package files

import (
	"encoding/json"
	"errors"
	"fmt"
	_ "image/gif"
	_ "image/jpeg"
	_ "image/png"
	"net/http"
	"strings"

	"github.com/google/uuid"

	"aether/pkg/response"
)

// Ordner anlegen, umbenennen, verschieben und löschen.
//
// Umbenennen und Verschieben ziehen die Blobs auf der Platte mit – der
// Speicherpfad soll lesbar bleiben und dem Ordnerbaum entsprechen.

// POST /api/v1/folders
func (h *Handler) CreateFolder(w http.ResponseWriter, r *http.Request) {

	var body struct {
		Name     string  `json:"name"`
		ParentID *string `json:"parent_id"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil || strings.TrimSpace(body.Name) == "" {
		response.Error(w, http.StatusBadRequest, "name required")
		return
	}

	// Ordnernamen werden Teil des Storage-Pfads – gleiche Regeln wie für Dateien.
	folderName := SanitizeFilename(body.Name)
	if folderName == "" {
		response.Error(w, http.StatusBadRequest, "name required")
		return
	}

	// Ein Unterordner in einem geliehenen Ordner gehört dem Eigentümer des
	// Elternordners, nicht dem, der ihn anlegt: Die Bytes liegen in dessen
	// Bereich, und beim Entzug der Freigabe soll er nicht plötzlich fremde
	// Ordner in seinem Baum haben.
	var parentID *uuid.UUID
	if body.ParentID != nil && *body.ParentID != "" {
		pid, err := uuid.Parse(*body.ParentID)
		if err != nil {
			response.Error(w, http.StatusBadRequest, "invalid parent_id")
			return
		}
		parentID = &pid
	}

	owner, ok := h.resolveFolder(w, r, parentID, true)
	if !ok {
		return
	}

	f := &Folder{
		OwnerID:  owner.OwnerRef(),
		GroupID:  owner.GroupRef(),
		Name:     folderName,
		ParentID: parentID,
	}

	created, err := h.store.CreateFolder(r.Context(), f)
	if errors.Is(err, ErrNameTaken) {
		response.Error(w, http.StatusConflict, "folder name already exists")
		return
	}
	if err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	}
	response.JSON(w, http.StatusCreated, created)
}

// PATCH /api/v1/folders/{id}/rename
func (h *Handler) RenameFolder(w http.ResponseWriter, r *http.Request) {
	id, err := parseID(r, "id")
	if err != nil {
		response.Error(w, http.StatusBadRequest, "invalid folder id")
		return
	}

	owner, ok := h.resolveFolder(w, r, &id, true)
	if !ok {
		return
	}

	// Der Wurzelordner einer Gruppe ist kein gewöhnlicher Ordner, sondern der
	// Zugang der Gruppe. Verwaltet wird er im Admin-Bereich.
	if isRoot, err := h.store.IsGroupRoot(r.Context(), id); err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	} else if isRoot {
		response.Error(w, http.StatusForbidden, ErrGroupRootProtected.Error())
		return
	}

	var body struct {
		Name string `json:"name"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil || strings.TrimSpace(body.Name) == "" {
		response.Error(w, http.StatusBadRequest, "name required")
		return
	}
	newName := SanitizeFilename(body.Name)
	if newName == "" {
		response.Error(w, http.StatusBadRequest, "name required")
		return
	}

	// Collect files before renaming so we have the old storage keys.
	filesToMove, err := h.store.ListFilesInSubtree(r.Context(), owner.OwnerID, id)
	if err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	}

	// Rename the folder in DB first — GetFolderPath will now return the new path.
	folder, err := h.store.RenameFolder(r.Context(), id, owner.OwnerID, newName)
	if errors.Is(err, ErrNotFound) {
		response.Error(w, http.StatusNotFound, "folder not found")
		return
	}
	if errors.Is(err, ErrNameTaken) {
		response.Error(w, http.StatusConflict, "name already exists")
		return
	}
	if err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	}

	// Cascade: move each blob to the updated path.
	ResyncBlobPaths(r.Context(), h.store, h.storage, owner.StorageRoot(), filesToMove)

	response.JSON(w, http.StatusOK, folder)
}

// DELETE /api/v1/folders/{id}
func (h *Handler) DeleteFolder(w http.ResponseWriter, r *http.Request) {
	id, err := parseID(r, "id")
	if err != nil {
		response.Error(w, http.StatusBadRequest, "invalid folder id")
		return
	}

	owner, ok := h.resolveFolder(w, r, &id, true)
	if !ok {
		return
	}

	// Der Wurzelordner einer Gruppe ist kein gewöhnlicher Ordner, sondern der
	// Zugang der Gruppe. Verwaltet wird er im Admin-Bereich.
	if isRoot, err := h.store.IsGroupRoot(r.Context(), id); err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	} else if isRoot {
		response.Error(w, http.StatusForbidden, ErrGroupRootProtected.Error())
		return
	}

	_, err = h.store.GetFolder(r.Context(), id, owner.OwnerID)
	if errors.Is(err, ErrNotFound) {
		response.Error(w, http.StatusNotFound, "folder not found")
		return
	}
	if err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	}

	// Move blobs to .trash/ before soft-deleting so the file system stays consistent.
	filesToTrash, err := h.store.ListFilesInSubtree(r.Context(), owner.OwnerID, id)
	if err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	}
	for _, f := range filesToTrash {
		trashKey := fmt.Sprintf("%s/.trash/%s_%s", owner.StorageRoot(), f.ID.String()[:8], f.Name)
		if err := h.storage.Move(r.Context(), f.StorageKey, trashKey); err != nil {
			continue
		}
		_ = h.store.UpdateFileStorageKey(r.Context(), f.ID, trashKey)
	}

	if err := h.store.DeleteFolder(r.Context(), id, owner.OwnerID); err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	}

	w.WriteHeader(http.StatusNoContent)
}

// PATCH /api/v1/folders/{id}/move
func (h *Handler) MoveFolder(w http.ResponseWriter, r *http.Request) {
	id, err := parseID(r, "id")
	if err != nil {
		response.Error(w, http.StatusBadRequest, "invalid folder id")
		return
	}

	owner, ok := h.resolveFolder(w, r, &id, true)
	if !ok {
		return
	}

	// Der Wurzelordner einer Gruppe ist kein gewöhnlicher Ordner, sondern der
	// Zugang der Gruppe. Verwaltet wird er im Admin-Bereich.
	if isRoot, err := h.store.IsGroupRoot(r.Context(), id); err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	} else if isRoot {
		response.Error(w, http.StatusForbidden, ErrGroupRootProtected.Error())
		return
	}

	var body struct {
		ParentID *uuid.UUID `json:"parent_id"`
	}
	if err := json.NewDecoder(r.Body).Decode(&body); err != nil {
		response.Error(w, http.StatusBadRequest, "invalid body")
		return
	}

	// Reject self-move.
	if body.ParentID != nil && *body.ParentID == id {
		response.Error(w, http.StatusBadRequest, "cannot move folder into itself")
		return
	}

	// Verify target folder exists and is owned by user.
	if body.ParentID != nil {
		if _, err := h.store.GetFolder(r.Context(), *body.ParentID, owner.OwnerID); err != nil {
			response.Error(w, http.StatusNotFound, "target folder not found")
			return
		}
	}

	// Collect files before moving so we have the old storage keys.
	filesToMove, err := h.store.ListFilesInSubtree(r.Context(), owner.OwnerID, id)
	if err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	}

	folder, err := h.store.MoveFolder(r.Context(), id, owner.OwnerID, body.ParentID)
	if errors.Is(err, ErrNotFound) {
		response.Error(w, http.StatusNotFound, "folder not found")
		return
	}
	if errors.Is(err, ErrCycle) {
		response.Error(w, http.StatusBadRequest, "cannot move folder into its own subtree")
		return
	}
	if errors.Is(err, ErrNameTaken) {
		response.Error(w, http.StatusConflict, "name already exists in target folder")
		return
	}
	if err != nil {
		response.Error(w, http.StatusInternalServerError, "database error")
		return
	}

	// Cascade blob moves to updated paths.
	ResyncBlobPaths(r.Context(), h.store, h.storage, owner.StorageRoot(), filesToMove)

	response.JSON(w, http.StatusOK, folder)
}