From b9b45ece39ed61b9709dd0b8d043f6e3dbfaa51c Mon Sep 17 00:00:00 2001
From: Muthu Kumar <muthukumar@thefeathers.in>
Date: Sat, 12 May 2018 20:42:13 +0530
Subject: [PATCH] [refactor]

---
 index.js             |  2 +-
 lib/errorsHelper.js  | 14 ++++++++++++++
 lib/slideHelper.js   | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/slider.js        | 17 +++++++++++++++++
 package.json         |  1 +
 structures/slider.js | 46 ----------------------------------------------
 test.js              |  7 +++++++
 7 files changed, 92 insertions(+), 47 deletions(-)
 create mode 100644 lib/errorsHelper.js
 create mode 100644 lib/slideHelper.js
 create mode 100644 lib/slider.js
 delete mode 100644 structures/slider.js
 create mode 100644 test.js

diff --git a/index.js b/index.js
index f4903ee..a9b07f6 100644
--- a/index.js
+++ b/index.js
@@ -1,5 +1,5 @@
 'use strict';
 
-const Slider = require('./structures/slider');
+const Slider = require('./lib/slider');
 
 module.exports = Slider;
diff --git a/lib/errorsHelper.js b/lib/errorsHelper.js
new file mode 100644
index 0000000..be12516
--- /dev/null
+++ b/lib/errorsHelper.js
@@ -0,0 +1,14 @@
+const returnError = (code, message) => {
+	return {
+		err: message,
+		code
+	}
+}
+
+const errors = {
+	'WIN_TOO_LARGE_HOST': returnError('WIN_TOO_LARGE_HOST', 'Window size is larger than host object'),
+	'WIN_TOO_LARGE_GUEST': returnError('WIN_TOO_LARGE_GUEST', 'Window size is larger than guest object'),
+	'COULD_NOT_SLIDE': returnError('COULD_NOT_SLIDE', 'Could not slide into position for given window')
+};
+
+module.exports = errors;
\ No newline at end of file
diff --git a/lib/slideHelper.js b/lib/slideHelper.js
new file mode 100644
index 0000000..272b8aa
--- /dev/null
+++ b/lib/slideHelper.js
@@ -0,0 +1,52 @@
+const isEq = require('@codefeathers/iseq');
+const Fuse = require('@codefeathers/fuse');
+
+const errors = require('./errorsHelper');
+
+const wrap = (f, ...x) => (...y) => f(...x, ...y);
+
+const converter = (
+	hostPosition,
+	guestPosition,
+	matchLength
+) => ({
+	hostPosition,
+	guestPosition,
+	matchLength
+});
+
+const slideNext = (host, window, hostPos, windowPos, len = 1) => {
+	const newHostPos = hostPos + 1;
+	const newWindowPos = windowPos + 1;
+	if (isEq(window[newWindowPos], host[newHostPos]))
+		return slideNext(host, window, newHostPos, newWindowPos, len + 1);
+	return (len);
+};
+
+const startSliding = (k, host, guest, window, windowPos) => {
+
+	const firstMatch = host.findIndex(wrap(isEq, window[0]));
+
+	// If first item returns a match, then continue to slideNext()
+	const len = firstMatch ? slideNext(host, guest, firstMatch, windowPos) : undefined;
+	if (len && len > 1) return converter(firstMatch, windowPos, len);
+
+	const nextWindowPos = windowPos + 1;
+	const newWindow = guest.slice(nextWindowPos, nextWindowPos + k);
+	if (newWindow.length === k) return startSliding(newWindow, nextWindowPos);
+
+	return errors.COULD_NOT_SLIDE;
+
+};
+
+const slide = (k, host, guest) => {
+
+	if (k > host.length) return errors.WIN_TOO_LARGE_HOST;
+	if (k > guest.length) return errors.WIN_TOO_LARGE_GUEST;
+
+	// Create a new window and start sliding
+	const window = guest.slice(0, k);
+	return startSliding(k, host, guest, window, 0);
+}
+
+module.exports = slide;
\ No newline at end of file
diff --git a/lib/slider.js b/lib/slider.js
new file mode 100644
index 0000000..172d11c
--- /dev/null
+++ b/lib/slider.js
@@ -0,0 +1,17 @@
+'use strict';
+
+const slideHelper = require('./slideHelper');
+
+class Slider {
+	constructor (options) {
+		this.windowSize = options.size;
+		this.prefer = options.prefer;
+		this.accepting = options.accepting;
+	}
+
+	slide (host, guest) {
+		return slideHelper(this.windowSize, host, guest);
+	}
+};
+
+module.exports = Slider;
diff --git a/package.json b/package.json
index 0b06367..85c7f90 100644
--- a/package.json
+++ b/package.json
@@ -24,6 +24,7 @@
   },
   "homepage": "https://github.com/codefeathers/sliding-window#readme",
   "dependencies": {
+    "@codefeathers/fuse": "^0.11.0",
     "@codefeathers/iseq": "^1.1.0"
   }
 }
diff --git a/structures/slider.js b/structures/slider.js
deleted file mode 100644
index 8b1ece3..0000000
--- a/structures/slider.js
+++ /dev/null
@@ -1,46 +0,0 @@
-'use strict';
-
-const isEq = require('@codefeathers/iseq');
-
-const wrap = (f, ...x) => (...y) => f(...x, ...y);
-
-class Slider {
-	constructor (options) {
-		this.windowSize = options.size;
-		this.prefer = options.prefer;
-		this.accepting = options.accepting;
-	}
-
-	slide (host, guest) {
-
-		const k = this.windowSize;
-
-		const get = {
-			val: 0,
-			next: () => ++get.val,
-		}
-
-		const startSliding = (window, i) => {
-
-			const firstMatch = host.findIndex(wrap(isEq, window[0]));
-			if(firstMatch !== -1) {
-				get.val = firstMatch;
-				if(window.every((item, j) => {
-					if(j === 0) return true;
-					return isEq(item, host[get.next()]);
-				})) return [ firstMatch, i ];
-			}
-
-			const nextI = i + 1;
-			const newWindow = guest.slice(nextI, nextI + k);
-			if(newWindow.length === k) return startSliding(newWindow, nextI);
-
-			return [ -1, -1 ];
-
-		};
-		const window = guest.slice(0, k);
-		return startSliding(window, 0);
-	}
-};
-
-module.exports = Slider;
diff --git a/test.js b/test.js
new file mode 100644
index 0000000..2d21dda
--- /dev/null
+++ b/test.js
@@ -0,0 +1,7 @@
+const Slider = require('.');
+
+const a = [ 0, 1, 2, 3, 4, 5 ];
+const b = [ 2, 3, 4 ];
+
+const w = new Slider({ size: 3 });
+console.log(w.slide(a, b));
\ No newline at end of file