var AWS = require('../core');
var util = require('../util');
var QueryParamSerializer = require('../query/query_param_serializer');
var Shape = require('../model/shape');
var populateHostPrefix = require('./helpers').populateHostPrefix;

function buildRequest(req) {
  var operation = req.service.api.operations[req.operation];
  var httpRequest = req.httpRequest;
  httpRequest.headers['Content-Type'] =
    'application/x-www-form-urlencoded; charset=utf-8';
  httpRequest.params = {
    Version: req.service.api.apiVersion,
    Action: operation.name
  };

  // convert the request parameters into a list of query params,
  // e.g. Deeply.NestedParam.0.Name=value
  var builder = new QueryParamSerializer();
  builder.serialize(req.params, operation.input, function(name, value) {
    httpRequest.params[name] = value;
  });
  httpRequest.body = util.queryParamsToString(httpRequest.params);

  populateHostPrefix(req);
}

function extractError(resp) {
  var data, body = resp.httpResponse.body.toString();
  if (body.match('<UnknownOperationException')) {
    data = {
      Code: 'UnknownOperation',
      Message: 'Unknown operation ' + resp.request.operation
    };
  } else {
    try {
      data = new AWS.XML.Parser().parse(body);
    } catch (e) {
      data = {
        Code: resp.httpResponse.statusCode,
        Message: resp.httpResponse.statusMessage
      };
    }
  }

  if (data.requestId && !resp.requestId) resp.requestId = data.requestId;
  if (data.Errors) data = data.Errors;
  if (data.Error) data = data.Error;
  if (data.Code) {
    resp.error = util.error(new Error(), {
      code: data.Code,
      message: data.Message
    });
  } else {
    resp.error = util.error(new Error(), {
      code: resp.httpResponse.statusCode,
      message: null
    });
  }
}

function extractData(resp) {
  var req = resp.request;
  var operation = req.service.api.operations[req.operation];
  var shape = operation.output || {};
  var origRules = shape;

  if (origRules.resultWrapper) {
    var tmp = Shape.create({type: 'structure'});
    tmp.members[origRules.resultWrapper] = shape;
    tmp.memberNames = [origRules.resultWrapper];
    util.property(shape, 'name', shape.resultWrapper);
    shape = tmp;
  }

  var parser = new AWS.XML.Parser();

  // TODO: Refactor XML Parser to parse RequestId from response.
  if (shape && shape.members && !shape.members._XAMZRequestId) {
    var requestIdShape = Shape.create(
      { type: 'string' },
      { api: { protocol: 'query' } },
      'requestId'
    );
    shape.members._XAMZRequestId = requestIdShape;
  }

  var data = parser.parse(resp.httpResponse.body.toString(), shape);
  resp.requestId = data._XAMZRequestId || data.requestId;

  if (data._XAMZRequestId) delete data._XAMZRequestId;

  if (origRules.resultWrapper) {
    if (data[origRules.resultWrapper]) {
      util.update(data, data[origRules.resultWrapper]);
      delete data[origRules.resultWrapper];
    }
  }

  resp.data = data;
}

/**
 * @api private
 */
module.exports = {
  buildRequest: buildRequest,
  extractError: extractError,
  extractData: extractData
};