var p = require('./parsec')
var c = p.combinators
var s = p.p_string
var f = p.funp

var char = function(ch) {
    return c.token(p.p_string.char(ch)) }
var digit = function() {
    return c.token(p.p_string.digit()) }

function literal(x, y) {
    return c.bind(
        c.nxtnxt.apply(null, x.split('').map(char))
      , function() { return c.always(y) }) }

function many_str(parser) {
    return c.bind(c.many(parser), function(x) { return c.always(x.join('')) }) }

function many1_str(parser) {
    return c.bind(c.many1(parser), function(x) { return c.always(x.join('')) }) }

var line_comment = c.nxtnxt(
    char('/')
  , char('/')
  , c.many(c.token(f.not(p.p_string.char('\n'))))
  , char('\n'))


var inline_comment_content = c.next(
    c.many(c.token(f.not(p.p_string.char('*'))))
  , char('*'))

var inline_comment = c.nxtnxt(
    char('/')
  , char('*')
  , c.many1(inline_comment_content)
  , char('/'))

var comment = c.either(line_comment, inline_comment)

var opt_space = c.many(c.either(c.token(p.p_string.whitespace()), comment))
function between_whitespace(parser) {
    return c.between(opt_space, opt_space, parser) }

function optional(def, parser) {
    return c.either(parser, c.always(def)) }

// I was legitimately running out of stack space :-)
var trampoline = function() {
    var i = 0
    return function trampoline(parser) {
        return function(state, cok, cerr, eok, eerr) {
            // decrease this number if you get stack overflow errors :P
            if (i++ < 15) return parser(state, cok, cerr, eok, eerr)
            i=0
            process.nextTick(function() { parser(state, cok, cerr, eok, eerr) })} } }()


var string = c.between(
    char('"'), char('"')
  , many_str(c.either(
            c.token(f.not(f.or(s.control(), s.char('"'), s.char('\\'))))
            // escaped chars
          , c.bind(
                char('\\')
              , c.choice(
                    char('"'), char('\\'), char('/'), char('b')
                  , char('f'), char('n'), char('r'), char('t'))
              , function(_, n) { return c.always('"\\/\b\f\n\r\t'['"\\/bfnrt'.indexOf(n)]) }))))
var number = c.bind(
    // sign
    optional('', char('-'))
    // integer part
  , c.either(char('0'), many1_str(digit()))
    // fractional part
  , optional('', c.next(char('.'), many1_str(digit())))
    // 'e' part
  , optional(0, c.bind(
        c.either(char('e'), char('E'))
      , c.choice(char('+'), char('-'), c.always('+'))
      , many1_str(digit())
      , function(_, sign, x) {
            return c.always(+(sign+x)) }))
  , function(sign, int, frac, exp) {
        return c.always(+(sign + int + '.' + frac + 'e' + exp)) })

function array() {
    return c.between(
        char('['), char(']')
      , c.many(c.bind(
            c.wrap(value)() // avoid infinite recursion
            // separator
          , c.either(char(','), c.lookahead(char(']'))) // wrong: [1,2,] will work
          , function(a) { return c.always(a) }))) }

function object() {
    return c.between(
        char('{')
      , char('}')
      , c.bind(
            c.many(c.bind(
                    between_whitespace(string)
                  , char(':')
                  , c.wrap(value)() // avoid infinite recursion
                  , c.either(char(','), c.lookahead(char('}'))) // wrong: {"1":2,} will work
                  , function(k, _, v, _) {
                        return c.always([k, v]) }))
          , function(pairs) {
                var obj = {}
                for (var i = 0; i < pairs.length; i++)
                    obj[pairs[i][0]] = pairs[i][1]                    
                return c.always(obj)})) }

function value() {
    return trampoline(between_whitespace(c.choice(
        string
      , number
      , object()
      , array()
      , literal('true', true)
      , literal('false', false)
      , literal('null', null)))) }
module.exports.value = value