp.with(vim.lsp.handlers.signature_help, {
          silent = true,
          focusable = false
        }),
        ["textDocument/hover"] = vim.lsp.with(vim.lsp.handlers.hover, {
          focusable = false
        })
      }
    }
    lspconfig[lss].setup(vim.tbl_deep_extend("force", params, lss_params))
  end
end

return lsp