feat: generalize text extraction to office docs

- swapped mimetype detect with gabriel-vasile/mimetype

Author: Bajahaw

backend/cmd/chat/utils.go

@@ -127,7 +127,7 @@ func buildContext(convID string, start int, user string) []providers.SimpleMessa
 			// embed docs and encode the rest if agentic retrieval is on, otherwise just provide links to files
 			for _, att := range msg.Attachments {
 
-				if att.File.Type == "application/pdf" && agenticRetrieval {
+				if fs.IsRetrievableDoc(att.File.Type) && agenticRetrieval {
 					// content of first page, model will figure to use tools to get rest of content if needed
 					msg.Content += embeddedAttachment(att)
 					continue

backend/cmd/files/pdf-utils.go

@@ -23,7 +23,7 @@ var (
 	matrixRe = regexp.MustCompile(`transform:matrix\([^,]+,[^,]+,[^,]+,[^,]+,\s*([-0-9.]+)\s*,\s*([-0-9.]+)\s*\)`)
 )
 
-func readPDFPages(path string, fileID string) ([]FilePage, error) {
+func readDocPages(path string, fileID string) ([]FilePage, error) {
 	doc, err := fitz.New(path)
 	if err != nil {
 		return nil, err
@@ -53,7 +53,7 @@ func readPDFPages(path string, fileID string) ([]FilePage, error) {
 			Content:    pageText,
 		})
 	}
-	log.Debug("Extracted pages from PDF", "pages", len(pages))
+	log.Debug("Extracted pages from document", "pages", len(pages))
 	return pages, nil
 }
 

backend/cmd/files/utils.go

@@ -9,14 +9,14 @@ import (
 	"image/png"
 	"io"
 	"mime/multipart"
-	"net/http"
 	"os"
 	"path"
 	"strconv"
 	"strings"
 	"time"
 
 	"github.com/Bajahaw/ai-ui/cmd/providers"
+	"github.com/gabriel-vasile/mimetype"
 
 	"github.com/google/uuid"
 )
@@ -135,27 +135,24 @@ func saveUploadedFile(file multipart.File, handler *multipart.FileHeader, user s
 }
 
 func detectFileType(file multipart.File) (string, error) {
-	buf := make([]byte, 512)
-	n, err := file.Read(buf)
-	if err != nil && err != io.EOF {
+	mtype, err := mimetype.DetectReader(file)
+	if err != nil {
 		return "", err
 	}
-	if n == 0 {
+	if mtype.String() == "" {
 		return "", fmt.Errorf("empty file")
 	}
 
-	fileType := http.DetectContentType(buf[:n])
-	log.Debug("Uploaded file type", "type", fileType)
+	log.Debug("Uploaded file type", "type", mtype.String())
 
-	// Reset file read pointer: prefer Seek if available
+	// Reset file read pointer
 	if seeker, ok := file.(io.Seeker); ok {
-		_, err = seeker.Seek(0, io.SeekStart)
-		if err != nil {
+		if _, err := seeker.Seek(0, io.SeekStart); err != nil {
 			return "", err
 		}
 	}
 
-	return fileType, nil
+	return mtype.String(), nil
 }
 
 // compressImage reads an image from r and re-encodes it with conservative
@@ -210,21 +207,21 @@ func extractFileContent(file File, model string) (string, error) {
 		return string(fileContent), nil
 	}
 
-	if file.Type == "application/pdf" {
-		pages, err := readPDFPages(file.Path, file.ID)
+	if IsRetrievableDoc(file.Type) {
+		pages, err := readDocPages(file.Path, file.ID)
 		if err != nil {
-			log.Error("Error reading PDF pages", "err", err)
+			log.Error("Error reading document pages", "err", err, "type", file.Type)
 			return "", err
 		}
 
 		// indexing all pages individually to allow retrieval of specific pages later.
 		err = repo.SavePages(pages)
 		if err != nil {
-			log.Error("Error saving PDF pages", "err", err)
+			log.Error("Error saving document pages", "err", err)
 			return "", err
 		}
 
-		return "PDF content page 1: \n\n" + pages[0].Content + "... retrieve rest of content using tools", nil
+		return "Document content page 1: \n\n" + pages[0].Content + "... retrieve rest of content using tools", nil
 	}
 
 	if strings.HasPrefix(file.Type, "image/") {
@@ -259,3 +256,20 @@ func extractFileContent(file File, model string) (string, error) {
 
 	return "", fmt.Errorf("unsupported file type for content extraction: %s", file.Type)
 }
+
+// IsRetrievableDoc returns true for document types supported by go-fitz
+// that can be page-extracted and searched via agentic retrieval tools.
+func IsRetrievableDoc(mimeType string) bool {
+	switch mimeType {
+	case "application/pdf",
+		"application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+		"application/vnd.openxmlformats-officedocument.presentationml.presentation",
+		"application/vnd.openxmlformats-officedocument.spreadsheetml.sheet",
+		"application/vnd.oasis.opendocument.text",
+		"application/vnd.oasis.opendocument.presentation",
+		"application/vnd.oasis.opendocument.spreadsheet",
+		"application/epub+zip":
+		return true
+	}
+	return false
+}

backend/go.mod

@@ -5,6 +5,7 @@ go 1.25.5
 require (
 	github.com/charmbracelet/log v1.0.0
 	github.com/evgensoft/ddgo v0.0.0-20250604183002-54c292420e4d
+	github.com/gabriel-vasile/mimetype v1.4.13
 	github.com/gen2brain/go-fitz v1.24.15
 	github.com/golang-jwt/jwt/v5 v5.3.1
 	github.com/google/uuid v1.6.0

backend/go.sum

@@ -30,6 +30,8 @@ github.com/ebitengine/purego v0.8.4 h1:CF7LEKg5FFOsASUj0+QwaXf8Ht6TlFxg09+S9wz0o
 github.com/ebitengine/purego v0.8.4/go.mod h1:iIjxzd6CiRiOG0UyXP+V1+jWqUXVjPKLAI0mRfJZTmQ=
 github.com/evgensoft/ddgo v0.0.0-20250604183002-54c292420e4d h1:V9TIlV+eSq9hrPOZs7Kcy5vUQxvros/8EekC3lewb/4=
 github.com/evgensoft/ddgo v0.0.0-20250604183002-54c292420e4d/go.mod h1:S42fkdocqGLIlRR2F3cJMp5yTv6C8SRI8ppzIPhuhTc=
+github.com/gabriel-vasile/mimetype v1.4.13 h1:46nXokslUBsAJE/wMsp5gtO500a4F3Nkz9Ufpk2AcUM=
+github.com/gabriel-vasile/mimetype v1.4.13/go.mod h1:d+9Oxyo1wTzWdyVUPMmXFvp4F9tea18J8ufA774AB3s=
 github.com/gen2brain/go-fitz v1.24.15 h1:sJNB1MOWkqnzzENPHggFpgxTwW0+S5WF/rM5wUBpJWo=
 github.com/gen2brain/go-fitz v1.24.15/go.mod h1:SftkiVbTHqF141DuiLwBBM65zP7ig6AVDQpf2WlHamo=
 github.com/go-logfmt/logfmt v0.6.1 h1:4hvbpePJKnIzH1B+8OR/JPbTx37NktoI9LE2QZBBkvE=