First pass at custom-theme-settings-service functionality

refs https://github.com/TryGhost/Team/issues/1070

- added `bread` util that acts as a wrapper for the provided model, if we have any business functionality needed when settings are added/removed then it will go here
- added primary "server" service that handles syncing of custom theme data extracted from a theme with the settings that are in the database and exported as "Service". Syncing rules on theme activation:
    - if a new setting is seen, create it with the default value
    - if a setting has it's type changed, remove it and create a new setting with the default value
    - if a select setting's value is not a valid option, reset it to the default value
- added shared "frontend/server" service that exposes an in-memory cache of key/value pairs for the currently active theme

ghost/custom-theme-settings-service/index.js

@@ -1 +1,4 @@
-module.exports = require('./lib/custom-theme-settings-service');
+module.exports = {
+    Service: require('./lib/service'),
+    Cache: require('./lib/cache')
+};

ghost/custom-theme-settings-service/lib/bread.js

@@ -0,0 +1,29 @@
+module.exports = class CustomThemeSettingsBREADService {
+    /**
+     * @param {Object} options
+     * @param {Object} options.model - Bookshelf model for custom theme settings
+     */
+    constructor({model}) {
+        this.Model = model;
+    }
+
+    async browse(data, options = {}) {
+        return this.Model.findAll(data, options);
+    }
+
+    async read(data, options = {}) {
+        return this.Model.findOne(data, options);
+    }
+
+    async edit(data, options = {}) {
+        return this.Model.edit(data, Object.assign({}, options, {method: 'update'}));
+    }
+
+    async add(data, options = {}) {
+        return this.Model.add(data, options);
+    }
+
+    async destroy(data, options = {}) {
+        return this.Model.destroy(data, options);
+    }
+};

ghost/custom-theme-settings-service/lib/cache.js

@@ -0,0 +1,43 @@
+const BREAD = require('./bread');
+const {GhostError} = require('@tryghost/errors');
+
+module.exports = class CustomThemeSettingsCache {
+    constructor() {
+        this.content = new Object();
+    }
+
+    init({model}) {
+        this.repository = new BREAD({model});
+    }
+
+    get(key) {
+        this._noUsageBeforeInit();
+
+        return this.content[key].value;
+    }
+
+    getAll() {
+        this._noUsageBeforeInit();
+
+        return this.content;
+    }
+
+    async populateForTheme(themeName) {
+        this._noUsageBeforeInit();
+
+        const settingsCollection = await this.repository.browse({theme: themeName});
+        const settingsJson = settingsCollection.toJSON();
+
+        this.content = new Object();
+
+        settingsJson.forEach((setting) => {
+            this.content[setting.key] = setting.value;
+        });
+    }
+
+    _noUsageBeforeInit() {
+        if (!this.repository) {
+            throw new GhostError('CustomThemeSettingsCache must have .init({model}) called before being used');
+        }
+    }
+};

ghost/custom-theme-settings-service/lib/service.js

@@ -0,0 +1,70 @@
+const _ = require('lodash');
+const BREAD = require('./bread');
+const debug = require('@tryghost/debug')('custom-theme-settings-service');
+
+module.exports = class CustomThemeSettingsService {
+    constructor({model, cache}) {
+        this.repository = new BREAD({model});
+        this.cache = cache;
+    }
+
+    // add/remove/edit theme setting records to match theme settings
+    async activateTheme(theme) {
+        const knownSettingsCollection = await this.repository.browse({theme: theme.name});
+        // convert to JSON so we can use a standard array rather than a bookshelf collection
+        let knownSettings = knownSettingsCollection.toJSON();
+
+        const themeSettings = theme.customSettings || {};
+
+        // exit early if there's nothing to sync for this theme
+        if (knownSettings.length === 0 && _.isEmpty(themeSettings)) {
+            return;
+        }
+
+        let removedIds = [];
+
+        // sync any knownSettings that have changed in the theme
+        for (const knownSetting of knownSettings) {
+            const themeSetting = themeSettings[knownSetting.key];
+
+            const hasBeenRemoved = !themeSetting;
+            const hasChangedType = themeSetting && themeSetting.type !== knownSetting.type;
+
+            if (hasBeenRemoved || hasChangedType) {
+                debug(`Removing custom theme setting '${theme.name}.${themeSetting.key}' - ${hasBeenRemoved ? 'not found in theme' : 'type changed'}`);
+                await this.repository.destroy({id: knownSetting.id});
+                removedIds.push(knownSetting.id);
+                return;
+            }
+
+            // replace value with default if it's not a valid select option
+            if (themeSetting.options && !themeSetting.options.includes(knownSetting.value)) {
+                debug(`Resetting custom theme setting value '${theme.name}.${themeSetting.key}' - "${knownSetting.value}" is not a valid option`);
+                await this.repository.edit({value: themeSetting.default}, {id: knownSetting.id});
+            }
+        }
+
+        // clean up any removed knownSettings now that we've finished looping over them
+        knownSettings = knownSettings.filter(setting => !removedIds.includes(setting.id));
+
+        // add any new settings found in theme (or re-add settings that were removed due to type change)
+        const knownSettingsKeys = knownSettings.map(setting => setting.key);
+
+        for (const [key, setting] of Object.entries(themeSettings)) {
+            if (!knownSettingsKeys.includes(key)) {
+                const newSettingValues = {
+                    theme: theme.name,
+                    key,
+                    type: setting.type,
+                    value: setting.default
+                };
+
+                debug(`Adding custom theme setting '${theme.name}.${key}'`);
+                await this.repository.add(newSettingValues);
+            }
+        }
+
+        // populate the cache with all key/value pairs for this theme
+        this.cache.populateForTheme(theme.name);
+    }
+};

ghost/custom-theme-settings-service/package.json

@@ -24,5 +24,8 @@
     "should": "13.2.3",
     "sinon": "11.1.2"
   },
-  "dependencies": {}
+  "dependencies": {
+    "@tryghost/debug": "^0.1.5",
+    "@tryghost/errors": "^0.2.14"
+  }
 }