From 6d5af995d9c6294a164e0b0056950731be948866 Mon Sep 17 00:00:00 2001
From: David Thompson <dthompson2@worcester.edu>
Date: Sat, 9 Aug 2014 09:20:44 -0400
Subject: Add pagination.

* js/guix-packages.js: (guix.chunk): New function.
  (guix.paginate): New function.
  (guix.controller.pages, guix.controller.currentPageIndex,
  guix.controller.pageSize): New variables.
  (guix.controller.currentPage, guix.controller.isFirstPage,
  guix.controller.isLastPage, guix.controller.isCurrentPage,
  guix.controller.packageCount): New functions.
  (guix.controller.doSearch): Paginate.
  (guix.view): Render pagination UI.
---
 js/guix-packages.js | 102 ++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 95 insertions(+), 7 deletions(-)

diff --git a/js/guix-packages.js b/js/guix-packages.js
index d4e975a..7ab30a0 100644
--- a/js/guix-packages.js
+++ b/js/guix-packages.js
@@ -17,25 +17,71 @@
 
 var guix = {};
 
+guix.chunk = function(array, size) {
+  return array.reduce(function(memo, value, i) {
+    var currentSlice = _(memo).last();
+
+    if(i / size < memo.length) {
+      currentSlice.push(value);
+    } else {
+      memo.push([value]);
+    }
+
+    return memo;
+  }, []);
+};
+
+guix.paginate = function(array, pageSize) {
+  return guix.chunk(array, pageSize);
+};
+
 guix.Packages = function() {
   return m.request({ method: "GET", url: "packages.json" });
 };
 
 guix.controller = function() {
+  var self = this;
+
   this.packages = guix.Packages();
-  this.visiblePackages = m.prop([]);
+  this.pages = m.prop([]);
+  this.currentPageIndex = 0;
+  this.pageSize = 20;
   this.searchTerm = m.prop("");
 
   // All packages are visible initially
-  this.packages.then(this.visiblePackages);
+  this.packages.then(function(packages) {
+    self.pages(guix.paginate(packages, self.pageSize));
+  });
+
+  this.currentPage = function() {
+    return self.pages()[self.currentPageIndex] || [];
+  };
+
+  this.isFirstPage = function() {
+    return self.currentPageIndex === 0;
+  };
+
+  this.isLastPage = function() {
+    return self.currentPageIndex === self.pages().length - 1;
+  };
+
+  this.isCurrentPage = function(i) {
+    return self.currentPageIndex === i;
+  };
+
+  this.packageCount = function() {
+    return self.pages().reduce(function(memo, page) {
+      return memo + page.length;
+    }, 0);
+  };
 
   this.doSearch = function() {
     var regexp = new RegExp(this.searchTerm(), "i");
 
-    this.visiblePackages(this.packages().filter(function(package) {
+    this.pages(guix.paginate(this.packages().filter(function(package) {
       return regexp.test(package.name) ||
         regexp.test(package.synopsis);
-    }));
+    }), self.pageSize));
   };
 };
 
@@ -70,10 +116,51 @@ guix.view = function(ctrl) {
     }
   }
 
+  function renderPagination() {
+    function renderPage(text, opts) {
+      return m("li", {
+        class: opts.class || "",
+        onclick: opts.onclick
+      }, m("a", { href: "#" }, text));
+    }
+
+    return m("ul.pagination", [
+      // Back page
+      renderPage("«", {
+        class: ctrl.isFirstPage() ? "disabled" : "",
+        onclick: function() {
+          ctrl.currentPageIndex--;
+
+          return false;
+        }
+      })
+    ].concat(ctrl.pages().map(function(page, i) {
+      // Jump to page
+      return renderPage(i + 1, {
+        class: ctrl.isCurrentPage(i) ? "active" : "",
+        onclick: function() {
+          ctrl.currentPageIndex = i;
+
+          return false;
+        }
+      });
+    })).concat([
+      // Forward page
+      renderPage("»", {
+        class: ctrl.isLastPage() ? "disabled" : "",
+        onclick: function() {
+          ctrl.currentPageIndex++;
+
+          return false;
+        }
+      })
+    ]));
+  }
+
   return [
     m("h2", [
       "Packages",
-      m("span.badge", ctrl.visiblePackages().length)
+      m("span.badge", ctrl.packageCount())
     ]),
     m("input.form-control", {
       type: "text",
@@ -97,7 +184,7 @@ guix.view = function(ctrl) {
         ])
       ]),
       m("tbody", [
-        ctrl.visiblePackages().map(function(package) {
+        ctrl.currentPage().map(function(package) {
           return m("tr", [
             m("td", renderName(package)),
             m("td", package.version),
@@ -107,7 +194,8 @@ guix.view = function(ctrl) {
           ]);
         })
       ])
-    ])
+    ]),
+    renderPagination()
   ];
 };
 
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