package uploads

import (
	"context"
	"net/http"
	"os"
	"strconv"
	"time"

	"github.com/google/uuid"

	"pipu/api/internal/api/gen"
	"pipu/api/internal/platform/apperr"
	"pipu/api/internal/platform/httpx"
)

// uploadStream serves private staging files through the API with Range support.
// Nginx runs as another user and cannot read tus files (0750 directories, 0640 files).
type uploadStream struct {
	req    *http.Request
	file   string
	format string
}

func (s uploadStream) VisitStreamUploadResponse(w http.ResponseWriter) error {
	w.Header().Set("Content-Type", contentType(s.format))
	w.Header().Set("Cache-Control", "private, max-age=600")
	f, err := os.Open(s.file)
	if err != nil {
		return err
	}
	defer func() { _ = f.Close() }()
	info, err := f.Stat()
	if err != nil {
		return err
	}
	if s.req == nil {
		http.ServeContent(w, &http.Request{}, "", info.ModTime(), f)
		return nil
	}
	http.ServeContent(w, s.req, "", info.ModTime(), f)
	return nil
}

func (h *Handler) streamURL(id uuid.UUID) string {
	exp := time.Now().Add(12 * time.Hour).Unix()
	sig := h.signer.Sign("upload", id.String(), strconv.FormatInt(exp, 10))
	return "/api/v1/admin/uploads/files/" + id.String() + "/stream?exp=" + strconv.FormatInt(exp, 10) + "&sig=" + sig
}

// StreamUpload реализует gen.StrictServerInterface.
func (h *Handler) StreamUpload(ctx context.Context, req gen.StreamUploadRequestObject) (gen.StreamUploadResponseObject, error) {
	if h.signer == nil || !h.signer.Verify(req.Params.Sig, "upload", req.Id.String(), strconv.FormatInt(req.Params.Exp, 10)) || time.Now().Unix() > req.Params.Exp {
		return nil, apperr.Forbidden("uploads.link_invalid", "link is invalid or expired")
	}
	f, err := h.svc.OpenStaging(ctx, req.Id)
	if err != nil {
		return nil, err
	}
	format := ""
	if f.Format != nil {
		format = *f.Format
	}
	return uploadStream{
		req: httpx.RequestFrom(ctx), file: f.Abs, format: format,
	}, nil
}

func contentType(format string) string {
	switch format {
	case "mp3":
		return "audio/mpeg"
	case "flac":
		return "audio/flac"
	case "m4a":
		return "audio/mp4"
	case "ogg", "opus":
		return "audio/ogg"
	case "wav":
		return "audio/wav"
	default:
		return "application/octet-stream"
	}
}