'use strict';


module.exports = {
  copy: copy,
  checkDataType: checkDataType,
  checkDataTypes: checkDataTypes,
  coerceToTypes: coerceToTypes,
  toHash: toHash,
  getProperty: getProperty,
  escapeQuotes: escapeQuotes,
  ucs2length: ucs2length,
  varOccurences: varOccurences,
  varReplace: varReplace,
  cleanUpCode: cleanUpCode,
  cleanUpVarErrors: cleanUpVarErrors,
  schemaHasRules: schemaHasRules,
  stableStringify: require('json-stable-stringify'),
  toQuotedString: toQuotedString,
  getPathExpr: getPathExpr,
  getPath: getPath,
  getData: getData,
  unescapeFragment: unescapeFragment,
  escapeFragment: escapeFragment,
  escapeJsonPointer: escapeJsonPointer
};


function copy(o, to) {
  to = to || {};
  for (var key in o) to[key] = o[key];
  return to;
}


function checkDataType(dataType, data, negate) {
  var EQUAL = negate ? ' !== ' : ' === '
    , AND = negate ? ' || ' : ' && '
    , OK = negate ? '!' : ''
    , NOT = negate ? '' : '!';
  switch (dataType) {
    case 'null': return data + EQUAL + 'null';
    case 'array': return OK + 'Array.isArray(' + data + ')';
    case 'object': return '(' + OK + data + AND +
                          'typeof ' + data + EQUAL + '"object"' + AND +
                          NOT + 'Array.isArray(' + data + '))';
    case 'integer': return '(typeof ' + data + EQUAL + '"number"' + AND +
                           NOT + '(' + data + ' % 1)' +
                           AND + data + EQUAL + data + ')';
    default: return 'typeof ' + data + EQUAL + '"' + dataType + '"';
  }
}


function checkDataTypes(dataTypes, data) {
  switch (dataTypes.length) {
    case 1: return checkDataType(dataTypes[0], data, true);
    default:
      var code = '';
      var types = toHash(dataTypes);
      if (types.array && types.object) {
        code = types.null ? '(': '(!' + data + ' || ';
        code += 'typeof ' + data + ' !== "object")';
        delete types.null;
        delete types.array;
        delete types.object;
      }
      if (types.number) delete types.integer;
      for (var t in types)
        code += (code ? ' && ' : '' ) + checkDataType(t, data, true);

      return code;
  }
}


var COERCE_TO_TYPES = toHash([ 'string', 'number', 'integer', 'boolean', 'null' ]);
function coerceToTypes(optionCoerceTypes, dataTypes) {
  if (Array.isArray(dataTypes)) {
    var types = [];
    for (var i=0; i<dataTypes.length; i++) {
      var t = dataTypes[i];
      if (COERCE_TO_TYPES[t]) types[types.length] = t;
	  else if (optionCoerceTypes === 'array' && t === 'array') types[types.length] = t;
    }
    if (types.length) return types;
  } else if (COERCE_TO_TYPES[dataTypes]) {
    return [dataTypes];
  } else if (optionCoerceTypes === 'array' && dataTypes === 'array') {
  	return ['array'];
  }
}


function toHash(arr) {
  var hash = {};
  for (var i=0; i<arr.length; i++) hash[arr[i]] = true;
  return hash;
}


var IDENTIFIER = /^[a-z$_][a-z$_0-9]*$/i;
var SINGLE_QUOTE = /'|\\/g;
function getProperty(key) {
  return typeof key == 'number'
          ? '[' + key + ']'
          : IDENTIFIER.test(key)
            ? '.' + key
            : "['" + escapeQuotes(key) + "']";
}


function escapeQuotes(str) {
  return str.replace(SINGLE_QUOTE, '\\$&')
            .replace(/\n/g, '\\n')
            .replace(/\r/g, '\\r')
            .replace(/\f/g, '\\f')
            .replace(/\t/g, '\\t');
}


// https://mathiasbynens.be/notes/javascript-encoding
// https://github.com/bestiejs/punycode.js - punycode.ucs2.decode
function ucs2length(str) {
  var length = 0
    , len = str.length
    , pos = 0
    , value;
  while (pos < len) {
    length++;
    value = str.charCodeAt(pos++);
    if (value >= 0xD800 && value <= 0xDBFF && pos < len) {
      // high surrogate, and there is a next character
      value = str.charCodeAt(pos);
      if ((value & 0xFC00) == 0xDC00) pos++; // low surrogate
    }
  }
  return length;
}


function varOccurences(str, dataVar) {
  dataVar += '[^0-9]';
  var matches = str.match(new RegExp(dataVar, 'g'));
  return matches ? matches.length : 0;
}


function varReplace(str, dataVar, expr) {
  dataVar += '([^0-9])';
  expr = expr.replace(/\$/g, '$$$$');
  return str.replace(new RegExp(dataVar, 'g'), expr + '$1');
}


var EMPTY_ELSE = /else\s*{\s*}/g
  , EMPTY_IF_NO_ELSE = /if\s*\([^)]+\)\s*\{\s*\}(?!\s*else)/g
  , EMPTY_IF_WITH_ELSE = /if\s*\(([^)]+)\)\s*\{\s*\}\s*else(?!\s*if)/g;
function cleanUpCode(out) {
  return out.replace(EMPTY_ELSE, '')
            .replace(EMPTY_IF_NO_ELSE, '')
            .replace(EMPTY_IF_WITH_ELSE, 'if (!($1))');
}


var ERRORS_REGEXP = /[^v\.]errors/g
  , REMOVE_ERRORS = /var errors = 0;|var vErrors = null;|validate.errors = vErrors;/g
  , REMOVE_ERRORS_ASYNC = /var errors = 0;|var vErrors = null;/g
  , RETURN_VALID = 'return errors === 0;'
  , RETURN_TRUE = 'validate.errors = null; return true;'
  , RETURN_ASYNC = /if \(errors === 0\) return true;\s*else throw new ValidationError\(vErrors\);/
  , RETURN_TRUE_ASYNC = 'return true;';

function cleanUpVarErrors(out, async) {
  var matches = out.match(ERRORS_REGEXP);
  if (!matches || matches.length !== 2) return out;
  return async
          ? out.replace(REMOVE_ERRORS_ASYNC, '')
               .replace(RETURN_ASYNC, RETURN_TRUE_ASYNC)
          : out.replace(REMOVE_ERRORS, '')
               .replace(RETURN_VALID, RETURN_TRUE);
}


function schemaHasRules(schema, rules) {
  for (var key in schema) if (rules[key]) return true;
}


function toQuotedString(str) {
  return '\'' + escapeQuotes(str) + '\'';
}


function getPathExpr(currentPath, expr, jsonPointers, isNumber) {
  var path = jsonPointers // false by default
              ? '\'/\' + ' + expr + (isNumber ? '' : '.replace(/~/g, \'~0\').replace(/\\//g, \'~1\')')
              : (isNumber ? '\'[\' + ' + expr + ' + \']\'' : '\'[\\\'\' + ' + expr + ' + \'\\\']\'');
  return joinPaths(currentPath, path);
}


function getPath(currentPath, prop, jsonPointers) {
  var path = jsonPointers // false by default
              ? toQuotedString('/' + escapeJsonPointer(prop))
              : toQuotedString(getProperty(prop));
  return joinPaths(currentPath, path);
}


var RELATIVE_JSON_POINTER = /^([0-9]+)(#|\/(?:[^~]|~0|~1)*)?$/;
function getData($data, lvl, paths) {
  var matches = $data.match(RELATIVE_JSON_POINTER);
  if (!matches) throw new Error('Invalid relative JSON-pointer: ' + $data);
  var up = +matches[1];
  var jsonPointer = matches[2];
  if (jsonPointer == '#') {
    if (up >= lvl) throw new Error('Cannot access property/index ' + up + ' levels up, current level is ' + lvl);
    return paths[lvl - up];
  }

  if (up > lvl) throw new Error('Cannot access data ' + up + ' levels up, current level is ' + lvl);
  var data = 'data' + ((lvl - up) || '');
  if (!jsonPointer) return data;

  var expr = data;
  var segments = jsonPointer.split('/');
  for (var i=0; i<segments.length; i++) {
    var segment = segments[i];
    if (segment) {
      data += getProperty(unescapeJsonPointer(segment));
      expr += ' && ' + data;
    }
  }
  return expr;
}


function joinPaths (a, b) {
  if (a == '""') return b;
  return (a + ' + ' + b).replace(/' \+ '/g, '');
}


function unescapeFragment(str) {
  return unescapeJsonPointer(decodeURIComponent(str));
}


function escapeFragment(str) {
  return encodeURIComponent(escapeJsonPointer(str));
}


function escapeJsonPointer(str) {
  return str.replace(/~/g, '~0').replace(/\//g, '~1');
}


function unescapeJsonPointer(str) {
  return str.replace(/~1/g, '/').replace(/~0/g, '~');
}