" GNU Info browser
"
" Copyright (c) 2001 Slavik Gorbanyov <rnd@web-drive.ru>
" All rights reserved.
"
" Redistribution and use, with or without modification, are permitted
" provided that the following conditions are met:
"
" 1. Redistributions must retain the above copyright notice, this list
"    of conditions and the following disclaimer.
"
" 2. The name of the author may not be used to endorse or promote
"    products derived from this script without specific prior written
"    permission.
"
" THIS SCRIPT IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
" OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
" DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
" POSSIBILITY OF SUCH DAMAGE.
"
" $Id: info.vim,v 1.4 2001/08/22 11:00:51 rnd Exp $

let s:infoCmd = 'info --output=-'
let s:dirPattern = '^\* [^:]*: \(([^)]*)\)'
let s:menuPattern = '^\* \([^:]*\)::'
let s:notePattern = '\*[Nn]ote \([^():]*\)\(::\|$\)'
let s:indexPattern = '^\* [^:]*:\s*\([^.]*\)\.$'
let s:indexPatternHL = '^\* [^:]*:\s\+[^(]'

command! -nargs=* Info	call s:Info(<f-args>)

fun! s:Info(...)
    let file = "(dir)"
    let node = "Top"
    if a:0
	let file = a:1
	if strpart(file, 0, 1) != '('
	    let file = '('.file.')'
	endif
	if a:0 > 1
	    let node = a:2
	endif
    endif

    call s:InfoExec(file, node)
    if winheight(2) != -1
	exe 'resize' &helpheight
    endif
endfun

fun! s:InfoExec(file, node, ...)
    " a:0 != 0 means last node requested
    if a:0
	let line = a:1
    else
	let line = 1
    endif
    if a:0 == 0 && exists('b:info_file')
	let last_file = b:info_file
	let last_node = b:info_node
	let last_line = line('.')
    endif
    let bufname = 'Info: '.a:file.a:node
    if bufexists(bufname) && a:0 < 2
	if &ft == 'info'
	    silent exe 'b!' escape(bufname, '\ ')
	else 
	    silent exe 'sb' escape(bufname, '\ ')
	endif
    else
    	if &ft == 'info'
    	    silent exe 'e!' escape(bufname, '\ ')
	else 
	    silent exe 'new' escape(bufname, '\ ')
	endif
	setlocal modifiable noswapfile buftype=nofile bufhidden=hide
	setf info
	let cmd = s:infoCmd." '".a:file.a:node."'"

	" handle shell redirection portable
	let srr_save = &srr
	set srr=>
	exe "0r!".cmd
	let &srr = srr_save

	call s:InfoBufferInit()
    endif
    let b:info_file = a:file
    let b:info_node = a:node
    if exists('last_file')
	let b:info_last_file = last_file
	let b:info_last_node = last_node
	let b:info_last_line = last_line
    endif
    call s:InfoFirstLine()
    setlocal nomodifiable
    exe line
endfun

fun! s:InfoBufferInit()

    " remove all insert mode abbreviations
    iabc <buffer>

    if has("syntax") && exists("g:syntax_on")
	syn case match
	syn match infoMenuTitle		/^\* Menu:/hs=s+2,he=e-1
	syn match infoTitle		/^[A-Z][0-9A-Za-z `',/&]\{,43}\([a-z']\|[A-Z]\{2}\)$/
	syn match infoTitle		/^[-=*]\{,45}$/
	syn match infoString		/`[^']*'/
	exec 'syn match infoLink	/'.s:notePattern.'/'
	exec 'syn match infoLink	/'.s:menuPattern.'/hs=s+2'
	exec 'syn match infoLink	/'.s:dirPattern.'/hs=s+2'
	exec 'syn match infoLink	/'.s:indexPatternHL.'/hs=s+2,he=e-2'

	if !exists("g:did_info_syntax_inits")
	    let g:did_info_syntax_inits = 1
	    hi def link infoMenuTitle	Title
	    hi def link infoTitle	Comment
	    hi def link infoLink	Directory
	    hi def link infoString	String
	endif
    endif

    " FIXME: <h> is move cursor left
    noremap <buffer> h		:call <SID>Help()<cr>
    noremap <buffer> <CR>	:call <SID>FollowLink()<cr>
    noremap <buffer> <C-]>	:call <SID>FollowLink()<cr>
    " FIXME: <l> is move cursor right
"    noremap <buffer> l		:call <SID>LastNode()<cr>
    noremap <buffer> ;		:call <SID>LastNode()<cr>
    noremap <buffer> <C-T>	:call <SID>LastNode()<cr>
    " FIXME: <n> is go to next match
"    noremap <buffer> n		:call <SID>NextNode()<cr>
    noremap <buffer> .		:call <SID>NextNode()<cr>
    noremap <buffer> p		:call <SID>PrevNode()<cr>
    noremap <buffer> >		:call <SID>NextNode()<cr>
    noremap <buffer> <		:call <SID>PrevNode()<cr>
    noremap <buffer> u		:call <SID>UpNode()<cr>
    noremap <buffer> t		:call <SID>TopNode()<cr>
    noremap <buffer> d		:call <SID>DirNode()<cr>
    noremap <buffer> s		:call <SID>Search()<cr>
    noremap <buffer> <TAB>	:call <SID>NextRef()<cr>
    nnoremap <buffer> q		:q!<cr>
    noremap <buffer> <Space>	<C-F>
    noremap <buffer> <Backspace> <C-B>
endfun

fun! s:Help()
    echohl Title
    echo 'Info browser keys'
    echo '-----------------'
    echohl None
    echo '<Space>		Scroll forward (page down).'
    echo '<Backspace>	Scroll backward (page up).'
    echo '<Tab>		Move cursor to next hyperlink within this node.'
    echo '<Enter>,<C-]>	Follow hyperlink under cursor.'
    echo ';,<C-T>		Return to last seen node.'
    echo '.,>		Move to the "next" node of this node.'
    echo 'p,<		Move to the "previous" node of this node.'
    echo 'u		Move "up" from this node.'
    echo 'd		Move to "directory" node.'
    echo 't		Move to the Top node.'
    echo 's		Search forward through all nodes for a specified string.'
    echo 'q		Quit browser.'
    echohl SpecialKey
    echo 'Note: "," means "or"'
    echohl None
endfun

fun! s:InfoFirstLine()
    let b:info_next_node = ''
    let b:info_prev_node = ''
    let b:info_up_node = ''
    let line = getline(1)
    let node_offset = matchend(line, '^File: [^, 	]*')
    if node_offset == -1
	echohl ErrorMsg | echo 'Info failed' | echohl None
	return
    endif
    let file = strpart(line, 6, node_offset-6)
    if file == 'dir'
	return
    endif
"    let file = substitute(file, '\(.*\)\.info\(\.gz\)\=', '\1', '')
    let b:info_next_node = s:GetSubmatch( line, '\s\+Next: \([^,]*\),')
    let b:info_prev_node = s:GetSubmatch( line, '\s\+Prev: \([^,]*\),')
    let b:info_up_node = s:GetSubmatch( line, '\s\+Up: \(.*\)')
endfun

fun! s:GetSubmatch(string, pattern)
    let matched = matchstr(a:string, a:pattern)
    if matched != ''
	let matched = substitute(matched, a:pattern, '\1', '')
    endif
    return matched
endfun

fun! s:NextNode()
    if exists('b:info_next_node') && b:info_next_node != ''
	\ && match(b:info_next_node, '(.*)') == -1
	call s:InfoExec(b:info_file, b:info_next_node)
	return 1
    else
	echohl ErrorMsg | echo 'This is the last node' | echohl None
    endif
endfun

fun! s:TopNode()
    if b:info_node == 'Top'
	if b:info_file == '(dir)'
	    echohl ErrorMsg | echo 'Already at top node' | echohl None
	    return
	endif
	let file = '(dir)'
	let node = b:info_node
    else
	let file = b:info_file
	let node = 'Top'
    endif
    call s:InfoExec(file, node)
endfun

fun! s:DirNode()
    call s:InfoExec('(dir)', 'Top')
endfun

fun! s:LastNode()
    if !exists('b:info_last_node')
	echohl ErrorMsg | echo 'No last node' | echohl None
	return
    endif
    call s:InfoExec(b:info_last_file, b:info_last_node, b:info_last_line)
endfun

fun! s:FollowLink()
    let current_line = getline('.')
    let link = matchstr(current_line, s:notePattern)
    if link == ''
	let link = matchstr(current_line, s:dirPattern)
	if link == ''
	    let link = matchstr(current_line, s:menuPattern)
	    if link == ''
		let link = matchstr(current_line, s:indexPattern)
		if link == ''
		    echohl ErrorMsg | echo 'No link under cursor' | echohl None
		    return
		endif
		let successPattern = s:indexPattern
	    else
		let successPattern = s:menuPattern
	    endif
	    let file = b:info_file
	    let node = substitute(link, successPattern, '\1', '')
	else
	    let successPattern = s:dirPattern
	    let file = substitute(link, successPattern, '\1', '')
	    let node = 'Top'
	endif
    else
	let successPattern = s:notePattern
	let file = b:info_file
	let node = substitute(link, successPattern, '\1', '')
    endif
    let link_start_pos = match(current_line, successPattern)
    let link_end_pos = matchend(current_line, successPattern)
    let cursor_pos = col('.')
    if cursor_pos <= link_start_pos || cursor_pos > link_end_pos
	echohl ErrorMsg | echo 'No link under cursor' | echohl None
	return
    endif
    if exists('g:info_debug')
	echo 'Link:' strpart(current_line, link_start_pos, link_end_pos - link_start_pos)
    	echo 'File:' file 'Node:' node
    endif
    call s:InfoExec(file, node)
endfun

fun! s:NextRef()
    let link_pos = search('\('.s:dirPattern.'\|'.s:menuPattern.'\|'.s:notePattern.'\|'.s:indexPatternHL.'\)', 'w')
    if link_pos == 0
	echohl ErrorMsg | echo 'No hyperlinks' | echohl None
    else
	echo
    endif
endfun

fun! s:PrevNode()
    if exists('b:info_prev_node') && b:info_prev_node != ''
	\ && match(b:info_prev_node, '(.*)') == -1
	call s:InfoExec(b:info_file, b:info_prev_node)
	return 1
    else
	echohl ErrorMsg | echo 'This is the first node' | echohl None
    endif
endfun

fun! s:UpNode()
    if exists('b:info_up_node') && b:info_up_node != ''
	\ && match(b:info_up_node, '(.*)') == -1
	call s:InfoExec(b:info_file, b:info_up_node)
	return 1
    else
	echohl ErrorMsg | echo 'This is the top node' | echohl None
    endif
endfun

" FIXME: there is no way to correctly abort searching.
" <CTRL-C> messes up the command window and stops at empty buffer.
fun! s:Search()
    if !exists('s:info_search_string')
	let s:info_search_string = ''
    endif
    let new_search = input('Search all nodes: ', s:info_search_string)
    if new_search == ''
	return
    endif
    let s:info_search_string = new_search
    let start_file = b:info_file
    let start_node = b:info_node
    let start_line = line('.')
    while search(s:info_search_string, 'W') == 0
	if !exists('b:info_next_node') || b:info_next_node == ''
	    \ || match(b:info_next_node, '(.*)') != -1
	    silent! exe 'bwipe' escape('Info: '.start_file.start_node, '\ ')
	    silent call s:InfoExec(start_file, start_node, start_line, 'force')
	    echohl ErrorMsg | echo "\rSearch pattern not found" | echohl None
	    return
	endif
	echo "\rSearching ... ".b:info_file b:info_next_node
	let file = b:info_file
	let node = b:info_next_node
	silent bwipe
	silent call s:InfoExec(file, node, 2)
    endwhile
endfun