package plugins

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"os"

	"code.icb4dc0.de/buildr/buildr/internal/ioutils"
)

type Downloader interface {
	Download(ctx context.Context, target string, src *url.URL) error
}

var (
	ErrUnsupportedProtocol            = errors.New("unsupported protocol")
	_                      Downloader = (*GenericDownloader)(nil)
	_                      Downloader = (*HTTPDownloader)(nil)
	_                      Downloader = (*FileDownloader)(nil)
)

type GenericDownloader map[string]Downloader

func (g GenericDownloader) Download(ctx context.Context, target string, src *url.URL) error {
	if protocolDownloader, ok := g[src.Scheme]; !ok {
		return fmt.Errorf("%w: %s", ErrUnsupportedProtocol, src.Scheme)
	} else {
		return protocolDownloader.Download(ctx, target, src)
	}
}

type HTTPDownloader struct {
	Client *http.Client
}

func (h HTTPDownloader) Download(ctx context.Context, target string, src *url.URL) (err error) {
	var req *http.Request
	req, err = http.NewRequest(http.MethodGet, src.String(), nil)
	if err != nil {
		return err
	}

	client := h.Client
	if client == nil {
		client = http.DefaultClient
	}

	resp, err := client.Do(req.WithContext(ctx))
	if err != nil {
		return err
	}
	defer func() {
		err = errors.Join(err, resp.Body.Close())
	}()

	var out io.WriteCloser
	if out, err = os.Create(target); err != nil {
		return err
	}

	defer func() {
		err = errors.Join(err, out.Close())
	}()

	_, err = ioutils.CopyWithPooledBuffer(out, resp.Body)
	return err
}

type FileDownloader struct{}

func (f FileDownloader) Download(_ context.Context, target string, src *url.URL) error {
	if src.Scheme != "file" {
		return fmt.Errorf("%w: %s", ErrUnsupportedProtocol, src.Scheme)
	}

	if _, err := os.Stat(target); err == nil {
		if err = os.Remove(target); err != nil {
			return err
		}
	}

	return os.Link(src.Path, target)
}