mod extract_docid_word_positions;
mod extract_facet_number_docids;
mod extract_facet_string_docids;
mod extract_fid_docid_facet_values;
mod extract_fid_word_count_docids;
mod extract_geo_points;
mod extract_word_docids;
mod extract_word_level_position_docids;
mod extract_word_pair_proximity_docids;

use std::collections::HashSet;
use std::fs::File;

use crossbeam_channel::Sender;
use log::debug;
use rayon::prelude::*;

use self::extract_docid_word_positions::extract_docid_word_positions;
use self::extract_facet_number_docids::extract_facet_number_docids;
use self::extract_facet_string_docids::extract_facet_string_docids;
use self::extract_fid_docid_facet_values::extract_fid_docid_facet_values;
use self::extract_fid_word_count_docids::extract_fid_word_count_docids;
use self::extract_geo_points::extract_geo_points;
use self::extract_word_docids::extract_word_docids;
use self::extract_word_level_position_docids::extract_word_level_position_docids;
use self::extract_word_pair_proximity_docids::extract_word_pair_proximity_docids;
use super::helpers::{
    into_clonable_grenad, keep_first_prefix_value_merge_roaring_bitmaps, merge_cbo_roaring_bitmaps,
    merge_readers, merge_roaring_bitmaps, CursorClonableMmap, GrenadParameters, MergeFn,
};
use super::{helpers, TypedChunk};
use crate::{FieldId, Result};

/// Extract data for each databases from obkv documents in parallel.
/// Send data in grenad file over provided Sender.
pub(crate) fn data_from_obkv_documents(
    obkv_chunks: impl Iterator<Item = Result<grenad::Reader<File>>> + Send,
    indexer: GrenadParameters,
    lmdb_writer_sx: Sender<Result<TypedChunk>>,
    searchable_fields: Option<HashSet<FieldId>>,
    faceted_fields: HashSet<FieldId>,
    primary_key_id: FieldId,
    geo_field_id: Option<FieldId>,
    stop_words: Option<fst::Set<&[u8]>>,
) -> Result<()> {
    let result: Result<(Vec<_>, (Vec<_>, Vec<_>))> = obkv_chunks
        .par_bridge()
        .map(|result| {
            extract_documents_data(
                result,
                indexer,
                lmdb_writer_sx.clone(),
                &searchable_fields,
                &faceted_fields,
                primary_key_id,
                geo_field_id,
                &stop_words,
            )
        })
        .collect();

    let (
        docid_word_positions_chunks,
        (docid_fid_facet_numbers_chunks, docid_fid_facet_strings_chunks),
    ) = result?;

    spawn_extraction_task(
        docid_word_positions_chunks.clone(),
        indexer.clone(),
        lmdb_writer_sx.clone(),
        extract_word_pair_proximity_docids,
        merge_cbo_roaring_bitmaps,
        TypedChunk::WordPairProximityDocids,
        "word-pair-proximity-docids",
    );

    spawn_extraction_task(
        docid_word_positions_chunks.clone(),
        indexer.clone(),
        lmdb_writer_sx.clone(),
        extract_fid_word_count_docids,
        merge_cbo_roaring_bitmaps,
        TypedChunk::FieldIdWordcountDocids,
        "field-id-wordcount-docids",
    );

    spawn_extraction_task(
        docid_word_positions_chunks.clone(),
        indexer.clone(),
        lmdb_writer_sx.clone(),
        extract_word_docids,
        merge_roaring_bitmaps,
        TypedChunk::WordDocids,
        "word-docids",
    );

    spawn_extraction_task(
        docid_word_positions_chunks.clone(),
        indexer.clone(),
        lmdb_writer_sx.clone(),
        extract_word_level_position_docids,
        merge_cbo_roaring_bitmaps,
        TypedChunk::WordLevelPositionDocids,
        "word-level-position-docids",
    );

    spawn_extraction_task(
        docid_fid_facet_strings_chunks.clone(),
        indexer.clone(),
        lmdb_writer_sx.clone(),
        extract_facet_string_docids,
        keep_first_prefix_value_merge_roaring_bitmaps,
        TypedChunk::FieldIdFacetStringDocids,
        "field-id-facet-string-docids",
    );

    spawn_extraction_task(
        docid_fid_facet_numbers_chunks.clone(),
        indexer.clone(),
        lmdb_writer_sx.clone(),
        extract_facet_number_docids,
        merge_cbo_roaring_bitmaps,
        TypedChunk::FieldIdFacetNumberDocids,
        "field-id-facet-number-docids",
    );

    Ok(())
}

/// Spawn a new task to extract data for a specific DB using extract_fn.
/// Generated grenad chunks are merged using the merge_fn.
/// The result of merged chunks is serialized as TypedChunk using the serialize_fn
/// and sent into lmdb_writer_sx.
fn spawn_extraction_task<FE, FS>(
    chunks: Vec<grenad::Reader<CursorClonableMmap>>,
    indexer: GrenadParameters,
    lmdb_writer_sx: Sender<Result<TypedChunk>>,
    extract_fn: FE,
    merge_fn: MergeFn,
    serialize_fn: FS,
    name: &'static str,
) where
    FE: Fn(grenad::Reader<CursorClonableMmap>, GrenadParameters) -> Result<grenad::Reader<File>>
        + Sync
        + Send
        + 'static,
    FS: Fn(grenad::Reader<File>) -> TypedChunk + Sync + Send + 'static,
{
    rayon::spawn(move || {
        let chunks: Result<Vec<_>> =
            chunks.into_par_iter().map(|chunk| extract_fn(chunk, indexer.clone())).collect();
        rayon::spawn(move || match chunks {
            Ok(chunks) => {
                debug!("merge {} database", name);
                let reader = merge_readers(chunks, merge_fn, indexer);
                let _ = lmdb_writer_sx.send(reader.map(|r| serialize_fn(r)));
            }
            Err(e) => {
                let _ = lmdb_writer_sx.send(Err(e));
            }
        })
    });
}

/// Extract chuncked data and send it into lmdb_writer_sx sender:
/// - documents
/// - documents_ids
/// - docid_word_positions
/// - docid_fid_facet_numbers
/// - docid_fid_facet_strings
fn extract_documents_data(
    documents_chunk: Result<grenad::Reader<File>>,
    indexer: GrenadParameters,
    lmdb_writer_sx: Sender<Result<TypedChunk>>,
    searchable_fields: &Option<HashSet<FieldId>>,
    faceted_fields: &HashSet<FieldId>,
    primary_key_id: FieldId,
    geo_field_id: Option<FieldId>,
    stop_words: &Option<fst::Set<&[u8]>>,
) -> Result<(
    grenad::Reader<CursorClonableMmap>,
    (grenad::Reader<CursorClonableMmap>, grenad::Reader<CursorClonableMmap>),
)> {
    let documents_chunk = documents_chunk.and_then(|c| unsafe { into_clonable_grenad(c) })?;

    let _ = lmdb_writer_sx.send(Ok(TypedChunk::Documents(documents_chunk.clone())));

    if let Some(geo_field_id) = geo_field_id {
        let documents_chunk_cloned = documents_chunk.clone();
        let lmdb_writer_sx_cloned = lmdb_writer_sx.clone();
        rayon::spawn(move || {
            let _ = match extract_geo_points(
                documents_chunk_cloned,
                indexer,
                primary_key_id,
                geo_field_id,
            ) {
                Ok(geo_points) => lmdb_writer_sx_cloned.send(Ok(TypedChunk::GeoPoints(geo_points))),
                Err(error) => lmdb_writer_sx_cloned.send(Err(error)),
            };
        });
    }

    let (docid_word_positions_chunk, docid_fid_facet_values_chunks): (Result<_>, Result<_>) =
        rayon::join(
            || {
                let (documents_ids, docid_word_positions_chunk) = extract_docid_word_positions(
                    documents_chunk.clone(),
                    indexer.clone(),
                    searchable_fields,
                    stop_words.as_ref(),
                )?;

                // send documents_ids to DB writer
                let _ = lmdb_writer_sx.send(Ok(TypedChunk::NewDocumentsIds(documents_ids)));

                // send docid_word_positions_chunk to DB writer
                let docid_word_positions_chunk =
                    unsafe { into_clonable_grenad(docid_word_positions_chunk)? };
                let _ = lmdb_writer_sx
                    .send(Ok(TypedChunk::DocidWordPositions(docid_word_positions_chunk.clone())));

                Ok(docid_word_positions_chunk)
            },
            || {
                let (docid_fid_facet_numbers_chunk, docid_fid_facet_strings_chunk) =
                    extract_fid_docid_facet_values(
                        documents_chunk.clone(),
                        indexer.clone(),
                        faceted_fields,
                    )?;

                // send docid_fid_facet_numbers_chunk to DB writer
                let docid_fid_facet_numbers_chunk =
                    unsafe { into_clonable_grenad(docid_fid_facet_numbers_chunk)? };

                let _ = lmdb_writer_sx.send(Ok(TypedChunk::FieldIdDocidFacetNumbers(
                    docid_fid_facet_numbers_chunk.clone(),
                )));

                // send docid_fid_facet_strings_chunk to DB writer
                let docid_fid_facet_strings_chunk =
                    unsafe { into_clonable_grenad(docid_fid_facet_strings_chunk)? };

                let _ = lmdb_writer_sx.send(Ok(TypedChunk::FieldIdDocidFacetStrings(
                    docid_fid_facet_strings_chunk.clone(),
                )));

                Ok((docid_fid_facet_numbers_chunk, docid_fid_facet_strings_chunk))
            },
        );

    Ok((docid_word_positions_chunk?, docid_fid_facet_values_chunks?))
}