package com.scraper.agents.dataextract;

import com.highradius.cpacommon.model.CPADataExtractConfig;
import com.scraper.fs.cpa.FSClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.List;
import java.util.regex.Pattern;

/**
 * Uses framework DataExtractTransporter to establish SFTP connection (via FSClient),
 * lists files in remote directory and validates name & size.
 * Retry logic is encapsulated here (configurable).
 */
public class SftpValidationService {

    private static final Logger LOGGER = LoggerFactory.getLogger(SftpValidationService.class);
    private static final Pattern FILE_PATTERN =
            Pattern.compile("^Deductions-\\d{8}T\\d{6}Z-\\d+\\.zip$", Pattern.CASE_INSENSITIVE);

    private final DataExtractTransporter transporter; // existing framework transporter
    private final int retryCount;
    private final long retryDelayMs;

    public SftpValidationService(DataExtractTransporter transporter, int retryCount, long retryDelayMs) {
        this.transporter = transporter;
        this.retryCount = retryCount;
        this.retryDelayMs = retryDelayMs;
    }

    public SftpValidationSummary validate(CPADataExtractConfig config, String remotePath) {
        int attempt = 0;
        Exception lastEx = null;
        while (attempt < retryCount) {
            attempt++;
            try {
                LOGGER.info("SFTP validation attempt {}/{} for path: {}", attempt, retryCount, remotePath);
                return performValidation(config, remotePath);
            } catch (Exception e) {
                lastEx = e;
                LOGGER.error("Attempt {}/{} failed: {}", attempt, retryCount, e.getMessage(), e);
                sleepQuietly();
            }
        }
        SftpValidationSummary summary = new SftpValidationSummary();
        summary.setFailed(true);
        summary.setFailureReason("SFTP validation failed after " + retryCount + " attempts: " +
                (lastEx != null ? lastEx.getMessage() : "unknown"));
        return summary;
    }

    private SftpValidationSummary performValidation(CPADataExtractConfig config, String remotePath) throws Exception {
        SftpValidationSummary summary = new SftpValidationSummary();

        // DataExtractTransporter exposes connectToSFTP(...) in your framework (see your transporter).
        FSClient fsClient = transporter.connectToSFTP(config, true);
        if (fsClient == null) {
            throw new Exception("FSClient is null after connectToSFTP.");
        }

        List<String> files = fsClient.listNames(remotePath);
        if (files == null || files.isEmpty()) {
            summary.setFailed(true);
            summary.setFailureReason("No files found in remote path: " + remotePath);
            try { fsClient.closeConnection(); } catch (Exception ignored) {}
            return summary;
        }

        for (String f : files) {
            SftpValidationResult r = new SftpValidationResult(f);
            r.setValidName(FILE_PATTERN.matcher(f).matches());
            long sizeBytes = fsClient.getFileSize(remotePath + (remotePath.endsWith("/") ? "" : "/") + f);
            r.setFileSizeBytes(sizeBytes);
            r.setValidSize(sizeBytes > 0);
            r.setRemarks(
                    !r.isValidName() && !r.isValidSize() ? "Invalid name & 0KB" :
                    !r.isValidName() ? "Invalid name" :
                    !r.isValidSize() ? "0KB file" : "Valid file"
            );
            summary.addResult(r);
        }

        fsClient.closeConnection();
        summary.computeMessage();
        return summary;
    }

    private void sleepQuietly() {
        try { Thread.sleep(retryDelayMs); } catch (InterruptedException ie) { Thread.currentThread().interrupt(); }
    }
}