<?php

namespace Modules\EcommerceFinance\Services;

use Illuminate\Support\Carbon;
use Illuminate\Support\Str;
use Modules\EcommerceFinance\Repositories\ProductPurchasePriceMirrorRepository;
use Modules\EcommerceFinance\Repositories\ProductPurchasePriceRepository;
use RuntimeException;
use Throwable;

class ProductPurchasePriceMirrorSynchronizer
{
    public function __construct(
        private readonly ProductPurchasePriceRepository $upstream,
        private readonly ProductPurchasePriceMirrorRepository $mirror,
    ) {
    }

    /** @return array{status:string,mode:string,batches:int,rows:int} */
    public function sync(bool $full = false, ?int $batchSize = null, ?int $maxBatches = null): array
    {
        if (! $this->mirror->available()) {
            throw new RuntimeException('product_purchase_price_mirror_schema_missing');
        }

        $state = $this->mirror->state();
        if (! $full && (
            ($state['initial_completed_at'] ?? null) === null
            || (int) ($state['projection_version'] ?? 1) < ProductPurchasePriceMirrorRepository::CURRENT_PROJECTION_VERSION
        )) {
            return ['status' => 'requires_full_sync', 'mode' => 'incremental', 'batches' => 0, 'rows' => 0];
        }

        $mode = $full ? 'full' : 'incremental';
        $resume = is_array($state)
            && ($state['run_mode'] ?? null) === $mode
            && in_array($state['status'] ?? null, ['running', 'failed'], true)
            && (int) ($state['projection_version'] ?? 1) >= ProductPurchasePriceMirrorRepository::CURRENT_PROJECTION_VERSION
            && ($state['window_started_at'] ?? null) !== null
            && ($state['window_ends_at'] ?? null) !== null;
        $generation = $resume && is_string($state['generation'] ?? null)
            ? (string) $state['generation']
            : (string) Str::uuid();

        if ($resume) {
            $since = Carbon::parse((string) $state['window_started_at']);
            $until = Carbon::parse((string) $state['window_ends_at']);
        } elseif ($full) {
            $since = Carbon::create(1900, 1, 1, 0, 0, 0, config('app.timezone'));
            $until = now()->addSecond();
        } else {
            $overlap = max((int) config('upstream_mirrors.product_purchase_prices.overlap_hours', 48), 1);
            $since = Carbon::parse((string) $state['last_succeeded_at'])->subHours($overlap);
            $until = now()->addSecond();
        }

        $state = $this->mirror->startRun($mode, $generation, $since, $until, $resume);
        $cursor = ($state['cursor_updated_at'] ?? null) === null
            ? null
            : [
                'updated_at' => (string) $state['cursor_updated_at'],
                'item_id' => (int) ($state['cursor_item_id'] ?? 0),
            ];
        $batchSize = min(max(
            $batchSize ?? (int) config('upstream_mirrors.product_purchase_prices.batch_size', 1000),
            1,
        ), 5000);
        $maxBatches = max(
            $maxBatches ?? (int) config('upstream_mirrors.product_purchase_prices.max_batches_per_run', 5),
            0,
        );
        $batches = 0;
        $rows = (int) ($state['last_upserted_rows'] ?? 0);

        try {
            while (true) {
                $batch = $this->upstream->mirrorBatch(
                    $cursor,
                    $since->format('Y-m-d\TH:i:s.v'),
                    $until->format('Y-m-d\TH:i:s.v'),
                    $batchSize,
                );

                if ($batch === []) {
                    $this->mirror->complete($mode, $generation, $until, $rows);

                    return ['status' => 'succeeded', 'mode' => $mode, 'batches' => $batches, 'rows' => $rows];
                }

                $last = $batch[array_key_last($batch)];
                $cursor = [
                    'updated_at' => (string) $last['purchase_updated_at'],
                    'item_id' => (int) $last['item_id'],
                ];
                $rows += count($batch);
                $batches++;
                $this->mirror->storeBatch($batch, $cursor, $generation, $rows);

                if (count($batch) < $batchSize) {
                    $this->mirror->complete($mode, $generation, $until, $rows);

                    return ['status' => 'succeeded', 'mode' => $mode, 'batches' => $batches, 'rows' => $rows];
                }

                if ($maxBatches > 0 && $batches >= $maxBatches) {
                    return ['status' => 'running', 'mode' => $mode, 'batches' => $batches, 'rows' => $rows];
                }
            }
        } catch (Throwable $exception) {
            $this->mirror->fail($exception::class);
            throw $exception;
        }
    }
}