package send

import (
	"context"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"os"
	"strconv"
	"time"

	"TengTuToolbox/localsend/logging"
	"TengTuToolbox/localsend/model"
)

// uploadFile streams one local file to the receiver over /upload.
func uploadFile(ctx context.Context, client *http.Client, device *model.Device, filePath, fileID, sessionID, token, scheme string, logger *logging.Logger) error {
	if logger == nil {
		logger = logging.NewQuiet()
	}

	file, err := os.Open(filePath)
	if err != nil {
		return fmt.Errorf("failed to open file: %w", err)
	}
	defer file.Close()

	stat, err := file.Stat()
	if err != nil {
		return fmt.Errorf("failed to get file stats: %w", err)
	}

	url := fmt.Sprintf("%s://%s/api/localsend/v2/upload?sessionId=%s&fileId=%s&token=%s",
		scheme, net.JoinHostPort(device.IP, strconv.Itoa(device.Port)), sessionID, fileID, token)

	var body io.ReadCloser = file

	// Wrap with idle timeout: cancel request if no data flows for 15s.
	uploadCtx, cancel := context.WithCancel(ctx)
	defer cancel()
	body = newIdleTimeoutReader(body, 15*time.Second, cancel)
	defer body.Close()

	req, err := http.NewRequestWithContext(uploadCtx, http.MethodPost, url, body)
	if err != nil {
		cancel()
		return fmt.Errorf("failed to create upload request: %w", err)
	}
	req.Header.Set("Content-Type", "application/octet-stream")
	req.ContentLength = stat.Size()

	resp, err := client.Do(req)
	if err != nil {
		if errors.Is(err, context.Canceled) {
			return errors.New("upload stalled: no data transmitted for 15s")
		}
		return fmt.Errorf("failed to send upload request: %w", err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		if resp.StatusCode == http.StatusUnprocessableEntity {
			return errors.New("upload rejected: receiver failed integrity verification (422)")
		}
		return fmt.Errorf("upload request failed with status: %s", resp.Status)
	}

	return nil
}

// idleTimeoutReader cancels the context if no data is read within the timeout.
type idleTimeoutReader struct {
	r           io.ReadCloser
	idleTimeout time.Duration
	timer       *time.Timer
	cancel      func()
}

func newIdleTimeoutReader(r io.ReadCloser, timeout time.Duration, cancel func()) *idleTimeoutReader {
	tr := &idleTimeoutReader{r: r, idleTimeout: timeout, cancel: cancel}
	tr.timer = time.AfterFunc(timeout, func() { tr.cancel() })
	return tr
}

func (tr *idleTimeoutReader) Read(p []byte) (int, error) {
	tr.timer.Reset(tr.idleTimeout)
	n, err := tr.r.Read(p)
	if err != nil {
		tr.timer.Stop()
	}
	return n, err
}

func (tr *idleTimeoutReader) Close() error {
	tr.timer.Stop()
	return tr.r.Close()
}