local util = {}
local fn = vim.fn

local os_name = vim.loop.os_uname().sysname
local is_windows = os_name == 'Windows' or os_name == 'Windows_NT'
-- Check whether current buffer contains main function
function util.has_main()
  local output = vim.api.nvim_exec('grep func\\ main\\(\\) %', true)
  local matchCount = vim.split(output, '\n')

  return #matchCount > 3
end

function util.sep()
  if is_windows then
    return '\\'
  end
  return '/'
end

function util.sep2()
  if is_windows then
    return ';'
  end
  return ':'
end

function util.is_windows()
  return is_windows
end

function util.ext()
  if is_windows then
    return '.exe'
  end
  return ''
end
local function get_path_sep()
  if is_windows then
    return ';'
  end
  return ':'
end

local function strip_path_sep(path)
  local l = path[#path]
  util.log(l, util.sep(), path:sub(1, #path - 1))
  if l == util.sep() then
    return path:sub(1, #path - 1)
  end
  return path
end

function util.root_dirs()
  local dirs = {}
  local root = fn.systemlist({ _GO_NVIM_CFG.go, 'env', 'GOROOT' })
  table.insert(dirs, root[1])
  local paths = fn.systemlist({ _GO_NVIM_CFG.go, 'env', 'GOPATH' })
  local sp = get_path_sep()

  paths = vim.split(paths[1], sp)
  for _, p in pairs(paths) do
    p = fn.substitute(p, '\\\\', '/', 'g')
    table.insert(dirs, p)
  end
  return dirs
end

function util.go_packages(dirs, arglead)
  util.log(debug.traceback())
  local pkgs = {}
  for _, dir in pairs(dirs) do
    util.log(dir)
    local scr_root = fn.expand(dir .. util.sep() .. 'src' .. util.sep())
    util.log(scr_root, arglead)
    local roots = fn.globpath(scr_root, arglead .. '*', 0, 1)
    if roots == { '' } then
      roots = {}
    end

    util.log(roots)
    for _, pkg in pairs(roots) do
      util.log(pkg)

      if fn.isdirectory(pkg) then
        pkg = pkg .. util.sep()
        table.insert(pkgs, pkg)
      elseif not pkg:match([[%.a$]]) then
        -- without this the result can have duplicates in form of
        -- 'encoding/json' and '/encoding/json/'
        pkg = strip_path_sep(pkg)

        -- remove the scr root and keep the package in tact
        pkg = fn.substitute(pkg, scr_root, '', '')
        table.insert(pkgs, pkg)
      end
    end
  end
  util.log(pkgs)
  return pkgs
end

-- function! s:interface_list(pkg) abort
--   let [contents, err] = go#util#Exec(['go', 'doc', a:pkg])
--   if err
--     return []
--   endif
--
--   let contents = split(contents, "\n")
--   call filter(contents, 'v:val =~# ''^type\s\+\h\w*\s\+interface''')
--   return map(contents, 'a:pkg . "." . matchstr(v:val, ''^type\s\+\zs\h\w*\ze\s\+interface'')')
-- endfunction

function util.interface_list(pkg)
  local p = fn.systemlist({ _GO_NVIM_CFG.go, 'doc', pkg })
  util.log(p)
  local ifaces = {}
  if p then
    local contents = p -- vim.split(p[1], "\n")
    for _, content in pairs(contents) do
      util.log(content)
      if content:find('interface') then
        local iface_name = fn.matchstr(content, [[^type\s\+\zs\h\w*\ze\s\+interface]])
        if iface_name ~= '' then
          table.insert(ifaces, pkg .. iface_name)
        end
      end
    end
  end
  util.log(ifaces)
  return ifaces
end

-- https://alpha2phi.medium.com/neovim-101-regular-expression-f15a6d782add
function util.get_fname_num(line)
  line = util.trim(line)

  local reg = [[\(.\+\.go\)\:\(\d\+\):]]
  local f = fn.matchlist(line, reg)
  if f[1] and f[1] ~= '' then
    return f[2], tonumber(f[3])
  end
end

function util.smartrun()
  local cmd
  if util.has_main() then
    cmd = string.format('lcd %:p:h | :set makeprg=%s\\ run\\ . | :make | :lcd -', _GO_NVIM_CFG.go)
    vim.cmd(cmd)
  else
    cmd = string.format('setl makeprg=%s\\ run\\ . | :make', _GO_NVIM_CFG.go)
    vim.cmd(cmd)
  end
end

function util.smartbuild()
  local cmd
  if util.has_main() then
    cmd = string.format('lcd %:p:h | :set makeprg=%s\\ build\\ . | :make | :lcd -', _GO_NVIM_CFG.go)
    vim.cmd(cmd)
  else
    cmd = string.format('setl makeprg=%s\\ build\\ . | :make', _GO_NVIM_CFG.go)
    vim.cmd(cmd)
  end
end

util.check_same = function(tbl1, tbl2)
  if #tbl1 ~= #tbl2 then
    return false
  end
  for k, v in ipairs(tbl1) do
    if v ~= tbl2[k] then
      return false
    end
  end
  return true
end

util.map = function(modes, key, result, options)
  options = util.merge({ noremap = true, silent = false, expr = false, nowait = false }, options or {})
  local buffer = options.buffer
  options.buffer = nil

  if type(modes) ~= 'table' then
    modes = { modes }
  end

  for i = 1, #modes do
    if buffer then
      vim.api.nvim_buf_set_keymap(0, modes[i], key, result, options)
    else
      vim.api.nvim_set_keymap(modes[i], key, result, options)
    end
  end
end

util.copy_array = function(from, to)
  for i = 1, #from do
    to[i] = from[i]
  end
end

util.deepcopy = function(orig)
  local orig_type = type(orig)
  local copy
  if orig_type == 'table' then
    copy = {}
    for orig_key, orig_value in next, orig, nil do
      copy[util.deepcopy(orig_key)] = util.deepcopy(orig_value)
    end
    setmetatable(copy, util.deepcopy(getmetatable(orig)))
  else -- number, string, boolean, etc
    copy = orig
  end
  return copy
end

util.handle_job_data = function(data)
  if not data then
    return nil
  end
  -- Because the nvim.stdout's data will have an extra empty line at end on some OS (e.g. maxOS), we should remove it.
  for _ = 1, 3, 1 do
    if data[#data] == '' then
      table.remove(data, #data)
    end
  end
  if #data < 1 then
    return nil
  end
  return data
end

local cache_dir = fn.stdpath('cache')
util.log = function(...)
  if not _GO_NVIM_CFG then
    return
  end
  if not _GO_NVIM_CFG.verbose then
    return
  end
  local arg = { ... }

  local log_default = string.format('%s%sgonvim.log', cache_dir, util.sep())

  local log_path = _GO_NVIM_CFG.log_path or log_default
  local str = '  '

  local info = debug.getinfo(2, 'Sl')
  str = str .. info.short_src .. ':' .. info.currentline
  for i, v in ipairs(arg) do
    if type(v) == 'table' then
      str = str .. ' |' .. tostring(i) .. ': ' .. vim.inspect(v) .. '\n'
    else
      str = str .. ' |' .. tostring(i) .. ': ' .. tostring(v)
    end
  end
  if #str > 2 then
    if log_path ~= nil and #log_path > 3 then
      local f, err = io.open(log_path, 'a+')
      if err then
        vim.notify('failed to open log' .. log_path .. err, vim.lsp.log_levels.ERROR)
        return
      end
      if not f then
        error('open file ' .. log_path, f)
      end
      io.output(f)
      io.write(str .. '\n')
      io.close(f)
    else
      vim.notify(str .. '\n', vim.lsp.log_levels.DEBUG)
    end
  end
end

util.trace = function(...) end

local rhs_options = {}

function rhs_options:new()
  local instance = {
    cmd = '',
    options = { noremap = false, silent = false, expr = false, nowait = false },
  }
  setmetatable(instance, self)
  self.__index = self
  return instance
end

function rhs_options:map_cmd(cmd_string)
  self.cmd = cmd_string
  return self
end

function rhs_options:map_cr(cmd_string)
  self.cmd = (':%s<CR>'):format(cmd_string)
  return self
end

function rhs_options:map_args(cmd_string)
  self.cmd = (':%s<Space>'):format(cmd_string)
  return self
end

function rhs_options:map_cu(cmd_string)
  self.cmd = (':<C-u>%s<CR>'):format(cmd_string)
  return self
end

function rhs_options:with_silent()
  self.options.silent = true
  return self
end

function rhs_options:with_noremap()
  self.options.noremap = true
  return self
end

function rhs_options:with_expr()
  self.options.expr = true
  return self
end

function rhs_options:with_nowait()
  self.options.nowait = true
  return self
end

function util.map_cr(cmd_string)
  local ro = rhs_options:new()
  return ro:map_cr(cmd_string)
end

function util.map_cmd(cmd_string)
  local ro = rhs_options:new()
  return ro:map_cmd(cmd_string)
end

function util.map_cu(cmd_string)
  local ro = rhs_options:new()
  return ro:map_cu(cmd_string)
end

function util.map_args(cmd_string)
  local ro = rhs_options:new()
  return ro:map_args(cmd_string)
end

function util.nvim_load_mapping(mapping)
  for key, value in pairs(mapping) do
    local mode, keymap = key:match('([^|]*)|?(.*)')
    if type(value) == 'table' then
      local rhs = value.cmd
      local options = value.options
      vim.api.nvim_set_keymap(mode, keymap, rhs, options)
    end
  end
end

function util.load_plugin(name, modulename)
  assert(name ~= nil, 'plugin should not empty')
  modulename = modulename or name
  local has, plugin = pcall(require, modulename)
  if has then
    return plugin
  end
  local pkg = packer_plugins or nil
  if pkg ~= nil then
    -- packer installed
    local has_packer = pcall(require, 'packer')
    if not has_packer then
      error('packer not found')
      return nil
    end
    local loader = require('packer').loader
    if not pkg[name] or not pkg[name].loaded then
      util.log('packer loader ' .. name)
      vim.cmd('packadd ' .. name) -- load with default
      if pkg[name] ~= nil then
        loader(name)
      end
    end
  else
    util.log('packadd ' .. name)
    local paths = vim.o.runtimepath
    if paths:find(name) then
      vim.cmd('packadd ' .. name)
    end
  end

  has, plugin = pcall(require, modulename)
  if not has then
    util.info('plugin ' .. name .. ' module ' .. modulename .. '  not loaded ')
    return nil
  end
  return plugin
end

-- deprecated
-- function util.check_capabilities(feature, client_id)
--   local clients = vim.lsp.buf_get_clients(client_id or 0)
--
--   local supported_client = false
--   for _, client in pairs(clients) do
--     -- util.log(client.resolved_capabilities)
--     util.log(client.server_capabilities)
--     supported_client = client.resolved_capabilities[feature]
--     supported_client = client.resolved_capabilities[feature]
--     if supported_client then
--       break
--     end
--   end
--
--   if supported_client then
--     return true
--   else
--     if #clients == 0 then
--       util.log("LSP: no client attached")
--     else
--       util.log("LSP: server does not support " .. feature)
--     end
--     return false
--   end
-- end

function util.relative_to_cwd(name)
  local rel = fn.isdirectory(name) == 0 and fn.fnamemodify(name, ':h:.') or fn.fnamemodify(name, ':.')
  if rel == '.' then
    return '.'
  else
    return '.' .. util.sep() .. rel
  end
end

function util.chdir(dir)
  if fn.exists('*chdir') then
    return fn.chdir(dir)
  end

  local oldir = fn.getcwd()
  local cd = 'cd'
  if fn.exists('*haslocaldir') and fn.haslocaldir() then
    cd = 'lcd'
    vim.cmd(cd .. ' ' .. fn.fnameescape(dir))
    return oldir
  end
end

function util.all_pkgs()
  return '.' .. util.sep() .. '...'
end

-- log and messages
function util.warn(msg)
  vim.notify('WARN: ' .. msg, vim.lsp.log_levels.WARN)
end

function util.error(msg)
  vim.notify('ERR: ' .. msg, vim.lsp.log_levels.ERROR)
end

function util.info(msg)
  vim.notify('INF: ' .. msg, vim.lsp.log_levels.INFO)
end

function util.debug(msg)
  vim.notify('DEBUG: ' .. msg, vim.lsp.log_levels.DEBUG)
end

function util.rel_path(folder)
  -- maybe expand('%:p:h:t')
  local mod = '%:p'
  if folder then
    mod = '%:p:h'
  end
  local fpath = fn.expand(mod)

  local workfolders = vim.lsp.buf.list_workspace_folders()

  if fn.empty(workfolders) == 0 then
    fpath = '.' .. fpath:sub(#workfolders[1] + 1)
  else
    fpath = fn.fnamemodify(fn.expand(mod), ':p:.')
  end

  util.log(fpath:sub(#fpath), fpath, util.sep())
  if fpath:sub(#fpath) == util.sep() then
    fpath = fpath:sub(1, #fpath - 1)
    util.log(fpath)
  end
  return fpath
end

function util.trim(s)
  if s then
    s = util.ltrim(s)
    return util.rtrim(s)
  end
end

function util.rtrim(s)
  local n = #s
  while n > 0 and s:find('^%s', n) do
    n = n - 1
  end
  return s:sub(1, n)
end

function util.ltrim(s)
  return (s:gsub('^%s*', ''))
end

function util.work_path()
  local fpath = fn.expand('%:p:h')
  local workfolders = vim.lsp.buf.list_workspace_folders()
  if #workfolders == 1 then
    return workfolders[1]
  end

  for _, value in pairs(workfolders) do
    local mod = value .. util.sep() .. 'go.mod'
    if util.file_exists(mod) then
      return value
    end
  end

  return workfolders[1] or fpath
end

function util.empty(t)
  if t == nil then
    return true
  end
  if type(t) ~= 'table' then
    return false
  end
  return next(t) == nil
end

local open = io.open

function util.read_file(path)
  local file = open(path, 'rb') -- r read mode and b binary mode
  if not file then
    return nil
  end
  local content = file:read('*a') -- *a or *all reads the whole file
  file:close()
  return content
end

function util.restart(cmd_args)
  local old_lsp_clients = vim.lsp.get_active_clients()
  local configs = require('lspconfig.configs')
  for _, client in pairs(old_lsp_clients) do
    if client.name == 'gopls' then
      vim.lsp.stop_client(client.id)
    end
  end

  if configs['gopls'] ~= nil then
    vim.defer_fn(function()
      configs['gopls'].launch()
    end, 500)
  end
end

util.deletedir = function(dir)
  local lfs = require('lfs')
  for file in lfs.dir(dir) do
    local file_path = dir .. '/' .. file
    if file ~= '.' and file ~= '..' then
      if lfs.attributes(file_path, 'mode') == 'file' then
        os.remove(file_path)
        print('remove file', file_path)
      elseif lfs.attributes(file_path, 'mode') == 'directory' then
        print('dir', file_path)
        util.deletedir(file_path)
      end
    end
  end
  lfs.rmdir(dir)
  util.log('remove dir', dir)
end

function util.file_exists(name)
  local f = io.open(name, 'r')
  if f ~= nil then
    io.close(f)
    return true
  end
  return false
end

-- get all lines from a file, returns an empty
-- list/table if the file does not exist
function util.lines_from(file)
  if not util.file_exists(file) then
    return {}
  end
  local lines = {}
  for line in io.lines(file) do
    lines[#lines + 1] = line
  end
  return lines
end

function util.list_directory()
  return fn.map(fn.glob(fn.fnameescape('./') .. '/{,.}*/', 1, 1), 'fnamemodify(v:val, ":h:t")')
end

function util.get_active_buf()
  local lb = fn.getbufinfo({ buflisted = 1 })
  util.log(lb)
  local result = {}
  for _, item in ipairs(lb) do
    if fn.empty(item.name) == 0 and item.hidden == 0 then
      util.log('buf loaded', item.name)
      table.insert(result, { name = fn.shellescape(item.name), bufnr = item.bufnr })
    end
  end

  return result
end
-- for l:item in l:blist
--     "skip unnamed buffers; also skip hidden buffers?
--     if empty(l:item.name) || l:item.hidden
--         continue
--     endif
--     call add(l:result, shellescape(l:item.name))
-- return l:result

function util.set_nulls()
  if _GO_NVIM_CFG.null_ls_document_formatting_disable then
    local query = {}
    if type(_GO_NVIM_CFG.null_ls_document_formatting_disable) ~= 'boolean' then
      query = _GO_NVIM_CFG.null_ls_document_formatting_disable
    end
    local ok, nulls = pcall(require, 'null-ls')
    if ok then
      nulls.disable(query)
    end
  end
end

-- run in current source code path
function util.exec_in_path(cmd, bufnr, ...)
  bufnr = bufnr or vim.api.nvim_get_current_buf()
  local path = fn.fnamemodify(fn.bufname(bufnr), ':p:h')
  local dir = util.chdir(path)
  local result
  if type(cmd) == 'function' then
    result = cmd(bufnr, ...)
  else
    result = fn.systemlist(cmd, ...)
  end
  util.log(result)
  util.chdir(dir)
  return result
end

function util.line_ending()
  if vim.o.fileformat == 'dos' then
    return '\r\n'
  elseif vim.o.fileformat == 'mac' then
    return '\r'
  end
  return '\n'
end

function util.offset(line, col)
  util.log(line, col)
  if vim.o.encoding ~= 'utf-8' then
    print('only utf-8 encoding is supported current encoding: ', vim.o.encoding)
  end
  return fn.line2byte(line) + col - 2
end

-- parse //+build integration unit
-- //go:build ci
function util.get_build_tags(buf)
  local tags = {}
  buf = buf or '%'
  local pattern = [[^//\s*[+|(go:)]*build\s\+\(.\+\)]]
  local cnt = vim.fn.getbufinfo(buf)[1]['linecount']
  cnt = math.min(cnt, 10)
  for i = 1, cnt do
    local line = vim.fn.trim(vim.fn.getbufline(buf, i)[1])
    if string.find(line, 'package') then
      break
    end
    local t = vim.fn.substitute(line, pattern, [[\1]], '')
    if t ~= line then -- tag found
      t = vim.fn.substitute(t, [[ \+]], ',', 'g')
      table.insert(tags, t)
    end
  end
  if #tags > 0 then
    return tags
  end
end

-- a uuid
function util.uuid()
  math.randomseed(tonumber(tostring(os.time()):reverse():sub(1, 9)))
  local random = math.random
  local template = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'
  return string.gsub(template, '[xy]', function(c)
    local v = (c == 'x') and random(0, 0xf) or random(8, 0xb)
    return string.format('%x', v)
  end)
end

local lorem =
  'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum'
function util.lorem()
  return lorem
end

function util.random_words(len)
  local str = util.lorem()
  local words = fn.split(str, ' ')
  str = ''
  for i = 1, len do
    str = str .. ' ' .. words[math.random(#words)]
  end
  return str
end

function util.random_line()
  local lines = vim.split(lorem, ', ')
  return lines[math.random(#lines)] .. ','
end

function util.run_command(cmd, ...)
  local result = fn.systemlist(cmd, ...)
  return result
end

function util.quickfix(cmd)
  if _GO_NVIM_CFG.trouble == true then
    local ok, trouble = pcall(require, 'trouble')
    if ok then
      if cmd:find('copen') then
        trouble.open('quickfix')
      else
        trouble.open('loclist')
      end
    else
      vim.notify('trouble not found')
    end
  else
    vim.cmd(cmd)
  end
end

util.debounce = function(func, duration)
  local timer = vim.loop.new_timer()
  local function inner(args)
    timer:stop()
    timer:start(
      duration,
      0,
      vim.schedule_wrap(function()
        func(args)
      end)
    )
  end

  local group = vim.api.nvim_create_augroup('gonvim__CleanupLuvTimers', {})
  vim.api.nvim_create_autocmd('VimLeavePre', {
    group = group,
    pattern = '*',
    callback = function()
      if timer then
        if timer:has_ref() then
          timer:stop()
          if not timer:is_closing() then
            timer:close()
          end
        end
        timer = nil
      end
    end,
  })

  return timer, inner
end

return util