Added support for custom metadata providers

WiP but already open to feedback

server/providers/CustomProviderAdapter.js

@@ -0,0 +1,76 @@
+const Database = require('../Database')
+const axios = require("axios");
+const Logger = require("../Logger");
+
+class CustomProviderAdapter {
+    constructor() {
+    }
+
+    async search(title, author, providerSlug) {
+        const providerId = providerSlug.split("custom-")[1]
+
+        console.log(providerId)
+        const provider = await Database.customMetadataProviderModel.findOne({
+            where: {
+                id: providerId,
+            }
+        });
+
+        if (!provider) {
+            throw new Error("Custom provider not found for the given id");
+        }
+
+        const matches = await axios.get(`${provider.url}/search?query=${encodeURIComponent(title)}${!!author ? `&author=${encodeURIComponent(author)}` : ""}`, {
+            headers: {
+                "Authorization": provider.apiKey,
+            },
+        }).then((res) => {
+            if (!res || !res.data || !Array.isArray(res.data.matches)) return null
+            return res.data.matches
+        }).catch(error => {
+            Logger.error('[CustomMetadataProvider] Search error', error)
+            return []
+        })
+
+        if (matches === null) {
+            throw new Error("Custom provider returned malformed response");
+        }
+
+        // re-map keys to throw out
+        return matches.map(({
+            title,
+            subtitle,
+            author,
+            narrator,
+            publisher,
+            published_year,
+            description,
+            cover,
+            isbn,
+            asin,
+            genres,
+            tags,
+            language,
+            duration,
+        }) => {
+            return {
+                title,
+                subtitle,
+                author,
+                narrator,
+                publisher,
+                publishedYear: published_year,
+                description,
+                cover,
+                isbn,
+                asin,
+                genres,
+                tags: tags.join(","),
+                language,
+                duration,
+            }
+        })
+    }
+}
+
+module.exports = CustomProviderAdapter