/*
    This file is part of jellything (https://codeberg.org/metamuffin/jellything)
    which is licensed under the GNU Affero General Public License (version 3); see /COPYING.
    Copyright (C) 2026 metamuffin <metamuffin.org>
*/

use crate::backends::{
    Database, ReadTransaction, ReadTxnFunction, WriteTransaction, WriteTxnFunction,
};
use anyhow::Result;
use redb::{AccessGuard, ReadableDatabase, ReadableTable, StorageError, Table, TableDefinition};
use std::path::Path;

const TABLE: TableDefinition<&[u8], &[u8]> = TableDefinition::new("kv");

pub fn new(path: &Path) -> Result<redb::Database> {
    Ok(redb::Database::create(path)?)
}

impl Database for redb::Database {
    fn write_transaction(&self, f: &mut WriteTxnFunction) -> Result<()> {
        let txn = self.begin_write()?;
        let mut table = txn.open_table(TABLE)?;
        f(&mut table)?;
        drop(table);
        txn.commit()?;
        Ok(())
    }
    fn read_transaction(&self, f: &mut ReadTxnFunction) -> Result<()> {
        let mut txn = self.begin_read()?;
        f(&mut txn)?;
        Ok(())
    }
}

impl WriteTransaction for Table<'_, &[u8], &[u8]> {
    fn set(&mut self, key: &[u8], value: &[u8]) -> Result<()> {
        self.insert(key, value)?;
        Ok(())
    }
    fn del(&mut self, key: &[u8]) -> Result<()> {
        self.remove(key)?;
        Ok(())
    }
}
impl ReadTransaction for Table<'_, &[u8], &[u8]> {
    fn get<'a>(&'a self, key: &[u8]) -> Result<Option<Vec<u8>>> {
        match <Self as ReadableTable<_, _>>::get(self, key)? {
            Some(v) => Ok(Some(v.value().to_vec())),
            None => Ok(None),
        }
    }
    fn iter<'a>(
        &'a self,
        key: &[u8],
        reverse: bool,
    ) -> Result<Box<dyn Iterator<Item = Result<Vec<u8>>> + 'a>> {
        let k = |e: Result<(AccessGuard<'_, &[u8]>, AccessGuard<'_, &[u8]>), StorageError>| {
            e.map(|e| e.0.value().to_vec()).map_err(|e| e.into())
        };
        Ok(if reverse {
            Box::new(self.range(..=key)?.rev().map(k))
        } else {
            Box::new(self.range(key..)?.map(k))
        })
    }
}
impl ReadTransaction for redb::ReadTransaction {
    fn get<'a>(&'a self, key: &[u8]) -> Result<Option<Vec<u8>>> {
        match self.open_table(TABLE)?.get(key)? {
            Some(v) => Ok(Some(v.value().to_vec())),
            None => Ok(None),
        }
    }
    fn iter<'a>(
        &'a self,
        key: &[u8],
        reverse: bool,
    ) -> Result<Box<dyn Iterator<Item = Result<Vec<u8>>> + 'a>> {
        let k = |e: Result<(AccessGuard<'_, &[u8]>, AccessGuard<'_, &[u8]>), StorageError>| {
            e.map(|e| e.0.value().to_vec()).map_err(|e| e.into())
        };
        Ok(if reverse {
            Box::new(self.open_table(TABLE)?.range(..=key)?.rev().map(k))
        } else {
            Box::new(self.open_table(TABLE)?.range(key..)?.map(k))
        })
    }
}