[web-src] Use prefix to search by expression

Fixes inconsistency in searching by recent search term, improves
usability if switching between search by query and search by expression.
Ignores searches by expression when switching to Spotify search.

web-src/src/pages/PageSearch.vue

@@ -13,14 +13,11 @@
                     <i class="mdi mdi-magnify"></i>
                   </span>
                 </p>
+                <p class="help has-text-centered">Tip: you can search by a smart playlist query language <a href="https://github.com/ejurgensen/forked-daapd/blob/master/README_SMARTPL.md" target="_blank">expression</a> if you prefix it
+                  with <code>query:</code>.
+                </p>
               </div>
             </form>
-            <div>
-              <label class="checkbox is-size-7">
-                <input type="checkbox" v-model="smart_query" :checked=true>
-                  SMART query
-              </label>
-            </div>
             <div class="tags" style="margin-top: 16px;">
               <a class="tag" v-for="recent_search in recent_searches" :key="recent_search" @click="open_recent_search(recent_search)">{{ recent_search }}</a>
             </div>
@@ -154,7 +151,7 @@ export default {
   data () {
     return {
       search_query: '',
-      smart_query: false,
+
       tracks: { items: [], total: 0 },
       artists: { items: [], total: 0 },
       albums: { items: [], total: 0 },
@@ -218,11 +215,15 @@ export default {
 
       var searchParams = {
         type: route.query.type,
-        query: this.smart_query ? undefined : route.query.query,
-        expression: this.smart_query ? route.query.query : undefined,
         media_kind: 'music'
       }
 
+      if (route.query.query.startsWith('query:')) {
+        searchParams.expression = route.query.query.replace(/^query:/, '').trim()
+      } else {
+        searchParams.query = route.query.query
+      }
+
       if (route.query.limit) {
         searchParams.limit = route.query.limit
         searchParams.offset = route.query.offset

web-src/src/pages/SpotifyPageSearch.vue

@@ -178,7 +178,7 @@ export default {
 
   computed: {
     recent_searches () {
-      return this.$store.state.recent_searches
+      return this.$store.state.recent_searches.filter(search => !search.startsWith('query:'))
     },
 
     show_tracks () {
@@ -222,7 +222,7 @@ export default {
       this.reset()
 
       // If no search query present reset and focus search field
-      if (!this.query.query || this.query.query === '') {
+      if (!this.query.query || this.query.query === '' || this.query.query.startsWith('query:')) {
         this.search_query = ''
         this.$refs.search_field.focus()
         return