indrasaputra/url-shortener

package repository

import (
    "context"

    "github.com/indrasaputra/aptx/entity"
)

// GetURLDatabase defines the interface to get URL from the database.
type GetURLDatabase interface {
    // GetAll gets all URLs from the database.
    GetAll(ctx context.Context) ([]*entity.URL, error)
    // GetByCode gets a single URL from the database.
    // If the URL can't be found, it returns entity.ErrNotFound().
    GetByCode(ctx context.Context, code string) (*entity.URL, error)
}

// GetURLCache defines the interface to get URL from the cache.
type GetURLCache interface {
    // Get gets a URL from the cache.
    Get(ctx context.Context, code string) (*entity.URL, error)
    InsertURLCache
}

// URLGetter is responsible to get URL from storage.
// It uses database and cache.
type URLGetter struct {
    database GetURLDatabase
    cache    GetURLCache
}

// NewURLGetter creates an instance of URLGetter.
func NewURLGetter(database GetURLDatabase, cache GetURLCache) *URLGetter {
    return &URLGetter{
        database: database,
        cache:    cache,
    }
}

// GetAll gets all URLs from storage.
func (ug *URLGetter) GetAll(ctx context.Context) ([]*entity.URL, error) {
    return ug.database.GetAll(ctx)
}

// GetByCode gets a single URL from storage.
// If the URL can't be found, it returns entity.ErrNotFound().
func (ug *URLGetter) GetByCode(ctx context.Context, code string) (*entity.URL, error) {
    url, cerr := ug.cache.Get(ctx, code)
    if cerr != nil {
        return nil, cerr
    }
    if url != nil {
        return url, nil
    }

    url, derr := ug.database.GetByCode(ctx, code)
    if derr != nil {
        return nil, derr
    }
    _ = ug.cache.Save(ctx, url)
    return url, nil
}