-- Copyright (c) 2020-2021 hoob3rt
-- MIT license, see LICENSE for more details.
local highlight = require('lualine.highlight')
local utils = require('lualine.utils.utils')

-- LuaFormatter off
local default_color_error = '#e32636'
local default_color_warn  = '#ffdf00'
local default_color_info  = '#ffffff'
-- LuaFormatter on

local diagnostic_sources = {
  nvim_lsp = function()
    local error_count = vim.lsp.diagnostic.get_count(0, 'Error')
    local warning_count = vim.lsp.diagnostic.get_count(0, 'Warning')
    local info_count = vim.lsp.diagnostic.get_count(0, 'Information') +
                           vim.lsp.diagnostic.get_count(0, 'Hint')
    return error_count, warning_count, info_count
  end,
  coc = function()
    local data = vim.b.coc_diagnostic_info
    if data then
      return data.error, data.warning, data.information
    else
      return 0, 0, 0
    end
  end,
  ale = function()
    local ok, data = pcall(vim.fn['ale#statusline#Count'], vim.fn.bufnr())
    if ok then
      return data.error, data.warning, data.info
    else
      return 0, 0, 0
    end
  end
}

local function get_diagnostics(sources)
  local result = {}
  for index, source in ipairs(sources) do
    local error_count, warning_count, info_count = diagnostic_sources[source]()
    result[index] = {
      error = error_count,
      warn = warning_count,
      info = info_count
    }
  end
  return result
end

local function diagnostics(options)
  local default_symbols = options.icons_enabled and {
    error = ' ', -- xf659
    warn = ' ', -- xf529
    info = ' ' -- xf7fc
  } or {error = 'E:', warn = 'W:', info = 'I:'}
  options.symbols = vim.tbl_extend('force', default_symbols,
                                   options.symbols or {})
  if options.sources == nil then
    print('no sources for diagnostics configured')
    return ''
  end
  if options.sections == nil then options.sections = {'error', 'warn', 'info'} end
  if options.colored == nil then options.colored = true end
  -- apply colors
  if not options.color_error then
    options.color_error = utils.extract_highlight_colors('DiffDelete',
                                                         'guifg') or
                              default_color_error
  end
  if not options.color_warn then
    options.color_warn =
        utils.extract_highlight_colors('DiffText', 'guifg') or
            default_color_warn
  end
  if not options.color_info then
    options.color_info =
        utils.extract_highlight_colors('Normal', 'guifg') or
            default_color_info
  end

  local highlight_groups = {}
  if options.colored then
    highlight_groups = {
      error = highlight.create_component_highlight_group(
          {fg = options.color_error}, 'diagnostics_error', options),
      warn = highlight.create_component_highlight_group(
          {fg = options.color_warn}, 'diagnostics_warn', options),
      info = highlight.create_component_highlight_group(
          {fg = options.color_info}, 'diagnostics_info', options)
    }
  end

  return function()
    local error_count, warning_count, info_count = 0, 0, 0
    local diagnostic_data = get_diagnostics(options.sources)
    for _, data in pairs(diagnostic_data) do
      error_count = error_count + data.error
      warning_count = warning_count + data.warn
      info_count = info_count + data.info
    end
    local result = {}
    local data = {error = error_count, warn = warning_count, info = info_count}
    if options.colored then
      local colors = {}
      for name, hl in pairs(highlight_groups) do
        colors[name] = highlight.component_format_highlight(hl)
      end
      for _, section in ipairs(options.sections) do
        if data[section] ~= nil and data[section] > 0 then
          table.insert(result, colors[section] .. options.symbols[section] ..
                           data[section])
        end
      end
    else
      for _, section in ipairs(options.sections) do
        if data[section] ~= nil and data[section] > 0 then
          table.insert(result, options.symbols[section] .. data[section])
        end
      end
    end
    if result[1] ~= nil then
      return table.concat(result, ' ')
    else
      return ''
    end
  end
end

return {
  init = function(options) return diagnostics(options) end,
  get_diagnostics = get_diagnostics
}