feat(router): implement dual-mode search endpoint (HTML/JSON)

Rewrite /api/media-items/search endpoint to detect HTMX requests and return appropriate response format. The endpoint now checks for HX-Request header and routes to HTML renderer or JSON handler accordingly.

- Check HX-Request header to detect HTMX requests
- Return HTML via BooksGrid template for HTMX requests
- Return JSON for API clients (existing behavior)
- Add handleSearchHTML function for HTML rendering
- Use shared MediaHandler.ExecuteSearch method
- Eliminates previous issue where JSON was rendered in browser

internal/router/search.go

@@ -1,13 +1,126 @@
 package router
 
+import (
+	"bookhoard/internal/database"
+	"bookhoard/internal/handlers"
+	"bookhoard/internal/services"
+	"bookhoard/internal/utils"
+	"bookhoard/templates"
+	"bytes"
+	"log"
+	"net/http"
+	"strconv"
+
+	"github.com/google/uuid"
+	"github.com/jackc/pgx/v5/pgtype"
+	"github.com/labstack/echo/v5"
+)
+
 func registerSearchRoutes(cfg *Config) {
 	e := cfg.Echo
-
 	// JWT middleware for protected routes
 	jwtMiddleware := createJWTMiddleware(cfg)
 	protected := e.Group("/api", jwtMiddleware)
+	// Search endpoint - returns JSON or HTML based on HX-Request header
+	protected.GET("/media-items/search", func(c *echo.Context) error {
+		// Check if HTMX request (expects HTML)
+		if c.Request().Header.Get("HX-Request") == "true" {
+			return handleSearchHTML(c, cfg)
+		}
 
-	// Search and query endpoints (all authenticated users)
-	protected.GET("/media-items/search", cfg.MediaHandler.SearchMediaItems)
+		// Otherwise return JSON (API clients)
+		return cfg.MediaHandler.SearchMediaItems(c)
+	})
 	protected.POST("/sync/books/query", cfg.MatchingHandler.QueryBooks)
 }
+
+// handleSearchHTML renders HTML response for HTMX requests
+func handleSearchHTML(c *echo.Context, cfg *Config) error {
+	user, ok := c.Get("user").(database.Users)
+	if !ok {
+		return c.String(http.StatusUnauthorized, "Unauthorized")
+	}
+	// Extract query parameters
+	query := c.QueryParam("q")
+	libraryID := c.QueryParam("library_id")
+	limit, _ := strconv.Atoi(c.QueryParam("limit"))
+	if limit == 0 {
+		limit = 50
+	}
+	offset, _ := strconv.Atoi(c.QueryParam("offset"))
+	// Validate library_id
+	var libUUID pgtype.UUID
+	if libraryID != "" {
+		lib, err := uuid.Parse(libraryID)
+		if err != nil {
+			return c.String(http.StatusBadRequest, "invalid library_id")
+		}
+		libUUID = pgtype.UUID{Bytes: lib, Valid: true}
+	} else {
+		libUUID = pgtype.UUID{Valid: false}
+	}
+	// Extract filters
+	authorFilter := c.QueryParam("author_filter")
+	seriesFilter := c.QueryParam("series_filter")
+	genreFilter := c.QueryParam("genre_filter")
+	tagsFilter := c.QueryParam("tags_filter")
+	languageFilter := c.QueryParam("language_filter")
+	yearMin, _ := strconv.Atoi(c.QueryParam("year_min"))
+	yearMax, _ := strconv.Atoi(c.QueryParam("year_max"))
+	hasCover := c.QueryParam("has_cover") == "true"
+	sortParam := c.QueryParam("sort")
+	if sortParam == "" {
+		sortParam = "title ASC"
+	}
+	// Build search params
+	params := services.SearchParams{
+		UserID:         user.ID,
+		LibraryID:      libUUID,
+		SearchQuery:    query,
+		AuthorFilter:   authorFilter,
+		SeriesFilter:   seriesFilter,
+		GenreFilter:    genreFilter,
+		TagsFilter:     tagsFilter,
+		LanguageFilter: languageFilter,
+		YearMin:        yearMin,
+		YearMax:        yearMax,
+		HasCover:       hasCover,
+		Sort:           sortParam,
+		Limit:          limit,
+		Offset:         offset,
+	}
+	// Execute search using handler method
+	results, totalCount, err := cfg.MediaHandler.ExecuteSearch(c.Request().Context(), params)
+	if err != nil {
+		log.Printf("Search error: %v", err)
+		return c.HTML(http.StatusInternalServerError, `<div style="color: red;">Search error</div>`)
+	}
+	// Convert to BookInfo
+	bookInfoList := make([]handlers.BookInfo, len(results))
+	for i, book := range results {
+		bookUUID, _ := uuid.FromBytes(book.ID.Bytes[0:16])
+		bookLibUUID, _ := uuid.FromBytes(book.LibraryID.Bytes[0:16])
+		bookInfoList[i] = handlers.BookInfo{
+			MediaItemID:    bookUUID.String(),
+			Title:          book.Title,
+			Author:         textToString(book.Author),
+			CoverImagePath: utils.ResolveMediaURL(pgtype.UUID{Bytes: bookLibUUID, Valid: true}, book.CoverImagePath),
+		}
+	}
+	// Render using BooksGrid template
+	var buf bytes.Buffer
+	err = templates.BooksGrid(bookInfoList, limit, offset, totalCount, libraryID).Render(c.Request().Context(), &buf)
+	if err != nil {
+		log.Printf("Template render error: %v", err)
+		return c.HTML(http.StatusInternalServerError, `<div style="color: red;">Render error</div>`)
+	}
+	return c.HTML(http.StatusOK, buf.String())
+}
+
+// textToString converts pgtype.Text to string
+func textToString(t pgtype.Text) string {
+	if t.Valid {
+		return t.String
+	}
+	return ""
+}