local M = {}

local api = vim.api

local function highlight(num, active)
  if active == 1 then
    if num == 1 then
      return '%#PmenuSel#'
    else
      return '%#StatusLine#'
    end
  else
    return '%#StatusLineNC#'
  end
end

function M.hldefs()
  local bg = api.nvim_get_hl_by_name('StatusLine', true).background
  for _, ty in ipairs { 'Warn', 'Error', 'Info', 'Hint' } do
    local hl = api.nvim_get_hl_by_name('Diagnostic'..ty, true)
    local name = ('Diagnostic%sStatus'):format(ty)
    api.nvim_set_hl(0, name, { fg = hl.foreground, bg = bg})
  end
end

function M.lsp_status(active)
  if vim.tbl_isempty(vim.lsp.buf_get_clients(0)) then
    return ''
  end

  local status = {}

  for _, ty in ipairs { 'Warn', 'Error', 'Info', 'Hint' } do
    local n = vim.diagnostic.get(0, {severity=ty})
    if #n > 0 then
      if active == 1 then
        table.insert(status, ('%%#Diagnostic%sStatus# %s:%s'):format(ty, ty:sub(1,1), #n))
      else
        table.insert(status, (' %s:%s'):format(ty:sub(1,1), #n))
      end
    end
  end

  if vim.g.metals_status then
    status[#status+1] = vim.g.metals_status:gsub('%%', '%%%%')
  end

  local r = table.concat(status, ' ')

  return r == '' and 'LSP' or r
end

function M.hunks()
  if vim.b.gitsigns_status then
    local status = vim.b.gitsigns_head
    if vim.b.gitsigns_status ~= '' then
      status = status ..' '..vim.b.gitsigns_status
    end
    return status
  elseif vim.g.gitsigns_head then
    return vim.g.gitsigns_head
  end
  return ''
end

function M.blame()
  if vim.b.gitsigns_blame_line_dict then
    local info = vim.b.gitsigns_blame_line_dict
    local date_time = require('gitsigns.util').get_relative_time(tonumber(info.author_time))
    return string.format('%s - %s', info.author, date_time)
  end
  return ''
end

local function filetype_symbol()
  local ok, res = pcall(api.nvim_call_function, 'WebDevIconsGetFileTypeSymbol', {})
  if ok then
    return res
  end
  local name = api.nvim_buf_get_name(0)
  res = require'nvim-web-devicons'.get_icon(name, vim.bo.filetype, {default = true})
  return res
end

local function is_treesitter()
  local bufnr = api.nvim_get_current_buf()
  return vim.treesitter.highlighter.active[bufnr] ~= nil
end

function M.filetype()
  return table.concat({
    vim.bo.filetype,
    filetype_symbol(),
    -- Causes artifacts in ruler section
    -- is_treesitter() and '🌴' or nil
    is_treesitter() and '' or nil
  } , ' ')
end

function M.encodingAndFormat()
    local e = vim.bo.fileencoding and vim.bo.fileencoding or vim.o.encoding

    local r = {}
    if e ~= 'utf-8' then
      r[#r+1] = e
    end

    local f = vim.bo.fileformat
    if f ~= 'unix' then
      r[#r+1] = '['..f..']'
      local ok, res = pcall(api.nvim_call_function, 'WebDevIconsGetFileFormatSymbol')
      if ok then
        r[#r+1] = res
      end
    end

    return table.concat(r, ' ')
end

local function recording()
    local reg = vim.fn.reg_recording()
    if reg ~= '' then
        return '%#ModeMsg#  RECORDING['..reg..']  '
    else
        return ''
    end
end

function M.bufname()
  ---@diagnostic disable-next-line: undefined-field
  local name = vim.api.nvim_eval_statusline('%f', {}).str
  if vim.startswith(name, 'fugitive://') then
    local _, _, commit, relpath = name:find([[^fugitive://.*/%.git.*/(%x-)/(.*)]])
    name = relpath..'@'..commit:sub(1, 7)
  end
  if vim.startswith(name, 'gitsigns://') then
    local _, _, revision, relpath = name:find([[^gitsigns://.*/%.git.*/(.*):(.*)]])
    name = relpath..'@'..revision:sub(1, 7)
  end
  return name
end

local function pad(x)
  return '%( '..x..' %)'
end

local function func(name, active)
  active = active or 1
  return '%{%v:lua.statusline.'..name..'('..tostring(active)..')%}'
end

function M.set(active, global)
  local scope = global and 'o' or 'wo'
  vim[scope].statusline = table.concat{
    '%=', -- Needed for the highlight below to work
    highlight(1, active),
    recording(),
    pad(func('hunks')),
    highlight(2, active),
    pad(func('lsp_status', active)),
    highlight(2, active),
    '%=',
    pad(func('bufname')..'%m%r%h%q'),
    -- '%<%0.60f%m%r',  -- file.txt[+][RO]
    '%=',
    pad(func('filetype')),
    pad(func('encodingAndFormat')),
    highlight(1, active),
    ' %3p%% %2l(%02c)/%-3L ', -- 80% 65[12]/120
  }
end

-- Only set up WinEnter autocmd when the WinLeave autocmd runs
api.nvim_create_augroup('statusline', {})
api.nvim_create_autocmd({'WinLeave', 'FocusLost'}, {
  group = 'statusline',
  callback = function()
    api.nvim_create_autocmd({'BufWinEnter', 'WinEnter', 'FocusGained'}, {
      group = 'statusline',
      callback = function()
        M.set(1)
      end
    })
    M.set(0)
  end
})

api.nvim_create_autocmd('VimEnter', {
  group = 'statusline',
  callback = function()
    M.set(1, true)
  end
})

api.nvim_create_autocmd('ColorScheme', {
  group = 'statusline',
  callback = M.hldefs
})

_G.statusline = M

return M