/*
    This file is part of jellything (https://codeberg.org/metamuffin/jellything)
    which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
    Copyright (C) 2023 metamuffin <metamuffin.org>
*/
#![feature(lazy_cell)]
pub mod infojson;
pub mod tmdb;

use anyhow::{anyhow, Context, Ok};
use async_recursion::async_recursion;
use futures::{stream::FuturesUnordered, StreamExt};
use jellybase::{
    cache::async_cache_file, database::Database, federation::Federation, AssetLocationExt, CONF,
};
use jellyclient::Session;
use jellycommon::{
    AssetLocation, AssetRole, ImportOptions, ImportSource, Node, NodePrivate, NodePublic,
};
use jellymatroska::read::EbmlReader;
use jellyremuxer::import::import_metadata;
use log::{debug, info};
use std::{
    cmp::Ordering,
    ffi::OsStr,
    fs::File,
    io::BufReader,
    os::unix::prelude::OsStrExt,
    path::{Path, PathBuf},
    sync::{Arc, LazyLock},
};
use tokio::{sync::Semaphore, task::spawn_blocking};

static IMPORT_SEM: LazyLock<Semaphore> = LazyLock::new(|| Semaphore::new(1));

pub async fn import(db: &Database, fed: &Federation) -> anyhow::Result<()> {
    let permit = IMPORT_SEM.try_acquire()?;
    info!("loading sources...");
    import_path(CONF.library_path.clone(), vec![], db, fed)
        .await
        .context("indexing")?;
    info!("merging nodes...");
    merge_nodes(db).context("merging nodes")?;
    info!("generating paths...");
    generate_node_paths(db).context("generating paths")?;
    info!("clearing temporary node tree...");
    db.node_import.clear()?;
    info!("import completed");
    drop(permit);
    Ok(())
}

pub fn merge_nodes(db: &Database) -> anyhow::Result<()> {
    for r in db.node_import.iter() {
        let (id, mut nodes) = r?;

        nodes.sort_by(|(x, _), (y, _)| compare_index_path(x, y));

        let mut node = nodes
            .into_iter()
            .map(|(_, x)| x)
            .reduce(|x, y| merge_node(x, y))
            .unwrap();

        node.public.id = Some(id.clone());
        node.public.path = vec![]; // will be reconstructed in the next pass

        db.node.insert(&id, &node)?;
    }
    Ok(())
}

pub fn generate_node_paths(db: &Database) -> anyhow::Result<()> {
    fn traverse(db: &Database, c: String, mut path: Vec<String>) -> anyhow::Result<()> {
        let node = db
            .node
            .update_and_fetch(&c, |mut nc| {
                if let Some(nc) = &mut nc {
                    if nc.public.path.is_empty() {
                        nc.public.path = path.clone();
                    }
                }
                nc
            })?
            .ok_or(anyhow!("node missing"))?;

        path.push(c);
        for c in node.public.children {
            traverse(db, c, path.clone())?;
        }
        Ok(())
    }
    traverse(db, "library".to_string(), vec![])?;
    Ok(())
}

fn compare_index_path(x: &[usize], y: &[usize]) -> Ordering {
    if x.is_empty() {
        Ordering::Greater
    } else if y.is_empty() {
        Ordering::Less
    } else {
        match x[0].cmp(&y[0]) {
            o @ (Ordering::Less | Ordering::Greater) => o,
            Ordering::Equal => compare_index_path(&x[1..], &y[1..]),
        }
    }
}

#[async_recursion]
pub async fn import_path(
    path: PathBuf,
    index_path: Vec<usize>,
    db: &Database,
    fed: &Federation,
) -> anyhow::Result<()> {
    if path.is_dir() {
        let mut children_paths = path
            .read_dir()?
            .map(Result::unwrap)
            .filter_map(|e| {
                if e.path().extension() == Some(&OsStr::from_bytes(b"yaml"))
                    || e.metadata().unwrap().is_dir()
                {
                    Some(e.path())
                } else {
                    None
                }
            })
            .collect::<Vec<_>>();

        children_paths.sort();

        let mut children: FuturesUnordered<_> = children_paths
            .into_iter()
            .enumerate()
            .map(|(i, p)| {
                import_path(
                    p.clone(),
                    {
                        let mut path = index_path.clone();
                        path.push(i);
                        path
                    },
                    db,
                    fed,
                )
            })
            .collect();

        while let Some(k) = children.next().await {
            k?
        }
    } else {
        let opts: ImportOptions = serde_yaml::from_reader(File::open(&path)?)?;

        for s in opts.sources {
            process_source(opts.id.clone(), s, &path, &index_path, db, fed).await?;
        }
    }
    Ok(())
}

async fn process_source(
    id: String,
    s: ImportSource,
    path: &Path,
    index_path: &[usize],
    db: &Database,
    fed: &Federation,
) -> anyhow::Result<()> {
    let insert_node = move |id: &String, n: Node| -> anyhow::Result<()> {
        db.node_import.fetch_and_update(id, |l| {
            let mut l = l.unwrap_or_default();
            l.push((index_path.to_vec(), n.clone()));
            Some(l)
        })?;
        Ok(())
    };
    match s {
        ImportSource::Override(n) => insert_node(&id, n)?,
        ImportSource::Tmdb(_) => todo!(),
        ImportSource::Media { location, .. } => {
            // TODO use ignore options
            let media_path = location.path();

            let metadata = spawn_blocking(move || {
                let input = BufReader::new(File::open(&media_path).unwrap());
                let mut input = EbmlReader::new(input);
                import_metadata(&mut input)
            })
            .await??;

            // if let Some(cover) = metadata.cover {
            //     let pu = path.join(format!(
            //         "cover.{}",
            //         match mime.as_str() {
            //             "image/webp" => "webp",
            //             "image/jpeg" => "jpeg",
            //             "image/png" => "png",
            //             _ => {
            //                 warn!("unknown mime, just using webp");
            //                 "webp"
            //             }
            //         }
            //     ));
            //     if !pu.exists() {
            //         let mut f = tokio::fs::File::create(&pu).await?;
            //         f.write_all(&data).await?;
            //     }
            // }

            let node = Node {
                public: NodePublic {
                    title: metadata.title,
                    description: metadata.description,
                    tagline: metadata.tagline,
                    ..Default::default()
                },
                private: NodePrivate::default(),
            };
            insert_node(&id, node)?;
        }
        ImportSource::Federated { host } => {
            let session = fed.get_session(&host).await.context("creating session")?;

            import_remote(id, &host, db, &session, index_path)
                .await
                .context("federated import")?
        }
        ImportSource::AutoChildren { path: cpath } => {
            let paths = cpath
                .unwrap_or_else(|| path.parent().unwrap().to_path_buf())
                .read_dir()?
                .map(Result::unwrap)
                .map(|e| e.path())
                .filter(|e| e.extension() == Some(&OsStr::from_bytes(b"yaml")));

            let mut children = Vec::new();
            for p in paths {
                let opts: ImportOptions = serde_yaml::from_reader(File::open(&p)?)?;
                if opts.id != id {
                    children.push(opts.id);
                }
            }
            insert_node(
                &id,
                Node {
                    private: NodePrivate::default(),
                    public: NodePublic {
                        children,
                        ..Default::default()
                    },
                },
            )?;
        }
    }
    Ok(())
}

fn merge_node(x: Node, y: Node) -> Node {
    Node {
        public: NodePublic {
            kind: x.public.kind.or(y.public.kind),
            title: x.public.title.or(y.public.title),
            id: x.public.id.or(y.public.id),
            path: vec![],
            children: x
                .public
                .children
                .into_iter()
                .chain(y.public.children)
                .collect(),
            tagline: x.public.tagline.or(y.public.tagline),
            description: x.public.description.or(y.public.description),
            release_date: x.public.release_date.or(y.public.release_date),
            index: x.public.index.or(y.public.index),
            media: x.public.media.or(y.public.media), // TODO proper media merging
            ratings: x
                .public
                .ratings
                .into_iter()
                .chain(y.public.ratings)
                .collect(),
            federated: x.public.federated.or(y.public.federated),
        },
        private: NodePrivate {
            id: x.private.id.or(y.private.id),
            poster: x.private.poster.or(y.private.poster),
            backdrop: x.private.backdrop.or(y.private.backdrop),
            source: x.private.source.or(y.private.source), // TODO here too
        },
    }
}

// #[async_recursion]
// pub async fn import_path(
//     path: PathBuf,
//     db: &Database,
//     fed: &Federation,
//     mut node_path: Vec<String>,
// ) -> anyhow::Result<(Vec<String>, usize)> {
//     if path.is_dir() {
//         let mpath = path.join("directory.json");
//         let children_paths = path.read_dir()?.map(Result::unwrap).filter_map(|e| {
//             if e.path().extension() == Some(&OsStr::from_bytes(b"jelly"))
//                 || e.metadata().unwrap().is_dir()
//             {
//                 Some(e.path())
//             } else {
//                 None
//             }
//         });
//         let identifier = if mpath.exists() {
//             path.file_name().unwrap().to_str().unwrap().to_string()
//         } else {
//             node_path
//                 .last()
//                 .cloned()
//                 .ok_or(anyhow!("non-root node requires parent"))?
//         };

//         node_path.push(identifier.clone());
//         let mut all: FuturesUnordered<_> = children_paths
//             .into_iter()
//             .map(|p| import_path(p.clone(), db, fed, node_path.clone()).map_err(|e| (p, e)))
//             .collect();
//         node_path.pop(); // we will set the dirs path later and need it to not be included

//         let mut children_ids = Vec::new();
//         let mut errs = 0;
//         while let Some(k) = all.next().await {
//             match k {
//                 core::result::Result::Ok((els, errs2)) => {
//                     errs += errs2;
//                     children_ids.extend(els)
//                 }
//                 Err((p, e)) => {
//                     errs += 1;
//                     error!("import of {p:?} failed: {e:?}")
//                 }
//             }
//         }
//         if mpath.exists() {
//             let mut node: Node =
//                 serde_json::from_reader(File::open(mpath).context("metadata missing")?)?;

//             node.public.children = children_ids;
//             node.public.path = node_path;
//             node.public.id = Some(identifier.to_owned());
//             info!("adding {identifier}");
//             db.node.insert(&identifier, &node)?;
//             Ok((vec![identifier], errs))
//         } else {
//             Ok((children_ids, errs))
//         }
//     } else if path.is_file() {
//         info!("loading {path:?}");
//         let datafile = File::open(path.clone()).context("cant load metadata")?;
//         let mut node: Node = serde_json::from_reader(datafile).context("invalid metadata")?;
//         let identifier = node.private.id.clone().unwrap_or_else(|| {
//             path.file_name()
//                 .unwrap()
//                 .to_str()
//                 .unwrap()
//                 .strip_suffix(".json")
//                 .unwrap()
//                 .to_string()
//         });

//         let idents = if let Some(io) = node.private.import.take() {
//             let session = fed
//                 .get_session(&io.host)
//                 .await
//                 .context("creating session")?;

//             import_remote(io, db, &session, identifier.clone(), node_path)
//                 .await
//                 .context("federated import")?
//         } else {
//             debug!("adding {identifier}");
//             node.public.path = node_path;
//             node.public.id = Some(identifier.to_owned());
//             let did_insert = db.node.insert(&identifier, &node)?.is_none();
//             if did_insert {
//                 vec![identifier]
//             } else {
//                 vec![]
//             }
//         };
//         Ok((idents, 0))
//     } else {
//         bail!("did somebody really put a fifo or socket in the library?!")
//     }
// }

static SEM_REMOTE_IMPORT: LazyLock<Semaphore> = LazyLock::new(|| Semaphore::new(16));

#[async_recursion]
async fn import_remote(
    id: String,
    host: &str,
    db: &Database,
    session: &Arc<Session>,
    index_path: &[usize],
) -> anyhow::Result<()> {
    let insert_node = move |id: &String, n: Node| -> anyhow::Result<()> {
        db.node_import.fetch_and_update(id, |l| {
            let mut l = l.unwrap_or_default();
            l.push((index_path.to_vec(), n.clone()));
            Some(l)
        })?;
        Ok(())
    };
    let _permit = SEM_REMOTE_IMPORT.acquire().await.unwrap();
    info!("loading federated node {id:?}");

    let node = session.node(&id).await.context("fetching remote node")?;

    if node.federated.as_ref() == Some(&CONF.hostname) {
        return Ok(());
    }

    // TODO maybe use lazy download
    let poster = cache_federation_asset(session.to_owned(), id.clone(), AssetRole::Poster).await?;
    let backdrop =
        cache_federation_asset(session.to_owned(), id.clone(), AssetRole::Backdrop).await?;

    drop(_permit);

    let node = Node {
        public: node.clone(),
        private: NodePrivate {
            backdrop: Some(backdrop),
            poster: Some(poster),
            id: None,
            source: None, // TODO
        },
    };

    debug!("adding {id}");
    insert_node(&id, node.clone())?;

    let mut children: FuturesUnordered<_> = node
        .public
        .children
        .iter()
        .map(|c| import_remote(c.to_owned(), host, db, session, index_path))
        .collect();

    while let Some(r) = children.next().await {
        r?;
    }

    Ok(())
}

async fn cache_federation_asset(
    session: Arc<Session>,
    identifier: String,
    role: AssetRole,
) -> anyhow::Result<AssetLocation> {
    async_cache_file(
        &["fed-asset", role.as_str(), &identifier.clone()],
        move |out| async move {
            let session = session;
            session
                .node_asset(identifier.as_str(), role, 1024, out)
                .await
        },
    )
    .await
}

fn make_ident(s: &str) -> String {
    let mut out = String::new();
    for s in s.chars() {
        match s {
            'a'..='z' | '0'..='9' => out.push(s),
            'A'..='Z' => out.push(s.to_ascii_lowercase()),
            '-' | ' ' | '_' | ':' => out.push('-'),
            _ => (),
        }
    }
    out
}