'use strict';

var PromiseA = require('bluebird');
var crypto = require('crypto');

module.exports.create = function (bigconf, deps, app) {
  var Jwks = { restful: {} };
  var Grants = { restful: {} };

  // This tablename is based on the tablename found in the objects in model.js.
  // Instead of the snake_case the name with be UpperCammelCase, converted by masterquest-sqlite3.
  function attachSiteStore(tablename, req, res, next) {
    return req.getSiteStore().then(function (store) {
      req.Store = store[tablename];
      next();
    });
  }
  function detachSiteStore(req, res, next) {
    delete req.Store;
    next();
  }

  Jwks.thumbprint = function (jwk) {
    // To produce a thumbprint we need to create a JSON string with only the required keys for
    // the key type, with the keys sorted lexicographically and no white space. We then need
    // run it through a SHA-256 and encode the result in url safe base64.
    // https://stackoverflow.com/questions/42588786/how-to-fingerprint-a-jwk
    var keys;
    if (jwk.kty === 'EC') {
      keys = ['crv', 'x', 'y'];
    } else if (jwk.kty === 'RSA') {
      keys = ['e', 'n'];
    } else {
      return PromiseA.reject(new Error('invalid JWK key type ' + jwk.kty));
    }
    keys.push('kty');
    keys.sort();

    var missing = keys.filter(function (name) { return !jwk.hasOwnProperty(name); });
    if (missing.length > 0) {
      return PromiseA.reject(new Error('JWK of type '+jwk.kty+' missing fields ' + missing));
    }

    // I'm not 100% sure this behavior is guaranteed by a real standard, but when we use an array
    // as the replacer argument the keys are always in the order they appeared in the array.
    var jwkStr = JSON.stringify(jwk, keys);
    var hash = crypto.createHash('sha256').update(jwkStr).digest('base64');
    return PromiseA.resolve(hash.replace(/\+/g, '-').replace(/\//g, '_').replace(/=+/g, ''));
  };

  Jwks.restful.get = function (req, res) {
    var promise = req.Store.find({ kid: req.params.kid }, { limit: 1 }).then(function (results) {
      if (!results.length) {
        throw new Error('no keys stored with kid "'+req.params.kid+'"');
      }
      var jwk = results[0];

      // We need to sanitize the key to make sure we don't deliver any private keys fields if
      // we were given a key we could use to sign tokens on behalf of the user. We also don't
      // want to deliver the sub or any other PPIDs.
      var whitelist = [ 'kty', 'alg', 'kid', 'use' ];
      if (jwk.kty === 'EC') {
        whitelist = whitelist.concat([ 'crv', 'x', 'y' ]);
      } else if (jwk.kty === 'RSA') {
        whitelist = whitelist.concat([ 'e', 'n' ]);
      }

      var result = {};
      whitelist.forEach(function (key) {
        result[key] = jwk[key];
      });
      return result;
    });

    app.handlePromise(req, res, promise, "[issuer@oauth3.org] retrieve JWK");
  };
  Jwks.restful.saveNew = function (req, res) {
    var jwk = req.body;
    var promise = Jwks.thumbprint(jwk).then(function (kid) {
      if (jwk.kid && jwk.kid !== kid) {
        throw new Error('provided kid "'+jwk.kid+'" does not match calculated "'+kid+'"');
      }
      jwk.kid = kid;
      jwk.sub = req.params.sub;

      return req.Store.upsert(jwk.sub+'/'+jwk.kid, jwk);
    }).then(function () {
      return { success: true };
    });

    app.handlePromise(req, res, promise, "[issuer@oauth3.org] create JWK");
  };

  Grants.authorizeReq = function (req) {
    return PromiseA.resolve().then(function () {
      // It might seem unnecessary to wrap a promise in another promise, but this way it will
      // catch the error thrown when a token isn't found and verifyAsync isn't a function.
      return req.oauth3.verifyAsync();
    }).then(function (token) {
      // Just because the token is valid doesn't mean the token is authorized to get or save grants.
      // The only place that should be allowed to access grants on behalf of the user is the issuer.
      if (token.iss !== token.azp) {
        throw new Error("token does not allow access to grants");
      }

      var sub = token.sub || token.ppid || (token.acx && (token.acx.id || token.acx.appScopedId));
      if (!sub) {
        if (!Array.isArray(token.axs) || !token.axs.length) {
          throw new Error("no account pairwise identifier");
        }

        var allowed = token.axs.some(function (acc) {
          return (req.params.sub || req.query.sub) === (acc.id || acc.ppid || acc.appScopedId);
        });
        if (!allowed) {
          throw new Error("no account pairwise identifier matching '" + req.params.sub + "'");
        }
        sub = req.params.sub || req.query.sub;
      }

      return sub;
    });
  };

  Grants.restful.get = function (req, res) {
    var promise = Grants.authorizeReq(req).then(function (sub) {
      return req.Store.get(sub+'/'+(req.params.azp || req.query.azp));
    }).then(function (result) {
      if (!result) {
        throw new Error('no grants found');
      }
      return {
        sub:   result.sub,
        azp:   result.azp,
        scope: result.scope,
      };
    });

    app.handlePromise(req, res, promise, "[issuer@oauth3.org] retrieve grants");
  };
  Grants.restful.saveNew = function (req, res) {
    var promise = Grants.authorizeReq(req).then(function (sub) {
      if (typeof req.body.scope !== 'string') {
        throw new Error("malformed request: 'scope' should be a string");
      }
      var scope = req.body.scope.split(/[+ ,]+/g).join(',');

      var grant = {
        sub:   sub,
        azp:   req.params.azp,
        scope: scope,
      };
      return req.Store.upsert(grant.sub+'/'+grant.azp, grant);
    }).then(function () {
      return {success: true};
    });

    app.handlePromise(req, res, promise, '[issuer@oauth3.org] save grants');
  };

  app.use(   '/jwks', attachSiteStore.bind(null, 'IssuerOauth3OrgJwks'));
  app.get(   '/jwks/:kid.json', Jwks.restful.get);
  app.post(  '/jwks/:sub', Jwks.restful.saveNew);

  app.use(   '/grants', attachSiteStore.bind(null, 'IssuerOauth3OrgGrants'));
  app.get(   '/grants', Grants.restful.get);
  app.get(   '/grants/:sub/:azp', Grants.restful.get);
  app.post(  '/grants/:sub/:azp', Grants.restful.saveNew);

  app.use(detachSiteStore);
};