if exists('g:polyglot_disabled') && index(g:polyglot_disabled, 'fsharp') != -1
  finish
endif

" Vim indent file
" Language:     FSharp
" Maintainers:  Jean-Francois Yuen   <jfyuen@happycoders.org>
"               Mike Leary           <leary@nwlink.com>
"               Markus Mottl         <markus.mottl@gmail.com>
"               Rudi Grinberg        <rudi.grinberg@gmail.com>
"               Gregor Uhlenheuer    <kongo2002@gmail.com>
" Last Change:  2013 Jun 29
"               2005 Jun 25 - Fixed multiple bugs due to 'else\nreturn ind' working
"               2005 May 09 - Added an option to not indent OCaml-indents specially (MM)
"               2013 June   - commented textwidth (Marc Weber)
"               2014 August - Ported to F#
"               2014 August - F# specific cleanup
"
" Marc Weber's comment: This file may contain a lot of (very custom) stuff
" which eventually should be moved somewhere else ..

" Only load this indent file when no other was loaded.

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

setlocal indentexpr=GetFsharpIndent()
setlocal indentkeys+=0=and,0=class,0=constraint,0=done,0=else,0=end,0=exception,0=external,0=if,0=in,0=include,0=inherit,0=let,0=method,0=open,0=then,0=type,0=val,0=with,0;;,0>\],0\|\],0>},0\|,0},0\],0)

" Only define the function once.
if exists("*GetFsharpIndent")
    finish
endif

" Skipping pattern, for comments
function! s:GetLineWithoutFullComment(lnum)
    let lnum = prevnonblank(a:lnum - 1)
    let lline = substitute(getline(lnum), '(\*.*\*)\s*$', '', '')
    while lline =~ '^\s*$' && lnum > 0
        let lnum = prevnonblank(lnum - 1)
        let lline = substitute(getline(lnum), '(\*.*\*)\s*$', '', '')
    endwhile
    return lnum
endfunction

" Indent for ';;' to match multiple 'let'
function! s:GetInd(lnum, pat, lim)
    let llet = search(a:pat, 'bW')
    let old = indent(a:lnum)
    while llet > 0
        let old = indent(llet)
        let nb = s:GetLineWithoutFullComment(llet)
        if getline(nb) =~ a:lim
            return old
        endif
        let llet = search(a:pat, 'bW')
    endwhile
    return old
endfunction

" Indent pairs
function! s:FindPair(pstart, pmid, pend)
    call search(a:pend, 'bW')
    return indent(searchpair(a:pstart, a:pmid, a:pend, 'bWn', 'synIDattr(synID(line("."), col("."), 0), "name") =~? "string\\|comment"'))
endfunction

" Indent 'let'
function! s:FindLet(pstart, pmid, pend)
    call search(a:pend, 'bW')
    return indent(searchpair(a:pstart, a:pmid, a:pend, 'bWn', 'synIDattr(synID(line("."), col("."), 0), "name") =~? "string\\|comment" || getline(".") =~ "^\\s*let\\>.*=.*\\<in\\s*$" || getline(prevnonblank(".") - 1) =~ s:beflet'))
endfunction

function! GetFsharpIndent()
    " Find a non-commented line above the current line.
    let lnum = s:GetLineWithoutFullComment(v:lnum)

    " At the start of the file use zero indent.
    if lnum == 0
        return 0
    endif

    let ind = indent(lnum)
    let lline = substitute(getline(lnum), '(\*.*\*)\s*$', '', '')

    " " Return single 'shiftwidth' after lines matching:
    " if lline =~ '^\s*|.*->\s*$'
    "     return ind + &sw
    " endif

    let line = getline(v:lnum)

    " Indent if current line begins with 'end':
    if line =~ '^\s*end\>'
        return s:FindPair(s:module, '','\<end\>')

        " Indent if current line begins with 'done' for 'do':
    elseif line =~ '^\s*done\>'
        return s:FindPair('\<do\>', '','\<done\>')

        " Indent if current line begins with '}' or '>}':
    elseif line =~ '^\s*\(\|>\)}'
        return s:FindPair('{', '','}')

        " Indent if current line begins with ']', '|]' or '>]':
    elseif line =~ '^\s*\(\||\|>\)\]'
        return s:FindPair('\[', '','\]')

        " Indent if current line begins with ')':
    elseif line =~ '^\s*)'
        return s:FindPair('(', '',')')

        " Indent if current line begins with 'let':
    elseif line =~ '^\s*let\>'
        if lline !~ s:lim . '\|' . s:letlim . '\|' . s:beflet
            return s:FindLet(s:type, '','\<let\s*$')
        endif

        " Indent if current line begins with 'class' or 'type':
    elseif line =~ '^\s*\(class\|type\)\>'
        if lline !~ s:lim . '\|\<and\s*$\|' . s:letlim
            return s:FindLet(s:type, '','\<\(class\|type\)\s*$')
        endif

        " Indent for pattern matching:
    elseif line =~ '^\s*|'
        if lline !~ '^\s*\(|[^\]]\|\(match\|type\|with\)\>\)\|\<\(function\|private\|with\)\s*$'
            call search('|', 'bW')
            return indent(searchpair('^\s*\(match\|type\)\>\|\<\(function\|private\|with\)\s*$', '', '^\s*|', 'bWn', 'synIDattr(synID(line("."), col("."), 0), "name") =~? "string\\|comment" || getline(".") !~ "^\\s*|.*->"'))
        endif

        " Indent if current line begins with ';;':
    elseif line =~ '^\s*;;'
        if lline !~ ';;\s*$'
            return s:GetInd(v:lnum, s:letpat, s:letlim)
        endif

        " Indent if current line begins with 'in':
    elseif line =~ '^\s*in\>'
        if lline !~ '^\s*\(let\|and\)\>'
            return s:FindPair('\<let\>', '', '\<in\>')
        endif

        " Indent if current line begins with 'else':
    elseif line =~ '^\s*else\>'
        if lline !~ '^\s*\(if\|then\)\>'
            return s:FindPair('\<if\>', '', '\<else\>')
        endif

        " Indent if current line begins with 'then':
    elseif line =~ '^\s*then\>'
        if lline !~ '^\s*\(if\|else\)\>'
            return s:FindPair('\<if\>', '', '\<then\>')
        endif

        " Indent if current line begins with 'and':
    elseif line =~ '^\s*and\>'
        if lline !~ '^\s*\(and\|let\|type\)\>\|\<end\s*$'
            return ind - &sw
        endif

        " Indent if current line begins with 'with':
    elseif line =~ '^\s*with\>'
        if lline !~ '^\s*\(match\|try\)\>'
            return s:FindPair('\<\%(match\|try\)\>', '','\<with\>')
        endif

        " Indent if current line begins with 'exception', 'external', 'include' or
        " 'open':
    elseif line =~ '^\s*\(exception\|external\|include\|open\)\>'
        if lline !~ s:lim . '\|' . s:letlim
            call search(line)
            return indent(search('^\s*\(\(exception\|external\|include\|open\|type\)\>\|val\>.*:\)', 'bW'))
        endif

        " Indent if current line begins with 'val':
    elseif line =~ '^\s*val\>'
        if lline !~ '^\s*\(exception\|external\|include\|open\)\>\|' . s:obj . '\|' . s:letlim
            return indent(search('^\s*\(\(exception\|include\|initializer\|method\|open\|type\|val\)\>\|external\>.*:\)', 'bW'))
        endif

        " Indent if current line begins with 'constraint', 'inherit', 'initializer'
        " or 'method':
    elseif line =~ '^\s*\(constraint\|inherit\|initializer\|method\)\>'
        if lline !~ s:obj
            return indent(search('\<\(object\|object\s*(.*)\)\s*$', 'bW')) + &sw
        endif

    endif

    " Add a 'shiftwidth' after lines ending with:
    if lline =~ '\(:\|=\|->\|<-\|(\|\[\|{\|{<\|\[|\|\[<\|\<\(begin\|do\|else\|fun\|function\|functor\|if\|initializer\|object\|private\|sig\|struct\|then\|try\)\|\<object\s*(.*)\)\s*$'
        let ind = ind + &sw

        " Back to normal indent after lines ending with ';;':
    elseif lline =~ ';;\s*$' && lline !~ '^\s*;;'
        let ind = s:GetInd(v:lnum, s:letpat, s:letlim)

        " Back to normal indent after lines ending with 'end':
    elseif lline =~ '\<end\s*$'
        let ind = s:FindPair(s:module, '','\<end\>')

        " Back to normal indent after lines ending with 'in':
    elseif lline =~ '\<in\s*$' && lline !~ '^\s*in\>'
        let ind = s:FindPair('\<let\>', '', '\<in\>')

        " Back to normal indent after lines ending with 'done':
    elseif lline =~ '\<done\s*$'
        let ind = s:FindPair('\<do\>', '','\<done\>')

        " Back to normal indent after lines ending with '}' or '>}':
    elseif lline =~ '\(\|>\)}\s*$'
        let ind = s:FindPair('{', '','}')

        " Back to normal indent after lines ending with ']', '|]' or '>]':
    elseif lline =~ '\(\||\|>\)\]\s*$'
        let ind = s:FindPair('\[', '','\]')

        " Back to normal indent after comments:
    elseif lline =~ '\*)\s*$'
        call search('\*)', 'bW')
        let ind = indent(searchpair('(\*', '', '\*)', 'bWn', 'synIDattr(synID(line("."), col("."), 0), "name") =~? "string"'))

        " Back to normal indent after lines ending with ')':
    elseif lline =~ ')\s*$'
        let ind = s:FindPair('(', '',')')

        " If this is a multiline comment then align '*':
    elseif lline =~ '^\s*(\*' && line =~ '^\s*\*'
        let ind = ind + 1

    else
        " Don't change indentation of this line
        " for new lines (indent==0) use indentation of previous line

        " This is for preventing removing indentation of these args:
        "   let f x =
        "     let y = x + 1 in
        "     Printf.printf
        "       "o"           << here
        "       "oeuth"       << don't touch indentation

        let i = indent(v:lnum)
        return i == 0 ? ind : i

    endif

    return ind

endfunction

" vim: sw=4 et sts=4