// Copyright (c) 2004-present, Facebook, Inc.
// All Rights Reserved.
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

#![deny(warnings)]

use blobrepo::BlobRepo;
use bookmarks::Bookmark;
use failure::Error;
use failure::Result;
use futures::{Future, Stream};
use futures_ext::{BoxFuture, FutureExt};
use hooks::{BlobRepoChangesetStore, BlobRepoFileContentStore, ChangesetHookExecutionID,
            FileHookExecutionID, HookExecution, HookManager, hook_loader::load_hooks};
use manifold::{ManifoldHttpClient, PayloadRange};
use mercurial_types::{HgChangesetId, HgNodeHash};
use metaconfig::repoconfig::RepoConfig;
use revset::AncestorsNodeStream;
use slog::Logger;
use std::sync::Arc;

pub struct Tailer {
    repo: Arc<BlobRepo>,
    hook_manager: Arc<HookManager>,
    bookmark: Bookmark,
    last_rev_key: String,
    manifold_client: ManifoldHttpClient,
    logger: Logger,
}

impl Tailer {
    pub fn new(
        repo_name: String,
        repo: Arc<BlobRepo>,
        config: RepoConfig,
        bookmark: Bookmark,
        manifold_client: ManifoldHttpClient,
        logger: Logger,
    ) -> Result<Tailer> {
        let changeset_store = BlobRepoChangesetStore::new((*repo).clone());
        let content_store = BlobRepoFileContentStore::new((*repo).clone());

        let mut hook_manager = HookManager::new(
            repo_name,
            Box::new(changeset_store),
            Arc::new(content_store),
            1024 * 1024,
            1024 * 1024 * 1024,
            logger.clone(),
        );

        load_hooks(&mut hook_manager, config)?;

        let repo_id = repo.get_repoid().id();
        let last_rev_key = format!("{}{}", "__mononoke_hook_tailer_last_rev.", repo_id).to_string();

        Ok(Tailer {
            repo,
            hook_manager: Arc::new(hook_manager),
            bookmark,
            last_rev_key,
            manifold_client,
            logger,
        })
    }

    pub fn get_last_rev_key(&self) -> String {
        self.last_rev_key.clone()
    }

    fn run_in_range0(
        repo: Arc<BlobRepo>,
        hm: Arc<HookManager>,
        last_rev: HgNodeHash,
        end_rev: HgNodeHash,
        bm: Bookmark,
        logger: Logger,
    ) -> BoxFuture<
        Vec<
            (
                Vec<(FileHookExecutionID, HookExecution)>,
                Vec<(ChangesetHookExecutionID, HookExecution)>,
            ),
        >,
        Error,
    > {
        debug!(logger, "Running in range {} to {}", last_rev, end_rev);
        let logger = logger.clone();
        let logger2 = logger.clone();
        let hm2 = hm.clone();
        let bm2 = bm.clone();
        AncestorsNodeStream::new(&repo, end_rev)
            .take(1000) // Limit number so we don't process too many
            .take_while(move |node_hash| {
                Ok(*node_hash != last_rev)
            })
            .and_then(move |node_hash| {
                info!(logger, "Running file hooks for changeset {:?}", node_hash);
                hm.run_file_hooks_for_bookmark(HgChangesetId::new(node_hash.clone()), &bm)
                .map(move |res| (node_hash, res))
            })
            .and_then(move |(node_hash, file_res)| {
                info!(logger2, "Running changeset hooks for changeset {:?}", node_hash);
                hm2.run_changeset_hooks_for_bookmark(HgChangesetId::new(node_hash.clone()), &bm2)
                .map(|res| (file_res, res))
            })
            .collect()
            .boxify()
    }

    pub fn run_in_range(
        &self,
        last_rev: HgNodeHash,
        end_rev: HgNodeHash,
    ) -> BoxFuture<
        Vec<
            (
                Vec<(FileHookExecutionID, HookExecution)>,
                Vec<(ChangesetHookExecutionID, HookExecution)>,
            ),
        >,
        Error,
    > {
        let repo = self.repo.clone();
        let hm = self.hook_manager.clone();
        let bm = self.bookmark.clone();
        Tailer::run_in_range0(repo, hm, last_rev, end_rev, bm, self.logger.clone())
    }

    pub fn run(
        &self,
    ) -> BoxFuture<
        Vec<
            (
                Vec<(FileHookExecutionID, HookExecution)>,
                Vec<(ChangesetHookExecutionID, HookExecution)>,
            ),
        >,
        Error,
    > {
        let bm = self.bookmark.clone();
        let bm2 = bm.clone();
        let repo = self.repo.clone();
        let hm = self.hook_manager.clone();
        let last_rev_key = self.last_rev_key.clone();
        let last_rev_key2 = last_rev_key.clone();
        let manifold_client = self.manifold_client.clone();
        let manifold_client2 = manifold_client.clone();

        info!(self.logger, "Running tailer on bookmark {}", bm);

        let logger = self.logger.clone();
        let logger2 = logger.clone();
        let logger3 = logger.clone();

        self.repo
            .get_bookmark(&bm)
            .and_then(|opt| opt.ok_or(ErrorKind::NoSuchBookmark(bm).into()))
            .and_then(move |current_bm_cs| {
                manifold_client
                    .read(last_rev_key, PayloadRange::Full)
                    .map(move |opt| (current_bm_cs, opt))
            })
            .and_then(|(current_bm_cs, opt)| match opt {
                Some(last_rev_bytes) => Ok((current_bm_cs, last_rev_bytes)),
                None => Err(ErrorKind::NoLastRevision.into()),
            })
            .and_then(|(current_bm_cs, last_rev_bytes)| {
                let node_hash = HgNodeHash::from_bytes(&*last_rev_bytes.payload.payload)?;
                Ok((current_bm_cs, node_hash))
            })
            .and_then(move |(current_bm_cs, last_rev)| {
                let end_rev = current_bm_cs.into_nodehash();
                info!(
                    logger,
                    "Bookmark is currently at {}, last processed revision is {}", end_rev, last_rev
                );
                if last_rev == end_rev {
                    info!(logger, "Nothing to do");
                }
                Tailer::run_in_range0(repo, hm, last_rev, end_rev, bm2, logger3)
                    .map(move |res| (end_rev, res))
            })
            .and_then(move |(end_rev, res)| {
                info!(logger2, "Setting last processed revision to {:?}", end_rev);
                let bytes = end_rev.as_bytes().into();
                manifold_client2.write(last_rev_key2, bytes).map(|()| res)
            })
            .boxify()
    }
}

#[derive(Debug, Fail)]
pub enum ErrorKind {
    #[fail(display = "No such bookmark '{}'", _0)] NoSuchBookmark(Bookmark),
    #[fail(display = "Cannot find last revision in blobstore")] NoLastRevision,
}