From 732b2575d1b499f61d638e8ea39427aaebeec9d3 Mon Sep 17 00:00:00 2001
From: Andrew Kingston <andrew@kingston.dev>
Date: Thu, 6 Feb 2025 14:21:39 +0000
Subject: [PATCH] Type grid DND handler

---
 .../components/preview/GridDNDHandler.svelte  | 124 ++++++++++++------
 .../src/components/preview/Indicator.svelte   |   6 +-
 packages/client/src/index.ts                  |   2 +-
 packages/client/src/utils/grid.ts             |  39 +++---
 packages/frontend-core/src/utils/memo.d.ts    |   2 +-
 5 files changed, 110 insertions(+), 63 deletions(-)

diff --git a/packages/client/src/components/preview/GridDNDHandler.svelte b/packages/client/src/components/preview/GridDNDHandler.svelte
index e2414e9d78..24d61bad2b 100644
--- a/packages/client/src/components/preview/GridDNDHandler.svelte
+++ b/packages/client/src/components/preview/GridDNDHandler.svelte
@@ -1,4 +1,4 @@
-<script>
+<script lang="ts">
   import { onMount, onDestroy, getContext } from "svelte"
   import {
     builderStore,
@@ -15,9 +15,37 @@
     GridParams,
     getGridVar,
     Devices,
-    GridDragModes,
+    GridDragMode,
   } from "@/utils/grid"
 
+  type GridDragSide =
+    | "top"
+    | "right"
+    | "bottom"
+    | "left"
+    | "top-left"
+    | "top-right"
+    | "bottom-left"
+    | "bottom-right"
+
+  interface GridDragInfo {
+    mode: GridDragMode
+    side?: GridDragSide
+    domTarget?: HTMLElement
+    domComponent: HTMLElement
+    domGrid: HTMLElement
+    id: string
+    gridId: string
+    grid: {
+      startX: number
+      startY: number
+      rowStart: number
+      rowEnd: number
+      colStart: number
+      colEnd: number
+    }
+  }
+
   const context = getContext("context")
 
   // Smallest possible 1x1 transparent GIF
@@ -25,11 +53,11 @@
   ghost.src =
     "data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw=="
 
-  let dragInfo
-  let styles = memo()
+  let dragInfo: GridDragInfo | undefined
+  let styles = memo<Record<string, number> | undefined>()
 
   // Grid CSS variables
-  $: device = $context.device.mobile ? Devices.Mobile : Devices.Desktop
+  $: device = $context.device?.mobile ? Devices.Mobile : Devices.Desktop
   $: vars = {
     colStart: getGridVar(device, GridParams.ColStart),
     colEnd: getGridVar(device, GridParams.ColEnd),
@@ -47,7 +75,10 @@
   // Reset when not dragging new components
   $: !$dndIsDragging && stopDragging()
 
-  const applyStyles = async (instance, styles) => {
+  const applyStyles = async (
+    instance: any,
+    styles: Record<string, number> | undefined
+  ) => {
     instance?.setEphemeralStyles(styles)
 
     // If dragging a new component on to a grid screen, tick to allow the
@@ -63,24 +94,28 @@
   }
 
   // Sugar for a combination of both min and max
-  const minMax = (value, min, max) => Math.min(max, Math.max(min, value))
+  const minMax = (value: number, min: number, max: number) =>
+    Math.min(max, Math.max(min, value))
 
-  const processEvent = Utils.domDebounce((mouseX, mouseY) => {
+  const processEvent = Utils.domDebounce((mouseX: number, mouseY: number) => {
     if (!dragInfo?.grid) {
       return
     }
-    const { mode, side, grid, domGrid } = dragInfo
+    const { mode, grid, domGrid } = dragInfo
     const { startX, startY, rowStart, rowEnd, colStart, colEnd } = grid
     if (!domGrid) {
       return
     }
-    const cols = parseInt(domGrid.dataset.cols)
-    const colSize = parseInt(domGrid.dataset.colSize)
+    const cols = parseInt(domGrid.dataset.cols || "")
+    const colSize = parseInt(domGrid.dataset.colSize || "")
+    if (isNaN(cols) || isNaN(colSize)) {
+      throw "DOM grid missing required dataset attributes"
+    }
     const diffX = mouseX - startX
     let deltaX = Math.round(diffX / colSize)
     const diffY = mouseY - startY
     let deltaY = Math.round(diffY / GridRowHeight)
-    if (mode === GridDragModes.Move) {
+    if (mode === GridDragMode.Move) {
       deltaX = minMax(deltaX, 1 - colStart, cols + 1 - colEnd)
       deltaY = Math.max(deltaY, 1 - rowStart)
       const newStyles = {
@@ -90,8 +125,9 @@
         [vars.rowEnd]: rowEnd + deltaY,
       }
       styles.set(newStyles)
-    } else if (mode === GridDragModes.Resize) {
-      let newStyles = {}
+    } else if (mode === GridDragMode.Resize) {
+      const { side } = dragInfo
+      let newStyles: Record<string, number> = {}
       if (side === "right") {
         newStyles[vars.colEnd] = Math.max(colEnd + deltaX, colStart + 1)
       } else if (side === "left") {
@@ -117,7 +153,7 @@
     }
   })
 
-  const handleEvent = e => {
+  const handleEvent = (e: DragEvent) => {
     e.preventDefault()
     e.stopPropagation()
     processEvent(e.clientX, e.clientY)
@@ -128,7 +164,10 @@
   const startDraggingPlaceholder = () => {
     const domComponent = document.getElementsByClassName(DNDPlaceholderID)[0]
     const domGrid = domComponent?.closest(".grid")
-    if (!domGrid) {
+    if (
+      !(domComponent instanceof HTMLElement) ||
+      !(domGrid instanceof HTMLElement)
+    ) {
       return
     }
     const styles = getComputedStyle(domComponent)
@@ -143,21 +182,21 @@
       domComponent,
       domGrid,
       id: DNDPlaceholderID,
-      gridId: domGrid.parentNode.dataset.id,
-      mode: GridDragModes.Move,
+      gridId: domGrid.parentElement!.dataset.id!,
+      mode: GridDragMode.Move,
       grid: {
         startX: bounds.left + bounds.width / 2,
         startY: bounds.top + bounds.height / 2,
-        rowStart: parseInt(styles["grid-row-start"]),
-        rowEnd: parseInt(styles["grid-row-end"]),
-        colStart: parseInt(styles["grid-column-start"]),
-        colEnd: parseInt(styles["grid-column-end"]),
+        rowStart: parseInt(styles.gridRowStart),
+        rowEnd: parseInt(styles.gridRowEnd),
+        colStart: parseInt(styles.gridColumnStart),
+        colEnd: parseInt(styles.gridColumnEnd),
       },
     }
   }
 
   // Callback when initially starting a drag on a draggable component
-  const onDragStart = e => {
+  const onDragStart = (e: DragEvent) => {
     if (!isGridEvent(e)) {
       return
     }
@@ -166,27 +205,30 @@
     e.dataTransfer.setDragImage(ghost, 0, 0)
 
     // Extract state
-    let mode, id, side
+    let mode: GridDragMode, id: string, side
     if (e.target.dataset.indicator === "true") {
-      mode = e.target.dataset.dragMode
-      id = e.target.dataset.id
-      side = e.target.dataset.side
+      mode = e.target.dataset.dragMode as GridDragMode
+      id = e.target.dataset.id!
+      side = e.target.dataset.side as GridDragSide
     } else {
       // Handle move
-      mode = GridDragModes.Move
-      const component = e.target.closest(".component")
-      id = component.dataset.id
+      mode = GridDragMode.Move
+      const component = e.target.closest(".component") as HTMLElement
+      id = component.dataset.id!
     }
 
     // If holding ctrl/cmd then leave behind a duplicate of this component
-    if (mode === GridDragModes.Move && (e.ctrlKey || e.metaKey)) {
+    if (mode === GridDragMode.Move && (e.ctrlKey || e.metaKey)) {
       builderStore.actions.duplicateComponent(id, "above", false)
     }
 
     // Find grid parent and read from DOM
     const domComponent = document.getElementsByClassName(id)[0]
     const domGrid = domComponent?.closest(".grid")
-    if (!domGrid) {
+    if (
+      !(domComponent instanceof HTMLElement) ||
+      !(domGrid instanceof HTMLElement)
+    ) {
       return
     }
     const styles = getComputedStyle(domComponent)
@@ -202,24 +244,24 @@
       domComponent,
       domGrid,
       id,
-      gridId: domGrid.parentNode.dataset.id,
+      gridId: domGrid.parentElement!.dataset.id!,
       mode,
       side,
       grid: {
         startX: e.clientX,
         startY: e.clientY,
-        rowStart: parseInt(styles["grid-row-start"]),
-        rowEnd: parseInt(styles["grid-row-end"]),
-        colStart: parseInt(styles["grid-column-start"]),
-        colEnd: parseInt(styles["grid-column-end"]),
+        rowStart: parseInt(styles.gridRowStart),
+        rowEnd: parseInt(styles.gridRowEnd),
+        colStart: parseInt(styles.gridColumnStart),
+        colEnd: parseInt(styles.gridColumnEnd),
       },
     }
 
     // Add event handler to clear all drag state when dragging ends
-    dragInfo.domTarget.addEventListener("dragend", stopDragging, false)
+    dragInfo.domTarget!.addEventListener("dragend", stopDragging, false)
   }
 
-  const onDragOver = e => {
+  const onDragOver = (e: DragEvent) => {
     if (!dragInfo) {
       // Check if we're dragging a new component
       if ($dndIsDragging && $dndSource?.isNew && $isGridScreen) {
@@ -248,8 +290,8 @@
     }
 
     // Reset state
-    dragInfo = null
-    styles.set(null)
+    dragInfo = undefined
+    styles.set(undefined)
   }
 
   onMount(() => {
diff --git a/packages/client/src/components/preview/Indicator.svelte b/packages/client/src/components/preview/Indicator.svelte
index d2268d50b5..800bc0423b 100644
--- a/packages/client/src/components/preview/Indicator.svelte
+++ b/packages/client/src/components/preview/Indicator.svelte
@@ -1,6 +1,6 @@
 <script lang="ts">
   import { Icon } from "@budibase/bbui"
-  import { GridDragModes } from "@/utils/grid"
+  import { GridDragMode } from "@/utils/grid"
 
   export let top: number
   export let left: number
@@ -50,7 +50,7 @@
       class:right={alignRight}
       draggable="true"
       data-indicator="true"
-      data-drag-mode={GridDragModes.Move}
+      data-drag-mode={GridDragMode.Move}
       data-id={componentId}
     >
       {#if icon}
@@ -69,7 +69,7 @@
         class="anchor {side}"
         draggable="true"
         data-indicator="true"
-        data-drag-mode={GridDragModes.Resize}
+        data-drag-mode={GridDragMode.Resize}
         data-side={side}
         data-id={componentId}
       >
diff --git a/packages/client/src/index.ts b/packages/client/src/index.ts
index a42a39a766..443648eb08 100644
--- a/packages/client/src/index.ts
+++ b/packages/client/src/index.ts
@@ -105,7 +105,7 @@ export type Component = Readable<{
   errorState: boolean
 }>
 
-export type Context = Readable<{}>
+export type Context = Readable<Record<string, any>>
 
 let app: ClientApp
 
diff --git a/packages/client/src/utils/grid.ts b/packages/client/src/utils/grid.ts
index c0e4bd5bfa..3412e734c6 100644
--- a/packages/client/src/utils/grid.ts
+++ b/packages/client/src/utils/grid.ts
@@ -37,38 +37,43 @@ interface GridMetadata {
  */
 
 // Enum representing the different CSS variables we use for grid metadata
-export const GridParams = {
-  HAlign: "h-align",
-  VAlign: "v-align",
-  ColStart: "col-start",
-  ColEnd: "col-end",
-  RowStart: "row-start",
-  RowEnd: "row-end",
+export enum GridParams {
+  HAlign = "h-align",
+  VAlign = "v-align",
+  ColStart = "col-start",
+  ColEnd = "col-end",
+  RowStart = "row-start",
+  RowEnd = "row-end",
 }
 
 // Classes used in selectors inside grid containers to control child styles
-export const GridClasses = {
-  DesktopFill: "grid-desktop-grow",
-  MobileFill: "grid-mobile-grow",
+export enum GridClasses {
+  DesktopFill = "grid-desktop-grow",
+  MobileFill = "grid-mobile-grow",
 }
 
 // Enum for device preview type, included in grid CSS variables
-export const Devices = {
-  Desktop: "desktop",
-  Mobile: "mobile",
+export enum Devices {
+  Desktop = "desktop",
+  Mobile = "mobile",
 }
 
-export const GridDragModes = {
-  Resize: "resize",
-  Move: "move",
+export enum GridDragMode {
+  Resize = "resize",
+  Move = "move",
 }
 
 // Builds a CSS variable name for a certain piece of grid metadata
 export const getGridVar = (device: string, param: string) =>
   `--grid-${device}-${param}`
 
+export interface GridEvent extends DragEvent {
+  target: HTMLElement
+  dataTransfer: DataTransfer
+}
+
 // Determines whether a JS event originated from immediately within a grid
-export const isGridEvent = (e: Event): boolean => {
+export const isGridEvent = (e: Event): e is GridEvent => {
   if (!(e.target instanceof HTMLElement)) {
     return false
   }
diff --git a/packages/frontend-core/src/utils/memo.d.ts b/packages/frontend-core/src/utils/memo.d.ts
index 04d3416e49..a00dc345b1 100644
--- a/packages/frontend-core/src/utils/memo.d.ts
+++ b/packages/frontend-core/src/utils/memo.d.ts
@@ -1,7 +1,7 @@
 import { Readable, Writable } from "svelte/store"
 
 declare module "./memo" {
-  export function memo<T>(value: T): Writable<T>
+  export function memo<T>(value?: T): Writable<T>
 
   export function derivedMemo<TStore, TResult>(
     store: Readable<TStore>,