feat(meta,core,app,android,ios): AniSkip where files have no chapters

Most files that are not fansub releases carry no chapters, so they had no
skip button. AniSkip knows where an episode's opening and ending are, by
MyAnimeList id and episode number. ani.zip sends each entry's MyAnimeList
id and enrichment now keeps it on every episode row; schema v14 adds the
column and marks AniList titles un-enriched, deleting nothing, as v13 did.

When a file has loaded with no chapter naming an opening or ending, and
its length is known, each client asks once, with enrichment on only. The
answer lives as long as the file is open. with_skip_ranges cuts it into
the chapters as chapters named Opening and Ending, so the skip button,
auto-skip, the up-next countdown and the seek bar's marks all work
through the code a chaptered file uses. A file's own opening or ending
always wins over AniSkip's.

PRIVACY.md lists what is sent: the MyAnimeList id, the episode number and
the file's length.

crates/pstr-core/src/catalog.rs

@@ -24,7 +24,7 @@ use crate::metadata::{
 use crate::naming::{self, ParsedName};
 
 /// Bump when adding a migration.
-pub const SCHEMA_VERSION: i64 = 13;
+pub const SCHEMA_VERSION: i64 = 14;
 
 const MIGRATION_V1: &str = r#"
 CREATE TABLE nodes (
@@ -255,6 +255,16 @@ ALTER TABLE episode_metadata ADD COLUMN runtime INTEGER;
 UPDATE title_metadata SET enriched_at = NULL WHERE provider = 'anilist';
 "#;
 
+/// Each episode's MyAnimeList id, for AniSkip.
+///
+/// ani.zip sends it with every entry and it was not kept. As with V13, every
+/// AniList title is marked un-enriched so the next match run fills it in, and
+/// nothing is deleted meanwhile.
+const MIGRATION_V14: &str = r#"
+ALTER TABLE episode_metadata ADD COLUMN mal_id INTEGER;
+UPDATE title_metadata SET enriched_at = NULL WHERE provider = 'anilist';
+"#;
+
 /// How old a share's last crawl may be before an app looks again on its own.
 /// Long enough that a launch rarely costs a crawl; short enough that a new
 /// episode turns up the same day.
@@ -516,6 +526,12 @@ impl Catalog {
             tx.pragma_update(None, "user_version", 13)?;
             tx.commit()?;
         }
+        if version < 14 {
+            let tx = self.conn.transaction()?;
+            tx.execute_batch(MIGRATION_V14)?;
+            tx.pragma_update(None, "user_version", 14)?;
+            tx.commit()?;
+        }
 
         Ok(())
     }
@@ -1266,7 +1282,7 @@ impl Catalog {
     pub fn all_episode_metadata(&self) -> Result<HashMap<String, EpisodeGuide>> {
         let mut statement = self.conn.prepare(
             "SELECT title_key, season, number, name, overview, still_url, air_date,
-                    absolute, entry_season, entry_number, runtime
+                    absolute, entry_season, entry_number, runtime, mal_id
              FROM episode_metadata",
         )?;
         let rows = statement.query_map([], |row| {
@@ -1285,6 +1301,7 @@ impl Catalog {
                     still_url: row.get(5)?,
                     air_date: row.get(6)?,
                     runtime: row.get(10)?,
+                    mal_id: row.get(11)?,
                 },
             ))
         })?;
@@ -1391,8 +1408,8 @@ fn replace_episodes(
         "INSERT OR REPLACE INTO episode_metadata (
              title_key, season, number, provider, fetched_at,
              name, overview, still_url, air_date,
-             absolute, entry_season, entry_number, runtime
-         ) VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10, ?11, ?12, ?13)",
+             absolute, entry_season, entry_number, runtime, mal_id
+         ) VALUES (?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8, ?9, ?10, ?11, ?12, ?13, ?14)",
     )?;
     for episode in episodes {
         insert.execute(params![
@@ -1409,6 +1426,7 @@ fn replace_episodes(
             episode.entry_season,
             episode.entry_number,
             episode.runtime,
+            episode.mal_id,
         ])?;
     }
     Ok(())
@@ -2106,6 +2124,7 @@ mod tests {
                     still_url: None,
                     air_date: None,
                     runtime: None,
+                    mal_id: None,
                 }],
             )
             .expect("store episodes");
@@ -2199,6 +2218,7 @@ mod tests {
                 still_url: None,
                 air_date: Some("2010-11-14".into()),
                 runtime: None,
+                mal_id: None,
             },
             EpisodeMetadata {
                 season: Some(1),
@@ -2211,6 +2231,7 @@ mod tests {
                 still_url: Some("still.jpg".into()),
                 air_date: None,
                 runtime: None,
+                mal_id: None,
             },
         ];
         catalog
@@ -2254,6 +2275,7 @@ mod tests {
             still_url: None,
             air_date: None,
             runtime: Some(24),
+            mal_id: None,
         };
         catalog
             .set_episode_metadata(
@@ -2298,6 +2320,7 @@ mod tests {
                     still_url: None,
                     air_date: None,
                     runtime: None,
+                    mal_id: None,
                 }],
             )
             .expect("store episodes");
@@ -2355,6 +2378,7 @@ mod tests {
                     still_url: None,
                     air_date: None,
                     runtime: None,
+                    mal_id: None,
                 }],
             )
             .expect("store episodes");
@@ -2463,6 +2487,7 @@ mod tests {
                 still_url: None,
                 air_date: None,
                 runtime: None,
+                mal_id: None,
             }],
             backdrop_url: None,
             logo_url: None,
@@ -2524,6 +2549,7 @@ mod tests {
             still_url: None,
             air_date: Some(air_date.into()),
             runtime: None,
+            mal_id: None,
         };
         let enrichment = Enrichment {
             episodes: vec![
@@ -2591,6 +2617,7 @@ mod tests {
                 still_url: None,
                 air_date: None,
                 runtime: None,
+                mal_id: None,
             }],
             backdrop_url: Some("fanart.jpg".into()),
             logo_url: None,
@@ -2909,6 +2936,7 @@ mod tests {
                     still_url: None,
                     air_date: None,
                     runtime: None,
+                    mal_id: None,
                 }],
             )
             .expect("store");

crates/pstr-core/src/chapters.rs

@@ -294,6 +294,116 @@ pub fn chapter_at(chapters: &[Chapter], position: f64) -> Option<usize> {
         .rposition(|chapter| position + f64::EPSILON >= chapter.start)
 }
 
+/// A stretch of a file someone has marked as its opening or its ending, for
+/// a file whose own chapters do not say: AniSkip's answer, in the file's
+/// seconds.
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub struct SkipRange {
+    /// [`ChapterRole::Opening`] or [`ChapterRole::Ending`].
+    pub role: ChapterRole,
+    pub start: f64,
+    pub end: f64,
+}
+
+impl SkipRange {
+    /// What the chapter cut for it is called, which is also what [`roles`]
+    /// reads it back as.
+    fn label(self) -> Option<&'static str> {
+        match self.role {
+            ChapterRole::Opening => Some("Opening"),
+            ChapterRole::Ending => Some("Ending"),
+            ChapterRole::Preview | ChapterRole::Content => None,
+        }
+    }
+}
+
+/// How close two chapter starts may be before they are the same place.
+const SAME_PLACE_SECONDS: f64 = 1.0;
+
+/// The file's chapters with `ranges` cut into them, as chapters named
+/// `Opening` and `Ending` — so that skipping, skipping on its own, the up-next
+/// countdown and the marks on the seek bar all work for a file that came with
+/// no such chapters, through the same code as one that did.
+///
+/// **The file wins.** When its own chapters already mark an opening or an
+/// ending, it is returned as it is: what the release says about its own cut
+/// beats what a viewer of some other release said. A file chapter that starts
+/// inside a range is dropped, since it would split the range in two; one that
+/// starts where a range ends gives that place its name. Every chapter is
+/// numbered again from zero, which is what the players key "already skipped"
+/// by.
+pub fn with_skip_ranges(
+    chapters: &[Chapter],
+    ranges: &[SkipRange],
+    duration: Option<f64>,
+) -> Vec<Chapter> {
+    let own = roles(chapters, duration);
+    if ranges.is_empty()
+        || own
+            .iter()
+            .any(|role| matches!(role, ChapterRole::Opening | ChapterRole::Ending))
+    {
+        return chapters.to_vec();
+    }
+
+    let mut ranges: Vec<SkipRange> = ranges
+        .iter()
+        .copied()
+        .filter(|range| range.label().is_some() && range.start >= 0.0 && range.end > range.start)
+        .collect();
+    ranges.sort_by(|a, b| a.start.total_cmp(&b.start));
+    // Two answers that overlap cannot both be right; the earlier one stays.
+    let mut kept: Vec<SkipRange> = Vec::with_capacity(ranges.len());
+    for range in ranges {
+        if kept.last().is_none_or(|last| range.start >= last.end) {
+            kept.push(range);
+        }
+    }
+
+    let title_at = |position: f64| {
+        chapter_at(chapters, position).and_then(|index| chapters[index].title.clone())
+    };
+    let mut points: Vec<(f64, Option<String>)> = Vec::new();
+    for range in &kept {
+        points.push((range.start, range.label().map(str::to_owned)));
+        let ends_the_file =
+            duration.is_some_and(|duration| range.end >= duration - SAME_PLACE_SECONDS);
+        if !ends_the_file {
+            points.push((range.end, title_at(range.end)));
+        }
+    }
+    let near_a_point = |start: f64, points: &[(f64, Option<String>)]| {
+        points
+            .iter()
+            .any(|(at, _)| (at - start).abs() < SAME_PLACE_SECONDS)
+    };
+    let inside_a_range = |start: f64| {
+        kept.iter()
+            .any(|range| start > range.start && start < range.end)
+    };
+    let from_ranges = points.clone();
+    for chapter in chapters {
+        if !near_a_point(chapter.start, &from_ranges) && !inside_a_range(chapter.start) {
+            points.push((chapter.start, chapter.title.clone()));
+        }
+    }
+    // Whatever comes before the first mark is a place in the file too.
+    if !points.iter().any(|(at, _)| *at < SAME_PLACE_SECONDS) {
+        points.push((0.0, None));
+    }
+    points.sort_by(|a, b| a.0.total_cmp(&b.0));
+
+    points
+        .into_iter()
+        .enumerate()
+        .map(|(index, (start, title))| Chapter {
+            index: index as i64,
+            title,
+            start,
+        })
+        .collect()
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -480,4 +590,123 @@ mod tests {
         // and a button that seeks to zero would be worse than no button.
         assert_eq!(chapter_end(&chapters, 1, None), None);
     }
+
+    fn range(role: ChapterRole, start: f64, end: f64) -> SkipRange {
+        SkipRange { role, start, end }
+    }
+
+    fn shape(chapters: &[Chapter]) -> Vec<(i64, Option<&str>, f64)> {
+        chapters
+            .iter()
+            .map(|chapter| (chapter.index, chapter.title.as_deref(), chapter.start))
+            .collect()
+    }
+
+    #[test]
+    fn a_file_with_no_chapters_gets_its_opening_and_ending_as_chapters_that_skip() {
+        let ranges = [
+            range(ChapterRole::Opening, 90.0, 180.0),
+            range(ChapterRole::Ending, 1300.0, 1390.0),
+        ];
+        let chapters = with_skip_ranges(&[], &ranges, Some(1420.0));
+        assert_eq!(
+            shape(&chapters),
+            vec![
+                (0, None, 0.0),
+                (1, Some("Opening"), 90.0),
+                (2, None, 180.0),
+                (3, Some("Ending"), 1300.0),
+                (4, None, 1390.0),
+            ]
+        );
+        let roles = roles(&chapters, Some(1420.0));
+        assert_eq!(roles[1], ChapterRole::Opening);
+        assert_eq!(roles[3], ChapterRole::Ending);
+    }
+
+    #[test]
+    fn a_files_own_opening_beats_anything_aniskip_says() {
+        let own = vec![
+            Chapter {
+                index: 0,
+                title: Some("Prologue".into()),
+                start: 0.0,
+            },
+            Chapter {
+                index: 1,
+                title: Some("OP".into()),
+                start: 60.0,
+            },
+            Chapter {
+                index: 2,
+                title: Some("Part A".into()),
+                start: 150.0,
+            },
+        ];
+        let ranges = [range(ChapterRole::Opening, 70.0, 160.0)];
+        assert_eq!(with_skip_ranges(&own, &ranges, Some(1420.0)), own);
+    }
+
+    #[test]
+    fn unnamed_chapters_inside_a_range_give_way_and_one_at_its_end_keeps_its_name() {
+        let own = vec![
+            Chapter {
+                index: 0,
+                title: None,
+                start: 0.0,
+            },
+            Chapter {
+                index: 1,
+                title: None,
+                start: 89.6,
+            },
+            Chapter {
+                index: 2,
+                title: None,
+                start: 120.0,
+            },
+            Chapter {
+                index: 3,
+                title: Some("Part A".into()),
+                start: 180.0,
+            },
+        ];
+        let ranges = [range(ChapterRole::Opening, 90.0, 180.0)];
+        let chapters = with_skip_ranges(&own, &ranges, Some(1420.0));
+        assert_eq!(
+            shape(&chapters),
+            vec![
+                (0, None, 0.0),
+                (1, Some("Opening"), 90.0),
+                (2, Some("Part A"), 180.0)
+            ]
+        );
+    }
+
+    #[test]
+    fn an_ending_that_runs_to_the_end_of_the_file_adds_no_chapter_after_it() {
+        let ranges = [range(ChapterRole::Ending, 1330.0, 1419.8)];
+        let chapters = with_skip_ranges(&[], &ranges, Some(1420.0));
+        assert_eq!(
+            shape(&chapters),
+            vec![(0, None, 0.0), (1, Some("Ending"), 1330.0)]
+        );
+        assert_eq!(
+            credits_start(&chapters, &roles(&chapters, Some(1420.0))),
+            Some(1330.0)
+        );
+    }
+
+    #[test]
+    fn overlapping_answers_keep_the_earlier_one() {
+        let ranges = [
+            range(ChapterRole::Opening, 0.0, 90.0),
+            range(ChapterRole::Ending, 60.0, 150.0),
+        ];
+        let chapters = with_skip_ranges(&[], &ranges, Some(1420.0));
+        assert_eq!(
+            shape(&chapters),
+            vec![(0, Some("Opening"), 0.0), (1, None, 90.0)]
+        );
+    }
 }

crates/pstr-core/src/discover.rs

@@ -557,6 +557,7 @@ mod tests {
             still_url: None,
             air_date: None,
             runtime: None,
+            mal_id: None,
         }]);
         let guides = HashMap::from([("frieren".to_owned(), guide)]);
 

crates/pstr-core/src/metadata.rs

@@ -420,6 +420,11 @@ pub struct EpisodeMetadata {
     /// Minutes.
     #[serde(default)]
     pub runtime: Option<u32>,
+    /// The provider entry's id on MyAnimeList, which is what AniSkip knows
+    /// openings and endings by. With `entry_number`, it names this episode
+    /// there.
+    #[serde(default)]
+    pub mal_id: Option<u32>,
 }
 
 /// What enriching a matched title found: its episodes, and art the search
@@ -735,6 +740,7 @@ mod tests {
             still_url: None,
             air_date: None,
             runtime: None,
+            mal_id: None,
         }
     }