//extern crate tantivy;

use clap::ArgMatches;
//use futures::Future;
use std::path::PathBuf;
use tantivy::{Index, SegmentMeta};

const HEAP_SIZE: usize = 300_000_000;

fn error_msg(err: tantivy::TantivyError) -> String {
    format!("Merge failed : {:?}", err)
}

pub fn run_merge_cli(argmatch: &ArgMatches) -> Result<(), String> {
    let index_directory = PathBuf::from(argmatch.value_of("index").unwrap());
    run_merge(index_directory).map_err(error_msg)

    // we rollback to force a gc.
}

fn run_merge(path: PathBuf) -> tantivy::Result<()> {
    let index = Index::open_in_dir(&path)?;
    let segments = index.searchable_segment_ids()?;
    let segment_meta: SegmentMeta =
        super::run(
            index
                .writer(HEAP_SIZE)?
                .merge(&segments)
        ).expect("Merge failed");
    //.map_err(|_| tantivy::Error::ErrorInThread(String::from("Merge got cancelled")));
    println!("Merge finished with segment meta {:?}", segment_meta);
    println!("Garbage collect irrelevant segments.");
    let gc_fut = Index::open_in_dir(&path)?
        .writer_with_num_threads(1, 40_000_000)?
        .garbage_collect_files();
    super::run(gc_fut)?;
    Ok(())
}