" SPDX-FileCopyrightText: © 2022 Caleb Maclennan <caleb@alerque.com>
" SPDX-FileCopyrightText: © 2009 Benjamin D. Williams <benw@plasticboy.com>
" SPDX-License-Identifier: MIT

scriptencoding utf-8

if exists('b:did_indent') | finish | endif
let b:did_indent = 1

setlocal indentexpr=GetMarkdownIndent()
setlocal nolisp
setlocal autoindent

" Automatically continue blockquote on line break
setlocal formatoptions+=r
setlocal comments=b:>
if get(g:, 'vim_markdown_auto_insert_bullets', 1)
    " Do not automatically insert bullets when auto-wrapping with text-width
    setlocal formatoptions-=c
    " Accept various markers as bullets
    setlocal comments+=b:*,b:+,b:-
endif

" Only define the function once
if exists('*GetMarkdownIndent') | finish | endif

function! s:IsMkdCode(lnum)
    let name = synIDattr(synID(a:lnum, 1, 0), 'name')
    return (name =~# '^mkd\%(Code$\|Snippet\)' || name !=# '' && name !~? '^\%(mkd\|html\)')
endfunction

function! s:IsLiStart(line)
    return a:line !~# '^ *\([*-]\)\%( *\1\)\{2}\%( \|\1\)*$' &&
      \    a:line =~# '^\s*[*+-] \+'
endfunction

function! s:IsHeaderLine(line)
    return a:line =~# '^\s*#'
endfunction

function! s:IsBlankLine(line)
    return a:line =~# '^$'
endfunction

function! s:PrevNonBlank(lnum)
    let i = a:lnum
    while i > 1 && s:IsBlankLine(getline(i))
        let i -= 1
    endwhile
    return i
endfunction

function GetMarkdownIndent()
    if v:lnum > 2 && s:IsBlankLine(getline(v:lnum - 1)) && s:IsBlankLine(getline(v:lnum - 2))
        return 0
    endif
    let list_ind = get(g:, 'vim_markdown_new_list_item_indent', 4)
    " Find a non-blank line above the current line.
    let lnum = s:PrevNonBlank(v:lnum - 1)
    " At the start of the file use zero indent.
    if lnum == 0 | return 0 | endif
    let ind = indent(lnum)
    let line = getline(lnum)    " Last line
    let cline = getline(v:lnum) " Current line
    if s:IsLiStart(cline)
        " Current line is the first line of a list item, do not change indent
        return indent(v:lnum)
    elseif s:IsHeaderLine(cline) && !s:IsMkdCode(v:lnum)
        " Current line is the header, do not indent
        return 0
    elseif s:IsLiStart(line)
        if s:IsMkdCode(lnum)
            return ind
        else
            " Last line is the first line of a list item, increase indent
            return ind + list_ind
        endif
    else
        return ind
    endif
endfunction
