use std::sync::Arc;
use meilidb_schema::Schema;
use zlmdb::types::{Str, OwnedType, ByteSlice, Serde};
use zlmdb::Result as ZResult;
use crate::RankedMap;

const CUSTOMS_KEY:             &str = "customs-key";
const NUMBER_OF_DOCUMENTS_KEY: &str = "number-of-documents";
const RANKED_MAP_KEY:          &str = "ranked-map";
const SCHEMA_KEY:              &str = "schema";
const SYNONYMS_KEY:            &str = "synonyms";
const WORDS_KEY:               &str = "words";

#[derive(Copy, Clone)]
pub struct Main {
    pub(crate) main: zlmdb::DynDatabase,
}

impl Main {
    pub fn put_words_fst(&self, writer: &mut zlmdb::RwTxn, fst: &fst::Set) -> ZResult<()> {
        let bytes = fst.as_fst().as_bytes();
        self.main.put::<Str, ByteSlice>(writer, WORDS_KEY, bytes)
    }

    pub fn words_fst(&self, reader: &zlmdb::RoTxn) -> ZResult<Option<fst::Set>> {
        match self.main.get::<Str, ByteSlice>(reader, WORDS_KEY)? {
            Some(bytes) => {
                let len = bytes.len();
                let bytes = Arc::from(bytes);
                let fst = fst::raw::Fst::from_shared_bytes(bytes, 0, len).unwrap();
                Ok(Some(fst::Set::from(fst)))
            },
            None => Ok(None),
        }
    }

    pub fn put_schema(&self, writer: &mut zlmdb::RwTxn, schema: &Schema) -> ZResult<()> {
        self.main.put::<Str, Serde<Schema>>(writer, SCHEMA_KEY, schema)
    }

    pub fn schema(&self, reader: &zlmdb::RoTxn) -> ZResult<Option<Schema>> {
        self.main.get::<Str, Serde<Schema>>(reader, SCHEMA_KEY)
    }

    pub fn put_ranked_map(&self, writer: &mut zlmdb::RwTxn, ranked_map: &RankedMap) -> ZResult<()> {
        self.main.put::<Str, Serde<RankedMap>>(writer, RANKED_MAP_KEY, &ranked_map)
    }

    pub fn ranked_map(&self, reader: &zlmdb::RoTxn) -> ZResult<Option<RankedMap>> {
        self.main.get::<Str, Serde<RankedMap>>(reader, RANKED_MAP_KEY)
    }

    pub fn put_synonyms_fst(&self, writer: &mut zlmdb::RwTxn, fst: &fst::Set) -> ZResult<()> {
        let bytes = fst.as_fst().as_bytes();
        self.main.put::<Str, ByteSlice>(writer, SYNONYMS_KEY, bytes)
    }

    pub fn synonyms_fst(&self, reader: &zlmdb::RoTxn) -> ZResult<Option<fst::Set>> {
        match self.main.get::<Str, ByteSlice>(reader, SYNONYMS_KEY)? {
            Some(bytes) => {
                let len = bytes.len();
                let bytes = Arc::from(bytes);
                let fst = fst::raw::Fst::from_shared_bytes(bytes, 0, len).unwrap();
                Ok(Some(fst::Set::from(fst)))
            },
            None => Ok(None),
        }
    }

    pub fn put_number_of_documents<F>(&self, writer: &mut zlmdb::RwTxn, f: F) -> ZResult<u64>
    where F: Fn(u64) -> u64,
    {
        let new = self.number_of_documents(writer).map(f)?;
        self.main.put::<Str, OwnedType<u64>>(writer, NUMBER_OF_DOCUMENTS_KEY, &new)?;
        Ok(new)
    }

    pub fn number_of_documents(&self, reader: &zlmdb::RoTxn) -> ZResult<u64> {
        match self.main.get::<Str, OwnedType<u64>>(reader, NUMBER_OF_DOCUMENTS_KEY)? {
            Some(value) => Ok(value),
            None => Ok(0),
        }
    }

    pub fn put_customs(&self, writer: &mut zlmdb::RwTxn, customs: &[u8]) -> ZResult<()> {
        self.main.put::<Str, ByteSlice>(writer, CUSTOMS_KEY, customs)
    }

    pub fn customs<'txn>(&self, reader: &'txn zlmdb::RoTxn) -> ZResult<Option<&'txn [u8]>> {
        self.main.get::<Str, ByteSlice>(reader, CUSTOMS_KEY)
    }
}