Add metadata Pinia store for ExifTool queue preview reads.

Introduce preview entry types, resolveErrorMessage, and nullcart-style resolveAxiosErrorMessage for upcoming upload API errors.

frontend/src/stores/metadata.ts

@@ -0,0 +1,83 @@
+import { parseMetadata } from '@uswriting/exiftool';
+import { defineStore } from 'pinia';
+import { ref } from 'vue';
+import type { MetadataPreviewEntry } from '@/types/metadata/MetadataPreview';
+import { resolveErrorMessage } from '@/utils/resolveErrorMessage';
+
+export const useMetadataStore = defineStore('metadata', () => {
+    const previewsByKey = ref<Record<string, MetadataPreviewEntry>>({});
+
+    const readExifToolStdout = async (file: File): Promise<string> => {
+        const result = await parseMetadata(file);
+
+        if (!result.success) {
+            throw new Error(result.error);
+        }
+
+        return result.data;
+    };
+
+    const makeKeyFromFile = (file: File): string => `${file.name}\0${file.size}\0${file.lastModified}`;
+
+    const getPreview = (file: File): MetadataPreviewEntry => {
+        const key = makeKeyFromFile(file);
+
+        return previewsByKey.value[key] ?? { status: 'idle' };
+    };
+
+    const loadPreview = async (file: File): Promise<MetadataPreviewEntry> => {
+        const key = makeKeyFromFile(file);
+
+        previewsByKey.value = { ...previewsByKey.value, [key]: { status: 'loading' } };
+
+        try {
+            const output = await readExifToolStdout(file);
+
+            const entry: MetadataPreviewEntry = { status: 'ready', output };
+
+            previewsByKey.value = { ...previewsByKey.value, [key]: entry };
+
+            return entry;
+        } catch (error) {
+            const entry: MetadataPreviewEntry = {
+                status: 'error',
+                message: resolveErrorMessage(error, 'Could not read image metadata')
+            };
+
+            previewsByKey.value = { ...previewsByKey.value, [key]: entry };
+
+            return entry;
+        }
+    };
+
+    const loadPreviews = async (files: readonly File[]): Promise<void> => {
+        await Promise.all(files.map(file => loadPreview(file)));
+    };
+
+    const clearPreview = (file: File): void => {
+        const key = makeKeyFromFile(file);
+
+        if (!(key in previewsByKey.value)) {
+            return;
+        }
+
+        const next = { ...previewsByKey.value };
+
+        delete next[key];
+        previewsByKey.value = next;
+    };
+
+    const clearAllPreviews = (): void => {
+        previewsByKey.value = {};
+    };
+
+    return {
+        previewsByKey,
+        makeKeyFromFile,
+        getPreview,
+        loadPreview,
+        loadPreviews,
+        clearPreview,
+        clearAllPreviews
+    };
+});

frontend/src/types/metadata/MetadataPreview.ts

@@ -0,0 +1,5 @@
+export type MetadataPreviewEntry =
+    | { status: 'idle' }
+    | { status: 'loading' }
+    | { status: 'ready'; output: string }
+    | { status: 'error'; message: string };

frontend/src/utils/http/resolveAxiosErrorMessage.ts

@@ -1,23 +1,40 @@
-import axios from 'axios';
+import { isAxiosError } from 'axios';
+import { resolveErrorMessage } from '@/utils/resolveErrorMessage';
 
-export function resolveAxiosErrorMessage(error: unknown, fallback = 'Request failed'): string {
-    if (axios.isAxiosError(error)) {
-        const data = error.response?.data;
-        if (typeof data === 'object' && data !== null && 'message' in data) {
-            const message = (data as { message: unknown }).message;
-            if (typeof message === 'string') {
-                return message;
-            }
-            if (Array.isArray(message)) {
-                return message.map(String).join(', ');
-            }
+const getAxiosErrorResponseMessage = (data: unknown): string | null => {
+    if (typeof data === 'string') {
+        return data;
+    }
+
+    if (typeof data !== 'object' || data === null || !('message' in data)) {
+        return null;
+    }
+
+    const { message } = data;
+
+    if (typeof message === 'string') {
+        return message;
+    }
+
+    if (Array.isArray(message)) {
+        const texts = message.filter((item): item is string => typeof item === 'string');
+
+        if (texts.length === 1) {
+            return texts[0];
         }
-        if (error.message) {
-            return error.message;
+
+        if (texts.length > 1) {
+            return texts.join(', ');
         }
     }
-    if (error instanceof Error) {
-        return error.message;
+
+    return null;
+};
+
+export const resolveAxiosErrorMessage = (error: unknown, fallback: string): string => {
+    if (!isAxiosError(error) || !error.response) {
+        return resolveErrorMessage(error, fallback);
     }
-    return fallback;
-}
+
+    return getAxiosErrorResponseMessage(error.response.data) ?? fallback;
+};

frontend/src/utils/resolveErrorMessage.ts

@@ -0,0 +1,7 @@
+export function resolveErrorMessage(error: unknown, fallback = 'Something went wrong'): string {
+    if (error instanceof Error && error.message.length > 0) {
+        return error.message;
+    }
+
+    return fallback;
+}