feat: add eloquent cursor pagination implementation (#37)

src/Pagination/Cursor/Cursor.php

@@ -0,0 +1,116 @@
+<?php
+/*
+ * Copyright 2023 Cloud Creativity Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+declare(strict_types=1);
+
+namespace LaravelJsonApi\Eloquent\Pagination\Cursor;
+
+use InvalidArgumentException;
+
+class Cursor
+{
+
+    /**
+     * @var string|null
+     */
+    private ?string $before;
+
+    /**
+     * @var string|null
+     */
+    private ?string $after;
+
+    /**
+     * @var int|null
+     */
+    private ?int $limit;
+
+    /**
+     * Cursor constructor.
+     *
+     * @param string|null $before
+     * @param string|null $after
+     * @param int|null $limit
+     */
+    public function __construct(string $before = null, string $after = null, int $limit = null)
+    {
+        if (is_int($limit) && 1 > $limit) {
+            throw new InvalidArgumentException('Expecting a limit that is 1 or greater.');
+        }
+
+        $this->before = $before ?: null;
+        $this->after = $after ?: null;
+        $this->limit = $limit;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isBefore(): bool
+    {
+        return !is_null($this->before);
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getBefore(): ?string
+    {
+        return $this->before;
+    }
+
+    /**
+     * @return bool
+     */
+    public function isAfter(): bool
+    {
+        return !is_null($this->after) && !$this->isBefore();
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getAfter(): ?string
+    {
+        return $this->after;
+    }
+
+    /**
+     * Set a limit, if no limit is set on the cursor.
+     *
+     * @param int $limit
+     * @return Cursor
+     */
+    public function withDefaultLimit(int $limit): self
+    {
+        if (is_null($this->limit)) {
+            $copy = clone $this;
+            $copy->limit = $limit;
+            return $copy;
+        }
+
+        return $this;
+    }
+
+    /**
+     * @return int|null
+     */
+    public function getLimit(): ?int
+    {
+        return $this->limit;
+    }
+}

src/Pagination/Cursor/CursorBuilder.php

@@ -0,0 +1,173 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LaravelJsonApi\Eloquent\Pagination\Cursor;
+
+use Illuminate\Database\Eloquent\Builder;
+use Illuminate\Database\Eloquent\Relations\Relation;
+use Illuminate\Pagination\Cursor as LaravelCursor;
+use LaravelJsonApi\Contracts\Schema\ID;
+use LaravelJsonApi\Core\Schema\IdParser;
+
+class CursorBuilder
+{
+    private Builder|Relation $query;
+
+    private ID $id;
+
+    private string $keyName;
+
+    private string $direction;
+
+    private ?int $defaultPerPage = null;
+
+    private bool $withTotal;
+
+    private bool $keySort = true;
+
+    private CursorParser $parser;
+
+    /**
+     * CursorBuilder constructor.
+     *
+     * @param Builder|Relation $query
+     *      the column to use for the cursor
+     * @param string|null $key
+     *      the key column that the before/after cursors related to
+     */
+    public function __construct($query, ID $id, string $key = null)
+    {
+        if (!$query instanceof Builder && !$query instanceof Relation) {
+            throw new \InvalidArgumentException('Expecting an Eloquent query builder or relation.');
+        }
+
+        $this->query = $query;
+        $this->id = $id;
+        $this->keyName = $key ?: $this->guessKey();
+        $this->parser = new CursorParser(IdParser::make($this->id), $this->keyName);
+    }
+
+    /**
+     * Set the default number of items per-page.
+     *
+     * If null, the default from the `Model::getPage()` method will be used.
+     *
+     * @return $this
+     */
+    public function withDefaultPerPage(?int $perPage): self
+    {
+        $this->defaultPerPage = $perPage;
+
+        return $this;
+    }
+
+
+    public function withKeySort(bool $keySort): self
+    {
+        $this->keySort = $keySort;
+
+        return $this;
+    }
+
+    /**
+     * Set the query direction.
+     *
+     * @return $this
+     */
+    public function withDirection(string $direction): self
+    {
+        if (\in_array($direction, ['asc', 'desc'])) {
+            $this->direction = $direction;
+
+            return $this;
+        }
+
+        throw new \InvalidArgumentException('Unexpected query direction.');
+    }
+
+    public function withTotal(bool $withTotal): self
+    {
+        $this->withTotal = $withTotal;
+
+        return $this;
+    }
+
+    /**
+     * @param array<string> $columns
+     */
+    public function paginate(Cursor $cursor, array $columns = ['*']): CursorPaginator
+    {
+        $cursor = $cursor->withDefaultLimit($this->getDefaultPerPage());
+
+        $this->applyKeySort();
+
+        $total = $this->getTotal();
+        $laravelPaginator = $this->query->cursorPaginate($cursor->getLimit(), $columns, 'cursor', $this->parser->decode($cursor));
+        $paginator = new CursorPaginator($this->parser, $laravelPaginator, $cursor, $total);
+
+        return $paginator->withCurrentPath();
+    }
+
+    private function applyKeySort(): void
+    {
+        if (!$this->keySort) {
+            return;
+        }
+
+        if (
+            empty($this->query->getQuery()->orders)
+            || collect($this->query->getQuery()->orders)
+                ->whereIn('column', [$this->keyName, $this->query->qualifyColumn($this->keyName)])
+                ->isEmpty()
+        ) {
+            $this->query->orderBy($this->keyName, $this->direction);
+        }
+    }
+
+    private function getTotal(): ?int
+    {
+        return $this->withTotal ? $this->query->count() : null;
+    }
+
+    private function convertCursor(Cursor $cursor): ?LaravelCursor
+    {
+        $encodedCursor = $cursor->isBefore() ? $cursor->getBefore() : $cursor->getAfter();
+        if (!is_string($encodedCursor)) {
+            return null;
+        }
+
+        $parameters = json_decode(base64_decode(str_replace(['-', '_'], ['+', '/'], $encodedCursor)), true);
+
+        if (json_last_error() !== JSON_ERROR_NONE) {
+            return null;
+        }
+
+        $pointsToNextItems = $parameters['_pointsToNextItems'];
+        unset($parameters['_pointsToNextItems']);
+        if (isset($parameters[$this->keyName])) {
+            $parameters[$this->keyName] = IdParser::make($this->id)->decode(
+                (string) $parameters[$this->keyName],
+            );
+        }
+
+        return new LaravelCursor($parameters, $pointsToNextItems);
+    }
+
+    private function getDefaultPerPage(): int
+    {
+        if (is_int($this->defaultPerPage)) {
+            return $this->defaultPerPage;
+        }
+
+        return $this->query->getModel()->getPerPage();
+    }
+
+    /**
+     * Guess the key to use for the cursor.
+     */
+    private function guessKey(): string
+    {
+        return $this->id?->key() ?? $this->query->getModel()->getKeyName();
+    }
+}