From 7bf979101f0fd4ec4b47dbefd3125076d06fe72a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Maciej=20P=C4=99dzich?= <contact@maciejpedzi.ch>
Date: Tue, 30 May 2023 17:55:56 +0200
Subject: [PATCH] Code up an algorithm for picking random photos

---
 src/composables/useRandomNumber.ts |  12 +++
 src/views/Vote.vue                 | 154 ++++++++++++++++++++++++-----
 2 files changed, 140 insertions(+), 26 deletions(-)
 create mode 100644 src/composables/useRandomNumber.ts

diff --git a/src/composables/useRandomNumber.ts b/src/composables/useRandomNumber.ts
new file mode 100644
index 0000000..1149ed9
--- /dev/null
+++ b/src/composables/useRandomNumber.ts
@@ -0,0 +1,12 @@
+// Why not a standalone randomNumber function?
+// I just couldn't be bothered creating a separate utils folder or installing a new package.
+
+export function useRandomNumber() {
+  // Shamelessly stolen from:
+  // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/random#getting_a_random_integer_between_two_values_inclusive
+  return (min: number, max: number) => {
+    min = Math.ceil(min);
+    max = Math.floor(max);
+    return Math.floor(Math.random() * (max - min + 1) + min);
+  };
+}
diff --git a/src/views/Vote.vue b/src/views/Vote.vue
index 703ea54..3bb5d82 100644
--- a/src/views/Vote.vue
+++ b/src/views/Vote.vue
@@ -1,32 +1,129 @@
 <script lang="ts" setup>
-import { onMounted, ref } from 'vue';
-import { storage } from '@/appwrite';
+import { computed, onMounted, ref, reactive } from 'vue';
+import { Query } from 'appwrite';
+
+import { databases } from '@/appwrite';
+import { useAuth } from '@/composables/useAuth';
+import { useSnackbar } from '@/composables/useSnackbar';
+import { useRandomNumber } from '@/composables/useRandomNumber';
+
+import { Vote } from '@/models/vote';
+import { Photo } from '@/models/photo';
+import { PhotoAppearanceCount } from '@/models/photoAppearanceCount';
+
+const { user } = useAuth();
+const { showSnackbar } = useSnackbar();
+const randomNumber = useRandomNumber();
 
 const isLoading = ref(true);
-const testImages = ref<string[]>([]);
+const photoAppearanceCount = reactive<Record<string, number>>({});
+const photosInCurrentVote = ref<Photo[]>([]);
 
-function randomNum(min: number, max: number) {
-  min = Math.ceil(min);
-  max = Math.floor(max);
-  return Math.floor(Math.random() * (max - min + 1) + min); // The maximum is inclusive and the minimum is inclusive
-}
+// Get IDs of photos that have appeared in votes between all the other photos
+const idsOfPhotosPairedWithAll = computed(() =>
+  Object.entries(JSON.parse(JSON.stringify(photoAppearanceCount)))
+    // You shouldn't be able to vote between two identical photos.
+    // That's why we need to subtract one from the number of photos.
+    .filter(([, count]) => count === import.meta.env.VITE_NUMBER_OF_PHOTOS - 1)
+    .map(([photoId]) => photoId)
+);
+
+const loadPhotosAppearanceCount = async () => {
+  const { documents: photoAppearanceCountEntries } =
+    await databases.listDocuments<PhotoAppearanceCount>(
+      import.meta.env.VITE_DATABASE_ID,
+      import.meta.env.VITE_PHOTO_APPEARANCE_COUNT_COLLECTION_ID,
+      [Query.equal('voterId', user.value?.$id as string)]
+    );
+
+  const appearanceCountRecord = photoAppearanceCountEntries.reduce(
+    (record, { photoId, count }) => {
+      record[photoId] = count;
+      return record;
+    },
+    {} as Record<string, number>
+  );
+
+  Object.assign(photoAppearanceCount, appearanceCountRecord);
+};
+
+const pickRandomPhotosAndCreateVote = async () => {
+  // Pick a random photo that hasn't been paired with every other photo in the user's votes
+
+  const { documents: allPhotos } = await databases.listDocuments<Photo>(
+    import.meta.env.VITE_DATABASE_ID,
+    import.meta.env.VITE_PHOTOS_COLLECTION_ID
+    // [
+    //   Query.select(['photoId', 'url', 'altText']) -> Unsupported in Appwrite v1.1.2,
+    //   Query.notEqual('photoId', idsOfPhotosPairedWithAll.value) -> Throws ambiguous Server Error
+    // ]
+  );
+
+  const photo1Candidates = allPhotos.filter(
+    ({ $id }) => !idsOfPhotosPairedWithAll.value.includes($id)
+  );
+
+  const maxPhoto1Index =
+    import.meta.env.VITE_NUMBER_OF_PHOTOS -
+    idsOfPhotosPairedWithAll.value.length -
+    1;
+
+  const photo1 = photo1Candidates[randomNumber(0, maxPhoto1Index)];
+
+  // Get IDs of photos that have already been paired with photo1 in user's votes
+
+  const idsOfPhotosPairedWithPhoto1 =
+    // Select votes where photo1Id is equal to photo1's ID
+    (
+      await databases.listDocuments<Vote>(
+        import.meta.env.VITE_DATABASE_ID,
+        import.meta.env.VITE_VOTES_COLLECTION_ID,
+        [
+          // Query.select(['photo2Id']),
+          Query.equal('voterId', [user.value?.$id as string]),
+          Query.search('photos', photo1.$id)
+        ]
+      )
+    ).documents.flatMap((doc) =>
+      Object.entries(doc)
+        .filter(([key]) => key === 'photos')
+        .map(([, arrayOfPhotoIds]) =>
+          arrayOfPhotoIds.filter((id: string) => id !== photo1.$id)
+        )
+    );
+
+  // Pick a random photo that isn't photo1 and that hasn't been paired with it in any of the user's votes
+
+  const photo2IdsToExclude = [
+    photo1.$id,
+    ...idsOfPhotosPairedWithPhoto1,
+    ...idsOfPhotosPairedWithAll.value
+  ];
+
+  const { documents: photo2Candidates } = await databases.listDocuments<Photo>(
+    import.meta.env.VITE_DATABASE_ID,
+    import.meta.env.VITE_PHOTOS_COLLECTION_ID,
+    [Query.notEqual('$id', photo2IdsToExclude)]
+  );
+
+  const maxPhoto2Index =
+    import.meta.env.VITE_NUMBER_OF_PHOTOS - photo2IdsToExclude.length - 1;
+
+  const photo2 = photo2Candidates[randomNumber(0, maxPhoto2Index)];
+
+  photosInCurrentVote.value.push(photo1, photo2);
+};
 
 onMounted(async () => {
   try {
-    const { files } = await storage.listFiles('photos');
-    const urls = files.map(
-      ({ $id }) => storage.getFileView('photos', $id).href
-    );
-
-    console.log(urls.join('\n\n'));
-
-    for (let i = 0; i < 2; i++) {
-      const randomUrlIndex = randomNum(0, urls.length - 1);
-      testImages.value.push(urls[randomUrlIndex]);
-      urls.splice(randomUrlIndex, 1);
-    }
+    await loadPhotosAppearanceCount();
+    await pickRandomPhotosAndCreateVote();
   } catch (error) {
     console.error(error);
+    showSnackbar({
+      status: 'error',
+      message: 'Failed to load photos'
+    });
   } finally {
     isLoading.value = false;
   }
@@ -46,18 +143,23 @@ onMounted(async () => {
       class="py-lg-6 py-3 d-flex flex-lg-row flex-lg-row flex-column align-center"
     >
       <div
-        v-for="(imgUrl, index) in testImages"
-        :key="imgUrl"
+        v-for="(photo, index) in photosInCurrentVote"
+        :key="photo.$id"
         class="d-flex flex-column align-center px-5 py-4"
       >
-        <v-img :src="imgUrl" max-width="480" :aspect-ratio="16 / 9" />
+        <v-img
+          :src="photo.url"
+          :alt="photo.altText"
+          max-width="480"
+          :aspect-ratio="16 / 9"
+        />
         <p class="mt-2 text-h6">Photo {{ index + 1 }}</p>
       </div>
     </div>
     <div id="vote-btns" class="mb-4 d-flex justify-center flex-wrap">
-      <v-btn size="large">Photo 1</v-btn>
-      <v-btn size="large">Photo 2</v-btn>
-      <v-btn size="large">I can't decide</v-btn>
+      <v-btn :disabled="isLoading" size="large">Photo 1</v-btn>
+      <v-btn :disabled="isLoading" size="large">Photo 2</v-btn>
+      <v-btn :disabled="isLoading" size="large">I can't decide</v-btn>
     </div>
   </section>
 </template>