var Busboy = require('busboy');
var Winston = require('winston');

// For handling serving stored documents.

var DocumentHandler = function(options = {}) {
  this.store = options.store;
  this.keyGenerator = options.keyGenerator;
};


// Handle retrieving a document.
DocumentHandler.prototype.handleGet = function(key, response) {
  this.store.get(key, function(ret) {
    if (ret) {
      Winston.verbose("Retrieved document.", { key: key });
      response.writeHead(200, { "content-type": "application/json" });
      response.end(JSON.stringify({ data: ret, key: key }));
    }
    else {
      Winston.warn("Document not found.", { key: key });
      response.writeHead(404, { "content-type": "application/json" });
      response.end(JSON.stringify({ message: "Document not found." }));
    }
  });
};

// Handle retrieving the raw version of a document.
DocumentHandler.prototype.handleRawGet = function(key, response) {
  this.store.get(key, function(ret) {
    if (ret) {
      Winston.verbose("Retrieved raw document.", { key: key });
      response.writeHead(200, { "content-type": "text/plain; charset=UTF-8" });
      response.end(ret);
    }
    else {
      Winston.warn("Raw document not found.", { key: key });
      response.writeHead(404, { "content-type": "application/json" });
      response.end(JSON.stringify({ message: "Document not found." }));
    }
  });
};

// Handle adding a new document.
DocumentHandler.prototype.handlePost = function (request, response) {
  var _this = this;
  var buffer = "";
  var cancelled = false;

  // If success...
  var onSuccess = function () {
    _this.chooseKey(function (key) {
      _this.store.set(key, buffer, function (res) {
        if (res) {
          Winston.verbose("Added document.", { key: key });
          response.writeHead(200, { "content-type": "application/json" });
          response.end(JSON.stringify({ key: key }));
        }
        else {
          Winston.verbose("Error adding document");
          response.writeHead(500, { "content-type": "application/json" });
          response.end(JSON.stringify({ message: "Error adding document." }));
        }
      });
    });
  };

  // Parse form to grab the data.
  var ct = request.headers["content-type"];
  if (ct && ct.split(";")[0] === "multipart/form-data") {
    var busboy = new Busboy({ headers: request.headers });
    busboy.on("field", function (fieldname, val) {
      if (fieldname === "data") {
        buffer = val;
      }
    });
    busboy.on("finish", function () {
      onSuccess();
    });
    request.pipe(busboy);
  // Otherwise, use our own and just grab flat data from POST body.
  } else {
    request.on("data", function (data) {
      buffer += data.toString();
    });
    request.on("end", function () {
      if (cancelled) { return; }
      onSuccess();
    });
    request.on("error", function (error) {
      Winston.error("Connection error: " + error.message);
      response.writeHead(500, { "content-type": "application/json" });
      response.end(JSON.stringify({ message: "Connection error." }));
      cancelled = true;
    });
  }
};

// Keep choosing keys until we find one that isn't taken.
DocumentHandler.prototype.chooseKey = function(callback) {
  var key = this.acceptableKey();
  var _this = this;
  this.store.get(key, function(ret) {
    if (ret) {
      _this.chooseKey(callback);
    } else {
      callback(key);
    }
  }, true); // Don't bump expirations when key searching.
};

DocumentHandler.prototype.acceptableKey = function() {
  return this.keyGenerator.createKey();
};

module.exports = DocumentHandler;