package main

import (
	"context"
	"fmt"
	"log"
	"os"
	"time"

	"git.intra.yksa.space/gsn/predictor/internal/pkg/grib"
)

func main() {
	ctx := context.Background()

	// Create S3 downloader
	downloader, err := grib.NewS3Downloader(
		"/tmp/grib_test",
		4, // parallel downloads
		"noaa-gfs-bdp-pds",
		"us-east-1",
	)
	if err != nil {
		log.Fatalf("Failed to create S3 downloader: %v", err)
	}

	// Ensure directory exists
	if err := os.MkdirAll("/tmp/grib_test", 0o755); err != nil {
		log.Fatalf("Failed to create directory: %v", err)
	}

	// Find nearest run (6-hour intervals: 00, 06, 12, 18 UTC)
	now := time.Now().UTC()
	hour := now.Hour() - (now.Hour() % 6)
	// Use data from 6 hours ago to ensure it's available
	run := time.Date(now.Year(), now.Month(), now.Day(), hour, 0, 0, 0, time.UTC).Add(-6 * time.Hour)

	fmt.Printf("Testing S3 download for run: %s\n", run.Format("2006-01-02 15:04 MST"))

	// List available files first
	runStr := run.Format("20060102")
	fmt.Printf("Listing available files for %s/%02d...\n", runStr, run.Hour())
	files, err := downloader.ListAvailableFiles(ctx, runStr, run.Hour())
	if err != nil {
		log.Fatalf("Failed to list files: %v", err)
	}

	fmt.Printf("Found %d files in S3:\n", len(files))
	if len(files) > 0 {
		// Show first 5 files
		for i, file := range files {
			if i >= 5 {
				fmt.Printf("... and %d more files\n", len(files)-5)
				break
			}
			fmt.Printf("  - %s\n", file)
		}
	}

	// Try downloading just first 3 forecast hours (f000, f001, f002)
	fmt.Println("\nTesting download of first 3 forecast hours...")
	testRun := run

	// Create a timeout context for the download
	downloadCtx, cancel := context.WithTimeout(ctx, 5*time.Minute)
	defer cancel()

	if err := downloader.Run(downloadCtx, testRun); err != nil {
		log.Fatalf("Failed to download: %v", err)
	}

	fmt.Println("\nDownload completed successfully!")

	// Check downloaded files
	entries, err := os.ReadDir("/tmp/grib_test")
	if err != nil {
		log.Fatalf("Failed to read directory: %v", err)
	}

	fmt.Printf("\nDownloaded %d files:\n", len(entries))
	for i, entry := range entries {
		if i >= 10 {
			fmt.Printf("... and %d more files\n", len(entries)-10)
			break
		}
		info, _ := entry.Info()
		fmt.Printf("  - %s (%.2f MB)\n", entry.Name(), float64(info.Size())/1024/1024)
	}
}