From 62fb107be5ac2f1a3fadfd04a73067157023252b Mon Sep 17 00:00:00 2001
From: Ivan Kopeykin <ikopeykin@ozon.ru>
Date: Sat, 28 Sep 2019 19:04:22 +0200
Subject: [PATCH] feat: "smart" numbers range

---
 src/ValidationError.js                |  17 +++-
 src/util/Range.js                     | 111 ++++++++++++++++++++++++++
 test/__snapshots__/index.test.js.snap |   8 +-
 test/range.test.js                    | 109 +++++++++++++++++++++++++
 4 files changed, 237 insertions(+), 8 deletions(-)
 create mode 100644 src/util/Range.js
 create mode 100644 test/range.test.js

diff --git a/src/ValidationError.js b/src/ValidationError.js
index d83137f..774387a 100644
--- a/src/ValidationError.js
+++ b/src/ValidationError.js
@@ -1,3 +1,5 @@
+const Range = require('./util/Range');
+
 const SPECIFICITY = {
   type: 1,
   not: 1,
@@ -348,21 +350,28 @@ class ValidationError extends Error {
 
     if (likeNumber(schema) || likeInteger(schema)) {
       const hints = [];
+      const range = new Range();
 
       if (typeof schema.minimum === 'number') {
-        hints.push(`should be >= ${schema.minimum}`);
+        range.left(schema.minimum);
       }
 
       if (typeof schema.exclusiveMinimum === 'number') {
-        hints.push(`should be > ${schema.exclusiveMinimum}`);
+        range.left(schema.exclusiveMinimum, true);
       }
 
       if (typeof schema.maximum === 'number') {
-        hints.push(`should be <= ${schema.maximum}`);
+        range.right(schema.maximum);
       }
 
       if (typeof schema.exclusiveMaximum === 'number') {
-        hints.push(`should be > ${schema.exclusiveMaximum}`);
+        range.right(schema.exclusiveMaximum, true);
+      }
+
+      const rangeFormat = range.format();
+
+      if (rangeFormat) {
+        hints.push(rangeFormat);
       }
 
       if (typeof schema.multipleOf === 'number') {
diff --git a/src/util/Range.js b/src/util/Range.js
new file mode 100644
index 0000000..ff0e498
--- /dev/null
+++ b/src/util/Range.js
@@ -0,0 +1,111 @@
+const left = Symbol('left');
+const right = Symbol('right');
+
+class Range {
+  static getOperator(side, exclusive) {
+    if (side === 'left') {
+      return exclusive ? '>' : '>=';
+    }
+
+    return exclusive ? '<' : '<=';
+  }
+
+  static formatRight(value, logic, exclusive) {
+    if (logic === false) {
+      return Range.formatLeft(value, !logic, !exclusive);
+    }
+
+    return `should be ${Range.getOperator('right', exclusive)} ${value}`;
+  }
+
+  static formatLeft(value, logic, exclusive) {
+    if (logic === false) {
+      return Range.formatRight(value, !logic, !exclusive);
+    }
+
+    return `should be ${Range.getOperator('left', exclusive)} ${value}`;
+  }
+
+  static formatRange(start, end, startExclusive, endExclusive, logic) {
+    let result = 'should be';
+
+    result += ` ${Range.getOperator(
+      logic ? 'left' : 'right',
+      logic ? startExclusive : !startExclusive
+    )} ${start} `;
+    result += logic ? 'and' : 'or';
+    result += ` ${Range.getOperator(
+      logic ? 'right' : 'left',
+      logic ? endExclusive : !endExclusive
+    )} ${end}`;
+
+    return result;
+  }
+
+  static getRangeValue(values, logic) {
+    let minMax = logic ? Infinity : -Infinity;
+    let j = -1;
+    const predicate = logic
+      ? ([value]) => value <= minMax
+      : ([value]) => value >= minMax;
+
+    for (let i = 0; i < values.length; i++) {
+      if (predicate(values[i])) {
+        minMax = values[i][0];
+        j = i;
+      }
+    }
+
+    if (j > -1) {
+      return values[j];
+    }
+
+    return [Infinity, true];
+  }
+
+  constructor() {
+    this[left] = [];
+    this[right] = [];
+  }
+
+  left(value, exclusive = false) {
+    this[left].push([value, exclusive]);
+  }
+
+  right(value, exclusive = false) {
+    this[right].push([value, exclusive]);
+  }
+
+  format(logic = true) {
+    const [start, leftExclusive] = Range.getRangeValue(this[left], logic);
+    const [end, rightExclusive] = Range.getRangeValue(this[right], !logic);
+
+    if (!Number.isFinite(start) && !Number.isFinite(end)) {
+      return '';
+    }
+
+    if (leftExclusive === rightExclusive) {
+      // e.g. 5 <= x <= 5
+      if (leftExclusive === false && start === end) {
+        return `should be ${logic ? '' : '!'}= ${start}`;
+      }
+
+      // e.g. 4 < x < 6
+      if (leftExclusive === true && start + 1 === end - 1) {
+        return `should be ${logic ? '' : '!'}= ${start + 1}`;
+      }
+    }
+
+    if (Number.isFinite(start) && !Number.isFinite(end)) {
+      return Range.formatLeft(start, logic, leftExclusive);
+    }
+
+    if (!Number.isFinite(start) && Number.isFinite(end)) {
+      return Range.formatRight(end, logic, rightExclusive);
+    }
+
+    return Range.formatRange(start, end, leftExclusive, rightExclusive, logic);
+  }
+}
+
+module.exports = Range;
diff --git a/test/__snapshots__/index.test.js.snap b/test/__snapshots__/index.test.js.snap
index d714692..e377874 100644
--- a/test/__snapshots__/index.test.js.snap
+++ b/test/__snapshots__/index.test.js.snap
@@ -749,7 +749,7 @@ exports[`Validation should fail validation for integer type 1`] = `
 
 exports[`Validation should fail validation for integer with exclusive maximum 1`] = `
 "Invalid configuration object. Object has been initialised using a configuration object that does not match the API schema.
- - configuration.integerWithExclusiveMaximum should be a integer (should be > 0)."
+ - configuration.integerWithExclusiveMaximum should be a integer (should be < 0)."
 `;
 
 exports[`Validation should fail validation for integer with exclusive maximum 2`] = `
@@ -769,7 +769,7 @@ exports[`Validation should fail validation for integer with exclusive minimum 2`
 
 exports[`Validation should fail validation for integer with minimum 1`] = `
 "Invalid configuration object. Object has been initialised using a configuration object that does not match the API schema.
- - configuration.integerWithMinimum should be a integer (should be >= 5, should be <= 20)."
+ - configuration.integerWithMinimum should be a integer (should be >= 5 and <= 20)."
 `;
 
 exports[`Validation should fail validation for integer with minimum and maximum 1`] = `
@@ -1050,7 +1050,7 @@ exports[`Validation should fail validation for multipleOf 1`] = `
 
 exports[`Validation should fail validation for multipleOf with minimum and maximum 1`] = `
 "Invalid configuration object. Object has been initialised using a configuration object that does not match the API schema.
- - configuration.multipleOfProp should be a number (should be >= 5, should be <= 20, should be multiple of 5)."
+ - configuration.multipleOfProp should be a number (should be >= 5 and <= 20, should be multiple of 5)."
 `;
 
 exports[`Validation should fail validation for multipleOf with type number 1`] = `
@@ -1299,7 +1299,7 @@ exports[`Validation should fail validation for number type 1`] = `
 
 exports[`Validation should fail validation for number with minimum and maximum 1`] = `
 "Invalid configuration object. Object has been initialised using a configuration object that does not match the API schema.
- - configuration.numberWithMinimum should be a number (should be >= 5, should be <= 20)."
+ - configuration.numberWithMinimum should be a number (should be >= 5 and <= 20)."
 `;
 
 exports[`Validation should fail validation for object #2 1`] = `
diff --git a/test/range.test.js b/test/range.test.js
new file mode 100644
index 0000000..6c509fc
--- /dev/null
+++ b/test/range.test.js
@@ -0,0 +1,109 @@
+import Range from '../src/util/Range';
+
+it('5 <= x <= 5', () => {
+  const range = new Range();
+  range.left(5);
+  range.right(5);
+
+  expect(range.format()).toEqual('should be = 5');
+});
+
+it('not 5 <= x <= 5', () => {
+  const range = new Range();
+  range.left(5);
+  range.right(5);
+
+  expect(range.format(false)).toEqual('should be != 5');
+});
+
+it('-1 < x < 1', () => {
+  const range = new Range();
+  range.left(-1, true);
+  range.right(1, true);
+
+  expect(range.format()).toEqual('should be = 0');
+});
+
+it('not -1 < x < 1', () => {
+  const range = new Range();
+  range.left(-1, true);
+  range.right(1, true);
+
+  expect(range.format(false)).toEqual('should be != 0');
+});
+
+it('not 0 < x <= 10', () => {
+  const range = new Range();
+  range.left(0, true);
+  range.right(10, false);
+
+  expect(range.format(false)).toEqual('should be <= 0 or > 10');
+});
+
+it('x > 1000', () => {
+  const range = new Range();
+  range.left(10000, false);
+  range.left(1000, true);
+
+  expect(range.format(true)).toEqual('should be > 1000');
+});
+
+it('x < 0', () => {
+  const range = new Range();
+  range.right(-1000, true);
+  range.right(-0, true);
+
+  expect(range.format()).toEqual('should be < 0');
+});
+
+it('x >= -1000', () => {
+  const range = new Range();
+  range.right(-1000, true);
+  range.right(0, false);
+
+  // expect x >= -1000 since it covers bigger range. [-1000, Infinity] is greater than [0, Infinity]
+  expect(range.format(false)).toEqual('should be >= -1000');
+});
+
+it('x <= 0', () => {
+  const range = new Range();
+  range.left(0, true);
+  range.left(-100, false);
+
+  // expect x <= 0 since it covers bigger range. [-Infinity, 0] is greater than [-Infinity, -100]
+  expect(range.format(false)).toEqual('should be <= 0');
+});
+
+it('Empty string for infinity range', () => {
+  const range = new Range();
+
+  expect(range.format(false)).toEqual('');
+});
+
+it('0 < x < 122', () => {
+  const range = new Range();
+  range.left(0, true);
+  range.right(12, false);
+  range.right(122, true);
+
+  expect(range.format()).toEqual('should be > 0 and < 122');
+});
+
+it('-1 <= x < 10', () => {
+  const range = new Range();
+  range.left(-1, false);
+  range.left(10, true);
+  range.right(10, true);
+
+  expect(range.format()).toEqual('should be >= -1 and < 10');
+});
+
+it('not 10 < x < 10', () => {
+  const range = new Range();
+  range.left(-1, false);
+  range.left(10, true);
+  range.right(10, true);
+
+  // expect x <= 10 since it covers bigger range. [-Infinity, 10] is greater than [-Infinity, -1]
+  expect(range.format(false)).toEqual('should be <= 10 or >= 10');
+});