Import lists from CSV or text and match each entry

The list editor gets an Import button. A .csv/.tsv/.txt file or pasted
text is parsed on the server: header columns (Title, Year, Artist or
Director, Note, Rank), numbered lines and trailing "(1999)" years are
understood, and Canon's own export round-trips.

Each row is then searched with the list's provider and scored. A row is
matched automatically only when one result fits exactly and nothing else
fits as well; a year or artist in the file breaks ties, an exact title
beats a bracketed version like "(Live)", and "Artist - Title" lines are
tried both ways. Custom lists need a year or subtitle to be certain.
Everything else is shown for review with a recommended pick, the other
results, "Add as written", Skip, and a search-again box. Entries are
added in file order after the existing ones, with any notes from the
file.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/server/import.go

@@ -0,0 +1,114 @@
+package server
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/http"
+	"strings"
+	"time"
+	"unicode/utf8"
+
+	"github.com/cdnutter/canon/internal/importer"
+	"github.com/cdnutter/canon/internal/store"
+)
+
+const maxImportBytes = 2 << 20
+
+// apiImportParse reads an uploaded CSV/TXT file, or pasted text, into rows.
+func (s *Server) apiImportParse(w http.ResponseWriter, r *http.Request) {
+	r.Body = http.MaxBytesReader(w, r.Body, maxImportBytes+64<<10)
+	var data []byte
+	name := "pasted.txt"
+	if strings.HasPrefix(r.Header.Get("Content-Type"), "multipart/") {
+		f, hdr, err := r.FormFile("file")
+		if err != nil {
+			s.writeErr(w, store.ValidationError{Msg: "Choose a .csv or .txt file (up to 2 MB)."})
+			return
+		}
+		defer f.Close()
+		if data, err = io.ReadAll(f); err != nil {
+			s.writeErr(w, store.ValidationError{Msg: "That file is too big (2 MB at most)."})
+			return
+		}
+		name = hdr.Filename
+	} else {
+		var in struct {
+			Text string `json:"text"`
+		}
+		if err := decodeJSON(r, &in); err != nil {
+			s.writeErr(w, err)
+			return
+		}
+		data = []byte(in.Text)
+	}
+	rows, err := importer.Parse(data, name)
+	if err != nil {
+		if errors.Is(err, importer.ErrEmpty) {
+			err = store.ValidationError{Msg: "No titles found. Use one title per line, or a CSV with a Title column."}
+		} else {
+			err = store.ValidationError{Msg: err.Error()}
+		}
+		s.writeErr(w, err)
+		return
+	}
+	writeJSON(w, http.StatusOK, map[string]any{"rows": rows, "max": importer.MaxRows})
+}
+
+type importMatch struct {
+	Status  string         `json:"status"`
+	Results []searchResult `json:"results"`
+}
+
+// apiImportMatch searches for one imported row and says how sure the best
+// result is.
+func (s *Server) apiImportMatch(w http.ResponseWriter, r *http.Request) {
+	ctx := r.Context()
+	listID, err := pathID(r)
+	if err != nil {
+		s.writeErr(w, err)
+		return
+	}
+	var row importer.Row
+	if err := decodeJSON(r, &row); err != nil {
+		s.writeErr(w, err)
+		return
+	}
+	row.Title = strings.TrimSpace(row.Title)
+	if row.Title == "" || utf8.RuneCountInString(row.Title) > 300 {
+		writeError(w, http.StatusBadRequest, "Each entry needs a title.")
+		return
+	}
+	list, err := s.store.ListByID(ctx, listID)
+	if err != nil {
+		s.writeErr(w, err)
+		return
+	}
+	p, err := s.providers.For(ctx, list.Category)
+	if err != nil {
+		s.writeErr(w, err)
+		return
+	}
+	sctx, cancel := context.WithTimeout(ctx, 20*time.Second)
+	defer cancel()
+	results, err := p.Search(sctx, importer.Query(row, list.Category))
+	if err != nil {
+		s.log.Warn("import search failed", "provider", p.Name(), "err", err)
+		writeError(w, http.StatusBadGateway, fmt.Sprintf("%s search failed: %v", p.Label(), err))
+		return
+	}
+	status, scored := importer.Rank(row, list.Category, results)
+	out := importMatch{Status: status, Results: []searchResult{}}
+	for _, sc := range scored[:min(len(scored), 6)] {
+		sr := searchResult{Result: sc.Result}
+		if sc.Provider == "deezer" && hasPreviews(list.Category) {
+			sr.PreviewRef = sc.ProviderID
+		}
+		if it, err := s.store.FindItemByProvider(ctx, listID, sc.Provider, sc.ProviderID); err == nil {
+			sr.ExistingRank = it.Rank
+		}
+		out.Results = append(out.Results, sr)
+	}
+	writeJSON(w, http.StatusOK, out)
+}

internal/server/server.go

@@ -146,6 +146,8 @@ func (s *Server) Handler() http.Handler {
 	api("POST /api/items/{id}/refresh", s.apiRefreshItem)
 	api("DELETE /api/items/{id}", s.apiDeleteItem)
 	api("GET /api/search", s.apiSearch)
+	api("POST /api/import/parse", s.apiImportParse)
+	api("POST /api/lists/{id}/import/match", s.apiImportMatch)
 	api("GET /api/settings", s.apiSettings)
 	api("PUT /api/settings", s.apiUpdateSettings)
 	api("POST /api/settings/avatar", s.apiUploadAvatar)