package api

import (
	"context"
	"errors"
	"net/http"
	"os"

	"git.fabledsword.com/bvandeusen/minstrel/internal/apierror"
	"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
	"git.fabledsword.com/bvandeusen/minstrel/internal/library"
)

// The library's folders (#6129): where the scan, the watcher and the import
// look for music, set here rather than only by MINSTREL_LIBRARY_SCAN_PATHS.

type libraryFolderView struct {
	Path string `json:"path"`
	// Present is whether the server can see the folder right now; a folder
	// whose mount went away reads false here before anything else notices.
	Present bool  `json:"present"`
	Tracks  int64 `json:"tracks"`
}

type libraryFoldersView struct {
	Folders []libraryFolderView `json:"folders"`
	// Saved is false while the folders still come from
	// MINSTREL_LIBRARY_SCAN_PATHS.
	Saved bool `json:"saved"`
	// Moved is how many tracks a save moved to a new folder.
	Moved int64 `json:"moved,omitempty"`
}

func (h *handlers) libraryFolders(ctx context.Context) (libraryFoldersView, error) {
	q := dbq.New(h.pool)
	row, err := q.GetLibrarySettings(ctx)
	if err != nil {
		return libraryFoldersView{}, err
	}
	v := libraryFoldersView{Folders: []libraryFolderView{}, Saved: len(row.ScanPaths) > 0}
	for _, root := range h.scanner.Roots() {
		n, err := q.CountTracksUnder(ctx, root)
		if err != nil {
			return libraryFoldersView{}, err
		}
		info, statErr := os.Stat(root)
		v.Folders = append(v.Folders, libraryFolderView{Path: root, Present: statErr == nil && info.IsDir(), Tracks: n})
	}
	return v, nil
}

// handleGetLibraryFolders implements GET /api/admin/library/folders.
func (h *handlers) handleGetLibraryFolders(w http.ResponseWriter, r *http.Request) {
	v, err := h.libraryFolders(r.Context())
	if err != nil {
		writeErrWithLog(w, h.logger, "admin library folders: get", apierror.Internal(err))
		return
	}
	writeJSON(w, http.StatusOK, v)
}

type putLibraryFoldersBody struct {
	Folders []struct {
		Path string `json:"path"`
		// Was is the folder this one replaces, whose files are now at Path;
		// "" is a folder added.
		Was string `json:"was"`
	} `json:"folders"`
}

// handlePutLibraryFolders implements PUT /api/admin/library/folders.
//
// The whole list. A folder whose path changed moves its tracks with it, so
// their plays, likes and playlists survive; one left out is no longer read,
// and its tracks are marked missing by the next scan. After a save a scan
// starts, to pick up anything the old folders did not hold.
func (h *handlers) handlePutLibraryFolders(w http.ResponseWriter, r *http.Request) {
	var body putLibraryFoldersBody
	if !decodeBody(w, r, &body) {
		return
	}
	if h.scanner == nil {
		writeErr(w, apierror.Internal(errors.New("no scanner")))
		return
	}
	changes := make([]library.RootChange, 0, len(body.Folders))
	for _, f := range body.Folders {
		changes = append(changes, library.RootChange{Path: f.Path, Was: f.Was})
	}
	res, err := h.scanner.SetRoots(r.Context(), changes)
	if err != nil {
		var re *library.RootsError
		if errors.As(err, &re) {
			writeErr(w, apierror.BadRequest("bad_folders", re.Error()))
			return
		}
		writeErrWithLog(w, h.logger, "admin library folders: put", apierror.Internal(err))
		return
	}
	if _, _, err := library.TryStartScan(context.Background(), h.pool, h.scanner, h.coverart,
		h.logger.With("source", "library_folders"), h.scanCfg); err != nil {
		h.logger.Warn("admin library folders: scan after save", "err", err)
	}
	v, err := h.libraryFolders(r.Context())
	if err != nil {
		writeErrWithLog(w, h.logger, "admin library folders: get", apierror.Internal(err))
		return
	}
	v.Moved = res.Tracks
	writeJSON(w, http.StatusOK, v)
}