<?php

declare(strict_types=1);

namespace Agent001\Admin;

\defined( 'ABSPATH' ) || exit;

use Agent001\Sync\SyncRunner;

final class SyncProgress
{
    public const OPTION = 'agent001_sync_progress';

    public const PHASE_IDLE    = 'idle';
    public const PHASE_QUEUED  = 'queued';
    public const PHASE_READING = 'reading';
    public const PHASE_POSTING = 'posting';
    public const PHASE_INDEXING = 'indexing';
    public const PHASE_DONE    = 'done';
    public const PHASE_ERROR   = 'error';

    public function start( ?int $total = null ): void
    {
        $payload = array_merge(
            self::defaults(),
            [
                'running'    => true,
                'phase'      => self::PHASE_QUEUED,
                'started_at' => time(),
            ]
        );

        if ( $total !== null && $total >= 0 ) {
            $payload['total'] = $total;
            $payload['phase'] = $total > 0 ? self::PHASE_READING : self::PHASE_QUEUED;
        }

        $this->write( $payload );
    }

    public function setTotal( int $total ): void
    {
        $progress              = $this->current();
        $progress['running']   = true;
        $progress['total']     = $total;
        $progress['processed'] = 0;
        $progress['phase']     = self::PHASE_READING;
        $this->write( $progress );
    }

    public function tickReading( int $processed ): void
    {
        $progress              = $this->current();
        $progress['running']   = true;
        $progress['phase']     = self::PHASE_READING;
        $progress['processed'] = $processed;
        $this->write( $progress );
    }

    public function indexing( string $sessionId, int $processed ): void
    {
        $progress                   = $this->current();
        $progress['running']        = true;
        $progress['phase']          = self::PHASE_INDEXING;
        $progress['processed']      = $processed;
        $progress['session_id']     = $sessionId;
        $progress['indexing_since'] = time();
        $progress['checked_at']     = null;
        $this->write( $progress );
    }

    public function indexingChecked( int $processedBatches, ?int $expectedBatches ): void
    {
        $progress                      = $this->current();
        $progress['checked_at']        = time();
        $progress['processed_batches'] = $processedBatches;
        $progress['expected_batches']  = $expectedBatches;
        $this->write( $progress );
    }

    public function finish( bool $success, string $message, int $processed ): void
    {
        $progress                = $this->current();
        $progress['running']     = false;
        $progress['phase']       = $success ? self::PHASE_DONE : self::PHASE_ERROR;
        $progress['processed']   = $processed;
        $progress['message']     = $message;
        $progress['finished_at'] = time();
        $this->write( $progress );
    }

    public function fail( string $message ): void
    {
        $progress                = $this->current();
        $progress['running']     = false;
        $progress['phase']       = self::PHASE_ERROR;
        $progress['message']     = $message;
        $progress['finished_at'] = time();
        $this->write( $progress );
    }

    public function isRunning(): bool
    {
        return (bool) ( $this->current()['running'] ?? false );
    }

    public function current(): array
    {
        $raw = \get_option( self::OPTION, null );

        if ( ! is_array( $raw ) ) {
            return self::defaults();
        }

        $progress = array_merge( self::defaults(), $raw );
        $updatedAt = (int) ( $progress['updated_at'] ?? $progress['started_at'] ?? 0 );
        if ( $progress['running'] && $progress['phase'] !== self::PHASE_INDEXING
            && $updatedAt > 0 && time() - $updatedAt > SyncRunner::LOCK_TTL_SECONDS ) {
            $progress['running'] = false;
            $progress['phase'] = self::PHASE_ERROR;
            $progress['message'] = \__( 'Synchronization timed out. Please try again.', 'agent001-support-assistant-for-woocommerce' );
            $progress['finished_at'] = time();
            $this->write( $progress );
        }

        return $progress;
    }

    private static function defaults(): array
    {
        return [
            'running'     => false,
            'phase'       => self::PHASE_IDLE,
            'processed'   => 0,
            'total'       => 0,
            'message'     => '',
            'started_at'  => null,
            'updated_at'  => null,
            'finished_at' => null,
            'session_id'        => null,
            'indexing_since'    => null,
            'checked_at'        => null,
            'processed_batches' => 0,
            'expected_batches'  => null,
        ];
    }

    private function write( array $progress ): void
    {
        $progress['updated_at'] = time();
        if ( $progress['running'] && \get_transient( SyncRunner::LOCK_TRANSIENT ) ) {
            \set_transient( SyncRunner::LOCK_TRANSIENT, 1, SyncRunner::LOCK_TTL_SECONDS );
        }
        \update_option( self::OPTION, $progress, false );
    }
}