bookhoard/internal/handlers/collections.go

package handlers

import (
	"bookhoard/internal/database"
	"bookhoard/internal/services"
	wsync "bookhoard/internal/sync"
	"bookhoard/internal/utils"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"strconv"
	"strings"
	"time"

	"github.com/google/uuid"
	"github.com/jackc/pgx/v5"
	"github.com/jackc/pgx/v5/pgtype"
	"github.com/labstack/echo/v5"
)

type CollectionHandler struct {
	db                *database.Queries
	collectionService *services.CollectionService
	libraryService    *services.LibraryService
	connManager       *wsync.ConnectionManager
}

func NewCollectionHandler(db *database.Queries, libraryService *services.LibraryService, connManager *wsync.ConnectionManager) *CollectionHandler {
	return &CollectionHandler{
		db:                db,
		collectionService: services.NewCollectionService(db),
		libraryService:    libraryService,
		connManager:       connManager,
	}
}

type CreateCollectionRequest struct {
	Name            string                 `form:"name" json:"name" validate:"required"`
	Description     string                 `form:"description" json:"description"`
	Color           string                 `form:"color" json:"color"`
	Icon            string                 `form:"icon" json:"icon"`
	CollectionType  string                 `form:"collection_type" json:"collection_type"` // "static" (default) or "smart" (rule-based)
	AutoAssignRules []services.Rule        `form:"auto_assign_rules" json:"auto_assign_rules"`
	ViewSettings    map[string]interface{} `form:"view_settings" json:"view_settings"`
}

type UpdateCollectionRequest struct {
	Name            string                 `form:"name" json:"name" validate:"required"`
	Description     string                 `form:"description" json:"description"`
	Color           string                 `form:"color" json:"color"`
	Icon            string                 `form:"icon" json:"icon"`
	AutoAssignRules []services.Rule        `form:"auto_assign_rules" json:"auto_assign_rules"`
	ViewSettings    map[string]interface{} `form:"view_settings" json:"view_settings"`
	// A2c §3.3: playlist toggles — merged into view_settings server-side
	// (nil = untouched). []string because the form posts a hidden "false"
	// sibling next to the checkbox; the LAST value wins. JSON clients may
	// send a single-element array (or omit — untouched).
	HideFinished []string `form:"hide_finished" json:"hide_finished"`
	ShowUpNext   []string `form:"show_up_next" json:"show_up_next"`
}

type AddBooksRequest struct {
	BookIDs []string `json:"book_ids" validate:"required"`
}

type CreateDeviceMappingRequest struct {
	CollectionID    string `json:"collection_id" validate:"required"`
	DeviceShelfName string `json:"device_shelf_name" validate:"required"`
	SyncDirection   string `json:"sync_direction" validate:"required,oneof=bidirectional book_to_device device_to_book none"`
}

type UpdateDeviceMappingRequest struct {
	DeviceShelfName string `json:"device_shelf_name" validate:"required"`
	SyncDirection   string `json:"sync_direction" validate:"required,oneof=bidirectional book_to_device device_to_book none"`
}

type SectionData struct {
	ID           string     `json:"id"`
	CollectionID string     `json:"collection_id"`
	IsSystem     bool       `json:"is_system"`
	Title        string     `json:"title"`
	Description  string     `json:"description"`
	Icon         string     `json:"icon"`
	Items        []BookInfo `json:"items"`
	ViewAllURL   string     `json:"view_all_url"`
	Priority     int        `json:"priority"`
	// A2c: curated playlist marker (imported reading-order collection) and
	// the hide_finished completion state — dashboard.ts renders both.
	IsPlaylist bool `json:"is_playlist"`
	Complete   bool `json:"complete"`
}

func (h *CollectionHandler) CreateCollection(c *echo.Context) error {
	user := c.Get("user").(database.Users)
	userUUID := uuid.UUID(user.ID.Bytes)

	var req CreateCollectionRequest
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	collection, err := h.collectionService.CreateCollection(
		c.Request().Context(),
		userUUID,
		req.Name,
		req.Description,
		req.Color,
		req.Icon,
		req.AutoAssignRules,
		req.ViewSettings,
	)
	if err != nil {
		if errors.Is(err, services.ErrCollectionNameTaken) {
			return c.JSON(http.StatusConflict, map[string]string{"error": "a collection with this name already exists"})
		}
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	bookCount := int32(0)
	isSmart := req.CollectionType == "smart" || len(req.AutoAssignRules) > 0
	response := map[string]interface{}{
		"id":                uuid.UUID(collection.ID.Bytes).String(),
		"user_id":           uuid.UUID(collection.UserID.Bytes).String(),
		"name":              collection.Name,
		"description":       utils.PgTextString(collection.Description),
		"color":             utils.PgTextString(collection.Color),
		"icon":              utils.PgTextString(collection.Icon),
		"collection_type":   map[bool]string{true: "smart", false: "static"}[isSmart],
		"auto_assign_rules": collection.AutoAssignRules,
		"view_settings":     collection.ViewSettings,
		"book_count":        bookCount,
		"created_at":        collection.CreatedAt.Time.String(),
	}

	// Add redirect header for HTMX requests
	if c.Request().Header.Get("HX-Request") == "true" {
		// A smart collection starts with an empty ruleset; the builder is
		// where it becomes real. Static collections head back to the grid.
		if isSmart {
			c.Response().Header().Set("HX-Redirect", "/collections/"+uuid.UUID(collection.ID.Bytes).String()+"/rules")
		} else {
			c.Response().Header().Set("HX-Redirect", "/collections")
		}
	}

	return c.JSON(http.StatusCreated, response)
}

func (h *CollectionHandler) GetCollections(c *echo.Context) error {
	includeAuto := c.QueryParam("include_auto") == "true"
	sortBy := c.QueryParam("sort_by")
	libraryID := c.QueryParam("library_id")

	collections, err := h.GetCollectionsData(c)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	type CollectionResponse struct {
		ID              uuid.UUID       `json:"id"`
		Name            string          `json:"name"`
		Description     string          `json:"description"`
		Color           string          `json:"color"`
		Icon            string          `json:"icon"`
		AutoAssignRules json.RawMessage `json:"auto_assign_rules"`
		CreatedAt       string          `json:"created_at"`
		BookCount       int             `json:"book_count"`
		IsSmart         bool            `json:"is_smart"`
	}

	response := make([]CollectionResponse, 0, len(collections))
	for _, col := range collections {
		isSmart := h.collectionService.IsSmartCollection(col.AutoAssignRules)
		if !includeAuto && isSmart {
			// Legacy default for API clients (the Android app pre-dates
			// smart collections): rule-driven collections stay opt-in so
			// their membership could never be stale for old readers.
			continue
		}

		bookCount := 0
		var libUUID pgtype.UUID
		if libraryID != "" {
			if libParsed, libErr := uuid.Parse(libraryID); libErr == nil {
				libUUID = pgtype.UUID{Bytes: libParsed, Valid: true}
			}
		}
		if isSmart {
			rules := h.collectionService.ParseRules(col.AutoAssignRules)
			visibleIDs, visErr := h.userVisibleLibraryIDs(c)
			if visErr == nil {
				matches, evalErr := h.collectionService.EvaluateSmartCollection(c.Request().Context(), rules, services.SmartEvalOptions{
					LibraryID:  libUUID,
					VisibleIDs: visibleIDs,
				})
				if evalErr == nil {
					bookCount = len(matches)
				}
			}
		} else {
			count, countErr := h.db.CountCollectionLiveItems(c.Request().Context(), database.CountCollectionLiveItemsParams{
				CollectionID: pgtype.UUID{Bytes: col.ID.Bytes, Valid: true},
				LibraryID:    libUUID,
			})
			if countErr == nil {
				bookCount = int(count)
			}
		}

		response = append(response, CollectionResponse{
			ID:              col.ID.Bytes,
			Name:            col.Name,
			Description:     utils.PgTextString(col.Description),
			Color:           utils.PgTextString(col.Color),
			Icon:            utils.PgTextString(col.Icon),
			AutoAssignRules: col.AutoAssignRules,
			CreatedAt:       col.CreatedAt.Time.String(),
			BookCount:       bookCount,
			IsSmart:         isSmart,
		})
	}

	if sortBy == "name" {
		for i := 0; i < len(response); i++ {
			for j := i + 1; j < len(response); j++ {
				if response[i].Name > response[j].Name {
					response[i], response[j] = response[j], response[i]
				}
			}
		}
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"collections": response,
		"total":       len(response),
	})
}

func (h *CollectionHandler) GetCollection(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}

	collection, err := h.GetCollectionData(c, collectionID)
	if err != nil {
		return c.JSON(http.StatusNotFound, map[string]string{"error": "collection not found"})
	}

	libraryID := c.QueryParam("library_id")
	var bookList []BookInfo

	var libUUID pgtype.UUID
	if libraryID != "" {
		parsed, parseErr := uuid.Parse(libraryID)
		if parseErr != nil {
			return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid library_id"})
		}
		libUUID = pgtype.UUID{Bytes: parsed, Valid: true}
	}

	isSmart := h.collectionService.IsSmartCollection(collection.AutoAssignRules)
	libTypes := LibraryTypeMap(c.Request().Context(), h.db)
	if isSmart {
		rules := h.collectionService.ParseRules(collection.AutoAssignRules)
		visibleIDs, err := h.userVisibleLibraryIDs(c)
		if err != nil {
			return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
		}
		matches, evalErr := h.collectionService.EvaluateSmartCollection(c.Request().Context(), rules, services.SmartEvalOptions{
			LibraryID:  libUUID,
			VisibleIDs: visibleIDs,
		})
		if evalErr != nil {
			return c.JSON(http.StatusInternalServerError, map[string]string{"error": evalErr.Error()})
		}
		bookList = BookCardsFromMediaItems(matches, libTypes)
	} else if collection.IsSystemCollection.Bool && collection.QueryType.Valid && collection.QueryType.String != "" && collection.QueryType.String != "filter" {
		user := c.Get("user").(database.Users)
		userUUID := uuid.UUID(user.ID.Bytes)
		dashboardSvc := services.NewDashboardService(h.db)
		sections, secErr := dashboardSvc.GetDashboardSections(c.Request().Context(), userUUID, libUUID, 1000, []string{}, []string{})
		if secErr != nil {
			return c.JSON(http.StatusInternalServerError, map[string]string{"error": secErr.Error()})
		}
		for _, section := range sections {
			if section.CollectionID == collectionID {
				bookList = BookCardsFromMediaItems(section.Items, libTypes)
				break
			}
		}
	} else if libUUID.Valid {
		// A2c §3.3: the detail page honors the same per-collection
		// hide_finished as the dashboard section, against the viewer's
		// progress. The viewer_percentage rides along for card graying.
		hideFinished := false
		if len(collection.ViewSettings) > 0 {
			var vs map[string]interface{}
			if json.Unmarshal(collection.ViewSettings, &vs) == nil {
				if b, ok := vs["hide_finished"].(bool); ok {
					hideFinished = b
				}
			}
		}
		var viewerID pgtype.UUID
		if u, ok := c.Get("user").(database.Users); ok {
			viewerID = u.ID
		}
		collItems, collErr := h.db.GetCollectionItemsForDashboard(c.Request().Context(),
			database.GetCollectionItemsForDashboardParams{
				CollectionID: pgtype.UUID{Bytes: collectionID, Valid: true},
				LibraryID:    libUUID,
				ViewerUserID: viewerID,
				HideFinished: pgtype.Bool{Bool: hideFinished, Valid: hideFinished},
				Limit:        pgtype.Int4{Int32: 10000, Valid: true},
			})
		if collErr != nil {
			bookList = BookCardsFromCollectionDashRows(nil, libTypes)
		} else {
			// The query filters excluded rows in SQL; cards build straight
			// from the embedded media rows.
			bookList = BookCardsFromCollectionDashRows(collItems, libTypes)
		}
	} else {
		books, booksErr := h.GetCollectionBooksData(c, collectionID)
		if booksErr != nil {
			return c.JSON(http.StatusInternalServerError, map[string]string{"error": booksErr.Error()})
		}
		bookList = BookCardsFromCollectionItemRows(books, libTypes)
	}

	if u, ok := c.Get("user").(database.Users); ok {
		bookList = MarkActiveConflicts(c.Request().Context(), h.db, u.ID, bookList)
	}

	var viewSettings map[string]interface{}
	if len(collection.ViewSettings) > 0 {
		err := json.Unmarshal(collection.ViewSettings, &viewSettings)
		if err != nil {
			return err
		}
	}

	// A2c §3.4: the collection's reading queue for the Up Next strip.
	// Library visibility enforced — a hidden library's books never surface
	// here even if they sit in a visible collection.
	upNext := []map[string]interface{}{}
	if !isSmart {
		hideFinished := false
		if b, ok := viewSettings["hide_finished"].(bool); ok {
			hideFinished = b
		}
		_ = hideFinished
		visibleIDs, visErr := h.userVisibleLibraryIDs(c)
		if visErr == nil {
			user := c.Get("user").(database.Users)
			rows, upErr := h.db.GetCollectionUpNext(c.Request().Context(), database.GetCollectionUpNextParams{
				CollectionID:      pgtype.UUID{Bytes: collectionID, Valid: true},
				ViewerUserID:      pgtype.UUID{Bytes: user.ID.Bytes, Valid: true},
				VisibleLibraryIds: visibleIDs,
				Limit:             pgtype.Int4{Int32: 10, Valid: true},
			})
			if upErr == nil {
				for _, row := range rows {
					upNext = append(upNext, map[string]interface{}{
						"id":       uuid.UUID(row.MediaItems.ID.Bytes).String(),
						"title":    row.MediaItems.Title,
						"author":   utils.PgTextString(row.MediaItems.Author),
						"cover":    utils.PgTextString(row.MediaItems.CoverImagePath),
						"format":   row.MediaItems.FormatGroup,
						"progress": row.ViewerPercentage,
					})
				}
			}
		}
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"id":                uuid.UUID(collection.ID.Bytes).String(),
		"user_id":           uuid.UUID(collection.UserID.Bytes).String(),
		"name":              collection.Name,
		"description":       utils.PgTextString(collection.Description),
		"color":             utils.PgTextString(collection.Color),
		"icon":              utils.PgTextString(collection.Icon),
		"auto_assign_rules": json.RawMessage(collection.AutoAssignRules),
		"view_settings":     viewSettings,
		"books":             bookList,
		"book_count":        len(bookList),
		"is_smart":          isSmart,
		"up_next":           upNext,
		"created_at":        collection.CreatedAt.Time.String(),
	})
}

func (h *CollectionHandler) UpdateCollection(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}

	var req UpdateCollectionRequest
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	// A2c §3.3: playlist toggles ride the edit form as top-level fields and
	// merge into view_settings server-side (the form can't bind a map).
	// The form posts a hidden "false" sibling before the checkbox, so the
	// LAST value is the checkbox state.
	if v := optionalFlag(req.HideFinished); v != nil {
		if req.ViewSettings == nil {
			req.ViewSettings = map[string]interface{}{}
		}
		req.ViewSettings["hide_finished"] = *v
	}
	if v := optionalFlag(req.ShowUpNext); v != nil {
		if req.ViewSettings == nil {
			req.ViewSettings = map[string]interface{}{}
		}
		req.ViewSettings["show_up_next"] = *v
	}

	collection, err := h.collectionService.UpdateCollection(
		c.Request().Context(),
		collectionID,
		req.Name,
		req.Description,
		req.Color,
		req.Icon,
		req.AutoAssignRules,
		req.ViewSettings,
	)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	response := map[string]interface{}{
		"id":                uuid.UUID(collection.ID.Bytes).String(),
		"user_id":           uuid.UUID(collection.UserID.Bytes).String(),
		"name":              collection.Name,
		"description":       utils.PgTextString(collection.Description),
		"color":             utils.PgTextString(collection.Color),
		"icon":              utils.PgTextString(collection.Icon),
		"auto_assign_rules": json.RawMessage(collection.AutoAssignRules),
		"view_settings":     json.RawMessage(collection.ViewSettings),
		"created_at":        collection.CreatedAt.Time.String(),
	}

	// Add redirect header for HTMX requests
	if c.Request().Header.Get("HX-Request") == "true" {
		c.Response().Header().Set("HX-Redirect", "/collections")
	}

	return c.JSON(http.StatusCreated, response)
}

func (h *CollectionHandler) DeleteCollection(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}

	err = h.collectionService.DeleteCollection(c.Request().Context(), collectionID)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	if c.Request().Header.Get("HX-Request") == "true" {
		html := `<div class="text-green-500">Collection deleted! Redirecting...</div><script>window.location.href = '/collections';</script>`
		return c.HTML(http.StatusOK, html)
	}

	return c.NoContent(http.StatusNoContent)
}

func (h *CollectionHandler) AddBooks(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}

	if guardErr := h.rejectSmartMutation(c, collectionID); guardErr != nil {
		return guardErr
	}

	user := c.Get("user").(database.Users)
	userUUID := uuid.UUID(user.ID.Bytes)

	var req AddBooksRequest
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	addedCount := 0
	var addedBookIDs []string
	for _, bookIDStr := range req.BookIDs {
		bookID, err := uuid.Parse(bookIDStr)
		if err != nil {
			continue
		}
		err = h.collectionService.AddBookToCollection(c.Request().Context(), collectionID, bookID, userUUID)
		if err == nil {
			addedCount++
			addedBookIDs = append(addedBookIDs, bookID.String())
		}
	}

	if addedCount > 0 && h.connManager != nil {
		h.connManager.BroadcastToUser(userUUID.String(), wsync.BroadcastMessage{
			Type:      "collection_updated",
			Timestamp: time.Now().Format(time.RFC3339),
			Data: map[string]interface{}{
				"collection_id": collectionID.String(),
				"action":        "books_added",
				"book_ids":      addedBookIDs,
				"count":         addedCount,
			},
		})
	}

	return c.NoContent(http.StatusNoContent)
}

func (h *CollectionHandler) RemoveBook(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}

	if guardErr := h.rejectSmartMutation(c, collectionID); guardErr != nil {
		return guardErr
	}

	bookID, err := uuid.Parse(c.Param("bookId"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid book id"})
	}

	// Get user from context for WebSocket broadcast
	user := c.Get("user").(database.Users)
	userUUID := uuid.UUID(user.ID.Bytes)

	err = h.collectionService.RemoveBookFromCollection(c.Request().Context(), collectionID, bookID)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	// Broadcast to user's other devices via WebSocket
	if h.connManager != nil {
		h.connManager.BroadcastToUser(userUUID.String(), wsync.BroadcastMessage{
			Type:      "collection_updated",
			Timestamp: time.Now().Format(time.RFC3339),
			Data: map[string]interface{}{
				"collection_id": collectionID.String(),
				"action":        "book_removed",
				"book_id":       bookID.String(),
			},
		})
	}

	return c.NoContent(http.StatusNoContent)
}

type BulkRemoveBooksRequest struct {
	BookIDs []string `json:"book_ids" validate:"required"`
}

func (h *CollectionHandler) BulkRemoveBooks(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}

	if guardErr := h.rejectSmartMutation(c, collectionID); guardErr != nil {
		return guardErr
	}

	user := c.Get("user").(database.Users)
	userUUID := uuid.UUID(user.ID.Bytes)

	var req BulkRemoveBooksRequest
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	removedCount := 0
	var removedBookIDs []string
	for _, bookIDStr := range req.BookIDs {
		bookID, err := uuid.Parse(bookIDStr)
		if err != nil {
			continue
		}

		err = h.collectionService.RemoveBookFromCollection(c.Request().Context(), collectionID, bookID)
		if err == nil {
			removedCount++
			removedBookIDs = append(removedBookIDs, bookID.String())
		}
	}

	if removedCount > 0 && h.connManager != nil {
		h.connManager.BroadcastToUser(userUUID.String(), wsync.BroadcastMessage{
			Type:      "collection_updated",
			Timestamp: time.Now().Format(time.RFC3339),
			Data: map[string]interface{}{
				"collection_id": collectionID.String(),
				"action":        "books_removed",
				"book_ids":      removedBookIDs,
				"count":         removedCount,
			},
		})
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"removed": removedCount,
		"total":   len(req.BookIDs),
	})
}

func (h *CollectionHandler) GetDeviceMappings(c *echo.Context) error {
	deviceID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid device id"})
	}

	mappings, err := h.collectionService.GetDeviceShelfMappings(c.Request().Context(), deviceID)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	type MappingResponse struct {
		ID              uuid.UUID `json:"id"`
		CollectionID    uuid.UUID `json:"collection_id"`
		CollectionName  string    `json:"collection_name"`
		DeviceShelfName string    `json:"device_shelf_name"`
		SyncDirection   string    `json:"sync_direction"`
		CreatedAt       string    `json:"created_at"`
	}

	response := make([]MappingResponse, 0, len(mappings))
	for _, m := range mappings {
		response = append(response, MappingResponse{
			ID:              m.ID.Bytes,
			CollectionID:    m.CollectionID.Bytes,
			CollectionName:  m.CollectionName,
			DeviceShelfName: utils.PgTextString(m.DeviceShelfName),
			SyncDirection:   utils.PgTextString(m.SyncDirection),
			CreatedAt:       m.CreatedAt.Time.String(),
		})
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"device_id": deviceID.String(),
		"mappings":  response,
		"total":     len(response),
	})
}

func (h *CollectionHandler) CreateDeviceMapping(c *echo.Context) error {
	deviceID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid device id"})
	}

	var req CreateDeviceMappingRequest
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	collectionID, err := uuid.Parse(req.CollectionID)
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}

	mapping, err := h.collectionService.CreateDeviceShelfMapping(
		c.Request().Context(),
		collectionID,
		deviceID,
		req.DeviceShelfName,
		req.SyncDirection,
	)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	return c.JSON(http.StatusCreated, map[string]interface{}{
		"id":                uuid.UUID(mapping.ID.Bytes).String(),
		"collection_id":     uuid.UUID(mapping.CollectionID.Bytes).String(),
		"device_id":         uuid.UUID(mapping.DeviceID.Bytes).String(),
		"device_shelf_name": utils.PgTextString(mapping.DeviceShelfName),
		"sync_direction":    utils.PgTextString(mapping.SyncDirection),
		"created_at":        mapping.CreatedAt.Time.String(),
	})
}

func (h *CollectionHandler) UpdateDeviceMapping(c *echo.Context) error {
	mappingID, err := uuid.Parse(c.Param("mappingId"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid mapping id"})
	}

	var req UpdateDeviceMappingRequest
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	mapping, err := h.collectionService.UpdateDeviceShelfMapping(
		c.Request().Context(),
		mappingID,
		req.DeviceShelfName,
		req.SyncDirection,
	)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"id":                uuid.UUID(mapping.ID.Bytes).String(),
		"collection_id":     uuid.UUID(mapping.CollectionID.Bytes).String(),
		"device_id":         uuid.UUID(mapping.DeviceID.Bytes).String(),
		"device_shelf_name": utils.PgTextString(mapping.DeviceShelfName),
		"sync_direction":    utils.PgTextString(mapping.SyncDirection),
		"created_at":        mapping.CreatedAt.Time.String(),
	})
}

func (h *CollectionHandler) DeleteDeviceMapping(c *echo.Context) error {
	mappingID, err := uuid.Parse(c.Param("mappingId"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid mapping id"})
	}

	err = h.collectionService.DeleteDeviceShelfMapping(c.Request().Context(), mappingID)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	return c.NoContent(http.StatusNoContent)
}

func (h *CollectionHandler) GetBookCollections(c *echo.Context) error {
	bookID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid book id"})
	}

	collections, err := h.collectionService.GetBookCollections(c.Request().Context(), bookID)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	type CollectionResponse struct {
		ID          uuid.UUID `json:"id"`
		Name        string    `json:"name"`
		Description string    `json:"description"`
		Color       string    `json:"color"`
		Icon        string    `json:"icon"`
	}

	response := make([]CollectionResponse, 0, len(collections))
	for _, col := range collections {
		response = append(response, CollectionResponse{
			ID:          col.ID.Bytes,
			Name:        col.Name,
			Description: utils.PgTextString(col.Description),
			Color:       utils.PgTextString(col.Color),
			Icon:        utils.PgTextString(col.Icon),
		})
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"book_id":     bookID.String(),
		"collections": response,
		"total":       len(response),
	})
}

func (h *CollectionHandler) GetCollectionsData(c *echo.Context) ([]database.Collections, error) {
	user := c.Get("user").(database.Users)
	userUUID := uuid.UUID(user.ID.Bytes)
	return h.collectionService.GetUserCollections(c.Request().Context(), userUUID)
}

func (h *CollectionHandler) GetCollectionData(c *echo.Context, collectionID uuid.UUID) (database.Collections, error) {
	return h.collectionService.GetCollection(c.Request().Context(), collectionID)
}

func (h *CollectionHandler) GetCollectionBooksData(c *echo.Context, collectionID uuid.UUID) ([]database.GetCollectionItemsRow, error) {
	return h.collectionService.GetCollectionBooks(c.Request().Context(), collectionID)
}

func (h *CollectionHandler) GetDeviceMappingsData(c *echo.Context, deviceID uuid.UUID) ([]database.GetDeviceShelfMappingsRow, error) {
	return h.collectionService.GetDeviceShelfMappings(c.Request().Context(), deviceID)
}

func (h *CollectionHandler) GetUserCollectionsList(c *echo.Context) ([]database.Collections, error) {
	user := c.Get("user").(database.Users)
	userUUID := uuid.UUID(user.ID.Bytes)
	return h.collectionService.GetUserCollections(c.Request().Context(), userUUID)
}

// userVisibleLibraryIDs loads the requester's visible-library set (the
// family lens). Smart-collection evaluation funnels every book candidate
// through it so hidden libraries contribute nothing.
// userVisibleLibraryIDs adapts the collection endpoints' identity
// source to the canonical resolver (H4.5).
func (h *CollectionHandler) userVisibleLibraryIDs(c *echo.Context) ([]pgtype.UUID, error) {
	user, ok := c.Get("user").(database.Users)
	if !ok {
		return nil, echo.NewHTTPError(http.StatusUnauthorized, "invalid user")
	}
	_, ids, err := h.libraryService.VisibleLibrarySet(c.Request().Context(), user.ID)
	return ids, err
}

// UserVisibleLibraryIDs is the exported entry point for the router's
// frontend page handlers, which resolve the visible-library set before
// evaluating smart-collection rule matches.
func (h *CollectionHandler) UserVisibleLibraryIDs(c *echo.Context) ([]pgtype.UUID, error) {
	return h.userVisibleLibraryIDs(c)
}

// CollectionService returns the underlying service so the router's
// frontend handlers can share the exact same evaluation the API uses.
func (h *CollectionHandler) CollectionService() *services.CollectionService {
	return h.collectionService
}

// rejectSmartMutation returns a 400 for smart collections: membership is
// derived live from rules, so stored link mutations have nothing to act
// on. v1 has no hybrid mode — add/remove with both rules and hand-picked
// books is deliberately unsupported (collection_items.excluded awaits it).
func (h *CollectionHandler) rejectSmartMutation(c *echo.Context, collectionID uuid.UUID) *echo.HTTPError {
	collection, err := h.GetCollectionData(c, collectionID)
	if err != nil {
		return echo.NewHTTPError(http.StatusNotFound, "collection not found")
	}
	if h.collectionService.IsSmartCollection(collection.AutoAssignRules) {
		return echo.NewHTTPError(http.StatusBadRequest, "smart collections are rule-based — membership is managed by the collection's rules, not by hand")
	}
	return nil
}

type AddRuleRequest struct {
	Field    string `json:"field" validate:"required"`
	Operator string `json:"operator" validate:"required"`
	Value    string `json:"value" validate:"required"`
	Enabled  *bool  `json:"enabled"`
	Priority int    `json:"priority"`
}

// AddRule handles POST /api/collections/:id/rules — appends one rule to
// the ruleset. The first rule converts a static collection to smart.
func (h *CollectionHandler) AddRule(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}

	collection, err := h.GetCollectionData(c, collectionID)
	if err != nil {
		return c.JSON(http.StatusNotFound, map[string]string{"error": "collection not found"})
	}
	if collection.IsSystemCollection.Bool {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "system collections cannot have rules"})
	}

	var req AddRuleRequest
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	updated, rule, err := h.collectionService.AddRule(c.Request().Context(), collectionID, services.Rule{
		Field:    req.Field,
		Operator: req.Operator,
		Value:    req.Value,
		Enabled:  req.Enabled,
		Priority: req.Priority,
	})
	if err != nil {
		var ruleErr *services.RuleValidationError
		if errors.As(err, &ruleErr) {
			return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
		}
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	return c.JSON(http.StatusCreated, map[string]interface{}{
		"collection_id": uuid.UUID(updated.ID.Bytes).String(),
		"rule":          rule,
		"is_smart":      h.collectionService.IsSmartCollection(updated.AutoAssignRules),
	})
}

// UpdateRule handles PUT /api/collections/:id/rules/:ruleId — currently
// the enabled toggle; the payload may only carry {"enabled": bool}.
func (h *CollectionHandler) UpdateRule(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}
	ruleID := c.Param("ruleId")
	if ruleID == "" {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "rule id required"})
	}

	var req struct {
		Enabled *bool `json:"enabled" validate:"required"`
	}
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	updated, err := h.collectionService.SetRuleEnabled(c.Request().Context(), collectionID, ruleID, *req.Enabled)
	if err != nil {
		if strings.Contains(err.Error(), "rule not found") {
			return c.JSON(http.StatusNotFound, map[string]string{"error": err.Error()})
		}
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"collection_id": uuid.UUID(updated.ID.Bytes).String(),
		"is_smart":      h.collectionService.IsSmartCollection(updated.AutoAssignRules),
	})
}

// RemoveRule handles DELETE /api/collections/:id/rules/:ruleId.
func (h *CollectionHandler) RemoveRule(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}
	ruleID := c.Param("ruleId")
	if ruleID == "" {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "rule id required"})
	}

	updated, err := h.collectionService.RemoveRule(c.Request().Context(), collectionID, ruleID)
	if err != nil {
		if strings.Contains(err.Error(), "rule not found") {
			return c.JSON(http.StatusNotFound, map[string]string{"error": err.Error()})
		}
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"collection_id": uuid.UUID(updated.ID.Bytes).String(),
		"is_smart":      h.collectionService.IsSmartCollection(updated.AutoAssignRules),
	})
}

type TestRulesRequest struct {
	Rules []map[string]interface{} `json:"rules" validate:"required"`
}

type BookMatch struct {
	MediaItemID    string `json:"media_item_id"`
	Title          string `json:"title"`
	Author         string `json:"author"`
	CoverImagePath string `json:"cover_image_path"`
	MatchReason    string `json:"match_reason"`
}

func (h *CollectionHandler) TestRules(c *echo.Context) error {
	var req TestRulesRequest
	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid request"})
	}
	if err := c.Validate(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": err.Error()})
	}

	// Candidates mirror what smart collections actually evaluate against:
	// the requester's visible libraries and live items only — the preview
	// must not promise matches the live render will never produce.
	visibleIDs, err := h.userVisibleLibraryIDs(c)
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}
	var visibleArg []pgtype.UUID
	if len(visibleIDs) > 0 {
		visibleArg = visibleIDs
	}
	mediaItems, err := h.db.GetVisibleLiveMediaForRules(c.Request().Context(), database.GetVisibleLiveMediaForRulesParams{
		LibraryID:         pgtype.UUID{},
		VisibleLibraryIds: visibleArg,
	})
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "failed to load media items"})
	}

	var matches []BookMatch
	for _, item := range mediaItems {
		matchReason := h.checkRulesAgainstBook(item, req.Rules)
		if matchReason != "" {
			author := ""
			if item.Author.Valid {
				author = item.Author.String
			}

			matches = append(matches, BookMatch{
				MediaItemID:    uuid.UUID(item.ID.Bytes).String(),
				Title:          item.Title,
				Author:         author,
				CoverImagePath: utils.ResolveMediaURL(item.LibraryID, item.CoverImagePath),
				MatchReason:    matchReason,
			})
		}
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"matches": matches,
		"total":   len(matches),
	})
}

func (h *CollectionHandler) checkRulesAgainstBook(item database.MediaItems, rules []map[string]interface{}) string {
	for _, rule := range rules {
		field, _ := rule["field"].(string)
		operator, _ := rule["operator"].(string)
		value, _ := rule["value"].(string)

		if h.evaluateRule(item, field, operator, value) {
			return fmt.Sprintf("Matched rule: %s %s %s", field, operator, value)
		}
	}
	return ""
}

func (h *CollectionHandler) evaluateRule(item database.MediaItems, field, operator, value string) bool {
	var itemValue string

	switch field {
	case "genre":
		if item.Genre.Valid {
			itemValue = item.Genre.String
		}
	case "series":
		if item.Series.Valid {
			itemValue = item.Series.String
		}
	case "author":
		if item.Author.Valid {
			itemValue = item.Author.String
		}
	case "language":
		if item.Language.Valid {
			itemValue = item.Language.String
		}
	case "publisher":
		if item.Publisher.Valid {
			itemValue = item.Publisher.String
		}
	case "copyright_year":
		if item.CopyrightYear.Valid {
			itemValue = fmt.Sprintf("%d", item.CopyrightYear.Int32)
		}
	case "tags":
		if len(item.Tags) > 0 {
			itemValue = strings.Join(item.Tags, ", ")
		}
	}

	return h.compareValues(itemValue, operator, value)
}

func (h *CollectionHandler) compareValues(itemValue, operator, ruleValue string) bool {
	switch operator {
	case "equals":
		return itemValue == ruleValue
	case "not_equals":
		return itemValue != ruleValue
	case "contains":
		return strings.Contains(strings.ToLower(itemValue), strings.ToLower(ruleValue))
	case "not_contains":
		return !strings.Contains(strings.ToLower(itemValue), strings.ToLower(ruleValue))
	case "starts_with":
		return strings.HasPrefix(strings.ToLower(itemValue), strings.ToLower(ruleValue))
	case "ends_with":
		return strings.HasSuffix(strings.ToLower(itemValue), strings.ToLower(ruleValue))
	case "greater_than":
		itemNum, err1 := strconv.Atoi(itemValue)
		ruleNum, err2 := strconv.Atoi(ruleValue)
		if err1 != nil || err2 != nil {
			return false
		}
		return itemNum > ruleNum
	case "less_than":
		itemNum, err1 := strconv.Atoi(itemValue)
		ruleNum, err2 := strconv.Atoi(ruleValue)
		if err1 != nil || err2 != nil {
			return false
		}
		return itemNum < ruleNum
	}
	return false
}

// Bulk Operations

// POST /api/collections/bulk-add-books
// Bulk add books to multiple collections
func (h *CollectionHandler) HandleBulkAddBooks(c *echo.Context) error {
	user := c.Get("user").(database.Users)
	userUUID := uuid.UUID(user.ID.Bytes)

	var req struct {
		Operations []struct {
			CollectionID string   `json:"collection_id" validate:"required"`
			BookIDs      []string `json:"book_ids" validate:"required"`
		} `json:"operations" validate:"required"`
	}

	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "Invalid request"})
	}

	if len(req.Operations) == 0 {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "operations required"})
	}

	// Smart collections are rejected up front per operation so the
	// caller sees a clean, actionable error instead of silent no-ops.
	for _, op := range req.Operations {
		if colUUID, err := uuid.Parse(op.CollectionID); err == nil {
			if guardErr := h.rejectSmartMutation(c, colUUID); guardErr != nil {
				return guardErr
			}
		}
	}

	results := make([]map[string]interface{}, 0)
	successCount := 0
	failedCount := 0

	for _, op := range req.Operations {
		collectionID, err := uuid.Parse(op.CollectionID)
		if err != nil {
			results = append(results, map[string]interface{}{
				"collection_id": op.CollectionID,
				"status":        "error",
				"error":         "Invalid collection UUID",
			})
			failedCount++
			continue
		}

		for _, bookIDStr := range op.BookIDs {
			bookID, err := uuid.Parse(bookIDStr)
			if err != nil {
				results = append(results, map[string]interface{}{
					"collection_id": op.CollectionID,
					"book_id":       bookIDStr,
					"status":        "error",
					"error":         "Invalid book UUID",
				})
				failedCount++
				continue
			}

			collectionUUID := pgtype.UUID{Bytes: collectionID, Valid: true}
			bookUUID := pgtype.UUID{Bytes: bookID, Valid: true}

			_, err = h.db.AddBookToCollection(c.Request().Context(), database.AddBookToCollectionParams{
				CollectionID:  collectionUUID,
				MediaItemID:   bookUUID,
				AddedByUserID: pgtype.UUID{Bytes: user.ID.Bytes, Valid: true},
			})

			if err != nil {
				results = append(results, map[string]interface{}{
					"collection_id": op.CollectionID,
					"book_id":       bookIDStr,
					"status":        "error",
					"error":         err.Error(),
				})
				failedCount++
				continue
			}

			results = append(results, map[string]interface{}{
				"collection_id": op.CollectionID,
				"book_id":       bookIDStr,
				"status":        "success",
			})
			successCount++
		}
	}

	if successCount > 0 && h.connManager != nil {
		h.connManager.BroadcastToUser(userUUID.String(), wsync.BroadcastMessage{
			Type:      "collection_updated",
			Timestamp: time.Now().Format(time.RFC3339),
			Data: map[string]interface{}{
				"action": "books_added_bulk",
				"count":  successCount,
			},
		})
	}

	return c.JSON(http.StatusOK, map[string]interface{}{
		"results": results,
		"total":   len(results),
		"added":   successCount,
		"failed":  failedCount,
	})
}

func (h *CollectionHandler) PreviewCollection(c *echo.Context) error {
	user := c.Get("user")
	if user == nil {
		return c.JSON(http.StatusUnauthorized, map[string]string{"error": "unauthorized"})
	}

	var req struct {
		LibraryID     string          `json:"library_id"`
		Rules         []services.Rule `json:"rules"`
		ManualBookIDs []string        `json:"manual_book_ids"`
		Limit         int             `json:"limit"`
	}

	if err := c.Bind(&req); err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "Invalid request"})
	}

	libUUID, err := uuid.Parse(req.LibraryID)
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid library_id"})
	}

	_, err = h.db.GetLibrary(c.Request().Context(), pgtype.UUID{Bytes: libUUID, Valid: true})
	if err != nil {
		if errors.Is(err, pgx.ErrNoRows) {
			return c.JSON(http.StatusBadRequest, map[string]string{"error": "library not found"})
		}
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}

	if req.Limit <= 0 || req.Limit > 100 {
		req.Limit = 20
	}

	allItems, err := h.db.GetLibraryItems(c.Request().Context(), pgtype.UUID{Bytes: libUUID, Valid: true})
	if err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": "Failed to load library items"})
	}

	var matchedItems []database.MediaItems
	for _, item := range allItems {
		evaluations := h.collectionService.EvaluateRules(item, req.Rules)
		for _, eval := range evaluations {
			if eval.Matches {
				matchedItems = append(matchedItems, item)
				break
			}
		}
	}

	for _, bookID := range req.ManualBookIDs {
		bookUUID, err := uuid.Parse(bookID)
		if err != nil {
			continue
		}

		for _, item := range allItems {
			itemUUID, _ := uuid.FromBytes(item.ID.Bytes[0:16])
			if itemUUID == bookUUID {
				alreadyAdded := false
				for _, added := range matchedItems {
					addedUUID, _ := uuid.FromBytes(added.ID.Bytes[0:16])
					if addedUUID == bookUUID {
						alreadyAdded = true
						break
					}
				}
				if !alreadyAdded {
					matchedItems = append(matchedItems, item)
				}
				break
			}
		}
	}

	if len(matchedItems) > req.Limit {
		matchedItems = matchedItems[:req.Limit]
	}

	bookCards := BookCardsFromMediaItems(matchedItems, LibraryTypeMap(c.Request().Context(), h.db))
	if u, ok := c.Get("user").(database.Users); ok {
		bookCards = MarkActiveConflicts(c.Request().Context(), h.db, u.ID, bookCards)
	}

	return c.JSON(http.StatusOK, map[string]interface{}{"items": bookCards})
}

// ReorderItems applies a static collection's manual playlist order
// (A2c §3.2). Owner-only; the payload is the COMPLETE ordered id list —
// ids omitted keep their relative order appended after (the service never
// deletes membership).
func (h *CollectionHandler) ReorderItems(c *echo.Context) error {
	collectionID, err := uuid.Parse(c.Param("id"))
	if err != nil {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid collection id"})
	}
	user, ok := c.Get("user").(database.Users)
	if !ok {
		return c.JSON(http.StatusUnauthorized, map[string]string{"error": "unauthorized"})
	}

	var req struct {
		ItemIDs []string `json:"item_ids"`
	}
	if err := c.Bind(&req); err != nil || len(req.ItemIDs) == 0 {
		return c.JSON(http.StatusBadRequest, map[string]string{"error": "item_ids must be a non-empty ordered id list"})
	}

	owns, err := h.collectionService.UserOwnsCollection(c.Request().Context(), collectionID, uuid.UUID(user.ID.Bytes))
	if err != nil || !owns {
		return c.JSON(http.StatusForbidden, map[string]string{"error": "only the collection owner can reorder it"})
	}

	ordered := make([]uuid.UUID, 0, len(req.ItemIDs))
	for _, raw := range req.ItemIDs {
		id, parseErr := uuid.Parse(raw)
		if parseErr != nil {
			return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid media item id: " + raw})
		}
		ordered = append(ordered, id)
	}

	if err := h.collectionService.ReorderItems(c.Request().Context(), collectionID, ordered); err != nil {
		return c.JSON(http.StatusInternalServerError, map[string]string{"error": err.Error()})
	}
	return c.JSON(http.StatusOK, map[string]string{"status": "reordered"})
}

// optionalFlag interprets a multi-valued form flag: last value wins
// (hidden-false sibling precedes the checkbox), absent → nil (untouched).
func optionalFlag(values []string) *bool {
	if len(values) == 0 {
		return nil
	}
	v := strings.EqualFold(values[len(values)-1], "true")
	return &v
}