use clap::ArgMatches;
use std::fs::File;
use std::io;
use std::io::BufRead;
use std::io::BufReader;
use std::path::Path;
use std::path::PathBuf;
use tantivy::collector::{Count, TopDocs};
use tantivy::query::QueryParser;
use tantivy::schema::{Field, Schema};
use tantivy::Index;
use crate::timer::TimerTree;

pub fn run_bench_cli(matches: &ArgMatches) -> Result<(), String> {
    let index_path = PathBuf::from(matches.value_of("index").unwrap());
    let queries_path = PathBuf::from(matches.value_of("queries").unwrap()); // the unwrap is safe as long as it is comming from the main cli.
    let num_repeat = value_t!(matches, "num_repeat", usize)
        .map_err(|e| format!("Failed to read num_repeat argument as an integer. {:?}", e))?;
    run_bench(&index_path, &queries_path, num_repeat).map_err(From::from)
}

fn extract_search_fields(schema: &Schema) -> Vec<Field> {
    schema
        .fields()
        .iter()
        .enumerate()
        .filter(|&(_, field_entry)| field_entry.is_indexed())
        .map(|(field_id, _)| Field(field_id as u32))
        .collect()
}

fn read_query_file(query_path: &Path) -> io::Result<Vec<String>> {
    let query_file: File = File::open(&query_path)?;
    let file = BufReader::new(&query_file);
    let mut queries = Vec::new();
    for line_res in file.lines() {
        queries.push(line_res?);
    }
    Ok(queries)
}

fn run_bench(index_path: &Path, query_filepath: &Path, num_repeat: usize) -> Result<(), String> {
    println!("index_path : {:?}", index_path);
    println!("Query : {:?}", index_path);
    println!("-------------------------------\n\n\n");

    let index =
        Index::open_in_dir(index_path).map_err(|e| format!("Failed to open index.\n{:?}", e))?;
    let searcher = index
        .reader()
        .map_err(|err| format!("{:?}", err))?
        .searcher();
    let default_search_fields: Vec<Field> = extract_search_fields(&index.schema());
    let queries = read_query_file(query_filepath)
        .map_err(|e| format!("Failed reading the query file:  {}", e))?;
    let query_parser = QueryParser::new(
        index.schema(),
        default_search_fields,
        index.tokenizers().clone(),
    );

    println!("SEARCH\n");
    println!(
        "{}\t{}\t{}\t{}",
        "query", "num_terms", "num hits", "time in microsecs"
    );
    for _ in 0..num_repeat {
        for query_txt in &queries {
            let query = query_parser.parse_query(&query_txt).unwrap();
            let mut timing = TimerTree::default();
            let (_top_docs, count) = {
                let _search = timing.open("search");
                searcher
                    .search(&query, &(TopDocs::with_limit(10), Count))
                    .map_err(|e| {
                        format!("Failed while searching query {:?}.\n\n{:?}", query_txt, e)
                    })?
            };
            println!("{}\t{}\t{}", query_txt, count, timing.total_time());
        }
    }

    println!("\n\nFETCH STORE\n");
    println!("{}\t{}", "query", "time in microsecs");
    for _ in 0..num_repeat {
        for query_txt in &queries {
            let query = query_parser.parse_query(&query_txt).unwrap();
            let top_docs = searcher
                .search(&*query, &TopDocs::with_limit(10))
                .map_err(|e| {
                    format!(
                        "Failed while retrieving document for query {:?}.\n{:?}",
                        query, e
                    )
                })?;
            let mut timer = TimerTree::default();
            {
                let _scoped_timer_ = timer.open("total");
                for (_score, doc_address) in top_docs {
                    searcher.doc(doc_address).unwrap();
                }
            }
            println!("{}\t{}", query_txt, timer.total_time());
        }
    }

    Ok(())
}