local buffer = require('pending.buffer')
local config = require('pending.config')
local log = require('pending.log')

---@class pending.textobj
local M = {}

---@param ... any
---@return nil
local function dbg(...)
  log.debug(string.format(...))
end

---@param lnum integer
---@param meta pending.LineMeta[]
---@return string
local function get_line_from_buf(lnum, meta)
  local _ = meta
  local bufnr = buffer.bufnr()
  if not bufnr then
    return ''
  end
  local lines = vim.api.nvim_buf_get_lines(bufnr, lnum - 1, lnum, false)
  return lines[1] or ''
end

---@param line string
---@return integer start_col
---@return integer end_col
function M.inner_task_range(line)
  local prefix_end = line:find('/') and select(2, line:find('^/%d+/%- %[.%] '))
  if not prefix_end then
    prefix_end = select(2, line:find('^%- %[.%] ')) or 0
  end
  local start_col = prefix_end + 1

  local dk = config.get().date_syntax or 'due'
  local rk = config.get().recur_syntax or 'rec'
  local dk_pat = '^' .. vim.pesc(dk) .. ':%S+$'
  local rk_pat = '^' .. vim.pesc(rk) .. ':%S+$'

  local rest = line:sub(start_col)
  local words = {}
  for word in rest:gmatch('%S+') do
    table.insert(words, word)
  end

  local i = #words
  while i >= 1 do
    local word = words[i]
    if word:match(dk_pat) or word:match('^cat:%S+$') or word:match(rk_pat) then
      i = i - 1
    else
      break
    end
  end

  if i < 1 then
    return start_col, start_col
  end

  local desc = table.concat(words, ' ', 1, i)
  local end_col = start_col + #desc - 1
  return start_col, end_col
end

---@param row integer
---@param meta pending.LineMeta[]
---@return integer? header_row
---@return integer? last_row
function M.category_bounds(row, meta)
  if not meta or #meta == 0 then
    return nil, nil
  end

  local header_row = nil
  local m = meta[row]
  if not m then
    return nil, nil
  end

  if m.type == 'header' then
    header_row = row
  else
    for r = row, 1, -1 do
      if meta[r] and meta[r].type == 'header' then
        header_row = r
        break
      end
    end
  end

  if not header_row then
    return nil, nil
  end

  local last_row = header_row
  local total = #meta
  for r = header_row + 1, total do
    if meta[r].type == 'header' then
      break
    end
    last_row = r
  end

  return header_row, last_row
end

---@param count integer
---@return nil
function M.a_task(count)
  local meta = buffer.meta()
  if not meta or #meta == 0 then
    return
  end
  local row = vim.api.nvim_win_get_cursor(0)[1]
  local m = meta[row]
  if not m or m.type ~= 'task' then
    return
  end

  local start_row = row
  local end_row = row
  count = math.max(1, count)
  for _ = 2, count do
    local next_row = end_row + 1
    if next_row > #meta then
      break
    end
    if meta[next_row] and meta[next_row].type == 'task' then
      end_row = next_row
    else
      break
    end
  end

  vim.cmd('normal! ' .. start_row .. 'GV' .. end_row .. 'G')
end

---@param count integer
---@return nil
function M.a_task_visual(count)
  vim.cmd('normal! \27')
  M.a_task(count)
end

---@param count integer
---@return nil
function M.i_task(count)
  local _ = count
  local meta = buffer.meta()
  if not meta or #meta == 0 then
    return
  end
  local row = vim.api.nvim_win_get_cursor(0)[1]
  local m = meta[row]
  if not m or m.type ~= 'task' then
    return
  end

  local line = get_line_from_buf(row, meta)
  local start_col, end_col = M.inner_task_range(line)
  if start_col > end_col then
    return
  end

  vim.api.nvim_win_set_cursor(0, { row, start_col - 1 })
  vim.cmd('normal! v')
  vim.api.nvim_win_set_cursor(0, { row, end_col - 1 })
end

---@param count integer
---@return nil
function M.i_task_visual(count)
  vim.cmd('normal! \27')
  M.i_task(count)
end

---@param count integer
---@return nil
function M.a_category(count)
  local _ = count
  local meta = buffer.meta()
  if not meta or #meta == 0 then
    return
  end
  local view = buffer.current_view_name()
  if view == 'priority' then
    return
  end

  local row = vim.api.nvim_win_get_cursor(0)[1]
  local header_row, last_row = M.category_bounds(row, meta)
  if not header_row or not last_row then
    return
  end

  local start_row = header_row
  if header_row > 1 and meta[header_row - 1] and meta[header_row - 1].type == 'blank' then
    start_row = header_row - 1
  end
  local end_row = last_row
  if last_row < #meta and meta[last_row + 1] and meta[last_row + 1].type == 'blank' then
    end_row = last_row + 1
  end

  vim.cmd('normal! ' .. start_row .. 'GV' .. end_row .. 'G')
end

---@param count integer
---@return nil
function M.a_category_visual(count)
  vim.cmd('normal! \27')
  M.a_category(count)
end

---@param count integer
---@return nil
function M.i_category(count)
  local _ = count
  local meta = buffer.meta()
  if not meta or #meta == 0 then
    return
  end
  local view = buffer.current_view_name()
  if view == 'priority' then
    return
  end

  local row = vim.api.nvim_win_get_cursor(0)[1]
  local header_row, last_row = M.category_bounds(row, meta)
  if not header_row or not last_row then
    return
  end

  local first_task = nil
  local last_task = nil
  for r = header_row + 1, last_row do
    if meta[r] and meta[r].type == 'task' then
      if not first_task then
        first_task = r
      end
      last_task = r
    end
  end

  if not first_task or not last_task then
    return
  end

  vim.cmd('normal! ' .. first_task .. 'GV' .. last_task .. 'G')
end

---@param count integer
---@return nil
function M.i_category_visual(count)
  vim.cmd('normal! \27')
  M.i_category(count)
end

---@param count integer
---@return nil
function M.next_header(count)
  local meta = buffer.meta()
  if not meta or #meta == 0 then
    return
  end
  local view = buffer.current_view_name()
  if view == 'priority' then
    return
  end

  local row = vim.api.nvim_win_get_cursor(0)[1]
  dbg('next_header: cursor=%d, meta_len=%d, view=%s', row, #meta, view or 'nil')
  local found = 0
  count = math.max(1, count)
  for r = row + 1, #meta do
    if meta[r] and meta[r].type == 'header' then
      found = found + 1
      dbg(
        'next_header: found header at row=%d, cat=%s, found=%d/%d',
        r,
        meta[r].category or '?',
        found,
        count
      )
      if found == count then
        vim.api.nvim_win_set_cursor(0, { r, 0 })
        dbg('next_header: cursor set to row=%d, actual=%d', r, vim.api.nvim_win_get_cursor(0)[1])
        return
      end
    else
      dbg('next_header: row=%d type=%s', r, meta[r] and meta[r].type or 'nil')
    end
  end
  dbg('next_header: no header found after row=%d', row)
end

---@param count integer
---@return nil
function M.prev_header(count)
  local meta = buffer.meta()
  if not meta or #meta == 0 then
    return
  end
  local view = buffer.current_view_name()
  if view == 'priority' then
    return
  end

  local row = vim.api.nvim_win_get_cursor(0)[1]
  dbg('prev_header: cursor=%d, meta_len=%d', row, #meta)
  local found = 0
  count = math.max(1, count)
  for r = row - 1, 1, -1 do
    if meta[r] and meta[r].type == 'header' then
      found = found + 1
      dbg(
        'prev_header: found header at row=%d, cat=%s, found=%d/%d',
        r,
        meta[r].category or '?',
        found,
        count
      )
      if found == count then
        vim.api.nvim_win_set_cursor(0, { r, 0 })
        return
      end
    end
  end
end

---@param count integer
---@return nil
function M.next_task(count)
  local meta = buffer.meta()
  if not meta or #meta == 0 then
    return
  end

  local row = vim.api.nvim_win_get_cursor(0)[1]
  dbg('next_task: cursor=%d, meta_len=%d', row, #meta)
  local found = 0
  count = math.max(1, count)
  for r = row + 1, #meta do
    if meta[r] and meta[r].type == 'task' then
      found = found + 1
      if found == count then
        dbg('next_task: jumping to row=%d', r)
        vim.api.nvim_win_set_cursor(0, { r, 0 })
        return
      end
    end
  end
  dbg('next_task: no task found after row=%d', row)
end

---@param count integer
---@return nil
function M.prev_task(count)
  local meta = buffer.meta()
  if not meta or #meta == 0 then
    return
  end

  local row = vim.api.nvim_win_get_cursor(0)[1]
  dbg('prev_task: cursor=%d, meta_len=%d', row, #meta)
  local found = 0
  count = math.max(1, count)
  for r = row - 1, 1, -1 do
    if meta[r] and meta[r].type == 'task' then
      found = found + 1
      if found == count then
        dbg('prev_task: jumping to row=%d', r)
        vim.api.nvim_win_set_cursor(0, { r, 0 })
        return
      end
    end
  end
  dbg('prev_task: no task found before row=%d', row)
end

return M