local configs = require "lspconfig/configs"
local lspui = require "lspconfig/_lspui"

return function()
  -- These options need to be cached before switching to the floating
  -- buffer.
  local buf_clients = vim.lsp.buf_get_clients()
  local clients = vim.lsp.get_active_clients()
  local buffer_filetype = vim.bo.filetype
  local buffer_dir = vim.fn.expand "%:p:h"

  local win_info = lspui.percentage_range_window(0.8, 0.7)
  local bufnr, win_id = win_info.bufnr, win_info.win_id

  local buf_lines = {}

  local buf_client_names = {}
  for _, client in pairs(buf_clients) do
    table.insert(buf_client_names, client.name)
  end

  local header = {
    "Configured servers: " .. table.concat(vim.tbl_keys(configs), ", "),
    "Neovim logs at: " .. (vim.lsp.get_log_path()),
    "",
    tostring(#vim.tbl_keys(buf_clients)) .. " client(s) attached to this buffer: " .. table.concat(
      buf_client_names,
      ", "
    ),
  }
  vim.list_extend(buf_lines, header)

  local function trim_whitespace(cmd)
    local trimmed_cmd = {}
    for _, str in pairs(cmd) do
      table.insert(trimmed_cmd, str:match "^%s*(.*)")
    end
    return trimmed_cmd
  end

  local function remove_newlines(cmd)
    cmd = trim_whitespace(cmd)
    cmd = table.concat(cmd, " ")
    cmd = vim.split(cmd, "\n")
    cmd = trim_whitespace(cmd)
    cmd = table.concat(cmd, " ")
    return cmd
  end

  local indent = "  "
  local function make_client_info(client)
    local server_specific_info = ""
    if client.config.lspinfo then
      server_specific_info = client.config.lspinfo(client.config)
    end
    return {
      "",
      indent .. "Client: " .. client.name .. " (id " .. tostring(client.id) .. ")",
      indent .. "\troot:      " .. client.workspaceFolders[1].name,
      indent .. "\tfiletypes: " .. table.concat(client.config.filetypes or {}, ", "),
      indent .. "\tcmd:       " .. remove_newlines(client.config.cmd),
      indent .. "\t" .. server_specific_info,
      "",
    }
  end

  for _, client in pairs(buf_clients) do
    local client_info = make_client_info(client)
    vim.list_extend(buf_lines, client_info)
  end

  local active_section_header = {
    "",
    tostring(#clients) .. " active client(s): ",
  }
  vim.list_extend(buf_lines, active_section_header)
  for _, client in pairs(clients) do
    local client_info = make_client_info(client)
    vim.list_extend(buf_lines, client_info)
  end
  local matching_config_header = {
    "",
    "Clients that match the filetype " .. buffer_filetype .. ":",
  }
  local cmd_not_found_msg = "False. Please check your path and ensure the server is installed"
  vim.list_extend(buf_lines, matching_config_header)
  for _, config in pairs(configs) do
    local cmd_is_executable, cmd
    if config.cmd then
      cmd = remove_newlines(config.cmd)
      if vim.fn.executable(config.cmd[1]) == 1 then
        cmd_is_executable = "True"
      else
        cmd_is_executable = cmd_not_found_msg
      end
    else
      cmd = "cmd not defined"
      cmd_is_executable = cmd
    end
    if config.filetypes then
      for _, filetype_match in pairs(config.filetypes) do
        if buffer_filetype == filetype_match then
          local matching_config_info = {
            indent .. "",
            indent .. "Config: " .. config.name,
            indent .. "\tcmd:               " .. cmd,
            indent .. "\tcmd is executable: " .. cmd_is_executable,
            indent .. "\tidentified root:   " .. (config.get_root_dir(buffer_dir) or "None"),
            indent .. "\tcustom handlers:   " .. table.concat(vim.tbl_keys(config.handlers), ", "),
          }
          vim.list_extend(buf_lines, matching_config_info)
        end
      end
    else
      local matching_config_info = {
        "",
        "Config: " .. config.name,
        "\tfiletype: " .. "No filetypes defined, please define filetypes in setup().",
      }
      vim.list_extend(buf_lines, matching_config_info)
    end
  end
  buf_lines = vim.lsp.util._trim(buf_lines, {})
  vim.api.nvim_buf_set_lines(bufnr, 0, -1, true, buf_lines)
  vim.api.nvim_buf_set_option(bufnr, "modifiable", false)
  vim.api.nvim_buf_set_option(bufnr, "filetype", "lspinfo")
  local configs_pattern = "\\%(" .. table.concat(vim.tbl_keys(configs), "\\|") .. "\\)"
  vim.cmd("syntax match Title /\\%(Client\\|Config\\):.*\\zs" .. configs_pattern .. "/")
  vim.cmd("syntax match Identifier /filetypes:.*\\zs\\<" .. buffer_filetype .. "\\>/")
  vim.fn.matchadd(
    "Error",
    "No filetypes defined, please define filetypes in setup().\\|" .. "cmd not defined\\|" .. cmd_not_found_msg
  )
  vim.api.nvim_buf_set_keymap(bufnr, "n", "<esc>", "<cmd>bd<CR>", { noremap = true })
  vim.lsp.util.close_preview_autocmd({ "BufHidden", "BufLeave" }, win_id)
end