/*!
 * letiny
 * Copyright(c) 2015 Anatol Sommer <anatol@anatol.at>
 * Some code used from https://github.com/letsencrypt/boulder/tree/master/test/js
 * MPL 2.0
*/
'use strict';

function _toStandardBase64(str) {
  var b64 = str.replace(/-/g, "+").replace(/_/g, "/").replace(/=/g, "");

  switch (b64.length % 4) {
    case 2: b64 += "=="; break;
    case 3: b64 += "="; break;
  }

  return b64;
}

module.exports.create = function (deps) {
  var request=deps.request;
  var Acme = deps.Acme;
  var RSA = deps.RSA;

  function getCert(options, cb) {

    function bodyToError(res, body) {
      var err;

      if (!body) {
        err = new Error("[Error] letiny-core: no request body");
        err.code = "E_NO_RESPONSE_BODY";
        throw err;
      }

      if ('{' === body[0] || '{' === String.fromCharCode(body[0])) {
        try {
          body = JSON.parse(body.toString('utf8'));
        } catch(e) {
          err = new Error("[Error] letiny-core: body could not be parsed");
          err.code = "E_BODY_PARSE";
          err.description = body;
          throw err;
        }
      }

      if (Math.floor(res.statusCode / 100) !== 2) {
        err = new Error("[Error] letiny-core: not 200 ok");
        err.code = "E_STATUS_CODE";
        err.type = body.type;
        err.description = body;
        err.detail = body.detail;
        console.error("TODO: modules which depend on this module should expose this error properly but since some of them don't, I expose it here directly:");
        console.error(err.stack);
        console.error(body);
        throw err;
      }

      if (body.type && body.detail) {
        err = new Error("[Error] letiny-core: " + body.detail);
        err.code = body.type;
        err.type = body.type;
        err.description = body.detail;
        err.detail = body.detail;
        throw err;
      }

      return body;
    }

    function nextDomain() {
      if (state.domains.length > 0) {
        getChallenges(state.domains.shift());
        return;
      } else {
        getCertificate();
      }
    }

    function getChallenges(domain) {
      state.domain=domain;

      state.acme.post(state.newAuthzUrl, {
        resource:'new-authz',
        identifier:{
          type:'dns',
          value:state.domain,
        }
      }, function (err, res, body) {
        if (!err && res.body) {
          try {
            body = bodyToError(res, body);
          } catch(e) {
            err = e;
          }
        }

        getReadyToValidate(err, res, body);
      });
    }

    function getReadyToValidate(err, res, body) {

      function challengeDone(err) {
        if (err) {
          console.error('[letiny-core] setChallenge Error:');
          console.error(err && err.stack || err);
          ensureValidation(err, null, null, function () {
            options.removeChallenge(state.domain, challenge.token, function () {
              // ignore
            });
          });
          return;
        }

        state.acme.post(state.responseUrl, {
          resource:'challenge',
          keyAuthorization:keyAuthorization
        }, function(err, res, body) {
          if (!err && res.body) {
            try {
              body = bodyToError(res, body);
            } catch(e) {
              err = e;
            }
          }

          ensureValidation(err, res, body, function unlink() {
            options.removeChallenge(state.domain, challenge.token, function () {
              // ignore
            });
          });
        });
      }

      var links, authz, httpChallenges, challenge, thumbprint, keyAuthorization;

      if (err) {
        return handleErr(err);
      }

      if (Math.floor(res.statusCode/100)!==2) {
        return handleErr(null, 'Authorization request failed ('+res.statusCode+')');
      }

      links=Acme.parseLink(res.headers.link);
      if (!links || !('next' in links)) {
        return handleErr(err, 'Server didn\'t provide information to proceed (2)');
      }

      state.authorizationUrl=res.headers.location;
      state.newCertUrl=links.next;

      authz=body;

      httpChallenges=authz.challenges.filter(function(x) {
        return x.type==='http-01';
      });
      if (httpChallenges.length===0) {
        return handleErr(null, 'Server didn\'t offer any challenge we can handle.');
      }
      challenge=httpChallenges[0];

      thumbprint=RSA.thumbprint(state.accountKeypair);
      keyAuthorization=challenge.token+'.'+thumbprint;
      state.responseUrl=challenge.uri;

      options.setChallenge(state.domain, challenge.token, keyAuthorization, challengeDone);

    }

    function ensureValidation(err, res, body, unlink) {
      var authz, challengesState;

      if (err || Math.floor(res.statusCode/100)!==2) {
        unlink();
        return handleErr(err, 'Authorization status request failed ('
          + (res && res.statusCode || err.code || err.message || err) + ')');
      }

      authz=body;

      if (authz.status==='pending') {
        setTimeout(function() {
          request({
            method: 'GET'
          , url: state.authorizationUrl
          }, function(err, res, body) {
            if (!err && res.body) {
              try {
                body = bodyToError(res, body);
              } catch(e) {
                err = e;
              }
            }

            ensureValidation(err, res, body, unlink);
          });
        }, 1000);
      } else if (authz.status==='valid') {
        log('Validating domain ... done');
        state.validatedDomains.push(state.domain);
        state.validAuthorizationUrls.push(state.authorizationUrl);
        unlink();
        nextDomain();
      } else if (authz.status==='invalid') {
        unlink();
        challengesState = (authz.challenges || []).map(function (challenge) {
          var result =  ' - ' + challenge.uri + ' [' + challenge.status + ']';
          if (challenge.error) {
            result += '\n   ' + challenge.error.detail;
          }
          return result;
        }).join('\n');
        return handleErr(null,
            'The CA was unable to validate the file you provisioned. '
          + (authz.detail ? 'Details: ' + authz.detail : '')
          + (challengesState ? '\n' + challengesState : ''), body);
      } else {
        unlink();
        return handleErr(null, 'CA returned an authorization in an unexpected state' + authz.detail, authz);
      }
    }

    function getCertificate() {
      var csr=RSA.generateCsrWeb64(RSA.exportPrivateKeyPem(state.certKeypair), state.validatedDomains);
      log('Requesting certificate...');
      state.acme.post(state.newCertUrl, {
        resource:'new-cert',
        csr:csr,
        authorizations:state.validAuthorizationUrls
      }, function (err, res, body ) {
        if (!err && res.body) {
          try {
            body = bodyToError(res, body);
          } catch(e) {
            err = e;
          }
        }

        downloadCertificate(err, res, body);
      });
    }

    function downloadCertificate(err, res, body) {
      var links, certUrl;

      if (err) {
        handleErr(err, 'Certificate request failed');
        return;
      }

      if (Math.floor(res.statusCode/100)!==2) {
        err = new Error("invalid status code: " + res.statusCode);
        err.code = "E_STATUS_CODE";
        err.description = body;
        handleErr(err);
        return;
      }

      links=Acme.parseLink(res.headers.link);
      if (!links || !('up' in links)) {
        return handleErr(err, 'Failed to fetch issuer certificate');
      }

      log('Requesting certificate: done');

      state.certificate=body;
      certUrl=res.headers.location;
      request({
        method: 'GET'
      , url: certUrl
      , encoding: null
      }, function(err, res, body) {
        if (!err) {
          try {
            body = bodyToError(res, body);
          } catch(e) {
            err = e;
          }
        }

        if (err) {
          return handleErr(err, 'Failed to fetch cert from '+certUrl);
        }

        if (res.statusCode!==200) {
          return handleErr(err, 'Failed to fetch cert from '+certUrl, res.body.toString());
        }

        if (body.toString()!==state.certificate.toString()) {
          return handleErr(null, 'Cert at '+certUrl+' did not match returned cert');
        }

        log('Successfully verified cert at '+certUrl);
        log('Requesting issuer certificate...');
        request({
          method: 'GET'
        , url: links.up
        , encoding: null
        }, function(err, res, body) {
          if (!err) {
            try {
              body = bodyToError(res, body);
            } catch(e) {
              err = e;
            }
          }

          if (err || res.statusCode!==200) {
            return handleErr(err, 'Failed to fetch issuer certificate');
          }

          state.caCert=certBufferToPem(body);
          log('Requesting issuer certificate: done');
          done();
        });
      });
    }

    function done() {
      var cert;

      try {
        cert = certBufferToPem(state.certificate);
      } catch(e) {
        console.error(e.stack);
        //cb(new Error("Could not write output files. Please check permissions!"));
        handleErr(e, 'Could not write output files. Please check permissions!');
        return;
      }

      cb(null, {
        cert: cert
      , key: RSA.exportPrivateKeyPem(state.certKeypair)
      , ca: state.caCert
      });
    }

    function handleErr(err, text, info) {
      log(text, err, info);
      cb(err || new Error(text));
    }

    var NOOP = function () {};
    var log = options.debug ? console.log : NOOP;
    var state={
      validatedDomains:[]
    , validAuthorizationUrls:[]
    , newAuthzUrl: options.newAuthzUrl
    , newCertUrl: options.newCertUrl
    };

    if (!options.newAuthzUrl) {
      return handleErr(new Error("options.newAuthzUrl must be the authorization url"));
    }
    if (!options.newCertUrl) {
      return handleErr(new Error("options.newCertUrl must be the new certificate url"));
    }
    if (!options.accountKeypair) {
      return handleErr(new Error("options.accountKeypair must be an object with `privateKeyPem` and/or `privateKeyJwk`"));
    }
    if (!options.domainKeypair) {
      return handleErr(new Error("options.domainKeypair must be an object with `privateKeyPem` and/or `privateKeyJwk`"));
    }
    if (!options.setChallenge) {
      return handleErr(new Error("options.setChallenge must be function(hostname, challengeKey, tokenValue, done) {}"));
    }
    if (!options.removeChallenge) {
      return handleErr(new Error("options.removeChallenge must be function(hostname, challengeKey, done) {}"));
    }
    if (!(options.domains && options.domains.length)) {
      return handleErr(new Error("options.domains must be an array of domains such as ['example.com', 'www.example.com']"));
    }

    state.domains = options.domains.slice(0); // copy array
    try {
      state.acme = new Acme(state.accountKeypair);
      state.accountKeypair = options.accountKeypair;
      state.certKeypair = options.domainKeypair;
    } catch(err) {
      return handleErr(err, 'Failed to parse privateKey');
    }

    nextDomain();
  }

  function certBufferToPem(cert) {
    cert=_toStandardBase64(cert.toString('base64'));
    cert=cert.match(/.{1,64}/g).join('\n');
    return '-----BEGIN CERTIFICATE-----\n'+cert+'\n-----END CERTIFICATE-----';
  }

  return getCert;
};