1 files changed, 112 insertions, 0 deletions
diff --git a/src/state/models/content/list-membership.ts b/src/state/models/content/list-membership.ts
new file mode 100644
index 000000000..b4af4472b
--- /dev/null
+++ b/src/state/models/content/list-membership.ts
@@ -0,0 +1,112 @@
+import {makeAutoObservable} from 'mobx'
+import {AtUri, AppBskyGraphListitem} from '@atproto/api'
+import {runInAction} from 'mobx'
+import {RootStoreModel} from '../root-store'
+
+const PAGE_SIZE = 100
+interface Membership {
+  uri: string
+  value: AppBskyGraphListitem.Record
+}
+
+export class ListMembershipModel {
+  // data
+  memberships: Membership[] = []
+
+  constructor(public rootStore: RootStoreModel, public subject: string) {
+    makeAutoObservable(
+      this,
+      {
+        rootStore: false,
+      },
+      {autoBind: true},
+    )
+  }
+
+  // public api
+  // =
+
+  async fetch() {
+    // NOTE
+    // this approach to determining list membership is too inefficient to work at any scale
+    // it needs to be replaced with server side list membership queries
+    // -prf
+    let cursor
+    let records = []
+    for (let i = 0; i < 100; i++) {
+      const res = await this.rootStore.agent.app.bsky.graph.listitem.list({
+        repo: this.rootStore.me.did,
+        cursor,
+        limit: PAGE_SIZE,
+      })
+      records = records.concat(
+        res.records.filter(record => record.value.subject === this.subject),
+      )
+      cursor = res.cursor
+      if (!cursor) {
+        break
+      }
+    }
+    runInAction(() => {
+      this.memberships = records
+    })
+  }
+
+  getMembership(listUri: string) {
+    return this.memberships.find(m => m.value.list === listUri)
+  }
+
+  isMember(listUri: string) {
+    return !!this.getMembership(listUri)
+  }
+
+  async add(listUri: string) {
+    if (this.isMember(listUri)) {
+      return
+    }
+    const res = await this.rootStore.agent.app.bsky.graph.listitem.create(
+      {
+        repo: this.rootStore.me.did,
+      },
+      {
+        subject: this.subject,
+        list: listUri,
+        createdAt: new Date().toISOString(),
+      },
+    )
+    const {rkey} = new AtUri(res.uri)
+    const record = await this.rootStore.agent.app.bsky.graph.listitem.get({
+      repo: this.rootStore.me.did,
+      rkey,
+    })
+    runInAction(() => {
+      this.memberships = this.memberships.concat([record])
+    })
+  }
+
+  async remove(listUri: string) {
+    const membership = this.getMembership(listUri)
+    if (!membership) {
+      return
+    }
+    const {rkey} = new AtUri(membership.uri)
+    await this.rootStore.agent.app.bsky.graph.listitem.delete({
+      repo: this.rootStore.me.did,
+      rkey,
+    })
+    runInAction(() => {
+      this.memberships = this.memberships.filter(m => m.value.list !== listUri)
+    })
+  }
+
+  async updateTo(uris: string) {
+    for (const uri of uris) {
+      await this.add(uri)
+    }
+    for (const membership of this.memberships) {
+      if (!uris.includes(membership.value.list)) {
+        await this.remove(membership.value.list)
+      }
+    }
+  }
+}