import { _, _l, cnst, g, id, n, pipe, _r } from './core';
import { iif } from './bool';
import { Zero, ge, ifz, pred, succ } from './num';
import { x00 } from './byte';
import { fromChar as _c, dec as cdec, inc as cinc, eq, ifn } from './char';
import { Pair, first, fst, second, snd, uncurry } from './pair';
import { cons, head, repeat, set, singleton, tail, update } from './list';
import { Empty, get, len, snoc } from './string';

n('bf');

const done = g('done', uncurry._(_l(p => cnst._(uncurry._(_l(is => _l(cs => ge._(head._(is))._(len._(cs)))))._(p)))));

const command = g('command', _l(c => uncurry._(_l(p => cnst._(eq._(c)._(uncurry._(pipe._(get)._(head))._(p)))))));

const advance = g('advance', first._(first._(update._(succ)._(Zero))));

const save = g('save', first._(first._(_l(is => cons._(head._(is))._(is)))));

const restore = g('restore', first._(first._(tail)));

const reset = g('reset', first._(first._(_l(is => cons._(head._(is))._(tail._(tail._(is)))))));

const inc = g('inc', second._(first._(_l(t => second._(update._(cinc)._(fst._(t)))._(t)))));

const dec = g('dec', second._(first._(_l(t => second._(update._(cdec)._(fst._(t)))._(t)))));

const read = g('read', pipe._(pipe._(uncurry._(get))._(fst))._(snd));

const input = g('input', second._(uncurry._(_l(t => _l(io => Pair._(second._(set._(head._(fst._(io)))._(fst._(t)))._(t))._(first._(tail)._(io)))))));

const output = g('output', second._(uncurry._(_l(t => pipe._(Pair._(t))._(second._(_l(os => snoc._(os)._(uncurry._(get)._(t)))))))));

const next = g('next', second._(first._(first._(succ))));

const prev = g('prev', second._(first._(first._(pred))));

const jump = g('jump', _l(d => _l(s =>
  iif._(command._(_c('['))._(s))._(_r('bf', 'jump')._(succ._(d)))
    ._(iif._(command._(_c(']'))._(s))._(ifz._(pred._(d))._(cnst._(s))._(_r('bf', 'jump')._(pred._(d))))
      ._(_r('bf', 'jump')._(d)))._(advance._(s)))));

const whlnz = g('whlnz', _l(s => ifn._(read._(s))._(jump._(Zero))._(save)._(s)));

const endwhl = g('endwhl', _l(s => ifn._(read._(s))._(reset)._(pipe._(save)._(restore))._(s)));

const exec = g('exec', _l(s => iif._(done._(s))._(s)._(_r('bf', 'exec')._(advance
  ._(iif._(command._(_c('>'))._(s))._(next)
    ._(iif._(command._(_c('<'))._(s))._(prev)
      ._(iif._(command._(_c('+'))._(s))._(inc)
        ._(iif._(command._(_c('-'))._(s))._(dec)
          ._(iif._(command._(_c('.'))._(s))._(output)
            ._(iif._(command._(_c(','))._(s))._(input)
              ._(iif._(command._(_c('['))._(s))._(whlnz)
                ._(iif._(command._(_c(']'))._(s))._(endwhl)
                  ._(id))))))))._(s))))));

export const run = g('run', _l(p => _l(i => snd._(snd._(snd._(exec._(Pair._(Pair._(singleton._(Zero))._(p))._(Pair._(Pair._(Zero)._(repeat._(x00)))._(Pair._(i)._(Empty))))))))));