//! The `/orphans` provider: a store garbage-collection view.
//!
//! `/orphans` surfaces content-store entries that no mounted local file
//! provider references any more (see `architecture/orphans.md`). It is a
//! read-mostly management subtree: each orphan is presented as an editable,
//! deletable, queueable child node, so every client's existing `e`/`d`/queue
//! gestures work unchanged (no proto surface is added).
//!
//! The heavy lifting lives on [`CrabidyStore`] (it owns the store root and the
//! derived index); this provider only supplies the reference roots to walk and
//! translates between library paths and store names.

use std::path::PathBuf;
use std::sync::Arc;

use async_trait::async_trait;
use crabidy_core::{
    proto::crabidy::{LibraryNode, LibraryNodeChild, Track},
    ProviderClient, ProviderError,
};
use tracing::warn;

use crate::crabidy_store::{CrabidyStore, StoreError};

/// The single library segment this provider owns.
pub const ORPHANS_PROVIDER_ROOT: &str = "/orphans";

/// Maps a [`StoreError`] to the provider-boundary error: a missing entry or a
/// malformed name is a bad path, a taken/invalid rename target is bad input,
/// everything else is internal.
fn to_provider_error(err: StoreError) -> ProviderError {
    match err {
        StoreError::NotFound(_) => ProviderError::MalformedPath,
        StoreError::NameTaken(_) | StoreError::InvalidName(_) => ProviderError::InvalidInput,
        other => {
            warn!("orphans store error: {other}");
            ProviderError::InternalError
        }
    }
}

/// The `/orphans` provider.
///
/// Holds the store (for enumeration and mutation) and the disk roots of every
/// mounted local file provider (for the reference scan). Constructed in
/// [`crate::provider::ProviderOrchestrator::init`] only when the store is
/// present.
#[derive(Debug)]
pub struct OrphansProvider {
    /// The content store: enumerates orphans and performs rename/delete.
    store: Arc<CrabidyStore>,
    /// Disk roots to walk for `Playable::Store` references — the `/crabidy`
    /// toml tree and (when enabled) the `/fs` root. "Referenced" is defined as
    /// reachable through one of these (architecture/orphans.md).
    ref_roots: Vec<PathBuf>,
}

impl OrphansProvider {
    /// Builds the provider over `store`, scanning `ref_roots` for references.
    pub fn new(store: Arc<CrabidyStore>, ref_roots: Vec<PathBuf>) -> Self {
        Self { store, ref_roots }
    }

    /// The bare store name addressed by an `/orphans/<seg>` path (its single
    /// decoded segment); `None` for the bare root, a deeper path, or a segment
    /// that is not a legal bare name (empty, `.`, `..`, or containing a
    /// separator) — which keeps a crafted path from escaping the store root.
    fn entry_name(&self, path: &str) -> Option<String> {
        let rest = path
            .strip_prefix(ORPHANS_PROVIDER_ROOT)?
            .strip_prefix('/')?;
        if rest.is_empty() || rest.contains('/') {
            return None;
        }
        let name = crabidy_core::decode_segment(rest);
        if name.is_empty() || name == "." || name == ".." || name.contains(['/', '\\', '\0']) {
            return None;
        }
        Some(name)
    }

    /// The library path of the orphan named `name`.
    fn entry_path(name: &str) -> String {
        crabidy_core::join_path(ORPHANS_PROVIDER_ROOT, &crabidy_core::encode_segment(name))
    }

    /// The `/orphans` root node, its children recomputed from the current
    /// orphan set.
    async fn root_node(&self) -> Result<LibraryNode, ProviderError> {
        let orphans = self
            .store
            .list_orphans(&self.ref_roots)
            .await
            .map_err(to_provider_error)?;
        let children = orphans
            .into_iter()
            .map(|orphan| {
                let mut child =
                    LibraryNodeChild::new(Self::entry_path(&orphan.name), orphan.name, true);
                // Reuse the existing rename/delete/queue gestures: an orphan is
                // an editable, deletable, queueable, already-captured child.
                child.is_editable = true;
                child.is_deletable = true;
                child.is_downloadable = false;
                child.is_captured = true;
                child
            })
            .collect();
        Ok(LibraryNode {
            path: ORPHANS_PROVIDER_ROOT.to_string(),
            title: "orphans".to_string(),
            children,
            parent: Some(crabidy_core::ROOT_PATH.to_string()),
            tracks: Vec::new(),
            is_queable: true,
            is_creatable: false,
            is_downloadable: false,
            tracks_deletable: false,
            is_captured: false,
        })
    }

    /// A single orphan's node: childless, queueable, carrying its one track.
    async fn entry_node(&self, path: &str, name: &str) -> Result<LibraryNode, ProviderError> {
        let track = self
            .store
            .orphan_track(name, path)
            .await
            .map_err(to_provider_error)?;
        Ok(LibraryNode {
            path: path.to_string(),
            title: name.to_string(),
            children: Vec::new(),
            parent: Some(ORPHANS_PROVIDER_ROOT.to_string()),
            tracks: vec![track],
            is_queable: true,
            is_creatable: false,
            is_downloadable: false,
            tracks_deletable: false,
            is_captured: true,
        })
    }
}

#[async_trait]
impl ProviderClient for OrphansProvider {
    /// Not constructed from a config string — built by the orchestrator with a
    /// store handle. Present only to satisfy the trait; never called.
    async fn init(_raw_toml_settings: &str) -> Result<Self, ProviderError> {
        Err(ProviderError::NotSupported)
    }

    fn settings(&self) -> String {
        String::new()
    }

    /// Always false: orphans are addressed as nodes. The one track per orphan
    /// is reached by resolving the node (the default `resolve_tracks_into`
    /// walk), not by a track path.
    fn is_track_path(&self, _path: &str) -> bool {
        false
    }

    /// Resolves an orphan's audio to its store file path (a local file, exactly
    /// like a resolved `Playable::Store`), so the walked-out track still plays.
    async fn get_urls_for_track(&self, track_path: &str) -> Result<Vec<String>, ProviderError> {
        let name = self
            .entry_name(track_path)
            .ok_or(ProviderError::MalformedPath)?;
        let url = self
            .store
            .orphan_url(&name)
            .await
            .map_err(to_provider_error)?;
        Ok(vec![url])
    }

    /// Track metadata for a single orphan (from the sidecar's first provider
    /// entry); `is_captured` is true.
    async fn get_metadata_for_track(&self, track_path: &str) -> Result<Track, ProviderError> {
        let name = self
            .entry_name(track_path)
            .ok_or(ProviderError::MalformedPath)?;
        self.store
            .orphan_track(&name, track_path)
            .await
            .map_err(to_provider_error)
    }

    /// A minimal `/orphans` root; children are discovered via
    /// [`Self::get_lib_node`] (listing needs async store access).
    fn get_lib_root(&self) -> LibraryNode {
        LibraryNode {
            path: ORPHANS_PROVIDER_ROOT.to_string(),
            title: "orphans".to_string(),
            children: Vec::new(),
            parent: Some(crabidy_core::ROOT_PATH.to_string()),
            tracks: Vec::new(),
            is_queable: true,
            is_creatable: false,
            is_downloadable: false,
            tracks_deletable: false,
            is_captured: false,
        }
    }

    /// The `/orphans` root lists one child per current orphan; an
    /// `/orphans/<seg>` path returns that orphan's single-track node.
    /// Recomputes the orphan set on every call (no cache).
    async fn get_lib_node(&self, path: &str) -> Result<LibraryNode, ProviderError> {
        if path == ORPHANS_PROVIDER_ROOT {
            return self.root_node().await;
        }
        let name = self.entry_name(path).ok_or(ProviderError::MalformedPath)?;
        self.entry_node(path, &name).await
    }

    /// The root is not creatable.
    async fn create_lib_node(
        &self,
        _parent_path: &str,
        _title: &str,
    ) -> Result<LibraryNode, ProviderError> {
        Err(ProviderError::NotSupported)
    }

    /// Renames an orphan's store files (audio + sidecar), keeping the index in
    /// sync; returns the node at its new `/orphans/<encode(new)>` path.
    async fn rename_lib_node(
        &self,
        path: &str,
        new_title: &str,
    ) -> Result<LibraryNode, ProviderError> {
        let old = self.entry_name(path).ok_or(ProviderError::NotSupported)?;
        self.store
            .rename_orphan(&old, new_title)
            .await
            .map_err(to_provider_error)?;
        let new_path = Self::entry_path(new_title.trim());
        let name = self
            .entry_name(&new_path)
            .ok_or(ProviderError::InvalidInput)?;
        self.entry_node(&new_path, &name).await
    }

    /// Deletes an orphan's audio file and sidecar; returns the refreshed
    /// `/orphans` root. Idempotent.
    async fn delete_lib_node(&self, path: &str) -> Result<LibraryNode, ProviderError> {
        let name = self.entry_name(path).ok_or(ProviderError::NotSupported)?;
        self.store
            .delete_orphan(&name)
            .await
            .map_err(to_provider_error)?;
        self.root_node().await
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::crabidy_store::{ProviderEntry, StoreSidecar};
    use std::path::Path;
    use tempfile::TempDir;

    async fn open_store() -> (Arc<CrabidyStore>, TempDir) {
        let dir = TempDir::new().expect("tempdir");
        let store = CrabidyStore::open(dir.path().join("state"), dir.path().join("store"))
            .await
            .expect("open store");
        (Arc::new(store), dir)
    }

    /// Writes a store entry (audio + sidecar) directly, bypassing capture.
    async fn write_entry(store: &CrabidyStore, name: &str, hash: &str, id: &str, title: &str) {
        let root = store.store_dir();
        tokio::fs::write(root.join(name), b"AUDIO")
            .await
            .expect("audio");
        let sidecar = StoreSidecar {
            hash: hash.to_string(),
            providers: vec![ProviderEntry {
                provider: "tidal".to_string(),
                id: id.to_string(),
                title: title.to_string(),
                artist: "artist".to_string(),
                duration: Some(123),
                album: None,
                aliases: Vec::new(),
            }],
        };
        let text = toml::to_string_pretty(&sidecar).expect("ser");
        tokio::fs::write(root.join(format!("{name}.cbd-store.toml")), text)
            .await
            .expect("sidecar");
    }

    /// Writes a `.cbd-track.toml` under `dir` that references store `name`.
    async fn write_store_reference(dir: &Path, file: &str, name: &str) {
        tokio::fs::create_dir_all(dir).await.expect("mkdir");
        let toml = format!("title = \"ref\"\n\n[playable]\nstore = \"{name}\"\n");
        tokio::fs::write(dir.join(file), toml)
            .await
            .expect("ref toml");
    }

    #[tokio::test]
    async fn orphans_are_store_entries_no_reference_reaches() {
        let (store, dir) = open_store().await;
        write_entry(&store, "a.flac", "blake3:a", "1", "A").await;
        write_entry(&store, "b.flac", "blake3:b", "2", "B").await;
        // A reference under a scanned root rescues b.flac only.
        let ref_root = dir.path().join("tree");
        write_store_reference(&ref_root, "0001 b.cbd-track.toml", "b.flac").await;

        let provider = OrphansProvider::new(store, vec![ref_root]);
        let root = provider.get_lib_node("/orphans").await.expect("root");
        let names: Vec<&str> = root.children.iter().map(|c| c.title.as_str()).collect();
        assert_eq!(names, vec!["a.flac"], "only the unreferenced entry orphans");
        let child = &root.children[0];
        assert!(child.is_editable && child.is_deletable && child.is_queable && child.is_captured);
        assert!(!child.is_downloadable);
    }

    #[tokio::test]
    async fn a_leaf_carries_one_captured_track_that_resolves_to_store_audio() {
        let (store, _dir) = open_store().await;
        write_entry(&store, "song.flac", "blake3:s", "9", "Song").await;
        let provider = OrphansProvider::new(store.clone(), vec![]);

        let path = OrphansProvider::entry_path("song.flac");
        let node = provider.get_lib_node(&path).await.expect("leaf");
        assert!(node.children.is_empty());
        assert_eq!(node.tracks.len(), 1);
        assert!(node.tracks[0].is_captured);
        assert_eq!(node.tracks[0].title, "Song");
        let urls = provider.get_urls_for_track(&path).await.expect("urls");
        let expected = store.store_dir().join("song.flac");
        assert_eq!(urls, vec![expected.to_str().unwrap().to_string()]);
    }

    #[tokio::test]
    async fn rename_moves_both_files_and_delete_removes_them() {
        let (store, _dir) = open_store().await;
        write_entry(&store, "old.flac", "blake3:x", "7", "Old").await;
        let provider = OrphansProvider::new(store.clone(), vec![]);
        let path = OrphansProvider::entry_path("old.flac");

        let renamed = provider
            .rename_lib_node(&path, "new.flac")
            .await
            .expect("rename");
        assert_eq!(renamed.title, "new.flac");
        assert!(store.store_dir().join("new.flac").is_file());
        assert!(!store.store_dir().join("old.flac").exists());
        assert!(store.store_dir().join("new.flac.cbd-store.toml").is_file());
        assert!(!store.store_dir().join("old.flac.cbd-store.toml").exists());

        let new_path = OrphansProvider::entry_path("new.flac");
        provider.delete_lib_node(&new_path).await.expect("delete");
        assert!(!store.store_dir().join("new.flac").exists());
        assert!(!store.store_dir().join("new.flac.cbd-store.toml").exists());
    }

    #[tokio::test]
    async fn unknown_and_traversal_paths_are_malformed() {
        let (store, _dir) = open_store().await;
        let provider = OrphansProvider::new(store, vec![]);
        // A never-created entry.
        assert!(matches!(
            provider.get_lib_node("/orphans/ghost.flac").await,
            Err(ProviderError::MalformedPath)
        ));
        // A traversal attempt decodes to a rejected segment.
        assert!(provider.entry_name("/orphans/..%2Fetc").is_none());
        assert!(provider.entry_name("/orphans/a/b").is_none());
        assert!(provider.entry_name("/orphans").is_none());
    }
}