if !exists("g:go_godef_bin")
	let g:go_godef_bin = "godef"
endif

if go#vimproc#has_vimproc()
	let s:vim_system = get(g:, 'gocomplete#system_function', 'vimproc#system2')
else
	let s:vim_system = get(g:, 'gocomplete#system_function', 'system')
endif

fu! s:system(str, ...)
	return call(s:vim_system, [a:str] + a:000)
endf

" modified and improved version of vim-godef
function! go#def#Jump(...)
	if !len(a:000)
		let arg = "-o=" . go#util#OffsetCursor()
	else
		let arg = a:1
	endif

	let bin_path = go#path#CheckBinPath(g:go_godef_bin)
	if empty(bin_path)
		return
	endif

	let old_gopath = $GOPATH
	let $GOPATH = go#path#Detect()

	let fname = fnamemodify(expand("%"), ':p:gs?\\?/?')
	let command = bin_path . " -t -f=" . shellescape(fname) . " -i " . shellescape(arg)

	" get output of godef
	let out = s:system(command, join(getbufline(bufnr('%'), 1, '$'), go#util#LineEnding()))

	" First line is <file>:<line>:<col>
	" Second line is <identifier><space><type>
	let godefout=split(out, go#util#LineEnding())

	" jump to it
	call s:godefJump(godefout, "")
	let $GOPATH = old_gopath
endfunction


function! go#def#JumpMode(mode)
	let arg = "-o=" . go#util#OffsetCursor()

	let bin_path = go#path#CheckBinPath(g:go_godef_bin)
	if empty(bin_path)
		return
	endif

	let old_gopath = $GOPATH
	let $GOPATH = go#path#Detect()

	let fname = fnamemodify(expand("%"), ':p:gs?\\?/?')
	let command = bin_path . " -t -f=" . shellescape(fname) . " -i " . shellescape(arg)

	" get output of godef
	let out = s:system(command, join(getbufline(bufnr('%'), 1, '$'), go#util#LineEnding()))

	" First line is <file>:<line>:<col>
	" Second line is <identifier><space><type>
	let godefout=split(out, go#util#LineEnding())

	" jump to it
	call s:godefJump(godefout, a:mode)
	let $GOPATH = old_gopath
endfunction


function! s:getOffset()
	return "-o=" . go#util#OffsetCursor()
endfunction


function! s:godefJump(out, mode)
	let old_errorformat = &errorformat
	let &errorformat = "%f:%l:%c"

	" Location is the first line of godef output. Ideally in the proper format
	" but it could also be an error
	let location = a:out[0]

	" Echo the godef error if we had one.
	if location =~ 'godef: '
		let gderr=substitute(location, go#util#LineEnding() . '$', '', '')
        call go#util#EchoError(gderr)
        return
    endif

    let parts = split(a:out[0], ':')

    " parts[0] contains filename
    let fileName = parts[0]

    " Don't jump if it's the same identifier we just jumped to
    if len(w:go_stack) > 0 && w:go_stack[w:go_stack_level-1]['ident'] == a:out[1] && w:go_stack[w:go_stack_level-1]['file'] == fileName
        return
    endif

    " needed for restoring back user setting this is because there are two
    " modes of switchbuf which we need based on the split mode
    let old_switchbuf = &switchbuf

    if a:mode == "tab"
        let &switchbuf = "usetab"

        if bufloaded(fileName) == 0
            tab split
        endif
    elseif a:mode  == "split"
        split
    elseif a:mode == "vsplit"
        vsplit
    else
        " Don't jump in this window if it's been modified
        if getbufvar(bufnr('%'), "&mod")
            call go#util#EchoError("No write since last change")
            return
        endif
    endif

    let stack_entry = {'line': line("."), 'col': col("."),
                \'file': expand('%:p'), 'ident': a:out[1]}

    " jump to file now
    call s:goToFileLocation(location)
    "
    " Remove anything newer than the current position, just like basic
    " vim tag support
    if w:go_stack_level == 0
        let w:go_stack = []
    else
        let w:go_stack = w:go_stack[0:w:go_stack_level-1]
    endif

    " increment the stack counter
    let w:go_stack_level += 1

    " push it on to the jumpstack
    call add(w:go_stack, stack_entry)

    let &switchbuf = old_switchbuf
endfunction

function! go#def#StackUI()
    if len(w:go_stack) == 0
        call go#util#EchoError("godef stack empty")
        return
    endif

    let stackOut = ['" <Up>,<Down>:navigate <Enter>:jump <Esc>,q:exit']

    let i = 0
    while i < len(w:go_stack)
        let entry = w:go_stack[i]
        let prefix = ""
        if i == w:go_stack_level
            let prefix = ">"
        else
            let prefix = " "
        endif
        call add(stackOut, printf("%s %d %s|%d col %d|%s", prefix, i+1, entry["file"], entry["line"], entry["col"], entry["ident"]))
        let i += 1
    endwhile
    if w:go_stack_level == i
        call add(stackOut, "> ")
    endif

    call go#ui#OpenWindow("GoDef Stack", stackOut, "godefstack")
    noremap <buffer> <silent> <CR>  :<C-U>call go#def#SelectStackEntry()<CR>
    noremap <buffer> <silent> <Esc> :<C-U>call go#ui#CloseWindow()<CR>
    noremap <buffer> <silent> q     :<C-U>call go#ui#CloseWindow()<CR>
endfunction

function! go#def#StackPop(...)
    if len(w:go_stack) == 0
        call go#util#EchoError("godef stack empty")
        return
    endif
    if w:go_stack_level == 0
        call go#util#EchoError("at bottom of the godef stack")
        return
    endif
    if !len(a:000)
        let numPop = 1
    else
        let numPop = a:1
    endif
    let newLevel = str2nr(w:go_stack_level) - str2nr(numPop)
    call go#def#StackJump(newLevel + 1)
endfunction

function! go#def#StackJump(...)
    if len(w:go_stack) == 0
        call go#util#EchoError("godef stack empty")
        return
    endif
	if !len(a:000)
        " Display interactive stack
        call go#def#StackUI()
        return
	else
		let jumpTarget= a:1
	endif

    if jumpTarget !~ '^\d\+$'
        if jumpTarget !~ '^\s*$'
            call go#util#EchoError("location must be a number")
        endif
        return
    endif

    let jumpTarget=str2nr(jumpTarget) - 1
    if jumpTarget >= 0 && jumpTarget < len(w:go_stack)
        let w:go_stack_level = jumpTarget
        let target = w:go_stack[w:go_stack_level]

        " jump
        call s:goToFileLocation(target["file"], target["line"], target["col"])
    else
        call go#util#EchoError("invalid godef stack location. Try :GoDefJump to see the list of valid entries")
    endif
endfunction

function! s:goToFileLocation(...)
	let old_errorformat = &errorformat
	let &errorformat = "%f:%l:%c"

    " put the error format into location list so we can jump automatically to
    " it
    if a:0 == 3
        lgetexpr printf("%s:%s:%s", a:1, a:2, a:3)
    elseif a:0 == 1
        lgetexpr a:1
    else
        lgetexpr ""
    endif

    sil ll 1
    normal zz

    let &errorformat = old_errorformat
endfunction

function! go#def#SelectStackEntry()
    let target_window = go#ui#GetReturnWindow()
    if empty(target_window)
        let target_window = winnr()
    endif
    let highlighted_stack_entry = matchstr(getline("."), '^..\zs\(\d\+\)')
    if !empty(highlighted_stack_entry)
        execute target_window . "wincmd w"
        call go#def#StackJump(str2nr(highlighted_stack_entry))
    endif
    call go#ui#CloseWindow()
endfunction