package internal

import (
	"context"
	"os"
	"path/filepath"
	"time"

	"git.markbailey.dev/cerbervs/joist/internal/errors"
	"github.com/dgraph-io/badger/v4"
)

const defaultBaseDir = "./data/badger"

type BadgerOpts func(*BadgerStore)

func WithBaseDir(baseDir string) BadgerOpts {
	return func(b *BadgerStore) {
		b.baseDir = baseDir
	}
}

func WithSubDir(subDir string) BadgerOpts {
	return func(b *BadgerStore) {
		b.subDir = subDir
	}
}

type BadgerStore struct {
	baseDir string
	subDir  string
	db      *badger.DB
}

func (b *BadgerStore) Put(ctx context.Context, key string, val []byte, ttl time.Duration) error {
	done := make(chan error, 1)

	go func() {
		err := b.db.Update(func(txn *badger.Txn) error {
			e := badger.NewEntry([]byte(key), val).WithTTL(ttl)
			return txn.SetEntry(e)
		})
		done <- err
	}()

	select {
	case <-ctx.Done():
		return ctx.Err()
	case err := <-done:
		return err
	}
}

func (b *BadgerStore) Get(ctx context.Context, key string) ([]byte, error) {
	done := make(chan struct {
		val []byte
		err error
	}, 1)

	go func() {
		var valCopy []byte
		err := b.db.View(func(txn *badger.Txn) error {
			item, err := txn.Get([]byte(key))
			if err != nil {
				return err
			}
			valCopy, err = item.ValueCopy(nil)
			return err
		})
		done <- struct {
			val []byte
			err error
		}{valCopy, err}
	}()

	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	case result := <-done:
		return result.val, result.err
	}
}

func (b *BadgerStore) Delete(ctx context.Context, key string) error {
	done := make(chan error, 1)

	go func() {
		err := b.db.Update(func(txn *badger.Txn) error {
			return txn.Delete([]byte(key))
		})
		done <- err
	}()

	select {
	case <-ctx.Done():
		return ctx.Err()
	case err := <-done:
		return err
	}
}

func (b *BadgerStore) Close() error {
	return b.db.Close()
}

func (b *BadgerStore) dir() string {
	if b.baseDir == "" {
		b.baseDir = defaultBaseDir
	}

	if b.subDir == "" {
		return b.baseDir
	}

	return filepath.Join(b.baseDir, b.subDir)
}

func NewBadgerStore(opts ...BadgerOpts) (*BadgerStore, error) {
	s := &BadgerStore{}

	for _, opt := range opts {
		opt(s)
	}

	fi, err := os.Stat(s.dir())
	if err == nil && !fi.IsDir() {
		if err := os.MkdirAll(s.dir(), 0755); err != nil {
			return nil, errors.NewErrBadgerInit(s.baseDir, s.subDir)
		}
	}

	bopts := badger.DefaultOptions(s.dir())
	s.db, err = badger.Open(bopts)
	if err != nil {
		return nil, err
	}

	return s, nil
}