-------------------------------------------------------------------------------
-- Tools to deal with task views
-------------------------------------------------------------------------------
local TaskViews = {}
local Util = require('util')
local Configuration = require('configuration')
local api = vim.api
-------------------------------------------------------------------------------
-- Internal Functions
-------------------------------------------------------------------------------
local function get_this_weeks_files()
  local today = os.time()
  local day_of_week = os.date('*t', today).wday
  local week_start = today - (day_of_week - 2) * 86400
  local filenames = {}

  for i = 0, 6 do
    local date = os.date('*t', week_start + i * 86400)
    table.insert(filenames, string.format('%04d-%02d-%02d.md', date.year, date.month, date.day))
  end

  return filenames
end

local function find_tasks(completed, important)
  local file_directory_path = Configuration.path_for()

  local completed_fragment = '(\\s|x)'
  if completed == 1 then
    completed_fragment = 'x'
  elseif completed == 0 then
    completed_fragment = '\\s'
  end

  local important_fragment = '(\\-|\\*)'
  if important == 1 then
    important_fragment = '\\*'
  elseif important == 0 then
    important_fragment = '\\-'
  end


  local pattern = '^\\s*' .. important_fragment .. '\\s\\[' .. completed_fragment .. ']'

  local command = string.format('rg --vimgrep \'%s\' \'%s\'', pattern, file_directory_path)
  local results = vim.fn.systemlist(command)

  if vim.v.shell_error == 0 then
    local items = {}
    for _, line in ipairs(results) do
      local filename, lnum, col, text = line:match('([^:]+):(%d+):(%d+):(.*)')
            table.insert(items, {
                filename = filename,
                lnum = tonumber(lnum),
                col = tonumber(col),
                text = text,
            })
    end

    -- Set location list for the current window and open it
    vim.fn.setloclist(0, items)
    vim.cmd('lopen')
  end
end

local function populate_quicklist_with_files(filenames)
  local uv = vim.loop
  local items = {}
  local task_pattern = '^%s*%- %[[ ]?x?%]'
  local important_task_pattern = '^%s*%* %[[ ]?x?%]'

  local file_directory_path = Configuration.path_for(Configuration.configuration.periodic_locations.daily)
  Util.ensure_directory_exists(file_directory_path)

  for _, filename in ipairs(filenames) do
    local daily_note = Util.join(file_directory_path, filename)
    local stat = uv.fs_stat(daily_note)

    if stat then -- File exists
      local file, err = io.open(daily_note, 'r')
      if file then
        local set_header = 0
        local line_number = 0
        for line in file:lines() do
          line_number = line_number + 1
          if line:match(task_pattern) or line:match(important_task_pattern) then
            if set_header == 0 then
              local header = string.sub(filename:match('([^/\\]+)$'), 1, -4)
              table.insert(items, {filename = '', lnum = 0, text = header})
              set_header = 1
            end
            table.insert(items, {filename = daily_note, text = line, lnum = line_number})
          end
        end
        file:close()
      end
    end
  end
  vim.fn.setloclist(0, {}, ' ', {title = 'Weekly Tasks', items = items})
  vim.cmd('lopen')
end

-------------------------------------------------------------------------------
-- Public Interface
-------------------------------------------------------------------------------

--- Opens the agenda view to show tasks
function TaskViews.open_agenda()
  local week_filenames = get_this_weeks_files()
  populate_quicklist_with_files(week_filenames)
end

--- Opens the view to show open tasks
function TaskViews.open_open()
  find_tasks(0)
end

--- Opens the view to show open important tasks
function TaskViews.open_open_important()
  find_tasks(0, 1)
end

--- Opens the view to search the journal
function TaskViews.open_journal()
  local pattern = '^\\s*(\\*|\\-)\\s\\[x]'
  -- local pattern = 'hell'
  local success, module = pcall(require, 'fzf-lua')
  if success then
    local notes_path = Configuration.path_for()
    Util.ensure_directory_exists(notes_path)
    module.files({ cwd = notes_path, cmd = 'rg --line-number --no-heading -- \'' .. pattern ..'\''})
  else
    api.nvim_err_writeln('This feature requires optional dependency fzf-lua')
  end
end

return TaskViews