" autoload/nuwiki/textobjects.vim — vimwiki parity text objects for plain Vim.
"
" Mirrors lua/nuwiki/textobjects.lua. Five operator-pending + visual pairs:
"
"   ah / ih   heading section only (stops at any next heading)
"   aH / iH   heading section + sub-tree (stops at same-or-shallower)
"   al / il   list item (line, with / without marker prefix + checkbox)
"   a\ / i\   table cell (with / without surrounding `|` separators)
"   ac / ic   table column (with / without the header separator row)
"
" Pure regex / `getline()` — no LSP round-trip. Each public function
" computes the (start_line, start_col, end_line, end_col) rectangle and
" hands it to `s:select_range` which issues a single `normal!` command
" with either `V` (linewise) or `v` / `<C-v>` (charwise / blockwise).
"
" The keymaps wire up via the standard Vim pattern:
"   xnoremap <silent><buffer> ah :<C-u>call nuwiki#textobjects#heading(0, 0)<CR>
"   onoremap <silent><buffer> ah :<C-u>call nuwiki#textobjects#heading(0, 0)<CR>
" `:<C-u>` clears the prefix count (and exits visual cleanly for xmap);
" the function then re-establishes the visual selection. From
" operator-pending mode Vim absorbs the resulting visual range as the
" pending operator's motion.

" ===== Heading helpers =====

function! s:heading_level(line) abort
  let l:lead = matchstr(a:line, '^\s*\zs=\+\ze\s')
  if empty(l:lead) | return 0 | endif
  let l:lvl = strlen(l:lead)
  if l:lvl > 6 | return 0 | endif
  let l:trail = matchstr(a:line, '\s\zs=\+\ze\s*$')
  if empty(l:trail) || strlen(l:trail) != l:lvl
    return 0
  endif
  return l:lvl
endfunction

" Returns `[start, end]` line numbers, or `[]` if no heading found.
function! s:heading_block(lnum, with_subtree) abort
  let l:total = line('$')
  let l:start = 0
  let l:i = a:lnum
  while l:i >= 1
    if s:heading_level(getline(l:i)) > 0
      let l:start = l:i
      break
    endif
    let l:i -= 1
  endwhile
  if l:start == 0 | return [] | endif
  let l:level = s:heading_level(getline(l:start))
  let l:stop = l:total
  let l:j = l:start + 1
  while l:j <= l:total
    let l:lvl = s:heading_level(getline(l:j))
    if l:lvl > 0
      if a:with_subtree
        if l:lvl <= l:level
          let l:stop = l:j - 1
          break
        endif
      else
        let l:stop = l:j - 1
        break
      endif
    endif
    let l:j += 1
  endwhile
  return [l:start, l:stop]
endfunction

" Drive a fresh visual selection covering the given range.
"   - mode='V' (linewise) — only s_line / e_line matter
"   - mode='v' (charwise) — s_col / e_col are 1-based
"   - mode='\<C-v>' (blockwise) — used by `ac` / `ic`
" Always issues a clean `<Esc>` first so any in-progress visual anchor
" doesn't stick.
function! s:select_range(s_line, s_col, e_line, e_col, mode) abort
  let l:cur_mode = mode(1)
  let l:prefix = ''
  if l:cur_mode =~# "^[vV\<C-v>]"
    let l:prefix = "\<Esc>"
  endif
  if a:mode ==# 'V'
    let l:keys = a:s_line . 'GV' . a:e_line . 'G'
  elseif a:mode ==# "\<C-v>"
    let l:keys = a:s_line . 'G' . a:s_col . '|' . "\<C-v>" . a:e_line . 'G' . a:e_col . '|'
  else
    let l:keys = a:s_line . 'G' . a:s_col . '|v' . a:e_line . 'G' . a:e_col . '|'
  endif
  call feedkeys(l:prefix . l:keys, 'nx')
endfunction

function! nuwiki#textobjects#heading(inner, with_subtree) abort
  let l:r = s:heading_block(line('.'), a:with_subtree)
  if empty(l:r) | return | endif
  let [l:s, l:e] = l:r
  if a:inner | let l:s += 1 | endif
  if l:e < l:s | return | endif
  call s:select_range(l:s, 0, l:e, 0, 'V')
endfunction

" ===== List item =====

function! s:is_list_line(line) abort
  return a:line =~# '^\s*[-*#]\s' || a:line =~# '^\s*\w\+[.)]\s'
endfunction

function! nuwiki#textobjects#list_item(inner) abort
  let l:lnum = line('.')
  let l:line = getline(l:lnum)
  if !s:is_list_line(l:line) | return | endif
  let l:line_len = strlen(l:line)
  if a:inner
    let l:m = matchend(l:line, '^\s*[-*#]\s\+')
    if l:m < 0
      let l:m = matchend(l:line, '^\s*\w\+[.)]\s\+')
    endif
    if l:m < 0 | return | endif
    let l:cb_len = matchend(l:line[l:m :], '^\[[ xXoO.\-]\]\s\+')
    if l:cb_len > 0
      let l:m += l:cb_len
    endif
    call s:select_range(l:lnum, l:m + 1, l:lnum, l:line_len, 'v')
  else
    call s:select_range(l:lnum, 1, l:lnum, l:line_len, 'v')
  endif
endfunction

" ===== Table cell / column =====

function! s:is_table_row(line) abort
  return a:line =~# '^\s*|.*|\s*$'
endfunction

" Returns a list of `[start_col, end_col]` byte positions (1-based,
" inclusive) for the *content* of each cell on the row — i.e. the
" character span between two `|` separators, not including the
" separators themselves.
function! s:cell_ranges(line) abort
  let l:out = []
  let l:lead = matchend(a:line, '^\s*|')
  if l:lead < 0 | return l:out | endif
  let l:pos = l:lead + 1
  while 1
    let l:next = stridx(a:line, '|', l:pos - 1)
    if l:next < 0 | break | endif
    " 1-based, inclusive: content runs from l:pos (after prior |) to l:next.
    call add(l:out, [l:pos, l:next])
    let l:pos = l:next + 2
  endwhile
  return l:out
endfunction

" Find which cell index (1-based) the cursor is in. Returns `[idx, range]`
" or `[0, []]` if not on a table row.
function! s:current_cell(lnum, col) abort
  let l:line = getline(a:lnum)
  if !s:is_table_row(l:line) | return [0, []] | endif
  let l:ranges = s:cell_ranges(l:line)
  let l:i = 0
  for l:r in l:ranges
    let l:i += 1
    if a:col >= l:r[0] && a:col <= l:r[1] + 1
      return [l:i, l:r]
    endif
  endfor
  if !empty(l:ranges)
    return [1, l:ranges[0]]
  endif
  return [0, []]
endfunction

function! nuwiki#textobjects#table_cell(inner) abort
  let l:lnum = line('.')
  let l:col = col('.')
  let [l:idx, l:range] = s:current_cell(l:lnum, l:col)
  if l:idx == 0 | return | endif
  if a:inner
    let l:line = getline(l:lnum)
    let l:s = l:range[0]
    let l:e = l:range[1]
    while l:s <= l:e && l:line[l:s - 1] ==# ' '
      let l:s += 1
    endwhile
    while l:e >= l:s && l:line[l:e - 1] ==# ' '
      let l:e -= 1
    endwhile
    if l:e < l:s | return | endif
    call s:select_range(l:lnum, l:s, l:lnum, l:e, 'v')
  else
    call s:select_range(l:lnum, l:range[0], l:lnum, l:range[1] + 1, 'v')
  endif
endfunction

" Walk up/down from `lnum` to find the contiguous block of table rows.
function! s:table_bounds(lnum) abort
  if !s:is_table_row(getline(a:lnum)) | return [] | endif
  let l:total = line('$')
  let l:s = a:lnum
  let l:e = a:lnum
  while l:s > 1 && s:is_table_row(getline(l:s - 1))
    let l:s -= 1
  endwhile
  while l:e < l:total && s:is_table_row(getline(l:e + 1))
    let l:e += 1
  endwhile
  return [l:s, l:e]
endfunction

function! nuwiki#textobjects#table_column(inner) abort
  let l:lnum = line('.')
  let l:col = col('.')
  let [l:idx, l:_r] = s:current_cell(l:lnum, l:col)
  if l:idx == 0 | return | endif
  let l:bnd = s:table_bounds(l:lnum)
  if empty(l:bnd) | return | endif
  let [l:s, l:e] = l:bnd
  if a:inner
    " Drop a header-separator row (`|---|---|`) from the inner column.
    while l:s <= l:e && getline(l:s) =~# '^\s*|[-:|\s]*|\s*$'
      let l:s += 1
    endwhile
    while l:e >= l:s && getline(l:e) =~# '^\s*|[-:|\s]*|\s*$'
      let l:e -= 1
    endwhile
  endif
  if l:e < l:s | return | endif
  let l:top = s:cell_ranges(getline(l:s))
  let l:bot = s:cell_ranges(getline(l:e))
  if l:idx > len(l:top) || l:idx > len(l:bot) | return | endif
  let l:left  = l:top[l:idx - 1][0]
  let l:right = max([l:top[l:idx - 1][1], l:bot[l:idx - 1][1]])
  call s:select_range(l:s, l:left, l:e, l:right, "\<C-v>")
endfunction

" ===== Debug exports (test harness) =====
"
" Mirror the `M._*` re-exports the Lua side has. Test code calls these
" so failures land at the calculation, not the visual-mode pipeline.

function! nuwiki#textobjects#_heading_block(lnum, with_subtree) abort
  return s:heading_block(a:lnum, a:with_subtree)
endfunction

function! nuwiki#textobjects#_cell_ranges(line) abort
  return s:cell_ranges(a:line)
endfunction

function! nuwiki#textobjects#_current_cell_for_line(line, col) abort
  if !s:is_table_row(a:line) | return 0 | endif
  let l:ranges = s:cell_ranges(a:line)
  let l:i = 0
  for l:r in l:ranges
    let l:i += 1
    if a:col >= l:r[0] && a:col <= l:r[1] + 1
      return l:i
    endif
  endfor
  if !empty(l:ranges) | return 1 | endif
  return 0
endfunction

function! nuwiki#textobjects#_table_bounds(lnum) abort
  return s:table_bounds(a:lnum)
endfunction