nimona/go-nimona

package kv

import (
    "encoding/json"
    "fmt"
    "os"
    "path/filepath"
    "strings"
)

type FileStore[K, V any] struct {
    baseDir string
}

const pathSeparator = string(os.PathSeparator)

func NewFileStore[K, V any](baseDir string) (Store[K, V], error) {
    err := os.MkdirAll(baseDir, 0o755)
    if err != nil {
        return nil, err
    }
    return &FileStore[K, V]{baseDir: baseDir}, nil
}

func (s *FileStore[K, V]) Set(key K, value V) error {
    keyPath := strings.TrimSuffix(keyToString(key), pathSeparator)
    filePath := filepath.Join(s.baseDir, keyPath+".json")
    dirPath := filepath.Dir(filePath)

    err := os.MkdirAll(dirPath, 0o755)
    if err != nil {
        return err
    }

    data, err := json.Marshal(value)
    if err != nil {
        return err
    }

    return os.WriteFile(filePath, data, 0o644)
}

func (s *FileStore[K, V]) Get(key K) (res V, err error) {
    keyPath := strings.TrimSuffix(keyToString(key), pathSeparator)
    filePath := filepath.Join(s.baseDir, keyPath+".json")

    data, err := os.ReadFile(filePath)
    if err != nil {
        if os.IsNotExist(err) {
            return res, fmt.Errorf("key not found: %w", err)
        }
        return res, err
    }

    var value V
    err = json.Unmarshal(data, &value)
    if err != nil {
        return res, err
    }

    return value, nil
}

func (s *FileStore[K, V]) GetPrefix(key K) ([]V, error) {
    prefix := strings.TrimSuffix(keyToString(key), pathSeparator)
    values := []V{}

    err := filepath.Walk(s.baseDir, func(path string, info os.FileInfo, err error) error {
        if err != nil {
            return err
        }
        if info.IsDir() || !strings.HasSuffix(path, ".json") {
            return nil
        }

        relPath, err := filepath.Rel(s.baseDir, path)
        if err != nil {
            return err
        }

        if !strings.HasPrefix(relPath, prefix) {
            return nil
        }

        data, err := os.ReadFile(path)
        if err != nil {
            return err
        }

        var value V
        err = json.Unmarshal(data, &value)
        if err != nil {
            return err
        }

        values = append(values, value)
        return nil
    })
    if err != nil {
        return nil, err
    }

    return values, nil
}