leaf-db/dist/leafdb.mjs

Small file-based database for node.js

import crypto from 'crypto';
import { merge } from 'rambda';
import deepEqual from 'fast-deep-equal';
import fs from 'fs';
import path from 'path';

const isObject = (x) => x !== null && !Array.isArray(x) && typeof x === "object";
const isTag = (x) => x[0] === "$";
const hasTag = ([key, value]) => isTag(key) && value !== void 0;
const hasTagDeep = ([key, value]) => value !== null && typeof value === "object" ? Object.entries(value).some(hasTagDeep) : hasTag([key, value]);
const isDraft = (x) => isObject(x) && !Object.entries(x).some(hasTagDeep);
const isDoc = (x) => isDraft(x) && typeof x._id === "string" && x._id.length > 0;
const isQueryMatch = (doc, query) => {
  const isMatchNumber = {
    $gt: (x, y) => x > y,
    $gte: (x, y) => x >= y,
    $lt: (x, y) => x < y,
    $lte: (x, y) => x <= y
  };
  return Object.entries(query).every(([key, y]) => {
    if (isObject(doc) && !(key in doc) && !isTag(key))
      return false;
    const x = isObject(doc) ? doc[key] : doc;
    if (key in isMatchNumber) {
      if (typeof x !== "number" || typeof y !== "number")
        return false;
      return isMatchNumber[key](x, y);
    }
    if (key === "$text") {
      if (typeof x !== "string" || typeof y !== "string")
        return false;
      return x.toLocaleLowerCase().includes(y.toLocaleLowerCase());
    }
    if (key === "$regex") {
      if (typeof x !== "string" || !(y instanceof RegExp))
        return false;
      return y.test(x);
    }
    if (key === "$has") {
      if (!Array.isArray(x))
        return false;
      return x.some((value) => deepEqual(y, value));
    }
    if (key === "$size") {
      if (!Array.isArray(x) || typeof y !== "number")
        return false;
      return x.length === y;
    }
    if (key === "$not")
      return x !== y;
    if (Array.isArray(y)) {
      if (!Array.isArray(x) || x.length !== y.length)
        return false;
      return deepEqual(x, y);
    }
    if (!isObject(y))
      return x === y;
    return isQueryMatch(x, y);
  });
};

const MEMORY_MODE = (fn) => `Tried to call '${fn}()' in memory mode`;
const DUPLICATE_DOC = (doc) => `Doc already exists with _id: ${doc._id}`;
const MISSING_FD = (fn) => `Cannot call '${fn}()' if file is not opened`;
const INVALID = (param) => (value) => `Invalid ${param}: ${JSON.stringify(value)}`;
const INVALID_DOC = INVALID("doc");

class Memory {
  constructor() {
    this._docs = new Map();
  }
  get(_id) {
    return this._docs.get(_id) || null;
  }
  set(doc) {
    this._docs.set(doc._id, doc);
    return doc;
  }
  has(_id) {
    if (!_id || !this._docs.has(_id))
      return false;
    return !this._docs.get(_id)?.__deleted;
  }
  delete(_id) {
    return this._docs.delete(_id);
  }
  docs() {
    return this._docs.values();
  }
  flush() {
    this._docs.clear();
  }
}

class Storage {
  constructor(options) {
    this._file = path.format({
      dir: options.root,
      name: options.name,
      ext: ".txt"
    });
  }
  open() {
    let data = [];
    if (fs.existsSync(this._file)) {
      data = fs.readFileSync(this._file, { encoding: "utf-8" }).split("\n");
    } else {
      fs.mkdirSync(path.parse(this._file).dir, { recursive: true });
    }
    this._fd = fs.openSync(this._file, "a");
    return data;
  }
  close() {
    if (typeof this._fd !== "number")
      throw new Error(MISSING_FD("close"));
    fs.closeSync(this._fd);
    delete this._fd;
  }
  append(raw) {
    if (typeof this._fd !== "number")
      throw new Error(MISSING_FD("append"));
    fs.appendFileSync(this._fd, `${raw}
`);
  }
  flush() {
    if (typeof this._fd !== "number")
      throw new Error(MISSING_FD("flush"));
    fs.closeSync(this._fd);
    fs.rmSync(this._file);
    this._fd = fs.openSync(this._file, "a");
  }
}

class LeafDB {
  static id() {
    return [
      Date.now().toString(16),
      crypto.randomBytes(4).toString("hex")
    ].join("");
  }
  _set(doc) {
    this._memory.set(doc);
    this._storage?.append(JSON.stringify(doc));
    return doc;
  }
  _delete(_id) {
    this._memory.delete(_id);
    this._storage?.append(JSON.stringify({ _id, __deleted: true }));
  }
  constructor(options) {
    this._memory = new Memory();
    const root = typeof options?.storage === "string" ? options?.storage : options?.storage?.root;
    if (root) {
      const name = typeof options?.storage !== "string" ? options?.storage?.name ?? "leaf-db" : "leaf-db";
      this._storage = new Storage({ root, name });
    }
  }
  open() {
    if (!this._storage)
      throw new Error(MEMORY_MODE("open"));
    const corrupted = [];
    const docs = [];
    this._storage.open().forEach((raw) => {
      try {
        if (raw.length > 0) {
          const doc = JSON.parse(raw);
          if (!isDoc(doc))
            throw new Error(INVALID_DOC(doc));
          docs.push(doc);
        }
      } catch (err) {
        corrupted.push({ raw, err });
      }
    });
    docs.filter((x) => x.__deleted).map((x) => x._id).forEach((doc) => {
      const i = docs.findIndex((x) => x._id === doc);
      if (i >= 0)
        docs.splice(i, 1);
    });
    this._storage.flush();
    docs.filter((doc) => !doc.__deleted).forEach((doc) => this._set(doc));
    return corrupted;
  }
  close() {
    if (!this._storage)
      throw new Error(MEMORY_MODE("close"));
    return this._storage?.close();
  }
  insert(drafts) {
    const docs = [];
    drafts.forEach((draft) => {
      if (isDoc(draft)) {
        if (this._memory.has(draft._id) || docs.some((doc) => doc._id === draft._id))
          throw new Error(DUPLICATE_DOC(draft));
        docs.push(draft);
      } else {
        docs.push({ _id: LeafDB.id(), ...draft });
      }
    });
    return docs.map((doc) => this._set(doc));
  }
  select(...queries) {
    const docs = [];
    for (const doc of this._memory.docs()) {
      if (!doc.__deleted && queries.some((query) => isQueryMatch(doc, query)))
        docs.push(doc);
    }
    return docs;
  }
  selectById(...ids) {
    return ids.reduce((acc, cur) => {
      const doc = this._memory.get(cur);
      if (doc)
        acc.push(doc);
      return acc;
    }, []);
  }
  update(update, ...queries) {
    if ("_id" in update)
      throw new Error("Invalid update, cannot contain key `_id`");
    return this.select(...queries).map((doc) => {
      this._delete(doc._id);
      return this._set(merge(doc, update));
    });
  }
  delete(...queries) {
    return this.select(...queries).reduce((acc, cur) => {
      this._delete(cur._id);
      return acc + 1;
    }, 0);
  }
  drop() {
    this._memory.flush();
    this._storage?.flush();
  }
}

export { LeafDB as default };