" banana.vim - Convert Base Banana (https://git.lattuga.net/itec/banana) and back
" T4 - totem4@tropici.net
" Version: 0.1

vim9script

if exists("g:autoloaded_Banana") || &cp
	finish
endif

g:autoloaded_Banana = 1

export def Enc()
	if line("'<") > 0
		call ReplSel(Dec2Ban(GetSel()))
	else
		call EncLine()
	endif
enddef

def EncLine()
	call setline('.', substitute(getline('.'), '\d\d*', '\=toupper(Doban(submatch(0)))', 'g'))
enddef

export def Dec()
	if line("'<") > 0
		call ReplSel(Ban2Dec(GetSel()))
	else
		call DecLine()
	endif
enddef

def DecLine()
	call setline('.', substitute(getline('.'), '\C\u\u*', '\=Unban(tolower(submatch(0)))', 'g'))
enddef

var dictionary = [['b', 'c', 'd', 'f', 'g', 'l', 'm', 'n', 'p', 'r', 's', 't', 'v', 'z'], ['a', 'e', 'i', 'o', 'u']]
var numdict = len(dictionary)

def Doban(num: string): string
	var v = str2nr(num)
	var st = ''
	var l = 0

	var i = (numdict - 1) % numdict

	while ! (v == 0 && i == (numdict - 1) % numdict && l >= 0)
		var r = v % len(dictionary[i])
		v = v / len(dictionary[i])
		st = dictionary[i][r] .. st
		i = abs((i - 1) % numdict)
		l = l + 1
	endwhile
	return st
enddef

def Unban(ban: string): string
	if ! IsBanana(ban)
		return toupper(ban)
	endif

	var v = 0
	for i in range(len(ban))

		var r = (numdict + i) % numdict
		var p = index(dictionary[r], ban[i])

		v = v * len(dictionary[r]) + p
	endfor

	return string(v)
enddef

def IsBanana(ban: string): bool
	if (len(ban) % numdict) != 0
		return 0
	endif

	for i in range(len(ban))
		var r = (numdict + i) % numdict
		if index(dictionary[r], ban[i]) == -1
			return 0
		endif
	endfor

	return 1
enddef

def GetSel(): string
	var [lstart, cstart] = getcharpos("'<")[1 : 2]
	var [lend, cend] = getcharpos("'>")[1 : 2]
	var lines = getline(lstart, lend)
	if len(lines) == 0
		return ''
	endif
	lines[-1] = lines[-1][: cend - (&selection == 'inclusive' ? 1 : 2)]
	lines[0] = lines[0][cstart - 1 : ]
	return join(lines, "\n")
enddef

def ReplSel(str: string)
	var [lstart, cstart] = getcharpos("'<")[1 : 2]
	var [lend, cend] = getcharpos("'>")[1 : 2]
	var lines = getline(lstart, lend)
	var new_str = slice(lines[0], 0, cstart - 1) .. str .. lines[-1][cend : ]
	var new_str_lst = split(new_str, '\n')
	call setline(lstart, new_str_lst)
	delmarks < >
enddef

def Dec2Ban(text: string): string
	return substitute(text, '\d\d*', '\=toupper(Doban(submatch(0)))', 'g')
enddef

def Ban2Dec(text: string): string
	return substitute(text, '\C\u\u*', '\=Unban(tolower(submatch(0)))', 'g')
enddef