package stations

import (
	"archive/zip"
	"bytes"
	"fmt"
	"io"
	"net/http"
)

const (
	// URL to RDG XML file
	url string = "https://internal.nationalrail.co.uk/4.0/stations.zip"

	// URL to additional XML file
	add string = "https://git.fjla.uk/OwlBoard/data/raw/branch/main/knowledgebase/additional.xml"
)

func download() ([]byte, []byte, error) {
	data1, err := downloadAndExtractZip(url)
	if err != nil {
		return nil, nil, err
	}

	data2, err := downloadUrl(add)
	if err != nil {
		return nil, nil, err
	}

	return data1, data2, nil
}

func downloadUrl(url string) ([]byte, error) {
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("failed to download from %s: status code: %d", url, resp.StatusCode)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}

	return body, nil
}

func downloadAndExtractZip(url string) ([]byte, error) {
	resp, err := http.Get(url)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("failed to download from %s: status code %d", url, resp.StatusCode)
	}

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}

	// Read zip
	reader, err := zip.NewReader(bytes.NewReader(body), int64(len(body)))
	if err != nil {
		return nil, err
	}

	// Check zip not empty
	if len(reader.File) == 0 {
		return nil, fmt.Errorf("no files found in the zip archive")
	}

	// Read first file
	file := reader.File[0]
	rc, err := file.Open()
	if err != nil {
		return nil, err
	}
	defer rc.Close()

	extractedData, err := io.ReadAll(rc)
	if err != nil {
		return nil, err
	}

	return extractedData, nil
}