From 8186e1bb1c600b4173996bbf3edf6e190bf77c3c Mon Sep 17 00:00:00 2001
From: Michael Roberts <michael@observerly.com>
Date: Fri, 14 Jan 2022 12:38:07 +0000
Subject: [PATCH 1/2] feat: Added readBlockAsArrayBuffer() in utilities module.

feat: Added readBlockAsArrayBuffer() in utilities module.
---
 src/index.ts                            |  2 +-
 src/utilities/index.ts                  |  2 ++
 src/utilities/readBlockAsArrayBuffer.ts | 29 +++++++++++++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 src/utilities/readBlockAsArrayBuffer.ts

diff --git a/src/index.ts b/src/index.ts
index 335ebd5..0569d05 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -8,4 +8,4 @@ export { getFITSHeaders, parseFITSHeaderRow } from './header'
 export { getFITSBlocks } from './fits'
 
 // Utilities
-export { getExcessByteSize } from './utilities'
+export { getExcessByteSize, readBlockAsArrayBuffer } from './utilities'
diff --git a/src/utilities/index.ts b/src/utilities/index.ts
index 657dce4..c0bd031 100644
--- a/src/utilities/index.ts
+++ b/src/utilities/index.ts
@@ -1 +1,3 @@
 export { getExcessByteSize } from './getExcessByteSize'
+
+export { readBlockAsArrayBuffer } from './readBlockAsArrayBuffer'
diff --git a/src/utilities/readBlockAsArrayBuffer.ts b/src/utilities/readBlockAsArrayBuffer.ts
new file mode 100644
index 0000000..e7df881
--- /dev/null
+++ b/src/utilities/readBlockAsArrayBuffer.ts
@@ -0,0 +1,29 @@
+/**
+ *
+ * readBlockAsArrayBuffer()
+ *
+ * @description asynchronously reads a file slice as an ArrayBuffer
+ * and onloadend will pass the ArrayBuffer result to a callback function.
+ *
+ * @param block represents a File or File.slice
+ * @param callback function callback to be called onloadend passing
+ * @returns a Promise which resolves the callback of the callback function provided
+ */
+export const readBlockAsArrayBuffer = async (
+  block: File,
+  callback: (result: ArrayBuffer) => unknown
+) => {
+  return new Promise((resolve, reject) => {
+    const reader = new FileReader()
+
+    reader.onloadend = (e: ProgressEvent<FileReader>) => {
+      if (e.target?.result && e.target.result instanceof ArrayBuffer) {
+        resolve(callback(e.target.result))
+      }
+    }
+
+    reader.onerror = reject
+
+    reader.readAsArrayBuffer(block)
+  })
+}

From 54fb921cc241be68e2b7686e1d44817865b05bea Mon Sep 17 00:00:00 2001
From: Michael Roberts <michael@observerly.com>
Date: Fri, 14 Jan 2022 16:45:33 +0000
Subject: [PATCH 2/2] feat: Improved TS for the readBlockAsArrayBuffer() call.

feat: Improved TS for the readBlockAsArrayBuffer() call. Added 's' to the FITSBlock interface which holds the buffer as a raw parsed string.
---
 src/types/block.ts                      |  6 ++++++
 src/utilities/readBlockAsArrayBuffer.ts | 12 +++++++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/types/block.ts b/src/types/block.ts
index 2bcdaf2..0e13ea0 100644
--- a/src/types/block.ts
+++ b/src/types/block.ts
@@ -5,6 +5,12 @@ export interface FITSBlock {
    *
    */
   buffer: string | ArrayBuffer
+  /**
+   *
+   * The ArrayBuffer as a raw parsed string
+   *
+   */
+  s?: string
   /**
    *
    *
diff --git a/src/utilities/readBlockAsArrayBuffer.ts b/src/utilities/readBlockAsArrayBuffer.ts
index e7df881..30adaa8 100644
--- a/src/utilities/readBlockAsArrayBuffer.ts
+++ b/src/utilities/readBlockAsArrayBuffer.ts
@@ -10,9 +10,9 @@
  * @returns a Promise which resolves the callback of the callback function provided
  */
 export const readBlockAsArrayBuffer = async (
-  block: File,
-  callback: (result: ArrayBuffer) => unknown
-) => {
+  block: Blob,
+  callback: (result: ArrayBuffer) => { s: string; end: boolean; parsed: boolean }
+): Promise<{ s: string; end: boolean; parsed: boolean }> => {
   return new Promise((resolve, reject) => {
     const reader = new FileReader()
 
@@ -20,6 +20,12 @@ export const readBlockAsArrayBuffer = async (
       if (e.target?.result && e.target.result instanceof ArrayBuffer) {
         resolve(callback(e.target.result))
       }
+
+      resolve({
+        s: '',
+        end: false,
+        parsed: false
+      })
     }
 
     reader.onerror = reject