Curator/src/core/file_manager/versions.rs

//! Movie versions and parts (Jellyfin "multiple versions" and "stacking").
//!
//! A movie with one video file stays flat (`<Library>/Title (rok) [tmdbid].ext`).
//! The moment a second file is added it is promoted to its own folder, where
//! every file starts with the folder's exact name:
//!
//! ```text
//! <Library>/Title (rok) [tmdbid]/
//!     Title (rok) [tmdbid].ext              (default version, bare name)
//!     Title (rok) [tmdbid] - 3D HSBS.ext    (another version)
//! ```
//!
//! or, for a film split across files, `Title (rok) [tmdbid]-part1.ext`, `-part2`…
//! A folder holds either versions or parts, never both.

use std::fs;
use std::path::{Path, PathBuf};

use super::{FileManager, LibraryKind, is_media_file};
use crate::core::error::{CoreError, CoreResult};
use crate::core::file::{File, now_iso};
use crate::core::movie::{
    DEFAULT_VERSION_LABEL, normalize_3d_label, normalize_part_label, part_label,
};
use crate::core::naming::{is_canonical_pool_stem, parse_3d_format};
use crate::core::paths;
use crate::core::series::looks_like_series_folder;
use crate::core::subtitles;

const PARTS_AND_VERSIONS_MIX: &str = "Film může mít buď díly (přehrají se za sebou), nebo verze (alternativy jako 2D/3D, 4K) — ne obojí v jedné složce. Uprav popisek, nebo nejdřív odeber soubory toho druhého druhu.";

/// How a film's files are laid out.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum GroupMode {
    /// One file in the library root.
    Flat,
    /// A folder of alternatives.
    Versions,
    /// A folder of pieces played back to back.
    Parts,
}

/// Filename of one version in a movie folder: the default version is bare
/// `<stem><ext>`, a part `<stem>-part<N><ext>`, anything else
/// `<stem> - <label><ext>`.
pub fn version_filename(stem: &str, label: &str, ext: &str) -> String {
    let label = label.trim();
    if label.is_empty() || label == DEFAULT_VERSION_LABEL {
        return format!("{stem}{ext}");
    }
    match normalize_part_label(label) {
        Some(part) => format!("{stem}-part{part}{ext}"),
        None => format!("{stem} - {label}{ext}"),
    }
}

/// True when `labels` contain both part labels and version labels.
fn mixes_parts_and_versions<'a>(labels: impl IntoIterator<Item = &'a str>) -> bool {
    let kinds: std::collections::HashSet<bool> = labels
        .into_iter()
        .map(|l| normalize_part_label(l).is_some())
        .collect();
    kinds.len() > 1
}

/// The version label a pooled path implies.
pub fn label_of(path: &Path) -> String {
    File::bare(path).identity_from_path().label
}

fn label_or_default(path: &Path) -> String {
    let l = label_of(path);
    if l.is_empty() {
        DEFAULT_VERSION_LABEL.to_string()
    } else {
        l
    }
}

impl FileManager {
    /// True when `path` is one version inside its own per-movie folder (in a
    /// movie or mixed library; in a mixed one the folder must not be a series).
    pub fn is_movie_group_member(&self, path: &Path) -> bool {
        let (Some(pool), Some(lib)) = (self.pool_dir(), self.library_of(path)) else {
            return false;
        };
        if !self.libraries_accepting_movies().contains(&lib) {
            return false;
        }
        let Some(parent) = path.parent() else {
            return false;
        };
        if parent == pool.join(&lib) || !is_canonical_pool_stem(&paths::name(parent)) {
            return false;
        }
        !(self.library_kind(&lib) == Some(LibraryKind::Mixed) && looks_like_series_folder(parent))
    }

    /// Every version sharing `path`'s movie folder, name-sorted (`[path]` when flat).
    pub fn list_movie_versions(&self, path: &Path) -> Vec<PathBuf> {
        if !self.is_movie_group_member(path) {
            return vec![path.to_path_buf()];
        }
        let folder = path.parent().unwrap_or(Path::new("."));
        paths::entries(folder)
            .into_iter()
            .filter(|p| p.is_file() && is_media_file(p))
            .collect()
    }

    /// The version shown for the movie in the table: plain file first, then the
    /// "Výchozí" one, then alphabetically.
    pub fn primary_version(&self, versions: &[PathBuf]) -> PathBuf {
        versions
            .iter()
            .min_by_key(|p| {
                let label = label_of(p);
                let order = if label.is_empty() {
                    0
                } else if label == DEFAULT_VERSION_LABEL {
                    1
                } else {
                    2
                };
                (order, paths::name(p).to_lowercase())
            })
            .cloned()
            .unwrap_or_default()
    }

    /// `filelist` collapsed to one row per movie (a folder contributes only its
    /// primary version).
    pub fn visible_movies(&self) -> Vec<PathBuf> {
        let mut seen = std::collections::HashSet::new();
        let mut out = Vec::new();
        for f in &self.filelist {
            if !self.is_movie_group_member(&f.file_path) {
                out.push(f.file_path.clone());
                continue;
            }
            let folder = f
                .file_path
                .parent()
                .map(Path::to_path_buf)
                .unwrap_or_default();
            if seen.insert(folder) {
                out.push(self.primary_version(&self.list_movie_versions(&f.file_path)));
            }
        }
        out
    }

    /// Add `source` as another playable version of `path`'s movie, promoting a
    /// flat movie to its own folder on the first extra version. An empty
    /// `label` becomes "Výchozí"; an unset `existing_label` is derived from the
    /// existing file (its 3D tag, else "Výchozí", or `part1` when adding parts).
    pub fn add_movie_version(
        &mut self,
        path: &Path,
        source: &Path,
        label: &str,
        move_source: bool,
        existing_label: Option<&str>,
    ) -> CoreResult<PathBuf> {
        let label = if label.trim().is_empty() {
            DEFAULT_VERSION_LABEL.to_string()
        } else {
            label.trim().to_string()
        };
        let pool = self.require_pool()?;

        let (folder, stem) = if self.is_movie_group_member(path) {
            let folder = path.parent().map(Path::to_path_buf).unwrap_or_default();
            let existing: Vec<String> = self
                .list_movie_versions(path)
                .iter()
                .map(|p| label_or_default(p))
                .collect();
            if mixes_parts_and_versions(existing.iter().map(String::as_str).chain([label.as_str()]))
            {
                return Err(CoreError::invalid(PARTS_AND_VERSIONS_MIX));
            }
            let stem = paths::name(&folder);
            (folder, stem)
        } else {
            let file = self.file(path).cloned().unwrap_or_else(|| File::bare(path));
            let stem = self.canonical_name_for(&file, false).ok_or_else(|| {
                CoreError::invalid("Film nemá platný název/rok — nejde založit složku verzí.")
            })?;
            let existing_label = match existing_label {
                Some(l) => l.to_string(),
                None if normalize_part_label(&label).is_some() => "part1".into(),
                None => parse_3d_format(&paths::stem(path))
                    .map_or_else(|| DEFAULT_VERSION_LABEL.to_string(), |f| format!("3D {f}")),
            };
            if mixes_parts_and_versions([existing_label.as_str(), label.as_str()]) {
                return Err(CoreError::invalid(PARTS_AND_VERSIONS_MIX));
            }
            let lib = self
                .library_of(path)
                .unwrap_or_else(|| self.movie_libraries()[0].clone());
            let folder = pool.join(lib).join(&stem);
            if folder.exists() {
                return Err(CoreError::Exists(format!(
                    "Složka „{stem}“ už v poolu existuje."
                )));
            }
            fs::create_dir_all(&folder)?;
            let existing_target = folder.join(version_filename(
                &stem,
                &existing_label,
                &paths::suffix(path),
            ));
            paths::move_file(path, &existing_target)?;
            subtitles::rename_subtitles_with(path, &existing_target)?;
            self.with_file(path, |f, tm, index| {
                f.relocate(&existing_target, Some(index))?;
                f.save_location(tm, index)
            })?;
            (folder, stem)
        };

        let target = folder.join(version_filename(&stem, &label, &paths::suffix(source)));
        if target.exists() {
            return Err(CoreError::Exists(format!("Verze „{label}“ už existuje.")));
        }
        paths::transfer(source, &target, move_source)?;
        let Self {
            tagmanager,
            index,
            filelist,
            ..
        } = self;
        let index = index
            .as_mut()
            .ok_or_else(|| CoreError::invalid("Pool není nastaven."))?;
        let mut version = File::load(&target, tagmanager, Some(index))?;
        version.added = Some(now_iso());
        version.save_metadata(index)?;
        filelist.push(version);
        Ok(target)
    }

    /// Add `source` as the next part of `path`'s film (a flat film becomes
    /// `part1` and `source` `part2`).
    pub fn add_movie_part(
        &mut self,
        path: &Path,
        source: &Path,
        move_source: bool,
    ) -> CoreResult<PathBuf> {
        if !self.is_movie_group_member(path) {
            return self.add_movie_version(path, source, &part_label(2), move_source, None);
        }
        let numbers: Vec<Option<u32>> = self
            .list_movie_versions(path)
            .iter()
            .map(|p| normalize_part_label(&label_of(p)))
            .collect();
        if numbers.iter().any(Option::is_none) {
            return Err(CoreError::invalid(
                "Film už má verze (2D/3D, kvalita…) — díly s verzemi zatím nejde kombinovat. Odeber nejdřív verze, nebo přidej soubor jako verzi.",
            ));
        }
        let next = numbers.into_iter().flatten().max().unwrap_or(0) + 1;
        self.add_movie_version(path, source, &part_label(next), move_source, None)
    }

    pub fn movie_group_mode(&self, path: &Path) -> GroupMode {
        if !self.is_movie_group_member(path) {
            return GroupMode::Flat;
        }
        let labels: Vec<String> = self
            .list_movie_versions(path)
            .iter()
            .map(|p| label_of(p))
            .collect();
        if !labels.is_empty() && labels.iter().all(|l| normalize_part_label(l).is_some()) {
            GroupMode::Parts
        } else {
            GroupMode::Versions
        }
    }

    /// The film's files in display order — parts by number, versions with the
    /// default first, then by popisek.
    pub fn ordered_media(&self, path: &Path) -> Vec<PathBuf> {
        let mut versions = self.list_movie_versions(path);
        versions.sort_by_key(|p| {
            let label = label_of(p);
            match normalize_part_label(&label) {
                Some(n) => (0, n, String::new()),
                None if label.is_empty() || label == DEFAULT_VERSION_LABEL => (0, 0, String::new()),
                None => (1, 0, label.to_lowercase()),
            }
        });
        versions
    }

    /// Give every file of the folder a new popisek at once (through temporary
    /// names, so swapping two labels never overwrites a file).
    fn relabel_movie_group(
        &mut self,
        path: &Path,
        assignments: &[(PathBuf, String)],
    ) -> CoreResult<()> {
        let folder = path.parent().map(Path::to_path_buf).unwrap_or_default();
        let current: std::collections::HashSet<PathBuf> =
            self.list_movie_versions(path).into_iter().collect();
        let assigned: std::collections::HashSet<PathBuf> =
            assignments.iter().map(|(p, _)| p.clone()).collect();
        if assigned != current || assignments.len() != current.len() {
            return Err(CoreError::invalid(
                "Přeřazení musí zahrnout každý soubor složky právě jednou.",
            ));
        }
        let labels: Vec<String> = assignments
            .iter()
            .map(|(_, l)| {
                if l.trim().is_empty() {
                    DEFAULT_VERSION_LABEL.to_string()
                } else {
                    l.trim().to_string()
                }
            })
            .collect();
        if mixes_parts_and_versions(labels.iter().map(String::as_str)) {
            return Err(CoreError::invalid(PARTS_AND_VERSIONS_MIX));
        }
        let stem = paths::name(&folder);
        let targets: Vec<PathBuf> = assignments
            .iter()
            .zip(&labels)
            .map(|((p, _), l)| folder.join(version_filename(&stem, l, &paths::suffix(p))))
            .collect();
        let unique: std::collections::HashSet<String> = targets
            .iter()
            .map(|t| paths::name(t).to_lowercase())
            .collect();
        if unique.len() != targets.len() {
            return Err(CoreError::invalid(
                "Dva soubory by dostaly stejný název — popisky se musí lišit.",
            ));
        }
        let mut temps = Vec::new();
        for (i, (p, _)) in assignments.iter().enumerate() {
            let temp = folder.join(format!("{stem} - .curator-tmp-{i}{}", paths::suffix(p)));
            self.relocate_file(p, &temp, true)?;
            temps.push(temp);
        }
        for (temp, target) in temps.iter().zip(&targets) {
            self.relocate_file(temp, target, true)?;
            self.with_file(target, |f, tm, index| f.save_location(tm, index))?;
        }
        Ok(())
    }

    /// Move one part earlier (`delta < 0`) or later; parts are renumbered.
    pub fn move_movie_part(&mut self, path: &Path, delta: i32) -> CoreResult<()> {
        if self.movie_group_mode(path) != GroupMode::Parts {
            return Err(CoreError::invalid("Film nemá díly, které by šlo přeřadit."));
        }
        let mut order = self.ordered_media(path);
        let Some(i) = order.iter().position(|p| p == path) else {
            return Ok(());
        };
        let j = i as i64 + i64::from(delta);
        if j < 0 || j >= order.len() as i64 {
            return Ok(());
        }
        order.swap(i, j as usize);
        let assignments: Vec<(PathBuf, String)> = order
            .into_iter()
            .enumerate()
            .map(|(n, p)| (p, part_label(n as u32 + 1)))
            .collect();
        self.relabel_movie_group(path, &assignments)
    }

    /// Switch a folder between versions and parts. To versions, the first part
    /// becomes the default and the others take `labels` in order.
    pub fn set_movie_group_mode(
        &mut self,
        path: &Path,
        mode: GroupMode,
        labels: &[String],
    ) -> CoreResult<()> {
        if mode == GroupMode::Flat {
            return Err(CoreError::invalid("Neznámý režim „flat“."));
        }
        let current = self.movie_group_mode(path);
        if current == GroupMode::Flat {
            return Err(CoreError::invalid(
                "Film má jen jeden soubor — režim složky zatím nemá co měnit.",
            ));
        }
        if current == mode {
            return Ok(());
        }
        let order = self.ordered_media(path);
        if mode == GroupMode::Parts {
            let a: Vec<(PathBuf, String)> = order
                .into_iter()
                .enumerate()
                .map(|(n, p)| (p, part_label(n as u32 + 1)))
                .collect();
            return self.relabel_movie_group(path, &a);
        }
        let clean: Vec<String> = labels.iter().map(|l| l.trim().to_string()).collect();
        if clean.len() != order.len() - 1 || clean.iter().any(String::is_empty) {
            return Err(CoreError::invalid(format!(
                "Každý další soubor potřebuje popisek verze ({}).",
                order.len() - 1
            )));
        }
        if clean
            .iter()
            .any(|l| l.to_lowercase() == DEFAULT_VERSION_LABEL.to_lowercase())
        {
            return Err(CoreError::invalid(format!(
                "„{DEFAULT_VERSION_LABEL}“ je vyhrazený pro první soubor."
            )));
        }
        let unique: std::collections::HashSet<String> =
            clean.iter().map(|l| l.to_lowercase()).collect();
        if unique.len() != clean.len() {
            return Err(CoreError::invalid("Popisky verzí se musí lišit."));
        }
        let mut a = vec![(order[0].clone(), String::new())];
        a.extend(order[1..].iter().cloned().zip(clean));
        self.relabel_movie_group(path, &a)
    }

    /// Rename one version's label within its folder (empty → "Výchozí").
    pub fn rename_movie_version(&mut self, path: &Path, new_label: &str) -> CoreResult<PathBuf> {
        if !self.is_movie_group_member(path) {
            return Err(CoreError::invalid(
                "Film nemá žádné další verze — popisek se uplatní až od druhé verze.",
            ));
        }
        let new_label = if new_label.trim().is_empty() {
            DEFAULT_VERSION_LABEL.to_string()
        } else {
            new_label.trim().to_string()
        };
        let others: Vec<String> = self
            .list_movie_versions(path)
            .iter()
            .filter(|p| p.as_path() != path)
            .map(|p| label_or_default(p))
            .collect();
        if mixes_parts_and_versions(
            others
                .iter()
                .map(String::as_str)
                .chain([new_label.as_str()]),
        ) {
            return Err(CoreError::invalid(PARTS_AND_VERSIONS_MIX));
        }
        let folder = path.parent().map(Path::to_path_buf).unwrap_or_default();
        let target = folder.join(version_filename(
            &paths::name(&folder),
            &new_label,
            &paths::suffix(path),
        ));
        if target == path {
            return Ok(target);
        }
        if target.exists() {
            return Err(CoreError::Exists(format!(
                "Verze „{new_label}“ už existuje."
            )));
        }
        self.relocate_file(path, &target, true)?;
        self.with_file(&target, |f, tm, index| f.save_location(tm, index))?;
        Ok(target)
    }

    /// Rename grouped default versions still called `<folder> - Výchozí.ext` to
    /// the bare `<folder>.ext`. Returns the `(old, new)` names.
    pub fn normalize_default_version_names(&mut self) -> CoreResult<Vec<(String, String)>> {
        let mut renamed = Vec::new();
        let paths_now: Vec<PathBuf> = self.filelist.iter().map(|f| f.file_path.clone()).collect();
        for path in paths_now {
            if !self.is_movie_group_member(&path) {
                continue;
            }
            let folder = path.parent().map(Path::to_path_buf).unwrap_or_default();
            let fname = paths::name(&folder);
            if paths::stem(&path) != format!("{fname} - {DEFAULT_VERSION_LABEL}") {
                continue;
            }
            let target = folder.join(format!("{fname}{}", paths::suffix(&path)));
            if target.exists() {
                continue;
            }
            self.relocate_file(&path, &target, true)?;
            self.with_file(&target, |f, tm, index| f.save_location(tm, index))?;
            renamed.push((paths::name(&path), paths::name(&target)));
        }
        Ok(renamed)
    }

    /// Remove one version (+ subtitles). When one version is left the movie is
    /// demoted back to a flat file (keeping a 3D tag if the survivor was 3D).
    pub fn remove_movie_version(&mut self, path: &Path) -> CoreResult<()> {
        if !self.is_movie_group_member(path) {
            return Err(CoreError::invalid(
                "Film nemá žádné další verze k odebrání.",
            ));
        }
        let folder = path.parent().map(Path::to_path_buf).unwrap_or_default();
        self.with_file(path, |f, _, index| f.delete_metadata(index))?;
        for sub in subtitles::find_subtitles(path) {
            fs::remove_file(&sub.path)?;
        }
        fs::remove_file(path)?;
        self.filelist.retain(|f| f.file_path != path);

        let remaining: Vec<PathBuf> = paths::entries(&folder)
            .into_iter()
            .filter(|p| p.is_file() && is_media_file(p))
            .collect();
        if remaining.len() == 1 {
            let sole = &remaining[0];
            let fname = paths::name(&folder);
            let prefix = format!("{fname} - ");
            let sole_stem = paths::stem(sole);
            let label = sole_stem.strip_prefix(&prefix).unwrap_or("");
            let new_stem = match normalize_3d_label(label) {
                Some(fmt) => format!("{fname}.3D.{fmt}"),
                None => fname.clone(),
            };
            let new_path = folder
                .parent()
                .unwrap_or(Path::new("."))
                .join(format!("{new_stem}{}", paths::suffix(sole)));
            self.relocate_file(sole, &new_path, true)?;
            self.with_file(&new_path, |f, tm, index| f.save_location(tm, index))?;
            let _ = fs::remove_dir_all(&folder);
        }
        Ok(())
    }

    /// Delete a whole movie — every version, subtitle and record.
    pub fn remove_movie(&mut self, path: &Path) -> CoreResult<()> {
        let versions = self.list_movie_versions(path);
        let grouped = self.is_movie_group_member(path);
        for v in &versions {
            self.with_file(v, |f, _, index| f.delete_metadata(index))?;
            for sub in subtitles::find_subtitles(v) {
                let _ = fs::remove_file(&sub.path);
            }
            let _ = fs::remove_file(v);
            self.filelist.retain(|f| &f.file_path != v);
        }
        if grouped && let Some(folder) = path.parent() {
            let _ = fs::remove_dir_all(folder);
        }
        Ok(())
    }

    /// Fold the duplicate movie `other` into `keep` as one more version. `keep`'s
    /// metadata wins; `other` only contributes missing tags and a ČSFD link.
    pub fn merge_as_version(
        &mut self,
        keep: &Path,
        other: &Path,
        label: &str,
        keep_label: Option<&str>,
    ) -> CoreResult<PathBuf> {
        if keep == other {
            return Err(CoreError::invalid("Nelze sloučit film sám se sebou."));
        }
        if self.is_movie_group_member(other) {
            return Err(CoreError::invalid(
                "Slučovaný film už má více verzí — slouč opačně, nebo verze nejdřív odeber.",
            ));
        }
        if self.is_movie_group_member(keep) && keep.parent() == other.parent() {
            return Err(CoreError::invalid(
                "Oba soubory už jsou verzemi téhož filmu.",
            ));
        }
        let other_file = self
            .file(other)
            .cloned()
            .unwrap_or_else(|| File::bare(other));
        self.with_file(keep, |k, _, index| {
            for tag in &other_file.tags {
                if !k.tags.contains(tag) {
                    k.tags.push(tag.clone());
                    if other_file.auto_tag_paths.contains(&tag.full_path()) {
                        k.auto_tag_paths.insert(tag.full_path());
                    }
                }
            }
            if k.csfd_url.is_none() && other_file.csfd_url.is_some() {
                k.csfd_url = other_file.csfd_url.clone();
            }
            k.save_metadata(index)
        })?;
        self.with_file(other, |f, _, index| f.delete_metadata(index))?;
        let new_version = match self.add_movie_version(keep, other, label, true, keep_label) {
            Ok(p) => p,
            Err(e) => {
                let _ = self.with_file(other, |f, _, index| f.save_metadata(index));
                return Err(e);
            }
        };
        subtitles::rename_subtitles_with(other, &new_version)?;
        self.filelist.retain(|f| f.file_path != other);
        Ok(new_version)
    }
}

#[cfg(test)]
mod tests {
    use super::super::movies::ImportOptions;
    use super::super::test_support::Fixture;
    use super::*;
    use crate::core::file_manager::Library;

    const STEM: &str = "Hobit (2013) [tmdbid-49051]";

    fn hobbit(fx: &mut Fixture) -> PathBuf {
        let opts = ImportOptions {
            year: Some("2013".into()),
            tmdb_id: Some("49051".into()),
            ..Default::default()
        };
        fx.fm
            .import_movie(&fx.source("h1.mkv"), "Hobit", opts)
            .unwrap()
            .unwrap()
    }

    fn folder(fx: &Fixture) -> PathBuf {
        fx.pool().join("Filmy").join(STEM)
    }

    #[test]
    fn test_version_filename_variants() {
        assert_eq!(version_filename("S", "", ".mkv"), "S.mkv");
        assert_eq!(
            version_filename("S", DEFAULT_VERSION_LABEL, ".mkv"),
            "S.mkv"
        );
        assert_eq!(version_filename("S", "CD2", ".mkv"), "S-part2.mkv");
        assert_eq!(version_filename("S", "3D HSBS", ".mkv"), "S - 3D HSBS.mkv");
    }

    #[test]
    fn test_add_version_promotes_flat_movie_with_subtitles() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        assert!(!fx.fm.is_movie_group_member(&movie));
        fs::write(fx.pool().join(format!("Filmy/{STEM}.cs.srt")), "s").unwrap();
        let v2 = fx
            .fm
            .add_movie_version(&movie, &fx.source("h2.mkv"), "3D HSBS", false, None)
            .unwrap();
        assert_eq!(v2, folder(&fx).join(format!("{STEM} - 3D HSBS.mkv")));
        let promoted = folder(&fx).join(format!("{STEM}.mkv"));
        assert!(promoted.exists());
        assert!(folder(&fx).join(format!("{STEM}.cs.srt")).exists());
        assert!(fx.fm.is_movie_group_member(&promoted));
        assert_eq!(fx.fm.list_movie_versions(&promoted).len(), 2);
        assert_eq!(fx.fm.visible_movies(), vec![promoted.clone()]);
        assert!(matches!(
            fx.fm
                .add_movie_version(&promoted, &fx.source("h3.mkv"), "3D HSBS", false, None),
            Err(CoreError::Exists(_))
        ));
        // empty label → Výchozí → bare name, already taken
        assert!(
            fx.fm
                .add_movie_version(&promoted, &fx.source("h4.mkv"), "", false, None)
                .is_err()
        );
    }

    #[test]
    fn test_import_existing_film_adds_version_or_refuses() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        fx.fm
            .add_movie_version(&movie, &fx.source("h2.mkv"), "3D HSBS", false, None)
            .unwrap();
        let opts = ImportOptions {
            year: Some("2013".into()),
            tmdb_id: Some("49051".into()),
            on_conflict: super::super::OnConflict::Version,
            version_label: Some("4K".into()),
            ..Default::default()
        };
        let p = fx
            .fm
            .import_movie(&fx.source("h5.mkv"), "Hobit", opts.clone())
            .unwrap()
            .unwrap();
        assert_eq!(p, folder(&fx).join(format!("{STEM} - 4K.mkv")));
        let plain = ImportOptions {
            version_label: None,
            ..opts.clone()
        };
        assert!(matches!(
            fx.fm.import_movie(&fx.source("h8.mkv"), "Hobit", plain),
            Err(CoreError::Exists(_))
        ));
        let ftab = ImportOptions {
            version_label: None,
            format_3d: Some("FTAB".into()),
            ..opts
        };
        let p3 = fx
            .fm
            .import_movie(&fx.source("h6.mkv"), "Hobit", ftab)
            .unwrap()
            .unwrap();
        assert_eq!(paths::name(&p3), format!("{STEM} - 3D FTAB.mkv"));
        let root_files: Vec<PathBuf> = paths::entries(&fx.pool().join("Filmy"))
            .into_iter()
            .filter(|p| p.is_file())
            .collect();
        assert!(root_files.is_empty());
    }

    #[test]
    fn test_remove_version_demotes_and_keeps_3d_and_metadata() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        fx.fm
            .assign_tag(std::slice::from_ref(&movie), "Žánr/Fantasy")
            .unwrap();
        let v2 = fx
            .fm
            .add_movie_version(&movie, &fx.source("h2.mkv"), "3D HSBS", false, None)
            .unwrap();
        let primary = folder(&fx).join(format!("{STEM}.mkv"));
        fx.fm.remove_movie_version(&primary).unwrap();
        let flat = fx.pool().join(format!("Filmy/{STEM}.3D.HSBS.mkv"));
        assert!(flat.exists());
        assert!(!folder(&fx).exists());
        assert!(!v2.exists());
        let f = fx.fm.file(&flat).unwrap();
        assert!(f.tag_paths().contains("Žánr/Fantasy"));
        assert!(fx.fm.remove_movie_version(&flat).is_err());
    }

    #[test]
    fn test_grouped_movie_refuses_rename_and_move_but_allows_metadata() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        fx.fm
            .add_movie_version(&movie, &fx.source("h2.mkv"), "4K", false, None)
            .unwrap();
        let primary = folder(&fx).join(format!("{STEM}.mkv"));
        assert!(fx.fm.rename_movie(&primary, "Jiný").is_err());
        assert!(fx.fm.move_to_library(&primary, "Filmy").is_err());
        assert_eq!(fx.fm.rename_to_canonical(&primary).unwrap(), None);
        let edits = super::super::movies::MovieEdits {
            title: "Hobit".into(),
            year: Some("2013".into()),
            tmdb_id: Some("49051".into()),
            date: Some("2026-02-02".into()),
            ..Default::default()
        };
        fx.fm.apply_movie_edits(&primary, edits).unwrap();
        let bad = super::super::movies::MovieEdits {
            title: "Jiný".into(),
            year: Some("2013".into()),
            ..Default::default()
        };
        assert!(fx.fm.apply_movie_edits(&primary, bad).is_err());
    }

    #[test]
    fn test_rename_movie_version_cases() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        let v2 = fx
            .fm
            .add_movie_version(&movie, &fx.source("h2.mkv"), "4K", false, None)
            .unwrap();
        fx.fm
            .assign_tag(std::slice::from_ref(&v2), "Žánr/Fantasy")
            .unwrap();
        let renamed = fx.fm.rename_movie_version(&v2, "Režisérská verze").unwrap();
        assert_eq!(
            paths::name(&renamed),
            format!("{STEM} - Režisérská verze.mkv")
        );
        assert!(
            fx.fm
                .file(&renamed)
                .unwrap()
                .tag_paths()
                .contains("Žánr/Fantasy")
        );
        assert_eq!(
            fx.fm
                .rename_movie_version(&renamed, "Režisérská verze")
                .unwrap(),
            renamed
        );
        assert!(fx.fm.rename_movie_version(&renamed, "").is_err()); // collides with Výchozí
        assert!(fx.fm.rename_movie_version(&renamed, "part2").is_err()); // mixes
        let flat = fx
            .fm
            .import_movie(
                &fx.source("o.mkv"),
                "Other",
                ImportOptions {
                    year: Some("2000".into()),
                    ..Default::default()
                },
            )
            .unwrap()
            .unwrap();
        assert!(fx.fm.rename_movie_version(&flat, "x").is_err());
    }

    #[test]
    fn test_parts_add_order_move_and_mode_switch() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        let p2 = fx
            .fm
            .add_movie_part(&movie, &fx.source("h2.mkv"), false)
            .unwrap();
        let p1 = folder(&fx).join(format!("{STEM}-part1.mkv"));
        assert!(p1.exists());
        assert_eq!(paths::name(&p2), format!("{STEM}-part2.mkv"));
        let p3 = fx
            .fm
            .add_movie_part(&p1, &fx.source("h3.mkv"), false)
            .unwrap();
        assert_eq!(paths::name(&p3), format!("{STEM}-part3.mkv"));
        assert_eq!(fx.fm.movie_group_mode(&p1), GroupMode::Parts);
        assert!(
            fx.fm
                .add_movie_version(&p1, &fx.source("x.mkv"), "4K", false, None)
                .is_err()
        );

        fs::write(folder(&fx).join(format!("{STEM}-part1.cs.srt")), "one").unwrap();
        fx.fm.move_movie_part(&p1, 1).unwrap();
        // the old part1 content is now part2, with its subtitle
        assert_eq!(
            fs::read_to_string(folder(&fx).join(format!("{STEM}-part2.mkv"))).unwrap(),
            "h1.mkv"
        );
        assert_eq!(
            fs::read_to_string(folder(&fx).join(format!("{STEM}-part2.cs.srt"))).unwrap(),
            "one"
        );
        fx.fm
            .move_movie_part(&folder(&fx).join(format!("{STEM}-part1.mkv")), -1)
            .unwrap(); // beyond the end: no-op

        let any = folder(&fx).join(format!("{STEM}-part1.mkv"));
        assert!(
            fx.fm
                .set_movie_group_mode(&any, GroupMode::Versions, &["a".into()])
                .is_err()
        );
        assert!(
            fx.fm
                .set_movie_group_mode(&any, GroupMode::Versions, &["a".into(), "A".into()])
                .is_err()
        );
        fx.fm
            .set_movie_group_mode(&any, GroupMode::Versions, &["4K".into(), "3D HSBS".into()])
            .unwrap();
        let first = folder(&fx).join(format!("{STEM}.mkv"));
        assert_eq!(fx.fm.movie_group_mode(&first), GroupMode::Versions);
        fx.fm
            .set_movie_group_mode(&first, GroupMode::Parts, &[])
            .unwrap();
        assert_eq!(
            fx.fm
                .movie_group_mode(&folder(&fx).join(format!("{STEM}-part1.mkv"))),
            GroupMode::Parts
        );
    }

    #[test]
    fn test_removing_down_to_one_part_demotes_to_flat() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        let p2 = fx
            .fm
            .add_movie_part(&movie, &fx.source("h2.mkv"), false)
            .unwrap();
        fx.fm.remove_movie_version(&p2).unwrap();
        assert!(fx.pool().join(format!("Filmy/{STEM}.mkv")).exists());
    }

    #[test]
    fn test_remove_movie_deletes_every_version() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        fx.fm
            .add_movie_version(&movie, &fx.source("h2.mkv"), "4K", false, None)
            .unwrap();
        let primary = folder(&fx).join(format!("{STEM}.mkv"));
        fx.fm.remove_movie(&primary).unwrap();
        assert!(!folder(&fx).exists());
        assert!(fx.fm.filelist.is_empty());
        assert!(fx.fm.index.as_ref().unwrap().records.is_empty());
    }

    #[test]
    fn test_merge_as_version_carries_tags_csfd_and_subtitles() {
        let mut fx = Fixture::new();
        let keep = hobbit(&mut fx);
        let other = fx
            .fm
            .import_movie(
                &fx.source("dup.mkv"),
                "Hobit kopie",
                ImportOptions::default(),
            )
            .unwrap()
            .unwrap();
        fx.fm
            .assign_tag(std::slice::from_ref(&other), "Žánr/Fantasy")
            .unwrap();
        fx.fm
            .with_file(&other, |f, _, index| {
                f.csfd_url = Some("u".into());
                f.save_metadata(index)
            })
            .unwrap();
        fs::write(fx.pool().join("Filmy/Hobit kopie.cs.srt"), "s").unwrap();
        let v = fx.fm.merge_as_version(&keep, &other, "4K", None).unwrap();
        assert_eq!(v, folder(&fx).join(format!("{STEM} - 4K.mkv")));
        assert!(folder(&fx).join(format!("{STEM} - 4K.cs.srt")).exists());
        let primary = folder(&fx).join(format!("{STEM}.mkv"));
        let f = fx.fm.file(&primary).unwrap();
        assert!(f.tag_paths().contains("Žánr/Fantasy"));
        assert_eq!(f.csfd_url.as_deref(), Some("u"));
        assert_eq!(fx.fm.index.as_ref().unwrap().records.len(), 1);
        assert!(
            fx.fm
                .merge_as_version(&primary, &primary, "x", None)
                .is_err()
        );
    }

    #[test]
    fn test_mixed_library_version_folder_vs_series() {
        let mut fx = Fixture::new();
        fx.fm
            .set_libraries(vec![Library::new("Mix", LibraryKind::Mixed)])
            .unwrap();
        let opts = ImportOptions {
            year: Some("2013".into()),
            tmdb_id: Some("49051".into()),
            library: Some("Mix".into()),
            ..Default::default()
        };
        let movie = fx
            .fm
            .import_movie(&fx.source("h1.mkv"), "Hobit", opts)
            .unwrap()
            .unwrap();
        let v2 = fx
            .fm
            .add_movie_version(&movie, &fx.source("h2.mkv"), "4K", false, None)
            .unwrap();
        assert!(fx.fm.is_movie_group_member(&v2));
        let ep = fx
            .pool()
            .join("Mix/Show (2010) [tmdbid-1]/Season 01/S01E01 - Show.mkv");
        fs::create_dir_all(ep.parent().unwrap()).unwrap();
        fs::write(&ep, "e").unwrap();
        assert!(!fx.fm.is_movie_group_member(&ep));
        fx.fm.load_pool_movies().unwrap();
        assert_eq!(fx.fm.filelist.len(), 2);
    }

    #[test]
    fn test_normalize_default_version_names() {
        let mut fx = Fixture::new();
        let movie = hobbit(&mut fx);
        fx.fm
            .add_movie_version(&movie, &fx.source("h2.mkv"), "4K", false, None)
            .unwrap();
        let primary = folder(&fx).join(format!("{STEM}.mkv"));
        let old = folder(&fx).join(format!("{STEM} - Výchozí.mkv"));
        fx.fm.relocate_file(&primary, &old, true).unwrap();
        let renamed = fx.fm.normalize_default_version_names().unwrap();
        assert_eq!(renamed, vec![(paths::name(&old), paths::name(&primary))]);
        assert!(primary.exists());
    }
}