implement backfilling for newly discovered actors

1 files changed, 60 insertions, 0 deletions

diff --git a/Digitigrade/Pagination.php b/Digitigrade/Pagination.php
new file mode 100644
index 0000000..75a876f
--- /dev/null
+++ b/Digitigrade/Pagination.php
@@ -0,0 +1,60 @@
+<?php
+namespace Digitigrade;
+
+use JsonMapper;
+
+class Pagination {
+    public int $page;
+    public int $totalPages;
+    public int $totalItems;
+    public ?string $nextPage = null;
+    public ?string $previousPage = null;
+    public array $items;
+
+    /**
+     * Fetches a pagination page.
+     * @param string $uri
+     * @param class-string $innerType Type of the contained items.
+     * @return self
+     */
+    public static function fromUri(string $uri): self {
+        $response = send_request_authenticated($uri);
+        $data = json_decode($response->body);
+        if (!isset($data->page)) {
+            throw new \RuntimeException("doesn't look like a pagination: $uri");
+        }
+        $p = (new JsonMapper())->map($data, self::class);
+        return $p;
+    }
+
+    private function become(self $other) {
+        $this->page = $other->page;
+        $this->totalPages = $other->totalPages;
+        $this->totalItems = $other->totalItems;
+        $this->nextPage = $other->nextPage;
+        $this->previousPage = $other->previousPage;
+        $this->items = &$other->items;
+    }
+
+    /**
+     * Gets the next item from the pagination, going to the next page if needed.
+     * 
+     * Careful! This behaves differently from PHP's built in `next`: it returns
+     * the first item, the first time it's called, rather than the second.
+     * @return mixed The next item, or `false` if at the end.
+     */
+    public function next(): mixed {
+        if (current($this->items) === false) {
+            if (isset($this->nextPage)) {
+                $this->become(self::fromUri($this->nextPage));
+                return $this->next();
+            } else {
+                return false;
+            }
+        } else {
+            $item = current($this->items);
+            next($this->items);
+            return $item;
+        }
+    }
+}
\ No newline at end of file