--------------------------------------------------------------------------------
-- LSP configuration. nvim-cmp related stuff taken from:
-- https://github.com/neovim/nvim-lspconfig/wiki/Autocompletion/217feffc675a17d8ab95259ed9d4c6d62e1cd2e1
--------------------------------------------------------------------------------

local lspconfig = require("lspconfig")

local capabilities = require("cmp_nvim_lsp").default_capabilities()

-- https://github.com/hrsh7th/nvim-cmp/issues/373#issuecomment-1434284568
capabilities.textDocument.completion.completionItem.snippetSupport = false

lspconfig.gopls.setup {
    capabilities = capabilities,
}

local cmp = require("cmp")
cmp.setup {
  mapping = cmp.mapping.preset.insert({
    ['<C-u>'] = cmp.mapping.scroll_docs(-4), -- Up
    ['<C-d>'] = cmp.mapping.scroll_docs(4), -- Down
    -- C-b (back) C-f (forward) for snippet placeholder navigation.
    ['<C-Space>'] = cmp.mapping.complete(),
    ['<CR>'] = cmp.mapping.confirm {
      behavior = cmp.ConfirmBehavior.Replace,
      select = true,
    },
    ['<Tab>'] = cmp.mapping(function(fallback)
      if cmp.visible() then
        cmp.select_next_item()
      else
        fallback()
      end
    end, { 'i', 's' }),
    ['<S-Tab>'] = cmp.mapping(function(fallback)
      if cmp.visible() then
        cmp.select_prev_item()
      else
        fallback()
      end
    end, { 'i', 's' }),
  }),
  sources = {
    { name = 'nvim_lsp' },
  },
}

-- Format files using LSP on save
vim.api.nvim_create_autocmd('BufWritePre', {
  callback = function(args)
    vim.lsp.buf.format()
  end,
})

-- Open LSP Diagnostics in quickfix list on save
vim.api.nvim_create_autocmd('BufWritePost', {
  callback = function(args)
    vim.diagnostic.setqflist()
  end,
})

--------------------------------------------------------------------------------
-- Run 'organizeImports' on save for go files. Apparently organizing imports is
-- considered a separate task than formatting, so it's implemented separately
-- (in a much more cumbersome way, for some reason).
-- https://github.com/golang/tools/blob/0b989c812dcb662451db0b70a8267fe7e211886e/gopls/doc/vim.md#neovim-imports
-- https://github.com/golang/go/issues/33587
--------------------------------------------------------------------------------

vim.api.nvim_create_autocmd("BufWritePre", {
  pattern = "*.go",
  callback = function()
    local params = vim.lsp.util.make_range_params()
    params.context = {only = {"source.organizeImports"}}
    -- buf_request_sync defaults to a 1000ms timeout. Depending on your
    -- machine and codebase, you may want longer. Add an additional
    -- argument after params if you find that you have to write the file
    -- twice for changes to be saved.
    -- E.g., vim.lsp.buf_request_sync(0, "textDocument/codeAction", params, 3000)
    local result = vim.lsp.buf_request_sync(0, "textDocument/codeAction", params)
    for cid, res in pairs(result or {}) do
      for _, r in pairs(res.result or {}) do
        if r.edit then
          local enc = (vim.lsp.get_client_by_id(cid) or {}).offset_encoding or "utf-16"
          vim.lsp.util.apply_workspace_edit(r.edit, enc)
        end
      end
    end
    vim.lsp.buf.format({async = false})
  end
})