add a query arg to the List endpoint used to determine what page a child item is on

src/api/routes/file/List.go

@@ -2,6 +2,7 @@ package file
 
 import (
 	"crazyfs/api/helpers"
+	"crazyfs/cacheitem"
 	"crazyfs/config"
 	"crazyfs/file"
 	"crazyfs/responseitem"
@@ -10,6 +11,11 @@ import (
 	"strconv"
 )
 
+const (
+	sortFolders = "folders"
+	sortDefault = sortFolders
+)
+
 func APIList(w http.ResponseWriter, r *http.Request) {
 	if helpers.CheckInitialCrawl() {
 		helpers.HandleRejectDuringInitialCrawl(w)
@@ -25,11 +31,11 @@ func APIList(w http.ResponseWriter, r *http.Request) {
 	var err error
 
 	sortArg := r.URL.Query().Get("sort")
-	var folderSorting string
-	if sortArg == "default" || sortArg == "" {
-		folderSorting = "default"
-	} else if sortArg == "folders" {
-		folderSorting = "folders"
+	var sortType string
+	if sortArg == sortDefault || sortArg == "" {
+		sortType = sortDefault
+	} else if sortArg == sortFolders {
+		sortType = sortFolders
 	} else {
 		helpers.Return400Msg("folders arg must be 'default' (to not do any sorting) or 'first' (to sort the folders to the front of the list)", w)
 		return
@@ -80,11 +86,6 @@ func APIList(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	// Create a copy of the cached Item, so we don't modify the Item in the cache
-	item := responseitem.NewResponseItem(cacheItem)
-
-	response := map[string]interface{}{}
-
 	// Pagination
 	var paginationLimit int
 	if r.URL.Query().Get("limit") != "" {
@@ -102,17 +103,58 @@ func APIList(w http.ResponseWriter, r *http.Request) {
 		paginationLimit = 100
 	}
 
+	// Generate the listing.
+	pageParam := r.URL.Query().Get("page")
+	response := map[string]interface{}{}
+	item, pages, responseError := generateListing(cacheItem, paginationLimit, sortType, pageParam)
+	if responseError != "" {
+		helpers.Return400Msg(responseError, w)
+		return
+	}
+
+	resolveItemName := r.URL.Query().Get("resolve")
+	if resolveItemName != "" {
+		var resolvedChild *responseitem.ResponseItem
+		var resolvedChildPage int
+		for i := range pages {
+			for _, child := range pages[i] {
+				if child.Name == resolveItemName {
+					resolvedChild = child
+					resolvedChildPage = i
+					break
+				}
+			}
+			if resolvedChild != nil {
+				break
+			}
+		}
+		if resolvedChild == nil {
+			helpers.Return400Msg("failed to find item", w)
+			return
+		}
+		item.Children = make([]*responseitem.ResponseItem, 1)
+		item.Children[0] = resolvedChild
+		response["resolved_page"] = resolvedChildPage
+	}
+
+	if r.URL.Query().Get("page") != "" || resolveItemName != "" {
+		response["total_pages"] = len(pages) + 1 // We add 1 to the count because arrays are zero-indexed.
+	}
+
+	response["item"] = item
+	helpers.WriteJsonResponse(response, true, w, r)
+}
+
+func generateListing(cacheItem *cacheitem.Item, paginationLimit int, sortType string, pageParam string) (*responseitem.ResponseItem, [][]*responseitem.ResponseItem, string) {
+	if sortType == "" {
+		panic("sortType was an empty string")
+	}
+
+	item := responseitem.NewResponseItem(cacheItem)
 	totalItems := len(item.Children)
 	totalPages := totalItems / paginationLimit
-	if totalItems%paginationLimit != 0 {
-		totalPages++
-	}
 
-	if r.URL.Query().Get("page") != "" {
-		response["total_pages"] = totalPages
-	}
-
-	if folderSorting == "folders" {
+	if sortType == sortFolders {
 		var dirs, files []*responseitem.ResponseItem
 		for _, child := range item.Children {
 			if child.IsDir {
@@ -121,45 +163,43 @@ func APIList(w http.ResponseWriter, r *http.Request) {
 				files = append(files, child)
 			}
 		}
+		item.Children = make([]*responseitem.ResponseItem, len(item.Children))
 		item.Children = append(dirs, files...)
 	}
 
-	// Set the children to an empty array so that the JSON encoder doesn't return it as nil.
-	var paginatedChildren []*responseitem.ResponseItem // this var will be either the full cacheitem list or a paginated list depending on the query args
-	if item.Children != nil {
-		paginatedChildren = item.Children
-	} else {
-		paginatedChildren = make([]*responseitem.ResponseItem, 0)
-	}
+	var pages [][]*responseitem.ResponseItem
 
-	pageParam := r.URL.Query().Get("page")
+	var page int
 	if pageParam != "" {
-		page, err := strconv.Atoi(pageParam)
-		if err != nil || page < 1 || page > totalPages {
-			// Don't return an error, just truncate things
-			page = totalPages
+		pageInt, err := strconv.Atoi(pageParam)
+		if err != nil || pageInt < 1 {
+			return nil, nil, "invalid page number"
 		}
-
-		start := (page - 1) * paginationLimit
-		end := start + paginationLimit
-
-		if start >= 0 { // avoid segfaults
-			if start > len(item.Children) {
-				start = len(item.Children)
-			}
-			if end > len(item.Children) {
-				end = len(item.Children)
-			}
-			paginatedChildren = paginatedChildren[start:end]
+		if pageInt > totalPages {
+			// Don't return an error, just set it to the max page number.
+			pageInt = totalPages
 		}
+		pageInt--
+		page = pageInt
+	} else {
+		page = 0
 	}
 
+	for i := 0; i < len(item.Children); i += paginationLimit {
+		end := i + paginationLimit
+		if end > len(item.Children) {
+			end = len(item.Children)
+		}
+		pages = append(pages, item.Children[i:end])
+	}
+
+	paginatedChildren := pages[page]
+
 	// Erase the children of the children so we aren't displaying things recursively.
 	for i := range paginatedChildren {
 		paginatedChildren[i].Children = nil
 	}
 
 	item.Children = paginatedChildren
-	response["item"] = item
-	helpers.WriteJsonResponse(response, true, w, r)
+	return item, pages, ""
 }