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"use strict";
// external modules
var Sequelize = require("sequelize");
var LZString = require('lz-string');
var async = require('async');
var moment = require('moment');
var DiffMatchPatch = require('diff-match-patch');
var dmp = new DiffMatchPatch();
// core
var config = require("../config.js");
var logger = require("../logger.js");
module.exports = function (sequelize, DataTypes) {
var Revision = sequelize.define("Revision", {
id: {
type: DataTypes.UUID,
primaryKey: true,
defaultValue: Sequelize.UUIDV4
},
patch: {
type: DataTypes.TEXT
},
lastContent: {
type: DataTypes.TEXT
},
content: {
type: DataTypes.TEXT
},
length: {
type: DataTypes.INTEGER
},
authorship: {
type: DataTypes.TEXT
}
}, {
classMethods: {
associate: function (models) {
Revision.belongsTo(models.Note, {
foreignKey: "noteId",
as: "note",
constraints: false
});
},
createPatch: function (lastDoc, CurrDoc) {
var ms_start = (new Date()).getTime();
var diff = dmp.diff_main(lastDoc, CurrDoc);
dmp.diff_cleanupSemantic(diff);
var patch = dmp.patch_make(lastDoc, diff);
patch = dmp.patch_toText(patch);
var ms_end = (new Date()).getTime();
if (config.debug) {
logger.info(patch);
logger.info((ms_end - ms_start) + 'ms');
}
return patch;
},
getNoteRevisions: function (note, callback) {
Revision.findAll({
where: {
noteId: note.id
},
order: '"createdAt" DESC'
}).then(function (revisions) {
var data = [];
for (var i = 0, l = revisions.length; i < l; i++) {
var revision = revisions[i];
data.push({
time: moment(revision.createdAt).valueOf(),
length: revision.length
});
}
callback(null, data);
}).catch(function (err) {
callback(err, null);
});
},
getPatchedNoteRevisionByTime: function (note, time, callback) {
// find all revisions to prepare for all possible calculation
Revision.findAll({
where: {
noteId: note.id
},
order: '"createdAt" DESC'
}).then(function (revisions) {
if (revisions.length <= 0) return callback(null, null);
// measure target revision position
Revision.count({
where: {
noteId: note.id,
createdAt: {
$gte: time
}
},
order: '"createdAt" DESC'
}).then(function (count) {
if (count <= 0) return callback(null, null);
var ms_start = (new Date()).getTime();
var startContent = null;
var lastPatch = [];
var applyPatches = [];
var authorship = [];
if (count <= Math.round(revisions.length / 2)) {
// start from top to target
for (var i = 0; i < count; i++) {
var revision = revisions[i];
if (i == 0) {
startContent = LZString.decompressFromBase64(revision.content || revision.lastContent);
}
if (i != count - 1) {
var patch = dmp.patch_fromText(LZString.decompressFromBase64(revision.patch));
applyPatches = applyPatches.concat(patch);
}
lastPatch = revision.patch;
authorship = revision.authorship;
}
// swap DIFF_INSERT and DIFF_DELETE to achieve unpatching
for (var i = 0, l = applyPatches.length; i < l; i++) {
for (var j = 0, m = applyPatches[i].diffs.length; j < m; j++) {
var diff = applyPatches[i].diffs[j];
if (diff[0] == DiffMatchPatch.DIFF_INSERT)
diff[0] = DiffMatchPatch.DIFF_DELETE;
else if (diff[0] == DiffMatchPatch.DIFF_DELETE)
diff[0] = DiffMatchPatch.DIFF_INSERT;
}
}
} else {
// start from bottom to target
var l = revisions.length - 1;
for (var i = l; i >= count - 1; i--) {
var revision = revisions[i];
if (i == l) {
startContent = LZString.decompressFromBase64(revision.lastContent);
authorship = revision.authorship;
}
if (revision.patch) {
var patch = dmp.patch_fromText(LZString.decompressFromBase64(revision.patch));
applyPatches = applyPatches.concat(patch);
}
lastPatch = revision.patch;
authorship = revision.authorship;
}
}
try {
var finalContent = dmp.patch_apply(applyPatches, startContent)[0];
} catch (err) {
return callback(err, null);
}
var data = {
content: finalContent,
patch: dmp.patch_fromText(LZString.decompressFromBase64(lastPatch)),
authorship: authorship ? JSON.parse(LZString.decompressFromBase64(authorship)) : null
};
var ms_end = (new Date()).getTime();
if (config.debug) {
logger.info((ms_end - ms_start) + 'ms');
}
return callback(null, data);
}).catch(function (err) {
return callback(err, null);
});
}).catch(function (err) {
return callback(err, null);
});
},
checkAllNotesRevision: function (callback) {
Revision.saveAllNotesRevision(function (err, notes) {
if (err) return callback(err, null);
if (!notes || notes.length <= 0) {
return callback(null, notes);
} else {
Revision.checkAllNotesRevision(callback);
}
});
},
saveAllNotesRevision: function (callback) {
sequelize.models.Note.findAll({
// query all notes that need to save for revision
where: {
$and: [
{
lastchangeAt: {
$or: {
$eq: null,
$and: {
$ne: null,
$gt: sequelize.col('createdAt')
}
}
}
},
{
savedAt: {
$or: {
$eq: null,
$lt: sequelize.col('lastchangeAt')
}
}
}
]
}
}).then(function (notes) {
if (notes.length <= 0) return callback(null, notes);
var savedNotes = [];
async.each(notes, function (note, _callback) {
// revision saving policy: note not been modified for 5 mins or not save for 10 mins
if (note.lastchangeAt && note.savedAt) {
var lastchangeAt = moment(note.lastchangeAt);
var savedAt = moment(note.savedAt);
if (moment().isAfter(lastchangeAt.add(1, 'minutes'))) {
savedNotes.push(note);
Revision.saveNoteRevision(note, _callback);
} else if (lastchangeAt.isAfter(savedAt.add(2, 'minutes'))) {
savedNotes.push(note);
Revision.saveNoteRevision(note, _callback);
} else {
return _callback(null, null);
}
} else {
savedNotes.push(note);
Revision.saveNoteRevision(note, _callback);
}
}, function (err) {
if (err) return callback(err, null);
// return null when no notes need saving at this moment but have delayed tasks to be done
var result = ((savedNotes.length == 0) && (notes.length > savedNotes.length)) ? null : savedNotes;
return callback(null, result);
});
}).catch(function (err) {
return callback(err, null);
});
},
saveNoteRevision: function (note, callback) {
Revision.findAll({
where: {
noteId: note.id
},
order: '"createdAt" DESC'
}).then(function (revisions) {
if (revisions.length <= 0) {
// if no revision available
Revision.create({
noteId: note.id,
lastContent: note.content,
length: LZString.decompressFromBase64(note.content).length,
authorship: note.authorship
}).then(function (revision) {
Revision.finishSaveNoteRevision(note, revision, callback);
}).catch(function (err) {
return callback(err, null);
});
} else {
var latestRevision = revisions[0];
var lastContent = LZString.decompressFromBase64(latestRevision.content || latestRevision.lastContent);
var content = LZString.decompressFromBase64(note.content);
var patch = Revision.createPatch(lastContent, content);
if (!patch) {
// if patch is empty (means no difference) then just update the latest revision updated time
latestRevision.changed('updatedAt', true);
latestRevision.update({
updatedAt: Date.now()
}).then(function (revision) {
Revision.finishSaveNoteRevision(note, revision, callback);
}).catch(function (err) {
return callback(err, null);
});
} else {
Revision.create({
noteId: note.id,
patch: LZString.compressToBase64(patch),
content: note.content,
length: LZString.decompressFromBase64(note.content).length,
authorship: note.authorship
}).then(function (revision) {
// clear last revision content to reduce db size
latestRevision.update({
content: null
}).then(function () {
Revision.finishSaveNoteRevision(note, revision, callback);
}).catch(function (err) {
return callback(err, null);
});
}).catch(function (err) {
return callback(err, null);
});
}
}
}).catch(function (err) {
return callback(err, null);
});
},
finishSaveNoteRevision: function (note, revision, callback) {
note.update({
savedAt: revision.updatedAt
}).then(function () {
return callback(null, revision);
}).catch(function (err) {
return callback(err, null);
});
}
}
});
return Revision;
};
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