initial commit

[squeep-indie-auther] / src / db / schema-version-helper.js

diff --git a/src/db/schema-version-helper.js b/src/db/schema-version-helper.js
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+++ b/src/db/schema-version-helper.js
@@ -0,0 +1,131 @@
+'use strict';
+
+const fs = require('fs');
+const path = require('path');
+
+/**
+ * Utility functions for wrangling schema migrations.
+ * This mostly just deals with sorting and comparing 'x.y.z' version
+ * strings, with some presumptions about directory layouts and whatnot.
+ */
+
+/**
+ * @typedef {Object} SchemaVersionObject
+ * @property {Number} major
+ * @property {Number} minor
+ * @property {Number} patch
+ */
+
+
+/**
+ * Split a dotted version string into parts.
+ * @param {String} v
+ * @returns {SchemaVersionObject}
+ */
+function schemaVersionStringToObject(v) {
+  const [ major, minor, patch ] = v.split('.', 3).map((x) => parseInt(x, 10));
+  return { major, minor, patch };
+}
+
+
+/**
+ * Render a version object numerically.
+ * @param {SchemaVersionObject} v
+ * @returns {Number}
+ */
+function schemaVersionObjectToNumber(v) {
+  const vScale = 1000;
+  return parseInt(v.major) * vScale * vScale + parseInt(v.minor) * vScale + parseInt(v.patch);
+}
+
+
+/**
+ * Convert dotted version string into number.
+ * @param {String} v
+ * @returns {Number}
+ */
+function schemaVersionStringToNumber(v) {
+  return schemaVersionObjectToNumber(schemaVersionStringToObject(v));
+}
+
+
+/**
+ * Version string comparison, for sorting.
+ * @param {String} a
+ * @param {String} b
+ * @returns {Number}
+ */
+function schemaVersionStringCmp(a, b) {
+  return schemaVersionStringToNumber(a) - schemaVersionStringToNumber(b);
+}
+
+
+/**
+ * Check if an entry in a directory is a directory containing a migration file.
+ * @param {String} schemaDir
+ * @param {String} name
+ * @returns {Boolean}
+ */
+function isSchemaMigrationDirectory(schemaDir, name, migrationFile = 'apply.sql') {
+  // eslint-disable-next-line security/detect-non-literal-fs-filename
+  const nameStat = fs.statSync(path.join(schemaDir, name));
+  if (nameStat.isDirectory()) {
+    let applyStat;
+    try {
+      // eslint-disable-next-line security/detect-non-literal-fs-filename
+      applyStat = fs.statSync(path.join(schemaDir, name, migrationFile));
+      return applyStat.isFile();
+    } catch (e) {
+      return false;
+    }
+  }
+  return false;
+}
+
+
+/**
+ * Return an array of schema migration directory names within engineDir,
+ * sorted in increasing order.
+ * @param {String} engineDir
+ * @returns {String[]}
+ */
+function allSchemaVersions(engineDir) {
+  const schemaDir = path.join(engineDir, 'sql', 'schema');
+  // eslint-disable-next-line security/detect-non-literal-fs-filename
+  const availableVersions = fs.readdirSync(schemaDir).filter((d) => isSchemaMigrationDirectory(schemaDir, d));
+  availableVersions.sort(schemaVersionStringCmp);
+  return availableVersions;
+}
+
+
+/**
+ * Return an array of schema migration directory names within engineDir,
+ * which are within supported range, and are greater than the current
+ * @param {String} engineDir
+ * @param {SchemaVersionObject} current
+ * @param {Object} supported
+ * @param {SchemaVersionObject} supported.min
+ * @param {SchemaVersionObject} supported.max
+ * @returns {String[]}
+ */
+function unappliedSchemaVersions(engineDir, current, supported) {
+  const min = schemaVersionObjectToNumber(supported.min);
+  const max = schemaVersionObjectToNumber(supported.max);
+  const cur = schemaVersionObjectToNumber(current);
+  const available = allSchemaVersions(engineDir);
+  return available.filter((a) => {
+    a = schemaVersionStringToNumber(a);
+    return a >= min && a <= max && a > cur;
+  });
+}
+
+
+module.exports = {
+  schemaVersionStringToObject,
+  schemaVersionObjectToNumber,
+  schemaVersionStringToNumber,
+  schemaVersionStringCmp,
+  isSchemaMigrationDirectory,
+  allSchemaVersions,
+  unappliedSchemaVersions,
+};
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