drag&drop support for report file #32 - Done

src/GitHubCostVisualizer.Web/Views/Home/Index.cshtml

@@ -8,13 +8,11 @@
 <p>Unsure of where your money is going with your Github account?  Upload your recent Usage report from Github to get a visual on where your money is going</p>
 
 <form asp-controller="Home" asp-action="Report" enctype="multipart/form-data">
-
-    <label>Github Usage File</label>
-    <div class="custom-file">
-        <input type="file" class="custom-file-input" asp-for="UploadFile">
-        <label class="custom-file-label" for="UploadFile">Choose file...</label>
-        <span class="text-danger" asp-validation-for="UploadFile"></span>
+    <div class="drop-zone">
+        <span class="drop-zone__prompt">Drop a Github usage file here or click to upload</span>
+        <input type="file" class="drop-zone__input" asp-for="UploadFile">      
     </div>
+    <span class="text-danger" asp-validation-for="UploadFile"></span>
 
     <div class="alert alert-info mt-1">
         Your uploaded file is never stored and processed in real-time only.
@@ -28,7 +26,8 @@
 </form>
 
 @section scripts{
-    <script>
+    <script>        
         handleFilePickers(".custom-file-input");
     </script>
+    <script type="text/javascript" src="/js/dragdrop.js" asp-append-version="true"></script>
 }

src/GitHubCostVisualizer.Web/Views/Shared/_Start.cshtml

@@ -11,6 +11,7 @@
     <!-- Stylesheets -->
     <link href="/css/style.min.css" rel="stylesheet" type="text/css" asp-append-version="true">
     <link href="/css/all.min.css" rel="stylesheet" type="text/css" asp-append-version="true">
+    <link href="/css/dragdrop.css" rel="stylesheet" type="text/css" asp-append-version="true">
 
     <!-- Javascript -->
     <script type="text/javascript" src="/js/jquery.min.js" asp-append-version="true"></script>

src/GitHubCostVisualizer.Web/wwwroot/css/dragdrop.css

@@ -0,0 +1,48 @@
+
+.drop-zone {
+    max-width: 100%;
+    height: 200px;
+    padding: 25px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    text-align: center;
+    font-family: "Quicksand", sans-serif;
+    font-weight: 500;
+    font-size: 20px;
+    cursor: pointer;
+    color: #cccccc;
+    border: 4px dashed #2286c9;
+    border-radius: 10px;
+}
+
+.drop-zone--over {
+    border-style: solid;
+}
+
+.drop-zone__input {
+    display: none;
+}
+
+.drop-zone__thumb {
+    width: 100%;
+    height: 100%;
+    border-radius: 10px;
+    overflow: hidden;
+    background-color: #4a8fbd;
+    background-size: cover;
+    position: relative;
+}
+
+.drop-zone__thumb::after {
+   content: attr(data-label);
+   position: absolute;
+   bottom: 0;
+   left: 0;
+   width: 100%;
+   padding: 5px 0;
+   color: #ffffff;
+   background: rgba(0, 0, 0, 0.75);
+   font-size: 14px;
+   text-align: center;
+}

src/GitHubCostVisualizer.Web/wwwroot/js/dragdrop.js

@@ -0,0 +1,71 @@
+document.querySelectorAll(".drop-zone__input").forEach((inputElement) => {
+    const dropZoneElement = inputElement.closest(".drop-zone");
+
+    dropZoneElement.addEventListener("click", (e) => {
+        inputElement.click();
+    });
+
+    inputElement.addEventListener("change", (e) => {
+        if (inputElement.files.length) {
+            updateThumbnail(dropZoneElement, inputElement.files[0]);
+        }
+    });
+
+    dropZoneElement.addEventListener("dragover", (e) => {
+        e.preventDefault();
+        dropZoneElement.classList.add("drop-zone--over");
+    });
+
+    ["dragleave", "dragend"].forEach((type) => {
+        dropZoneElement.addEventListener(type, (e) => {
+            dropZoneElement.classList.remove("drop-zone--over");
+        });
+    });
+
+    dropZoneElement.addEventListener("drop", (e) => {
+        e.preventDefault();
+
+        if (e.dataTransfer.files.length) {
+            inputElement.files = e.dataTransfer.files;
+            updateThumbnail(dropZoneElement, e.dataTransfer.files[0]);
+        }
+
+        dropZoneElement.classList.remove("drop-zone--over");
+    });
+});
+
+/**
+ * Updates the thumbnail on a drop zone element.
+ *
+ * @param {HTMLElement} dropZoneElement
+ * @param {File} file
+ */
+function updateThumbnail(dropZoneElement, file) {
+    let thumbnailElement = dropZoneElement.querySelector(".drop-zone__thumb");
+
+    // First time - remove the prompt
+    if (dropZoneElement.querySelector(".drop-zone__prompt")) {
+        dropZoneElement.querySelector(".drop-zone__prompt").remove();
+    }
+
+    // First time - there is no thumbnail element, so lets create it
+    if (!thumbnailElement) {
+        thumbnailElement = document.createElement("div");
+        thumbnailElement.classList.add("drop-zone__thumb");
+        dropZoneElement.appendChild(thumbnailElement);
+    }
+
+    thumbnailElement.dataset.label = file.name;
+
+    // Show thumbnail for image files
+    if (file.type.startsWith("image/")) {
+        const reader = new FileReader();
+
+        reader.readAsDataURL(file);
+        reader.onload = () => {
+            thumbnailElement.style.backgroundImage = `url('${reader.result}')`;
+        };
+    } else {
+        thumbnailElement.style.backgroundImage = null;
+    }
+}