package api

import (
	"errors"
	"net/http"

	"github.com/go-chi/chi/v5"

	"git.fabledsword.com/bvandeusen/minstrel/internal/apierror"
	"git.fabledsword.com/bvandeusen/minstrel/internal/tracks"
)

// removeTrackResponse is the wire shape from spec §5 (M7 #372). The two
// optional fields are omitted unless the corresponding cleanup actually
// happened, so the response stays minimal in the common case.
type removeTrackResponse struct {
	DeletedTrackID  string  `json:"deleted_track_id"`
	DeletedAlbumID  *string `json:"deleted_album_id,omitempty"`
	DeletedArtistID *string `json:"deleted_artist_id,omitempty"`
}

// handleRemoveTrack implements DELETE /api/admin/tracks/{id}.
//
// Admin-only (gated by auth.RequireAdmin on the /admin route group). Deletes the
// file, then the DB row, and runs the album/artist cascade tidy-up — and deletes
// nothing at all when the file cannot be removed (#3918).
//
// The codes this handler emits are not_found,
// library_not_writable (409) and file_delete_failed when the file could not be
// removed, server_error, plus the auth codes the middleware emits upstream.
func (h *handlers) handleRemoveTrack(w http.ResponseWriter, r *http.Request) {
	idStr := chi.URLParam(r, "id")
	trackID, ok := parseUUID(idStr)
	if !ok {
		// Malformed id is functionally equivalent to "no such track" for
		// the spec's error surface — collapse both to 404 not_found so
		// the client doesn't have to handle a separate bad_request branch
		// for a code path that's only reachable via UI bugs.
		writeErr(w, &apierror.Error{Status: http.StatusNotFound, Code: "not_found", Message: "track not found"})
		return
	}

	// Defensive: RequireUser+RequireAdmin should have run upstream. If
	// we got here without a user in context the routing is broken.
	admin, ok := requireUser(w, r)
	if !ok {
		return
	}

	deletedAlbum, deletedArtist, err := h.tracks.RemoveTrack(r.Context(), trackID, admin.ID)
	if err != nil {
		if errors.Is(err, tracks.ErrNotFound) {
			writeErr(w, &apierror.Error{Status: http.StatusNotFound, Code: "not_found", Message: "track not found"})
			return
		}
		if apiErr, ok := fileRemoveAPIError(err); ok {
			logFileRemoveFailure(h.logger, apiErr, "track_id", idStr)
			writeErr(w, apiErr)
			return
		}
		h.logger.Error("api: remove track failed", "err", err, "track_id", idStr)
		writeErr(w, apierror.InternalMsg("remove failed", err))
		return
	}

	resp := removeTrackResponse{DeletedTrackID: idStr}
	if deletedAlbum != nil {
		s := uuidToString(*deletedAlbum)
		resp.DeletedAlbumID = &s
	}
	if deletedArtist != nil {
		s := uuidToString(*deletedArtist)
		resp.DeletedArtistID = &s
	}
	writeJSON(w, http.StatusOK, resp)
}