From 4702c7a18bf1266aabe06808a310385fb18aecbb Mon Sep 17 00:00:00 2001
From: "Grigorii K. Shartsev" <me@shgk.me>
Date: Tue, 3 Sep 2024 17:25:22 +0200
Subject: [PATCH] feat(viewer): add PDF viewer

Signed-off-by: Grigorii K. Shartsev <me@shgk.me>
---
 src/talk/renderer/Viewer/Viewer.js            |  6 +++
 src/talk/renderer/Viewer/ViewerHandlerPdf.vue | 28 ++++++++++
 .../renderer/Viewer/viewer.composables.ts     | 54 +++++++++++++++++++
 src/talk/renderer/Viewer/viewer.service.ts    | 32 +++++++++++
 4 files changed, 120 insertions(+)
 create mode 100644 src/talk/renderer/Viewer/ViewerHandlerPdf.vue
 create mode 100644 src/talk/renderer/Viewer/viewer.composables.ts
 create mode 100644 src/talk/renderer/Viewer/viewer.service.ts

diff --git a/src/talk/renderer/Viewer/Viewer.js b/src/talk/renderer/Viewer/Viewer.js
index 13ca1bfe..228cc986 100644
--- a/src/talk/renderer/Viewer/Viewer.js
+++ b/src/talk/renderer/Viewer/Viewer.js
@@ -13,6 +13,7 @@ export async function createViewer() {
 	const { default: ViewerApp } = await import('./ViewerApp.vue')
 	const { default: ViewerHandlerImages } = await import('./ViewerHandlerImages.vue')
 	const { default: ViewerHandlerVideos } = await import('./ViewerHandlerVideos.vue')
+	const { default: ViewerHandlerPdf } = await import('./ViewerHandlerPdf.vue')
 
 	const Viewer = {
 		availableHandlers: [{
@@ -44,6 +45,11 @@ export async function createViewer() {
 				'video/x-matroska',
 			],
 			component: ViewerHandlerVideos,
+		}, {
+			id: 'pdf',
+			group: 'document',
+			mimes: ['application/pdf'],
+			component: ViewerHandlerPdf,
 		}],
 
 		open(...args) {
diff --git a/src/talk/renderer/Viewer/ViewerHandlerPdf.vue b/src/talk/renderer/Viewer/ViewerHandlerPdf.vue
new file mode 100644
index 00000000..3885d3f3
--- /dev/null
+++ b/src/talk/renderer/Viewer/ViewerHandlerPdf.vue
@@ -0,0 +1,28 @@
+<!--
+  - SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+  - SPDX-License-Identifier: AGPL-3.0-or-later
+-->
+
+<script setup>
+import { computed } from 'vue'
+import { toRef } from '@vueuse/core'
+import { useFileContent } from './viewer.composables.ts'
+import ViewerHandlerBase from './ViewerHandlerBase.vue'
+
+const props = defineProps({
+	file: {
+		type: Object,
+		required: true,
+	},
+})
+
+const { content, loading, error } = useFileContent(toRef(() => props.file.filename), 'binary')
+
+const src = computed(() => content.value ? URL.createObjectURL(content.value) : undefined)
+</script>
+
+<template>
+	<ViewerHandlerBase :loading="loading" :error="error">
+		<iframe v-if="src" :src="src" />
+	</ViewerHandlerBase>
+</template>
diff --git a/src/talk/renderer/Viewer/viewer.composables.ts b/src/talk/renderer/Viewer/viewer.composables.ts
new file mode 100644
index 00000000..831c44ba
--- /dev/null
+++ b/src/talk/renderer/Viewer/viewer.composables.ts
@@ -0,0 +1,54 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { ref, watchEffect } from 'vue'
+import type { Ref } from 'vue'
+import { toValue } from '@vueuse/core'
+import type { MaybeRefOrGetter } from '@vueuse/core'
+import { fetchFileContent } from './viewer.service.ts'
+
+type FileContentComposableResult<T> = {
+	content: Ref<T>,
+	loading: Ref<boolean>,
+	error: Ref<boolean | string>,
+}
+
+export function useFileContent(filename: MaybeRefOrGetter<string>, format: 'binary'): FileContentComposableResult<Blob | null>
+export function useFileContent(filename: MaybeRefOrGetter<string>, format: 'text'): FileContentComposableResult<string | null>
+/**
+ * Fetch file content with reactive state in a watch effect
+ * @param filename - Path to user's file, e.g. '/Talk/file.txt'
+ * @param format - Format of the file content to be returned. Binary is returned as Blob
+ */
+export function useFileContent(filename: MaybeRefOrGetter<string>, format: 'text' | 'binary'): FileContentComposableResult<Blob | string | null> {
+	const content: Ref<Blob | string | null> = ref(null)
+	const loading: Ref<boolean> = ref(false)
+	const error: Ref<boolean | string> = ref(false)
+
+	watchEffect(async () => {
+		loading.value = true
+		content.value = null
+		error.value = false
+		try {
+			// Help TS to infer the type from overloads
+			content.value = format === 'text'
+				? await fetchFileContent(toValue(filename), format)
+				: await fetchFileContent(toValue(filename), format)
+		} catch (e) {
+			console.error('Failed to fetch file content', e)
+			// TODO: We can parse error from e.response, but it is not translated
+			// Or we can add messages for different status codes but it seems
+			// that it's always 404 if file cannot be loaded for any reason
+			error.value = true
+		}
+		loading.value = false
+	})
+
+	return {
+		content,
+		loading,
+		error,
+	}
+}
diff --git a/src/talk/renderer/Viewer/viewer.service.ts b/src/talk/renderer/Viewer/viewer.service.ts
new file mode 100644
index 00000000..6306e67c
--- /dev/null
+++ b/src/talk/renderer/Viewer/viewer.service.ts
@@ -0,0 +1,32 @@
+/*
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { davGetClient, davRemoteURL, davRootPath } from '@nextcloud/files'
+import type { FileStat } from 'webdav' // eslint-disable-line n/no-extraneous-import -- not exported from @nextcloud/files
+
+export async function fetchFileContent(filename: string, format: 'text'): Promise<string>
+export async function fetchFileContent(filename: string, format: 'binary'): Promise<Blob>
+/**
+ * Fetch file content
+ * @param filename - Path to user's file, e.g. '/Talk/file.txt'
+ * @param format - Format of the file content to be returned. 'binary' is returned as Blob
+ */
+export async function fetchFileContent(filename: string, format: 'text' | 'binary'): Promise<string | Blob> {
+	const webDavClient = davGetClient(davRemoteURL + davRootPath)
+
+	// Get the MIME type of the file for the binary file to generate a correct Blob later
+	let mimeType: string
+	if (format === 'binary') {
+		const stat = await webDavClient.stat(filename) as FileStat
+		mimeType = stat.mime
+	}
+
+	// Fetch file content
+	type FileContent = typeof format extends 'binary' ? ArrayBuffer : string
+	const content = await webDavClient.getFileContents(filename, { format }) as FileContent
+
+	// Return the content in the requested format
+	return format === 'binary' ? new Blob([content], { type: mimeType }) : content
+}