/*
    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) 2025 metamuffin <metamuffin.org>
*/
pub mod search;

use anyhow::{Context, Result, anyhow, bail};
use bincode::{Decode, Encode, config::standard};
use jellycommon::{
    Node, NodeID,
    user::{NodeUserData, User},
};
use log::info;
use redb::{Durability, ReadableTable, StorageError, TableDefinition};
use search::NodeTextSearchIndex;
use std::{
    fs::create_dir_all,
    hash::{DefaultHasher, Hasher},
    path::{Path, PathBuf},
    str::FromStr,
    sync::Arc,
    time::SystemTime,
};
use tantivy::{
    DateTime, TantivyDocument,
    collector::{Count, TopDocs},
    doc,
    query::QueryParser,
    schema::Value,
};

const T_USER: TableDefinition<&str, Ser<User>> = TableDefinition::new("user");
const T_USER_NODE: TableDefinition<(&str, [u8; 32]), Ser<NodeUserData>> =
    TableDefinition::new("user_node");
const T_INVITE: TableDefinition<&str, ()> = TableDefinition::new("invite");
const T_NODE: TableDefinition<[u8; 32], Ser<Node>> = TableDefinition::new("node");
const T_NODE_CHILDREN: TableDefinition<([u8; 32], [u8; 32]), ()> =
    TableDefinition::new("node_children");
const T_TAG_NODE: TableDefinition<(&str, [u8; 32]), ()> = TableDefinition::new("tag_node");
const T_NODE_EXTERNAL_ID: TableDefinition<(&str, &str), [u8; 32]> =
    TableDefinition::new("node_external_id");
const T_IMPORT_FILE_MTIME: TableDefinition<&[u8], u64> = TableDefinition::new("import_file_mtime");
const T_NODE_MTIME: TableDefinition<[u8; 32], u64> = TableDefinition::new("node_mtime");
const T_NODE_MEDIA_PATHS: TableDefinition<([u8; 32], &str), ()> =
    TableDefinition::new("node_media_paths");

#[derive(Clone)]
pub struct Database {
    inner: Arc<redb::Database>,
    text_search: Arc<NodeTextSearchIndex>,
}

impl Database {
    pub fn open(path: &Path) -> Result<Self, anyhow::Error> {
        create_dir_all(path).context("creating database directory")?;
        info!("opening kv store...");
        let db = redb::Database::create(path.join("data")).context("opening kv store")?;
        info!("opening node index...");
        let ft_node = NodeTextSearchIndex::new(path).context("in node index")?;
        let r = Self {
            inner: db.into(),
            text_search: ft_node.into(),
        };

        {
            // this creates all tables such that read operations on them do not fail.
            let txn = r.inner.begin_write()?;
            txn.open_table(T_INVITE)?;
            txn.open_table(T_USER)?;
            txn.open_table(T_USER_NODE)?;
            txn.open_table(T_NODE)?;
            txn.open_table(T_NODE_MTIME)?;
            txn.open_table(T_NODE_CHILDREN)?;
            txn.open_table(T_NODE_EXTERNAL_ID)?;
            txn.open_table(T_NODE_MEDIA_PATHS)?;
            txn.open_table(T_IMPORT_FILE_MTIME)?;
            txn.commit()?;
        }

        info!("ready");
        Ok(r)
    }

    pub fn get_node_slug(&self, slug: &str) -> Result<Option<Arc<Node>>> {
        self.get_node(NodeID::from_slug(slug))
    }

    pub fn get_node(&self, id: NodeID) -> Result<Option<Arc<Node>>> {
        let txn = self.inner.begin_read()?;
        let t_node = txn.open_table(T_NODE)?;
        if let Some(node) = t_node.get(id.0)? {
            Ok(Some(node.value().0.into()))
        } else {
            Ok(None)
        }
    }
    pub fn get_node_external_id(&self, platform: &str, eid: &str) -> Result<Option<NodeID>> {
        let txn = self.inner.begin_read()?;
        let t_node_external_id = txn.open_table(T_NODE_EXTERNAL_ID)?;
        if let Some(id) = t_node_external_id.get((platform, eid))? {
            Ok(Some(NodeID(id.value())))
        } else {
            Ok(None)
        }
    }
    pub fn get_node_children(&self, id: NodeID) -> Result<Vec<NodeID>> {
        let txn = self.inner.begin_read()?;
        let t_node_children = txn.open_table(T_NODE_CHILDREN)?;
        Ok(t_node_children
            .range((id.0, NodeID::MIN.0)..(id.0, NodeID::MAX.0))?
            .map(|r| r.map(|r| NodeID(r.0.value().1)))
            .collect::<Result<Vec<_>, StorageError>>()?)
    }
    pub fn get_tag_nodes(&self, tag: &str) -> Result<Vec<NodeID>> {
        let txn = self.inner.begin_read()?;
        let t_tag_node = txn.open_table(T_TAG_NODE)?;
        Ok(t_tag_node
            .range((tag, NodeID::MIN.0)..(tag, NodeID::MAX.0))?
            .map(|r| r.map(|r| NodeID(r.0.value().1)))
            .collect::<Result<Vec<_>, StorageError>>()?)
    }
    pub fn get_nodes_modified_since(&self, since: u64) -> Result<Vec<NodeID>> {
        let txn = self.inner.begin_read()?;
        let t_node_mtime = txn.open_table(T_NODE_MTIME)?;
        Ok(t_node_mtime
            .iter()?
            .flat_map(|r| r.map(|r| (NodeID(r.0.value()), r.1.value())))
            .filter(|(_, mtime)| *mtime >= since)
            .map(|(id, _)| id)
            .collect())
    }

    pub fn clear_nodes(&self) -> Result<()> {
        let mut txn = self.inner.begin_write()?;
        let mut t_node = txn.open_table(T_NODE)?;
        let mut t_node_mtime = txn.open_table(T_NODE_MTIME)?;
        let mut t_node_children = txn.open_table(T_NODE_CHILDREN)?;
        let mut t_node_external_id = txn.open_table(T_NODE_EXTERNAL_ID)?;
        let mut t_import_file_mtime = txn.open_table(T_IMPORT_FILE_MTIME)?;
        let mut t_node_media_paths = txn.open_table(T_NODE_MEDIA_PATHS)?;
        t_node.retain(|_, _| false)?;
        t_node_mtime.retain(|_, _| false)?;
        t_node_children.retain(|_, _| false)?;
        t_node_external_id.retain(|_, _| false)?;
        t_import_file_mtime.retain(|_, _| false)?;
        t_node_media_paths.retain(|_, _| false)?;
        drop((
            t_node,
            t_node_mtime,
            t_node_children,
            t_node_external_id,
            t_import_file_mtime,
            t_node_media_paths,
        ));
        txn.set_durability(Durability::Eventual);
        txn.commit()?;
        Ok(())
    }

    pub fn get_node_udata(&self, id: NodeID, username: &str) -> Result<Option<NodeUserData>> {
        let txn = self.inner.begin_read()?;
        let t_node = txn.open_table(T_USER_NODE)?;
        if let Some(node) = t_node.get((username, id.0))? {
            Ok(Some(node.value().0))
        } else {
            Ok(None)
        }
    }

    pub fn update_node_init(
        &self,
        id: NodeID,
        update: impl FnOnce(&mut Node) -> Result<()>,
    ) -> Result<()> {
        let time = SystemTime::now()
            .duration_since(SystemTime::UNIX_EPOCH)
            .unwrap()
            .as_secs();
        let mut txn = self.inner.begin_write()?;
        let mut t_node = txn.open_table(T_NODE)?;
        let mut t_node_mtime = txn.open_table(T_NODE_MTIME)?;
        let mut t_node_children = txn.open_table(T_NODE_CHILDREN)?;
        let mut t_node_external_id = txn.open_table(T_NODE_EXTERNAL_ID)?;
        let mut t_tag_node = txn.open_table(T_TAG_NODE)?;
        let mut node = t_node.get(id.0)?.map(|v| v.value().0).unwrap_or_default();

        let mut dh_before = HashWriter(DefaultHasher::new());
        bincode::encode_into_writer(&node, &mut dh_before, standard()).unwrap();
        update(&mut node)?;
        let mut dh_after = HashWriter(DefaultHasher::new());
        bincode::encode_into_writer(&node, &mut dh_after, standard()).unwrap();

        if dh_before.0.finish() == dh_after.0.finish() {
            return Ok(());
        }

        for parent in &node.parents {
            t_node_children.insert((parent.0, id.0), ())?;
        }
        for (pl, eid) in &node.external_ids {
            t_node_external_id.insert((pl.as_str(), eid.as_str()), id.0)?;
        }
        for tag in &node.tags {
            t_tag_node.insert((tag.as_str(), id.0), ())?;
        }
        t_node.insert(&id.0, Ser(node))?;
        t_node_mtime.insert(&id.0, time)?;
        drop((
            t_node,
            t_node_mtime,
            t_node_children,
            t_node_external_id,
            t_tag_node,
        ));
        txn.set_durability(Durability::Eventual);
        txn.commit()?;
        Ok(())
    }
    pub fn get_node_media_paths(&self, id: NodeID) -> Result<Vec<PathBuf>> {
        let txn = self.inner.begin_read()?;
        let table = txn.open_table(T_NODE_MEDIA_PATHS)?;
        let mut paths = Vec::new();
        // TODO fix this
        for p in table.range((id.0, "\0")..(id.0, "\x7f"))? {
            paths.push(PathBuf::from_str(p?.0.value().1)?);
        }
        Ok(paths)
    }
    pub fn insert_node_media_path(&self, id: NodeID, path: &Path) -> Result<()> {
        let txn = self.inner.begin_write()?;
        let mut table = txn.open_table(T_NODE_MEDIA_PATHS)?;
        table.insert((id.0, path.to_str().unwrap()), ())?;
        drop(table);
        txn.commit()?;
        Ok(())
    }

    pub fn update_node_udata(
        &self,
        node: NodeID,
        username: &str,
        update: impl FnOnce(&mut NodeUserData) -> Result<()>,
    ) -> Result<()> {
        let txn = self.inner.begin_write()?;
        let mut user_nodes = txn.open_table(T_USER_NODE)?;

        let mut udata = user_nodes
            .get((username, node.0))?
            .map(|x| x.value().0)
            .unwrap_or_default();

        update(&mut udata)?;

        user_nodes.insert((username, node.0), Ser(udata))?;
        drop(user_nodes);
        txn.commit()?;
        Ok(())
    }

    pub fn get_user(&self, username: &str) -> Result<Option<User>> {
        let txn = self.inner.begin_read()?;
        let t_user = txn.open_table(T_USER)?;
        if let Some(user) = t_user.get(username)? {
            Ok(Some(user.value().0))
        } else {
            Ok(None)
        }
    }
    pub fn update_user(
        &self,
        username: &str,
        update: impl FnOnce(&mut User) -> Result<()>,
    ) -> Result<()> {
        let txn = self.inner.begin_write()?;
        let mut users = txn.open_table(T_USER)?;
        let mut user = users
            .get(username)?
            .ok_or(anyhow!("user does not exist"))?
            .value()
            .0;
        update(&mut user)?;
        users.insert(&username, Ser(user))?;
        drop(users);
        txn.commit()?;

        Ok(())
    }
    pub fn delete_user(&self, username: &str) -> Result<bool> {
        let txn = self.inner.begin_write()?;
        let mut table = txn.open_table(T_USER)?;
        let r = table.remove(username)?.is_some();
        drop(table);
        txn.commit()?;
        Ok(r)
    }
    pub fn list_users(&self) -> Result<Vec<User>> {
        let txn = self.inner.begin_read()?;
        let table = txn.open_table(T_USER)?;
        let i = table
            .iter()?
            .map(|a| {
                let (_, y) = a.unwrap(); // TODO
                y.value().0
            })
            .collect::<Vec<_>>();
        drop(table);
        Ok(i)
    }
    pub fn list_invites(&self) -> Result<Vec<String>> {
        let txn = self.inner.begin_read()?;
        let table = txn.open_table(T_INVITE)?;
        let i = table
            .iter()?
            .map(|a| {
                let (x, _) = a.unwrap();
                x.value().to_owned()
            })
            .collect::<Vec<_>>();
        drop(table);
        Ok(i)
    }
    pub fn create_invite(&self, inv: &str) -> Result<()> {
        let txn = self.inner.begin_write()?;
        let mut table = txn.open_table(T_INVITE)?;
        table.insert(inv, ())?;
        drop(table);
        txn.commit()?;
        Ok(())
    }
    pub fn delete_invite(&self, inv: &str) -> Result<bool> {
        let txn = self.inner.begin_write()?;
        let mut table = txn.open_table(T_INVITE)?;
        let r = table.remove(inv)?.is_some();
        drop(table);
        txn.commit()?;
        Ok(r)
    }
    pub fn register_user(&self, invite: &str, username: &str, user: User) -> Result<()> {
        let txn = self.inner.begin_write()?;
        let mut invites = txn.open_table(T_INVITE)?;
        let mut users = txn.open_table(T_USER)?;

        if invites.remove(invite)?.is_none() {
            bail!("invitation invalid");
        }
        let prev_user = users.insert(username, Ser(user))?.map(|x| x.value().0);
        if prev_user.is_some() {
            bail!("username taken");
        }

        drop(users);
        drop(invites);
        txn.commit()?;
        Ok(())
    }
    pub fn list_nodes_with_udata(&self, username: &str) -> Result<Vec<(Arc<Node>, NodeUserData)>> {
        let txn = self.inner.begin_read()?;
        let nodes = txn.open_table(T_NODE)?;
        let node_users = txn.open_table(T_USER_NODE)?;
        let i = nodes
            .iter()?
            .map(|a| {
                let (x, y) = a.unwrap();
                let (x, y) = (x.value().to_owned(), Arc::new(y.value().0));
                let z = node_users
                    .get(&(username, x))
                    .unwrap()
                    .map(|z| z.value().0)
                    .unwrap_or_default();
                (y, z)
            })
            .collect::<Vec<_>>();
        drop(nodes);
        Ok(i)
    }
    pub fn search(&self, query: &str, limit: usize, offset: usize) -> Result<(usize, Vec<NodeID>)> {
        let query = QueryParser::for_index(
            &self.text_search.index,
            vec![self.text_search.title, self.text_search.description],
        )
        .parse_query(query)
        .context("parsing query")?;

        let searcher = self.text_search.reader.searcher();
        let sres = searcher.search(&query, &TopDocs::with_limit(limit).and_offset(offset))?;
        let scount = searcher.search(&query, &Count)?;

        let mut results = Vec::new();
        for (_, daddr) in sres {
            let doc: TantivyDocument = searcher.doc(daddr)?;
            let id = doc
                .get_first(self.text_search.id)
                .unwrap()
                .as_bytes()
                .unwrap();
            let id = NodeID(id.try_into().unwrap());
            results.push(id);
        }
        Ok((scount, results))
    }

    pub fn search_create_index(&self) -> Result<()> {
        let mut w = self.text_search.writer.write().unwrap();
        w.delete_all_documents()?;

        let txn = self.inner.begin_read()?;
        let nodes = txn.open_table(T_NODE)?;
        for node in nodes.iter()? {
            let (x, y) = node?;
            let (id, node) = (x.value().to_owned(), y.value().0);

            w.add_document(doc!(
                self.text_search.id => id.to_vec(),
                self.text_search.title => node.title.unwrap_or_default(),
                self.text_search.description => node.description.unwrap_or_default(),
                self.text_search.releasedate => DateTime::from_timestamp_millis(node.release_date.unwrap_or_default()),
                self.text_search.f_index => node.index.unwrap_or_default() as u64,
            ))?;
        }

        w.commit()?;
        Ok(())
    }

    pub fn create_admin_user(&self, username: &str, password_hash: Vec<u8>) -> Result<()> {
        let txn = self.inner.begin_write().unwrap();
        let mut users = txn.open_table(T_USER).unwrap();

        let admin = users.get(username).unwrap().map(|x| x.value().0);
        users
            .insert(
                username,
                Ser(User {
                    admin: true,
                    name: username.to_owned(),
                    password: password_hash,
                    ..admin.unwrap_or_else(|| User {
                        display_name: "Admin".to_string(),
                        ..Default::default()
                    })
                }),
            )
            .unwrap();

        drop(users);
        txn.commit().unwrap();
        Ok(())
    }
    pub fn get_import_file_mtime(&self, path: &Path) -> Result<Option<u64>> {
        let bytes = path.as_os_str().as_encoded_bytes();
        let txn = self.inner.begin_read()?;
        let table = txn.open_table(T_IMPORT_FILE_MTIME)?;
        if let Some(v) = table.get(bytes)? {
            Ok(Some(v.value()))
        } else {
            Ok(None)
        }
    }
    pub fn set_import_file_mtime(&self, path: &Path, mtime: u64) -> Result<()> {
        let bytes = path.as_os_str().as_encoded_bytes();
        let txn = self.inner.begin_write()?;
        let mut table = txn.open_table(T_IMPORT_FILE_MTIME)?;
        table.insert(bytes, mtime)?;
        drop(table);
        txn.commit()?;
        Ok(())
    }
}

pub struct HashWriter(DefaultHasher);
impl bincode::enc::write::Writer for HashWriter {
    fn write(&mut self, bytes: &[u8]) -> std::result::Result<(), bincode::error::EncodeError> {
        self.0.write(bytes);
        Ok(())
    }
}

#[derive(Debug)]
#[cfg(not(feature = "db_json"))]
pub struct Ser<T>(pub T);
#[cfg(not(feature = "db_json"))]
impl<T: Encode + Decode<()> + std::fmt::Debug> redb::Value for Ser<T> {
    type SelfType<'a>
        = Ser<T>
    where
        Self: 'a;
    type AsBytes<'a>
        = Vec<u8>
    where
        Self: 'a;

    fn fixed_width() -> Option<usize> {
        None
    }

    fn from_bytes<'a>(data: &'a [u8]) -> Self::SelfType<'a>
    where
        Self: 'a,
    {
        Ser(bincode::decode_from_slice(data, bincode::config::legacy())
            .unwrap()
            .0)
    }

    fn as_bytes<'a, 'b: 'a>(value: &'a Self::SelfType<'b>) -> Self::AsBytes<'a>
    where
        Self: 'a,
        Self: 'b,
    {
        bincode::encode_to_vec(&value.0, bincode::config::legacy()).unwrap()
    }

    fn type_name() -> redb::TypeName {
        redb::TypeName::new("bincode")
    }
}

#[derive(Debug)]
#[cfg(feature = "db_json")]
pub struct Ser<T>(pub T);
#[cfg(feature = "db_json")]
impl<T: Serialize + for<'a> Deserialize<'a> + std::fmt::Debug> redb::Value for Ser<T> {
    type SelfType<'a>
        = Ser<T>
    where
        Self: 'a;
    type AsBytes<'a>
        = Vec<u8>
    where
        Self: 'a;

    fn fixed_width() -> Option<usize> {
        None
    }

    fn from_bytes<'a>(data: &'a [u8]) -> Self::SelfType<'a>
    where
        Self: 'a,
    {
        Ser(serde_json::from_slice(data).unwrap())
    }

    fn as_bytes<'a, 'b: 'a>(value: &'a Self::SelfType<'b>) -> Self::AsBytes<'a>
    where
        Self: 'a,
        Self: 'b,
    {
        serde_json::to_vec(&value.0).unwrap()
    }

    fn type_name() -> redb::TypeName {
        redb::TypeName::new("json")
    }
}