/* This file is part of DarkFi (https://dark.fi)
 *
 * Copyright (C) 2020-2026 Dyne.org foundation
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

use darkfi::{
    net::{
        session::{SESSION_DIRECT, SESSION_INBOUND},
        settings::{MagicBytes, NetworkProfile, Settings as NetSettings},
        P2p, P2pPtr,
    },
    system::{sleep, Publisher, PublisherPtr},
};
use darkfi_serial::{Decodable, Encodable};
use fud::{
    event::FudEvent,
    proto::ProtocolFud,
    resource::ResourceStatus,
    settings::Args as FudSettings,
    util::{hash_to_string, FileSelection},
    Fud,
};
use kvdb_overlay::Database;
use smol::lock::Mutex;
use std::{
    collections::HashSet,
    io::Cursor,
    path::PathBuf,
    sync::{Arc, OnceLock, Weak},
};
use url::Url;

use crate::{
    error::{Error, Result},
    prop::{PropertyAtomicGuard, PropertyBool, Role},
    scene::{MethodCall, MethodCallSub, Pimpl, SceneNodePtr, SceneNodeWeak},
    ui::chatview::FileMessageStatus,
    ExecutorPtr,
};

const P2P_RETRY_TIME: u64 = 20;

#[cfg(target_os = "android")]
mod paths {
    use crate::android::{get_appdata_path, get_external_storage_path};
    use std::path::PathBuf;

    pub fn get_base_path() -> PathBuf {
        get_external_storage_path().join("fud")
    }
    pub fn get_db_path() -> PathBuf {
        get_external_storage_path().join("fud/db")
    }
    pub fn get_downloads_path() -> PathBuf {
        get_external_storage_path().join("fud/downloads")
    }
    pub fn get_use_tor_filename() -> PathBuf {
        get_external_storage_path().join("use_tor.txt")
    }

    pub fn p2p_datastore_path() -> PathBuf {
        get_appdata_path().join("fud/p2p")
    }
    pub fn hostlist_path() -> PathBuf {
        get_appdata_path().join("fud/hostlist.tsv")
    }
}

#[cfg(not(target_os = "android"))]
mod paths {
    use std::path::PathBuf;

    pub fn get_base_path() -> PathBuf {
        dirs::data_local_dir().unwrap().join("darkfi/app/fud")
    }
    pub fn get_db_path() -> PathBuf {
        dirs::data_local_dir().unwrap().join("darkfi/app/fud/db")
    }
    pub fn get_downloads_path() -> PathBuf {
        dirs::data_local_dir().unwrap().join("darkfi/app/fud/downloads")
    }
    pub fn get_use_tor_filename() -> PathBuf {
        dirs::data_local_dir().unwrap().join("darkfi/app/use_tor.txt")
    }

    pub fn p2p_datastore_path() -> PathBuf {
        dirs::cache_dir().unwrap().join("darkfi/app/fud/p2p")
    }
    pub fn hostlist_path() -> PathBuf {
        dirs::cache_dir().unwrap().join("darkfi/app/fud/hostlist.tsv")
    }
}

use paths::*;

macro_rules! t { ($($arg:tt)*) => { trace!(target: "plugin::fud", $($arg)*); } }
macro_rules! d { ($($arg:tt)*) => { debug!(target: "plugin::fud", $($arg)*); } }
macro_rules! i { ($($arg:tt)*) => { info!(target: "plugin::fud", $($arg)*); } }
macro_rules! e { ($($arg:tt)*) => { error!(target: "plugin::fud", $($arg)*); } }

pub type FudPluginPtr = Arc<FudPlugin>;

pub struct FudPlugin {
    node: SceneNodeWeak,
    sg_root: SceneNodePtr,
    tasks: OnceLock<Vec<smol::Task<()>>>,

    p2p: P2pPtr,
    event_pub: PublisherPtr<FudEvent>,
    fud: Arc<Fud>,

    tracked_files: Arc<Mutex<HashSet<Url>>>,
}

impl FudPlugin {
    pub async fn new(node: SceneNodeWeak, sg_root: SceneNodePtr, ex: ExecutorPtr) -> Result<Pimpl> {
        let node_ref = &node.upgrade().unwrap();
        // let fud_node_id = PropertyStr::wrap(node_ref, Role::Internal, "node_id", 0).unwrap();
        let fud_ready = PropertyBool::wrap(node_ref, Role::Internal, "ready", 0).unwrap();
        fud_ready.set(&mut PropertyAtomicGuard::none(), false);

        let basedir = get_base_path();

        i!("Starting Fud backend");
        let db_path = get_db_path();
        let db = match Database::open_default(&db_path) {
            Ok(db) => db,
            Err(err) => {
                e!("Kvdb database '{}' failed to open: {err}!", db_path.display());
                return Err(Error::KvdbErr)
            }
        };

        let mut fud_settings: FudSettings = Default::default();
        fud_settings.base_dir = basedir.to_string_lossy().to_string();
        let mut p2p_settings: NetSettings = Default::default();
        p2p_settings.magic_bytes = MagicBytes([73, 59, 41, 23]);
        p2p_settings.app_version = semver::Version::parse("0.5.0").unwrap();
        p2p_settings.app_name = "fud".to_string();
        if get_use_tor_filename().exists() {
            i!("Setup P2P network [tor]");
            let mut tor_profile = NetworkProfile::tor_default();
            tor_profile.outbound_connect_timeout = 60;
            p2p_settings.profiles.insert("tor".to_string(), tor_profile);
            p2p_settings.outbound_peer_discovery_cooloff_time = 60;

            p2p_settings.seeds.push(
                url::Url::parse(
                    "tor://wgxxaifz5gv4iggcflyl67lgmsihffs6bbwobqah4np52t3y3olrnpid.onion:9701",
                )
                .unwrap(),
            );
            p2p_settings.seeds.push(
                url::Url::parse(
                    "tor://inx5s3pdzddvgb5ii3oydutmbvw6fvor3oqu65wtxl3pyevtvrdn4had.onion:9701",
                )
                .unwrap(),
            );
            p2p_settings.active_profiles = vec!["tor".to_string()];

            fud_settings.pow.btc_electrum_nodes.push(
                url::Url::parse(
                    "tor://hezojf7rda2c33yxgcgcvvsxflechdz5vkm64gwlszgx2r4gc5e42kqd.onion:50001",
                )
                .unwrap(),
            );
            fud_settings.pow.btc_electrum_nodes.push(
                url::Url::parse(
                    "tor://n4widoxtm3xpo2fjvtdffhb63q5td3utaxkolaegnpzb5khbwxvdrlad.onion:50001",
                )
                .unwrap(),
            );
            fud_settings.pow.btc_electrum_nodes.push(
                url::Url::parse(
                    "tor://duras25aqnp3tnn2zgma7pusms6c7umtunyu2sp6e5byotr3c4c6rzad.onion:50001",
                )
                .unwrap(),
            );
            fud_settings.pow.btc_electrum_nodes.push(
                url::Url::parse(
                    "tor://n3dz6thzxobyphuosoftgtf36rnsxlsjknke4yrbdys55zvd7nsx7qid.onion:50001",
                )
                .unwrap(),
            );
        } else {
            i!("Setup P2P network [clearnet]");
            let mut profile = NetworkProfile::default();
            profile.outbound_connect_timeout = 40;
            profile.channel_handshake_timeout = 30;
            p2p_settings.profiles.insert("tcp+tls".to_string(), profile);
            p2p_settings.active_profiles = vec!["tcp+tls".to_string()];

            p2p_settings.seeds.push(url::Url::parse("tcp+tls://lilith0.dark.fi:9700").unwrap());
            p2p_settings.seeds.push(url::Url::parse("tcp+tls://lilith1.dark.fi:9700").unwrap());

            fud_settings
                .pow
                .btc_electrum_nodes
                .push(url::Url::parse("tcp://fulcrum.grey.pw:50001").unwrap());
            fud_settings
                .pow
                .btc_electrum_nodes
                .push(url::Url::parse("tcp://blockstream.info:110").unwrap());
            fud_settings
                .pow
                .btc_electrum_nodes
                .push(url::Url::parse("tcp://btc.electroncash.dk:60001").unwrap());
            fud_settings
                .pow
                .btc_electrum_nodes
                .push(url::Url::parse("tcp://electrum.direwolfm14.com:50001").unwrap());
            fud_settings
                .pow
                .btc_electrum_nodes
                .push(url::Url::parse("tcp://electrum.blockstream.info:50001").unwrap());
        }
        p2p_settings.p2p_datastore = p2p_datastore_path().into_os_string().into_string().ok();
        p2p_settings.hostlist = hostlist_path().into_os_string().into_string().ok();

        let p2p = match P2p::new(p2p_settings.clone(), ex.clone()).await {
            Ok(p2p) => p2p,
            Err(err) => {
                e!("Create p2p network failed: {err}!");
                return Err(Error::ServiceFailed)
            }
        };

        p2p.session_direct().start_peer_discovery();

        let event_pub = Publisher::new();
        let fud: Arc<Fud> =
            match Fud::new(fud_settings, p2p.clone(), &db, event_pub.clone(), ex.clone()).await {
                Ok(fud) => fud,
                Err(err) => {
                    e!("Cannot create fud instance: {err}");
                    return Err(Error::ServiceFailed)
                }
            };

        let self_ = Arc::new(Self {
            node: node.clone(),
            sg_root,
            tasks: OnceLock::new(),
            p2p,
            event_pub,
            fud,
            tracked_files: Arc::new(Mutex::new(HashSet::new())),
        });
        self_.clone().start(ex).await;
        Ok(Pimpl::Fud(self_))
    }

    async fn start(self: Arc<Self>, ex: ExecutorPtr) {
        i!("Registering Fud protocol");
        let registry = self.p2p.protocol_registry();
        let fud = self.fud.clone();
        let p2p = self.p2p.clone();
        registry
            .register(SESSION_DIRECT | SESSION_INBOUND, move |channel, _| {
                let fud_ = fud.clone();
                let p2p_ = p2p.clone();
                async move { ProtocolFud::init(fud_, channel, p2p_).await.unwrap() }
            })
            .await;

        let me = Arc::downgrade(&self);

        let node = &self.node.upgrade().unwrap();

        let method_sub = node.subscribe_method_call("get").unwrap();
        let me2 = me.clone();
        let get_method_task =
            ex.spawn(async move { while Self::process_get(&me2, &method_sub).await {} });

        let method_sub = node.subscribe_method_call("track_file").unwrap();
        let me2 = me.clone();
        let track_file_method_task =
            ex.spawn(async move { while Self::process_track_file(&me2, &method_sub).await {} });

        let event_pub = self.event_pub.clone();
        let me2 = me.clone();
        let ev_task = ex.spawn(async move {
            Self::process_events(&me2, event_pub).await;
        });

        let fud = self.fud.clone();
        let start_task = ex.spawn(async move {
            while fud.start().await.is_err() {
                sleep(10).await;
            }
        });

        let tasks = vec![get_method_task, track_file_method_task, ev_task, start_task];
        self.tasks.set(tasks).unwrap();

        i!("Starting Fud P2P");
        while let Err(err) = self.p2p.clone().start().await {
            // This usually means we cannot listen on the inbound ports
            e!("Failed to start fud's p2p network: {err}!");
            e!("Usually this means there is another process listening on the same ports.");
            e!("Trying again in {P2P_RETRY_TIME} secs");
            sleep(P2P_RETRY_TIME).await;
        }
    }

    fn string_to_hash(str: &str) -> std::io::Result<blake3::Hash> {
        let mut hash_buf = vec![];

        match bs58::decode(str).onto(&mut hash_buf) {
            Ok(_) => {}
            Err(_) => {
                return Err(std::io::Error::new(std::io::ErrorKind::Other, "Invalid fud hash"))
            }
        }

        if hash_buf.len() != 32 {
            return Err(std::io::Error::new(std::io::ErrorKind::Other, "Invalid fud hash"))
        }

        let mut hash_buf_arr = [0u8; 32];
        hash_buf_arr.copy_from_slice(&hash_buf);

        Ok(blake3::Hash::from_bytes(hash_buf_arr))
    }

    fn parse_url(url: &Url) -> std::io::Result<(String, blake3::Hash)> {
        let hash_string = url
            .host_str()
            .map(|s| s.to_string())
            .ok_or_else(|| std::io::Error::new(std::io::ErrorKind::Other, "Missing fud hash"))?;

        let hash = Self::string_to_hash(&hash_string)?;

        Ok((hash_string, hash))
    }

    fn url_to_file_selection(url: &Url) -> FileSelection {
        match url.path() {
            "/" | "" => FileSelection::All,
            path => {
                let mut selection = HashSet::new();
                selection.insert(PathBuf::from(path.strip_prefix("/").unwrap_or(path)));
                FileSelection::Set(selection)
            }
        }
    }

    async fn find_urls_by_hash(&self, hash: &blake3::Hash) -> Vec<Url> {
        let tracked = self.tracked_files.lock().await;
        let hash_str = hash_to_string(hash);
        tracked.iter().filter(|url| url.host_str() == Some(hash_str.as_str())).cloned().collect()
    }

    fn decode_data(
        &self,
        method_call: &MethodCall,
    ) -> (Option<String>, std::io::Result<(blake3::Hash, Url, Option<String>)>) {
        fn decode_data(data: &[u8]) -> std::io::Result<(String, Url, Option<String>)> {
            let mut cur = Cursor::new(&data);
            let url = Url::decode(&mut cur)?;
            let Some(hash_string) = url.host_str() else {
                return Err(std::io::Error::new(std::io::ErrorKind::Other, "Missing fud hash"))
            };
            let hash_string = hash_string.to_string();
            let err_msg = String::decode(&mut cur).ok();

            Ok((hash_string, url, err_msg))
        }

        let Ok((hash_string, url, err_msg)) = decode_data(&method_call.data) else {
            return (None, Err(std::io::Error::new(std::io::ErrorKind::Other, "Invalid fud url")))
        };

        let Ok(hash) = FudPlugin::string_to_hash(&hash_string) else {
            return (
                Some(hash_string),
                Err(std::io::Error::new(std::io::ErrorKind::Other, "Invalid fud url")),
            )
        };

        (Some(hash_string), Ok((hash, url, err_msg)))
    }

    async fn process_get(me: &Weak<Self>, sub: &MethodCallSub) -> bool {
        let Ok(method_call) = sub.receive().await else {
            d!("Fud event relayer closed");
            return false
        };

        t!("method called: get({method_call:?})");
        assert!(method_call.send_res.is_none());

        let Some(self_) = me.upgrade() else {
            // Should not happen
            panic!("self destroyed before get_method_task was stopped!");
        };

        let (hash_string, data) = self_.decode_data(&method_call);
        if let Err(e) = data {
            e!("get() method invalid arg data: {e}");
            return true
        };

        let hash_string = hash_string.unwrap();
        let (hash, url, _) = data.unwrap();

        if self_.node.upgrade().unwrap().get_property_bool("ready").unwrap() {
            let file_selection = Self::url_to_file_selection(&url);
            let _ = self_
                .fud
                .get(&hash, &get_downloads_path().join(&hash_string), file_selection)
                .await;
        }

        true
    }

    /// Get the current file status for a fileurl, a `None` means it should not
    /// be updated
    async fn get_status(&self, hash: &blake3::Hash, url: &Url) -> Option<FileMessageStatus> {
        let resources = self.fud.resources().await;
        let resource = resources.get(hash);
        if resource.is_none() {
            return Some(FileMessageStatus::Idle)
        }
        let resource = resource.unwrap();
        let mut path = resource.path.clone();
        let file_selection = Self::url_to_file_selection(url);
        if let FileSelection::Set(selection) = &file_selection {
            if let Some(rel_path) = selection.iter().next() {
                path = path.join(rel_path);
            }
        }
        let path = path.to_string_lossy().to_string();

        if file_selection.is_disjoint(&resource.last_file_selection) {
            return None::<FileMessageStatus>
        }

        let (bytes_downloaded, bytes_total) = self.fud.get_progress(hash, &file_selection).await;
        let progress =
            if bytes_total != 0 { bytes_downloaded as f32 / bytes_total as f32 * 100. } else { 0. };

        match resource.status {
            ResourceStatus::Discovering => Some(FileMessageStatus::Downloading { progress }),
            ResourceStatus::Downloading => {
                if progress < 100. {
                    Some(FileMessageStatus::Downloading { progress })
                } else {
                    Some(FileMessageStatus::Downloaded { path })
                }
            }
            ResourceStatus::Incomplete(ref err) => {
                if progress < 100. {
                    if let Some(msg) = err {
                        Some(FileMessageStatus::Error { msg: msg.clone(), progress })
                    } else {
                        Some(FileMessageStatus::Error { msg: "incomplete".to_string(), progress })
                    }
                } else {
                    Some(FileMessageStatus::Downloaded { path })
                }
            }
            ResourceStatus::Verifying => None,
            // Seeding status means we have the full resource
            // (partial seeding is not supported by fud)
            ResourceStatus::Seeding => Some(FileMessageStatus::Downloaded { path }),
        }
    }

    async fn process_track_file(me: &Weak<Self>, sub: &MethodCallSub) -> bool {
        let Ok(method_call) = sub.receive().await else {
            d!("Fud event relayer closed");
            return false
        };

        t!("method called: track_file({method_call:?})");
        assert!(method_call.send_res.is_none());

        let Some(self_) = me.upgrade() else {
            // Should not happen
            panic!("self destroyed before track_file_method_task was stopped!");
        };

        let mut cur = Cursor::new(&method_call.data);
        let Ok(url) = Url::decode(&mut cur) else {
            e!("track_file() method invalid arg data");
            return true
        };

        self_.track_file(url).await;

        true
    }

    /// Emit file_status_updated signal to all ChatViews
    async fn emit_file_status(&self, url: &Url, status: &FileMessageStatus) {
        let mut data = vec![];
        url.encode(&mut data).unwrap();
        status.encode(&mut data).unwrap();
        let _ = self.node.upgrade().unwrap().trigger("file_status_updated", data).await;
    }

    /// Emit error status for a URL
    async fn emit_error(&self, url: &Url, msg: String) {
        self.emit_file_status(url, &FileMessageStatus::Error { msg, progress: 0. }).await;
    }

    /// Update tracked files and emit status signal
    async fn update_resource(&self, hash: &blake3::Hash) {
        let urls = self.find_urls_by_hash(hash).await;
        for url in urls {
            self.update_fileurl(&url).await;
        }
    }

    async fn update_fileurl(&self, url: &Url) -> bool {
        let (_hash_string, hash) = match Self::parse_url(url) {
            Ok(h) => h,
            Err(err) => {
                self.emit_error(url, err.to_string()).await;
                return true
            }
        };

        let status = self.get_status(&hash, url).await;

        // Emit signal
        if let Some(status) = status {
            self.emit_file_status(url, &status).await;
            return true
        }

        false
    }

    /// Emit status for all tracked files
    async fn ready_files(&self) {
        let tracked = self.tracked_files.lock().await;
        let urls: Vec<Url> = tracked.iter().cloned().collect();
        drop(tracked);

        for url in urls {
            let (_hash_string, hash) = match Self::parse_url(&url) {
                Ok(h) => h,
                Err(err) => {
                    self.emit_error(&url, err.to_string()).await;
                    continue
                }
            };

            let status = self.get_status(&hash, &url).await;

            if let Some(status) = status {
                self.emit_file_status(&url, &status).await;
            } else {
                self.emit_file_status(&url, &FileMessageStatus::Idle).await;
            }
        }
    }

    /// Track a file URL (called when the fileurl_detected signal is emitted)
    async fn track_file(&self, url: Url) {
        let (_hash_string, _hash) = match Self::parse_url(&url) {
            Ok(h) => h,
            Err(err) => {
                self.emit_error(&url, err.to_string()).await;
                return
            }
        };

        if self.node.upgrade().unwrap().get_property_bool("ready").unwrap() {
            let updated = self.update_fileurl(&url).await;
            if !updated {
                self.emit_file_status(&url, &FileMessageStatus::Idle).await;
            }
        }

        let mut tracked = self.tracked_files.lock().await;
        tracked.insert(url);
    }

    async fn process_events(me: &Weak<Self>, publisher: PublisherPtr<FudEvent>) {
        let Some(self_) = me.upgrade() else {
            // Should not happen
            panic!("self destroyed before ev_task was stopped!");
        };

        let sub = publisher.subscribe().await;

        loop {
            match sub.receive().await {
                FudEvent::Ready => {
                    let atom = &mut PropertyAtomicGuard::none();
                    self_
                        .node
                        .upgrade()
                        .unwrap()
                        .set_property_bool(atom, Role::App, "ready", true)
                        .unwrap();

                    self_.ready_files().await;
                }
                FudEvent::DownloadStarted(ev) => {
                    self_.update_resource(&ev.resource.hash).await;
                }
                FudEvent::ChunkDownloadCompleted(ev) => {
                    self_.update_resource(&ev.resource.hash).await;
                }
                FudEvent::DownloadCompleted(ev) => {
                    self_.update_resource(&ev.resource.hash).await;
                }
                FudEvent::ResourceUpdated(ev) => {
                    self_.update_resource(&ev.resource.hash).await;
                }
                FudEvent::DownloadError(ev) => {
                    self_.update_resource(&ev.hash).await;
                }
                FudEvent::MissingChunks(ev) => {
                    self_.update_resource(&ev.hash).await;
                }
                FudEvent::MetadataNotFound(ev) => {
                    self_.update_resource(&ev.hash).await;
                }
                _ => {}
            };
        }
    }
}