local brain_home = os.getenv('HOME') .. '/brain'
local templates_path = brain_home .. '/1 periodic/99 templates'

-------------------------------------------------------------------------------
-- Private functions for Periodic Tasks
-------------------------------------------------------------------------------

local function load_template(template_name)
  local template_path = templates_path .. '/' .. template_name

  print(template_path)

  local template_file = io.open(template_path, 'r')
  if not template_file then
      print('Template file not found')
      return
  end
  local content = template_file:read('*a')
  template_file:close()
  return content
end

local function open_or_create_from_template(template_name, file)
  local journal_file = io.open(file, 'r')
  if not journal_file then
    local template_contents = load_template(template_name)

    journal_file = io.open(file, 'w')
    journal_file:write(template_contents)
    journal_file:close()
  end
  vim.cmd('edit ' .. file)
end

local function find_tasks(completed)
  local journal_path = brain_home .. '/1 periodic/01 journal/'

  local pattern = '^\\s*\\- \\[ \\]'
  if completed == 1 then
    pattern = '^\\s*\\- \\[x\\]'
  end

  local command = string.format('rg --vimgrep \'%s\' \'%s\'', pattern, journal_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 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 populate_quicklist_with_files(filenames)
  local uv = vim.loop
  local items = {}
  local pattern = '^%s*%- %[[ ]?x?%]'

  for _, filename in ipairs(filenames) do
    local daily_note = brain_home .. '/1 periodic/01 journal/' .. 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(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

-------------------------------------------------------------------------------
-- Periodic Notes
-------------------------------------------------------------------------------

function open_daily_note()
    local filename_format = os.date('%Y-%m-%d')
    local template_name = '001 daily.md'

    local daily_note = brain_home .. '/1 periodic/01 journal/' .. filename_format .. '.md'
    open_or_create_from_template(template_name, daily_note)
end

function open_weekly_note()
    local filename_format = os.date('%Y-w%V')
    local template_name = '002 weekly.md'

    local weekly_note = brain_home .. '/1 periodic/02 weeks/' .. filename_format .. '.md'
    open_or_create_from_template(template_name, weekly_note)
end

-------------------------------------------------------------------------------
-- Task Utilities
-------------------------------------------------------------------------------

function toggle_task()
    local line_num = vim.api.nvim_win_get_cursor(0)[1]
    local line = vim.api.nvim_get_current_line()

    local unchecked_pattern = '^%s*%- %[ %]'
    local checked_pattern = '^%s*%- %[x%]'

    if line:match(unchecked_pattern) then
        line = line:gsub(unchecked_pattern, '- [x]', 1)
    elseif line:match(checked_pattern) then
        line = line:gsub(checked_pattern, '- [ ]', 1)
    end

    vim.api.nvim_buf_set_lines(0, line_num - 1, line_num, false, {line})
end

-------------------------------------------------------------------------------
-- Task Quicklist Views
-------------------------------------------------------------------------------

function open_agenda()
  local week_filenames = get_this_weeks_files()
  populate_quicklist_with_files(week_filenames)
end

function open_open()
  find_tasks(0)
end

-------------------------------------------------------------------------------
-- Key Bindings
-------------------------------------------------------------------------------
-- Periodic Notes
vim.api.nvim_set_keymap('n', '<leader>od', '<cmd>lua open_daily_note()<CR>', { noremap = true, silent = true })
vim.api.nvim_set_keymap('n', '<leader>ow', '<cmd>lua open_weekly_note()<CR>', { noremap = true, silent = true })
-- Planned: \om to open monthly, \os to open seasonly, and \oy to open yearly
-- Agenda Views
vim.api.nvim_set_keymap('n', '<leader>oa', '<cmd>lua open_agenda()<CR>', { noremap = true, silent = true })
vim.api.nvim_set_keymap('n', '<leader>oo', '<cmd>lua open_open()<CR>', { noremap = true, silent = true })
-- Planned: \oj to open journal
-- Task Helpers
vim.api.nvim_set_keymap('n', '<leader>t', '<cmd>lua toggle_task()<CR>', { noremap = true, silent = true })
-- Planned: \it to insert tasks
-- Planned: \ct to capture task to an inbox
-- Planned: \cl to capture a learning
-- Planned: \cp to capture .plan
-- Planned: \rt reschedule task to today
-- Planned: \rT reschedule task for tomorrow
-- Planned But even later: \rr reschedule task for an arbitrary date.
-- Planned: \rs reschedule task for someday
-------------------------------------------------------------------------------
-- Ideas:
-- Navigate through the weeks like in org mode?
-- Labels?