"use strict";

function assert(val, msg) {
  if (!val) {
    throw new Error(msg);
  }
}

function Instafeed(options) {
  assert(!options || typeof options === 'object', 'options must be an object, got ' + options + ' ('+ typeof options +')');

  // default options
  var opts = {
    accessToken: null,
    accessTokenTimeout: 10000,
    after: null,
    apiTimeout: 10000,
    apiLimit: null,
    before: null,
    debug: false,
    error: null,
    filter: null,
    limit: null,
    mock: false,
    render: null,
    sort: null,
    success: null,
    target: 'instafeed',
    template: '<a href="{{link}}"><img title="{{caption}}" src="{{image}}" /></a>',
    templateBoundaries: ['{{','}}'],
    transform: null
  };

  // state holder
  var state = {
    running: false,
    node: null,
    token: null,
    paging: null,
    pool: []
  };

  // copy options over defaults
  if (options) {
    for (var optKey in opts) {
      if (typeof options[optKey] !== 'undefined') {
        opts[optKey] = options[optKey];
      }
    }
  }

  // validate options
  assert(typeof opts.target === 'string' || typeof opts.target === 'object', 'target must be a string or DOM node, got ' + opts.target + ' ('+ typeof opts.target +')');
  assert(typeof opts.accessToken === 'string' || typeof opts.accessToken === 'function', 'accessToken must be a string or function, got ' + opts.accessToken + ' ('+ typeof opts.accessToken +')');
  assert(typeof opts.accessTokenTimeout === 'number', 'accessTokenTimeout must be a number, got '+ opts.accessTokenTimeout + ' ('+ typeof opts.accessTokenTimeout +')');
  assert(typeof opts.apiTimeout === 'number', 'apiTimeout must be a number, got '+ opts.apiTimeout + ' ('+ typeof opts.apiTimeout +')');
  assert(typeof opts.debug === 'boolean', 'debug must be true or false, got ' + opts.debug + ' ('+ typeof opts.debug +')');
  assert(typeof opts.mock === 'boolean', 'mock must be true or false, got ' + opts.mock + ' ('+ typeof opts.mock +')');
  assert(typeof opts.templateBoundaries === 'object' && opts.templateBoundaries.length === 2 && typeof opts.templateBoundaries[0] === 'string' && typeof opts.templateBoundaries[1] === 'string', 'templateBoundaries must be an array of 2 strings, got ' + opts.templateBoundaries + ' ('+ typeof opts.templateBoundaries +')');
  assert(!opts.template || typeof opts.template === 'string', 'template must null or string, got ' + opts.template + ' ('+ typeof opts.template +')');
  assert(!opts.error || typeof opts.error === 'function', 'error must be null or function, got ' + opts.error + ' ('+ typeof opts.error +')');
  assert(!opts.before || typeof opts.before === 'function', 'before must be null or function, got ' + opts.before + ' ('+ typeof opts.before +')');
  assert(!opts.after || typeof opts.after === 'function', 'after must be null or function, got ' + opts.after + ' ('+ typeof opts.after +')');
  assert(!opts.success || typeof opts.success === 'function', 'success must be null or function, got ' + opts.success + ' ('+ typeof opts.success +')');
  assert(!opts.filter || typeof opts.filter === 'function', 'filter must be null or function, got ' + opts.filter + ' ('+ typeof opts.filter +')');
  assert(!opts.transform || typeof opts.transform === 'function', 'transform must be null or function, got ' + opts.transform + ' ('+ typeof opts.transform +')');
  assert(!opts.sort || typeof opts.sort === 'function', 'sort must be null or function, got ' + opts.sort + ' ('+ typeof opts.sort +')');
  assert(!opts.render || typeof opts.render === 'function', 'render must be null or function, got ' + opts.render + ' ('+ typeof opts.render +')');
  assert(!opts.limit || typeof opts.limit === 'number', 'limit must be null or number, got ' + opts.limit + ' ('+ typeof opts.limit +')');
  assert(!opts.apiLimit || typeof opts.apiLimit === 'number', 'apiLimit must null or number, got ' + opts.apiLimit + ' ('+ typeof opts.apiLimit +')');

  // set instance info
  this._state = state;
  this._options = opts;
}

Instafeed.prototype.run = function run() {
  var scope = this;

  this._debug('run', 'options', this._options);
  this._debug('run', 'state', this._state);

  // prevent re-entry
  if (this._state.running) {
    this._debug('run', 'already running, skipping');
    return false;
  }

  // set as running
  this._start();

  // get dom node
  this._debug('run', 'getting dom node');
  if (typeof this._options.target === 'string') {
    this._state.node = document.getElementById(this._options.target);
  } else {
    this._state.node = this._options.target;
  }
  if (!this._state.node) {
    this._fail(new Error('no element found with ID ' + this._options.target));
    return false;
  }
  this._debug('run', 'got dom node', this._state.node);

  // get access token
  this._debug('run', 'getting access token');
  this._getAccessToken(function onTokenReceived(err, token) {
    if (err) {
      scope._debug('onTokenReceived', 'error', err);
      scope._fail(new Error('error getting access token: ' + err.message));
      return;
    }

    scope._debug('onTokenReceived', 'got token', token);
    scope._state.token = token;

    scope._showNext(function onNextShown(err) {
      if (err) {
        scope._debug('onNextShown', 'error', err);
        scope._fail(err);
        return;
      }

      scope._finish();
    });
  });

  return true;
};

Instafeed.prototype.hasNext = function hasNext() {
  var paging = this._state.paging;
  var pool = this._state.pool;

  this._debug('hasNext', 'paging', paging);
  this._debug('hasNext', 'pool', pool.length, pool);

  return (pool.length > 0 || (paging && typeof paging.next === 'string'));
};

Instafeed.prototype.next = function next() {
  var scope = this;

  if (!scope.hasNext()) {
    scope._debug('next', 'hasNext is false, skipping');
    return false;
  }

  // prevent re-entry
  if (scope._state.running) {
    scope._debug('next', 'already running, skipping');
    return false;
  }

  // set as running
  scope._start();

  // show next set
  scope._showNext(function onNextShown(err) {
    if (err) {
      scope._debug('onNextShown', 'error', err);
      scope._fail(err);
      return;
    }

    scope._finish();
  });
};

Instafeed.prototype._showNext = function showNext(callback) {
  var scope = this;
  var url = null;
  var poolItems = null;
  var hasLimit = (typeof this._options.limit === 'number');

  scope._debug('showNext', 'pool', scope._state.pool.length, scope._state.pool);

  if (scope._state.pool.length > 0) {
    if (hasLimit) {
      poolItems = scope._state.pool.splice(0, scope._options.limit);
    } else {
      poolItems = scope._state.pool.splice(0);
    }

    scope._debug('showNext', 'items from pool', poolItems.length, poolItems);
    scope._debug('showNext', 'updated pool', scope._state.pool.length, scope._state.pool);

    if (scope._options.mock) {
      scope._debug('showNext', 'mock enabled, skipping render');
    } else {
      try {
        scope._renderData(poolItems);
      } catch (renderErr) {
        callback(renderErr);
        return;
      }
    }

    callback(null);
  } else {
    if (scope._state.paging && typeof scope._state.paging.next === 'string') {
      url = scope._state.paging.next;
    } else {
      url = 'https://graph.instagram.com/me/media?fields=caption,id,media_type,media_url,permalink,thumbnail_url,timestamp,username&access_token='+ scope._state.token;
      if (!scope._options.apiLimit && typeof scope._options.limit === 'number') {
        scope._debug('showNext', 'no apiLimit set, falling back to limit', scope._options.apiLimit, scope._options.limit);
        url = url + '&limit=' + scope._options.limit;
      } else if (typeof scope._options.apiLimit === 'number') {
        scope._debug('showNext', 'apiLimit set, overriding limit', scope._options.apiLimit, scope._options.limit);
        url = url + '&limit=' + scope._options.apiLimit;
      }
    }

    scope._debug('showNext', 'making request', url);

    // make network request
    scope._makeApiRequest(url, function onResponseReceived(err, data) {
      var processed = null;

      if (err) {
        scope._debug('onResponseReceived', 'error', err);
        callback(new Error('api request error: ' + err.message));
        return;
      }

      scope._debug('onResponseReceived', 'data', data);
      scope._success(data);

      scope._debug('onResponseReceived', 'setting paging', data.paging);
      scope._state.paging = data.paging;

      try {
        processed = scope._processData(data);
        scope._debug('onResponseReceived', 'processed data', processed);

        if (processed.unused && processed.unused.length > 0) {
          scope._debug('onResponseReceived', 'saving unused to pool', processed.unused.length, processed.unused);
          for (var i = 0; i < processed.unused.length; i++) {
            scope._state.pool.push(processed.unused[i]);
          }
        }
      } catch (processErr) {
        callback(processErr);
        return;
      }

      if (scope._options.mock) {
        scope._debug('onResponseReceived', 'mock enabled, skipping append');
      } else {
        try {
          scope._renderData(processed.items);
        } catch (renderErr) {
          callback(renderErr);
          return;
        }
      }

      callback(null);
    });
  }
};

Instafeed.prototype._processData = function processData(data) {
  var hasTransform = (typeof this._options.transform === 'function');
  var hasFilter = (typeof this._options.filter === 'function');
  var hasSort = (typeof this._options.sort === 'function');
  var hasLimit = (typeof this._options.limit === 'number');
  var transformedFiltered = [];
  var limitDelta = null;
  var dataItem = null;
  var transformedItem = null;
  var filterResult = null;
  var unusedItems = null;

  this._debug('processData', 'hasFilter', hasFilter, 'hasTransform', hasTransform, 'hasSort', hasSort, 'hasLimit', hasLimit);

  if (typeof data !== 'object' || typeof data.data !== 'object' || data.data.length <= 0) {
    return null;
  }

  for (var i = 0; i < data.data.length; i++) {
    dataItem = this._getItemData(data.data[i]);

    // transform
    if (hasTransform) {
      try {
        transformedItem = this._options.transform(dataItem);
        this._debug('processData', 'transformed item', dataItem, transformedItem);
      } catch (err) {
        this._debug('processData', 'error calling transform', err);
        throw new Error('error in transform: ' + err.message);
      }
    } else {
      transformedItem = dataItem;
    }

    // filter
    if (hasFilter) {
      try {
        filterResult = this._options.filter(transformedItem);
        this._debug('processData', 'filter item result', transformedItem, filterResult);
      } catch (err) {
        this._debug('processData', 'error calling filter', err);
        throw new Error('error in filter: ' + err.message);
      }
      if (filterResult) {
        transformedFiltered.push(transformedItem);
      }
    } else {
      transformedFiltered.push(transformedItem);
    }
  }

  // sort
  if (hasSort) {
    try {
      transformedFiltered.sort(this._options.sort);
    } catch (err) {
      this._debug('processData', 'error calling sort', err);
      throw new Error('error in sort: ' + err.message);
    }
  }

  // limit
  if (hasLimit) {
    limitDelta = transformedFiltered.length - this._options.limit;
    this._debug('processData', 'checking limit', transformedFiltered.length, this._options.limit, limitDelta);

    if (limitDelta > 0) {
      unusedItems = transformedFiltered.slice(transformedFiltered.length - limitDelta);
      this._debug('processData', 'unusedItems', unusedItems.length, unusedItems);
      transformedFiltered.splice(transformedFiltered.length - limitDelta, limitDelta);
    }
  }

  return {
    items: transformedFiltered,
    unused: unusedItems
  };
};

Instafeed.prototype._extractTags = function extractTags(str) {
  var exp = /#([^\s]+)/gi;
  var badChars = /[~`!@#$%^&*\(\)\-\+={}\[\]:;"'<>\?,\./|\\\s]+/i; // non-allowed characters
  var tags = [];
  var match = null;

  if (typeof str === 'string') {
    while ((match = exp.exec(str)) !== null) {
      if (badChars.test(match[1]) === false) {
        tags.push(match[1]);
      }
    }
  }

  return tags;
};

Instafeed.prototype._getItemData = function getItemData(data) {
  var type = null;
  var image = null;

  switch (data.media_type) {
    case 'IMAGE':
      type = 'image';
      image = data.media_url;
      break;
    case 'VIDEO':
      type = 'video';
      image = data.thumbnail_url;
      break;
    case 'CAROUSEL_ALBUM':
      type = 'album';
      image = data.media_url;
      break;
  }

  return {
    caption: data.caption,
    tags: this._extractTags(data.caption),
    id: data.id,
    image: image,
    link: data.permalink,
    model: data,
    timestamp: data.timestamp,
    type: type,
    username: data.username
  };
};

Instafeed.prototype._renderData = function renderData(items) {
  var hasTemplate = (typeof this._options.template === 'string');
  var hasRender = (typeof this._options.render === 'function');
  var item = null;
  var itemHtml = null;
  var container = null;
  var html = '';

  this._debug('renderData', 'hasTemplate', hasTemplate, 'hasRender', hasRender);

  if (typeof items !== 'object' || items.length <= 0) {
    return;
  }

  for (var i = 0; i < items.length; i++) {
    item = items[i];

    if (hasRender) {
      try {
        itemHtml = this._options.render(item, this._options);
        this._debug('renderData', 'custom render result', item, itemHtml);
      } catch (err) {
        this._debug('renderData', 'error calling render', err);
        throw new Error('error in render: ' + err.message);
      }
    } else if (hasTemplate) {
      itemHtml = this._basicRender(item);
    }

    if (itemHtml) {
      html = html + itemHtml;
    } else {
      this._debug('renderData', 'render item did not return any content', item);
    }
  }

  this._debug('renderData', 'html content', html);

  container = document.createElement('div');
  container.innerHTML = html;

  this._debug('renderData', 'container', container, container.childNodes.length, container.childNodes);

  while (container.childNodes.length > 0) {
    this._debug('renderData', 'appending child', container.childNodes[0]);
    this._state.node.appendChild(container.childNodes[0]);
  }
};

Instafeed.prototype._basicRender = function basicRender(data) {
  var exp = new RegExp(this._options.templateBoundaries[0] + '([\\s\\w.]+)' + this._options.templateBoundaries[1], 'gm');
  var template = this._options.template;
  var match = null;
  var output = '';
  var substr = null;
  var lastIndex = 0;
  var keyPath = null;
  var keyPathValue = null;

  while((match = exp.exec(template)) !== null) {
    keyPath = match[1];
    substr = template.slice(lastIndex, match.index);
    output = output + substr;
    keyPathValue = this._valueForKeyPath(keyPath, data);
    if (keyPathValue) {
      output = output + keyPathValue.toString();
    }
    lastIndex = exp.lastIndex;
  }

  if (lastIndex < template.length) {
    substr = template.slice(lastIndex, template.length);
    output = output + substr;
  }

  return output;
};

Instafeed.prototype._valueForKeyPath = function valueForKeyPath(keyPath, data) {
  var exp = /([\w]+)/gm;
  var match = null;
  var key = null;
  var lastValue = data;

  while((match = exp.exec(keyPath)) !== null) {
    if (typeof lastValue !== 'object') {
      return null;
    }
    key = match[1];
    lastValue = lastValue[key];
  }

  return lastValue;
};

Instafeed.prototype._fail = function fail(err) {
  var didHook = this._runHook('error', err);
  if (!didHook && console && typeof console.error === 'function') {
    console.error(err);
  }
  this._state.running = false;
};

Instafeed.prototype._start = function start() {
  this._state.running = true;
  this._runHook('before');
};

Instafeed.prototype._finish = function finish() {
  this._runHook('after');
  this._state.running = false;
};

Instafeed.prototype._success = function success(data) {
  this._runHook('success', data);
  this._state.running = false;
};

Instafeed.prototype._makeApiRequest = function makeApiRequest(url, callback) {
  var called = false;
  var scope = this;
  var apiRequest = null;
  var callbackOnce = function callbackOnce(err, value) {
    if (!called) {
      called = true;
      callback(err, value);
    }
  };

  apiRequest = new XMLHttpRequest();

  apiRequest.ontimeout = function apiRequestTimedOut() {
    callbackOnce(new Error('api request timed out'));
  };

  apiRequest.onerror = function apiRequestOnError() {
    callbackOnce(new Error('api connection error'));
  };

  apiRequest.onload = function apiRequestOnLoad(event) {
    var contentType = apiRequest.getResponseHeader('Content-Type');
    var responseJson = null;

    scope._debug('apiRequestOnLoad', 'loaded', event);
    scope._debug('apiRequestOnLoad', 'response status', apiRequest.status);
    scope._debug('apiRequestOnLoad', 'response content type', contentType);

    if (contentType.indexOf('application/json') >= 0) {
      try {
        responseJson = JSON.parse(apiRequest.responseText);
      } catch (err) {
        scope._debug('apiRequestOnLoad', 'json parsing error', err, apiRequest.responseText);
        callbackOnce(new Error('error parsing response json'));
        return;
      }
    }

    if (apiRequest.status !== 200) {
      if (responseJson && responseJson.error) {
        callbackOnce(new Error(responseJson.error.code + ' ' + responseJson.error.message));
      } else {
        callbackOnce(new Error('status code ' + apiRequest.status));
      }
      return;
    }

    callbackOnce(null, responseJson);
  };

  apiRequest.open('GET', url, true);
  apiRequest.timeout = this._options.apiTimeout;
  apiRequest.send();
};

Instafeed.prototype._getAccessToken = function getAccessToken(callback) {
  var called = false;
  var scope = this;
  var timeoutCheck = null;

  var callbackOnce = function callbackOnce(err, value) {
    if (!called) {
      called = true;
      clearTimeout(timeoutCheck);
      callback(err, value);
    }
  };

  if (typeof this._options.accessToken === 'function') {
    this._debug('getAccessToken', 'calling accessToken as function');

    timeoutCheck = setTimeout(function accessTokenTimeoutCheck() {
      scope._debug('getAccessToken', 'timeout check', called);
      callbackOnce(new Error('accessToken timed out'), null);
    }, this._options.accessTokenTimeout);

    try {
      this._options.accessToken(function accessTokenReceiver(err, value) {
        scope._debug('getAccessToken', 'received accessToken callback', called, err, value);
        callbackOnce(err, value);
      });
    } catch (err) {
      this._debug('getAccessToken', 'error invoking the accessToken as function', err);
      callbackOnce(err, null);
    }
  } else {
    this._debug('getAccessToken', 'treating accessToken as static', typeof this._options.accessToken);
    callbackOnce(null, this._options.accessToken);
  }
};

Instafeed.prototype._debug = function debug() {
  var args = null;

  if (this._options.debug && console && typeof console.log === 'function') {
    args = [].slice.call(arguments);
    args[0] = '[Instafeed] ['+args[0]+']'; // first argument should be the callers name
    console.log.apply(null, args);
  }
};

Instafeed.prototype._runHook = function runHook(hookName, data) {
  var success = false;
  if (typeof this._options[hookName] === 'function') {
    try {
      this._options[hookName](data);
      success = true;
    } catch (err) {
      this._debug('runHook', 'error calling hook', hookName, err);
    }
  }
  return success;
};

export default Instafeed;