Add CSV preview

ftl/core/importing.ftl

@@ -108,3 +108,4 @@ importing-preserve = Preserve
 importing-update = Update
 importing-tag-all-notes = Tag all notes
 importing-tag-updated-notes = Tag updated notes
+importing-file = File

proto/anki/import_export.proto

@@ -163,6 +163,7 @@ message CsvMetadata {
   uint32 tags_column = 10;
   bool force_delimiter = 11;
   bool force_is_html = 12;
+  repeated generic.StringList preview = 13;
 }
 
 message ExportCardCsvRequest {

rslib/src/import_export/text/csv/import.rs

@@ -135,16 +135,10 @@ impl ColumnContext {
 
     fn deserialize_csv(
         &mut self,
-        mut reader: impl Read + Seek,
+        reader: impl Read + Seek,
         delimiter: Delimiter,
     ) -> Result<Vec<ForeignNote>> {
-        remove_tags_line_from_reader(&mut reader)?;
-        let mut csv_reader = csv::ReaderBuilder::new()
-            .has_headers(false)
-            .flexible(true)
-            .comment(Some(b'#'))
-            .delimiter(delimiter.byte())
-            .from_reader(reader);
+        let mut csv_reader = build_csv_reader(reader, delimiter)?;
         self.deserialize_csv_reader(&mut csv_reader)
     }
 
@@ -210,6 +204,19 @@ impl ColumnContext {
     }
 }
 
+pub(super) fn build_csv_reader(
+    mut reader: impl Read + Seek,
+    delimiter: Delimiter,
+) -> Result<csv::Reader<impl Read + Seek>> {
+    remove_tags_line_from_reader(&mut reader)?;
+    Ok(csv::ReaderBuilder::new()
+        .has_headers(false)
+        .flexible(true)
+        .comment(Some(b'#'))
+        .delimiter(delimiter.byte())
+        .from_reader(reader))
+}
+
 fn stringify_fn(is_html: bool) -> fn(&str) -> String {
     if is_html {
         ToString::to_string
@@ -275,6 +282,7 @@ mod test {
                     id: 1,
                     field_columns: vec![1, 2],
                 })),
+                preview: Vec::new(),
             }
         }
     }

rslib/src/import_export/text/csv/metadata.rs

@@ -7,17 +7,24 @@ use std::{
     io::{BufRead, BufReader, Read, Seek, SeekFrom},
 };
 
+use itertools::Itertools;
 use strum::IntoEnumIterator;
 
+use super::import::build_csv_reader;
 pub use crate::backend_proto::import_export::{
     csv_metadata::{Deck as CsvDeck, Delimiter, MappedNotetype, Notetype as CsvNotetype},
     CsvMetadata,
 };
 use crate::{
-    error::ImportError, import_export::text::NameOrId, notetype::NoteField, prelude::*,
-    text::is_html,
+    backend_proto::StringList, error::ImportError, import_export::text::NameOrId,
+    notetype::NoteField, prelude::*, text::is_html,
 };
 
+/// The maximum number of preview rows.
+const PREVIEW_LENGTH: usize = 5;
+/// The maximum number of characters per preview field.
+const PREVIEW_FIELD_LENGTH: usize = 80;
+
 impl Collection {
     pub fn get_csv_metadata(
         &mut self,
@@ -25,30 +32,22 @@ impl Collection {
         delimiter: Option<Delimiter>,
         notetype_id: Option<NotetypeId>,
     ) -> Result<CsvMetadata> {
-        let reader = BufReader::new(File::open(path)?);
-        self.get_reader_metadata(reader, delimiter, notetype_id)
+        let mut reader = File::open(path)?;
+        self.get_reader_metadata(&mut reader, delimiter, notetype_id)
     }
 
     fn get_reader_metadata(
         &mut self,
-        mut reader: impl BufRead + Seek,
+        mut reader: impl Read + Seek,
         delimiter: Option<Delimiter>,
         notetype_id: Option<NotetypeId>,
     ) -> Result<CsvMetadata> {
         let mut metadata = CsvMetadata::default();
         let meta_len = self.parse_meta_lines(&mut reader, &mut metadata)? as u64;
-
-        reader.seek(SeekFrom::Start(meta_len))?;
-        maybe_set_fallback_delimiter(delimiter, &mut metadata, &mut reader)?;
-
-        reader.seek(SeekFrom::Start(meta_len))?;
-        let mut csv_reader = csv::ReaderBuilder::new()
-            .delimiter(metadata.delimiter().byte())
-            .from_reader(reader);
-        let record = csv_reader.headers()?;
-
-        maybe_set_fallback_columns(&mut metadata, record)?;
-        maybe_set_fallback_is_html(&mut metadata, record)?;
+        maybe_set_fallback_delimiter(delimiter, &mut metadata, &mut reader, meta_len)?;
+        set_preview(&mut metadata, reader)?;
+        maybe_set_fallback_columns(&mut metadata)?;
+        maybe_set_fallback_is_html(&mut metadata)?;
         self.maybe_set_fallback_notetype(&mut metadata, notetype_id)?;
         self.maybe_init_notetype_map(&mut metadata)?;
         self.maybe_set_fallback_deck(&mut metadata)?;
@@ -57,12 +56,9 @@ impl Collection {
     }
 
     /// Parses the meta head of the file and returns the total of meta bytes.
-    fn parse_meta_lines(
-        &mut self,
-        mut reader: impl BufRead,
-        metadata: &mut CsvMetadata,
-    ) -> Result<usize> {
+    fn parse_meta_lines(&mut self, reader: impl Read, metadata: &mut CsvMetadata) -> Result<usize> {
         let mut meta_len = 0;
+        let mut reader = BufReader::new(reader);
         let mut line = String::new();
         let mut line_len = reader.read_line(&mut line)?;
         if self.parse_first_line(&line, metadata) {
@@ -213,6 +209,32 @@ fn parse_columns(line: &str, delimiter: Delimiter) -> Result<Vec<String>> {
     })
 }
 
+fn set_preview(metadata: &mut CsvMetadata, mut reader: impl Read + Seek) -> Result<()> {
+    reader.rewind()?;
+    let mut csv_reader = build_csv_reader(reader, metadata.delimiter())?;
+    let mut records = csv_reader.records().into_iter().take(PREVIEW_LENGTH);
+
+    let first = records.next().transpose()?.unwrap_or_default();
+    metadata.preview.push(build_preview_row(1, &first));
+
+    let min_len = metadata.preview[0].vals.len();
+    for record in records {
+        metadata.preview.push(build_preview_row(min_len, &record?));
+    }
+
+    Ok(())
+}
+
+fn build_preview_row(min_len: usize, record: &csv::StringRecord) -> StringList {
+    StringList {
+        vals: record
+            .iter()
+            .pad_using(min_len, |_| "")
+            .map(|field| field.chars().take(PREVIEW_FIELD_LENGTH).collect())
+            .collect(),
+    }
+}
+
 pub(super) fn collect_tags(txt: &str) -> Vec<String> {
     txt.split_whitespace()
         .filter(|s| !s.is_empty())
@@ -271,24 +293,17 @@ fn ensure_first_field_is_mapped(
     Ok(())
 }
 
-fn maybe_set_fallback_columns(
-    metadata: &mut CsvMetadata,
-    record: &csv::StringRecord,
-) -> Result<()> {
+fn maybe_set_fallback_columns(metadata: &mut CsvMetadata) -> Result<()> {
     if metadata.column_labels.is_empty() {
-        metadata.column_labels = vec![String::new(); record.len()];
+        metadata.column_labels = vec![String::new(); metadata.iter_preview_fields(1).count()];
     }
     Ok(())
 }
 
-fn maybe_set_fallback_is_html(
-    metadata: &mut CsvMetadata,
-    record: &csv::StringRecord,
-) -> Result<()> {
-    // TODO: should probably check more than one line; can reuse preview lines
-    // when it's implemented
+fn maybe_set_fallback_is_html(metadata: &mut CsvMetadata) -> Result<()> {
     if !metadata.force_is_html {
-        metadata.is_html = record.iter().any(is_html);
+        let is_html = metadata.iter_preview_fields(PREVIEW_LENGTH).any(is_html);
+        metadata.is_html = is_html;
     }
     Ok(())
 }
@@ -296,11 +311,13 @@ fn maybe_set_fallback_is_html(
 fn maybe_set_fallback_delimiter(
     delimiter: Option<Delimiter>,
     metadata: &mut CsvMetadata,
-    reader: impl Read,
+    mut reader: impl Read + Seek,
+    meta_len: u64,
 ) -> Result<()> {
     if let Some(delim) = delimiter {
         metadata.set_delimiter(delim);
     } else if !metadata.force_delimiter {
+        reader.seek(SeekFrom::Start(meta_len))?;
         metadata.set_delimiter(delimiter_from_reader(reader)?);
     }
     Ok(())
@@ -401,6 +418,14 @@ impl CsvMetadata {
         }
         columns
     }
+
+    fn iter_preview_fields(&self, rows: usize) -> impl Iterator<Item = &String> {
+        self.preview
+            .iter()
+            .take(rows)
+            .map(|row| row.vals.iter())
+            .flatten()
+    }
 }
 
 impl NameOrId {
@@ -413,6 +438,14 @@ impl NameOrId {
     }
 }
 
+impl From<csv::StringRecord> for StringList {
+    fn from(record: csv::StringRecord) -> Self {
+        Self {
+            vals: record.iter().map(ToString::to_string).collect(),
+        }
+    }
+}
+
 #[cfg(test)]
 mod test {
     use std::io::Cursor;
@@ -425,7 +458,7 @@ mod test {
             metadata!($col, $csv, None)
         };
         ($col:expr,$csv:expr, $delim:expr) => {
-            $col.get_reader_metadata(BufReader::new(Cursor::new($csv.as_bytes())), $delim, None)
+            $col.get_reader_metadata(Cursor::new($csv.as_bytes()), $delim, None)
                 .unwrap()
         };
     }
@@ -620,4 +653,12 @@ mod test {
         let meta = metadata!(col, "#columns:Back\tFront\nfoo,bar,baz\n");
         assert_eq!(meta.unwrap_notetype_map(), &[2, 1]);
     }
+
+    #[test]
+    fn should_gather_first_lines_into_preview() {
+        let mut col = open_test_collection();
+        let meta = metadata!(col, "#separator: \nfoo bar\nbaz\n");
+        assert_eq!(meta.preview[0].vals, ["foo", "bar"]);
+        assert_eq!(meta.preview[1].vals, ["baz", ""]);
+    }
 }

rslib/src/text.rs

@@ -172,8 +172,8 @@ lazy_static! {
     "#).unwrap();
 }
 
-pub fn is_html(text: &str) -> bool {
-    HTML.is_match(text)
+pub fn is_html(text: impl AsRef<str>) -> bool {
+    HTML.is_match(text.as_ref())
 }
 
 pub fn html_to_text_line(html: &str, preserve_media_filenames: bool) -> Cow<str> {

ts/import-csv/ImportCsvPage.svelte

@@ -8,7 +8,13 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import Row from "../components/Row.svelte";
     import Spacer from "../components/Spacer.svelte";
     import * as tr from "../lib/ftl";
-    import { Decks, ImportExport, importExport, Notetypes } from "../lib/proto";
+    import {
+        Decks,
+        Generic,
+        ImportExport,
+        importExport,
+        Notetypes,
+    } from "../lib/proto";
     import DeckSelector from "./DeckSelector.svelte";
     import DelimiterSelector from "./DelimiterSelector.svelte";
     import DupeResolutionSelector from "./DupeResolutionSelector.svelte";
@@ -17,6 +23,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     import HtmlSwitch from "./HtmlSwitch.svelte";
     import { getColumnOptions, getCsvMetadata } from "./lib";
     import NotetypeSelector from "./NotetypeSelector.svelte";
+    import Preview from "./Preview.svelte";
     import StickyFooter from "./StickyFooter.svelte";
     import Tags from "./Tags.svelte";
 
@@ -32,6 +39,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     export let updatedTags: string[];
     export let columnLabels: string[];
     export let tagsColumn: number;
+    export let preview: Generic.StringList[];
     // Protobuf oneofs. Exactly one of these pairs is expected to be set.
     export let notetypeColumn: number | null;
     export let globalNotetype: ImportExport.CsvMetadata.MappedNotetype | null;
@@ -44,6 +52,7 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
     $: columnOptions = getColumnOptions(columnLabels, notetypeColumn, deckColumn);
     $: getCsvMetadata(path, delimiter).then((meta) => {
         columnLabels = meta.columnLabels;
+        preview = meta.preview;
     });
     $: if (globalNotetype?.id !== lastNotetypeId) {
         lastNotetypeId = globalNotetype?.id;
@@ -78,6 +87,15 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
 
 <Container class="csv-page">
     <Row --cols={2}>
+        <Col --col-size={1} breakpoint="md">
+            <Container>
+                <Header heading={tr.importingFile()} />
+                <Spacer --height="1.5rem" />
+                <DelimiterSelector bind:delimiter disabled={forceDelimiter} />
+                <HtmlSwitch bind:isHtml disabled={forceIsHtml} />
+                <Preview {columnOptions} {preview} />
+            </Container>
+        </Col>
         <Col --col-size={1} breakpoint="md">
             <Container>
                 <Header heading={tr.importingImportOptions()} />
@@ -92,8 +110,6 @@ License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
                     <DeckSelector {deckNameIds} bind:deckId />
                 {/if}
                 <DupeResolutionSelector bind:dupeResolution />
-                <DelimiterSelector bind:delimiter disabled={forceDelimiter} />
-                <HtmlSwitch bind:isHtml disabled={forceIsHtml} />
                 <Tags bind:globalTags bind:updatedTags />
             </Container>
         </Col>

ts/import-csv/Preview.svelte

@@ -0,0 +1,55 @@
+<!--
+Copyright: Ankitects Pty Ltd and contributors
+License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
+-->
+<script lang="ts">
+    import type { Generic } from "../lib/proto";
+    import type { ColumnOption } from "./lib";
+
+    export let columnOptions: ColumnOption[];
+    export let preview: Generic.StringList[];
+</script>
+
+<table id="preview">
+    {#each columnOptions.slice(1) as { label }}
+        <th>
+            {label}
+        </th>
+    {/each}
+    {#each preview as row}
+        <tr>
+            {#each row.vals as cell}
+                <td>{cell}</td>
+            {/each}
+        </tr>
+    {/each}
+</table>
+
+<style lang="scss">
+    #preview {
+        border-collapse: collapse;
+        width: 100%;
+        white-space: nowrap;
+
+        th,
+        td {
+            border: 1px solid var(--faint-border);
+            padding: 0.25rem 0.5rem;
+        }
+
+        th {
+            background: var(--medium-border);
+            text-align: center;
+        }
+
+        tr {
+            &:nth-child(even) {
+                background: var(--frame-bg);
+            }
+        }
+
+        td {
+            text-align: start;
+        }
+    }
+</style>

ts/import-csv/index.ts

@@ -60,6 +60,7 @@ export async function setupImportCsvPage(path: string): Promise<ImportCsvPage> {
             columnLabels: metadata.columnLabels,
             tagsColumn: metadata.tagsColumn,
             globalNotetype: metadata.globalNotetype ?? null,
+            preview: metadata.preview,
             // Unset oneof numbers default to 0, which also means n/a here,
             // but it's vital to differentiate between unset and 0 when reserializing.
             notetypeColumn: metadata.notetypeColumn ? metadata.notetypeColumn : null,