From cb0e69489cee9916c53c374e53d6594169e7817f Mon Sep 17 00:00:00 2001
From: Elias Kohout <elias@kohout.de>
Date: Sat, 28 Dec 2024 15:51:57 +0100
Subject: [PATCH] almost finish implementation of DefaultRepository

---
 internal/data/DefaultRepository.go | 75 ++++++++++++++++++++++++------
 1 file changed, 61 insertions(+), 14 deletions(-)

diff --git a/internal/data/DefaultRepository.go b/internal/data/DefaultRepository.go
index 1babe10..f23bee9 100644
--- a/internal/data/DefaultRepository.go
+++ b/internal/data/DefaultRepository.go
@@ -1,21 +1,26 @@
 package data
 
 import (
-    "encoding/json"
-    "errors"
-    "strconv"
+	"encoding/json"
+	"errors"
+	"strconv"
+	"strings"
 )
 
-
 // Default implementation of IRepository using an IDatastore.
 type DefaultRepository[T IIdentifiable] struct {
     ds      IDatastore
     prefix  string
 }
 
-// TODO docstring
-func NewDefaultRepository[T IIdentifiable](ds IDatastore, prefix string) *DefaultRepository[T] {
-    return &DefaultRepository[T]{ ds: ds, prefix: prefix }
+// Creates a new DefaultRepository for a generic type T given a IDatastore and
+// a prefix. The type T must implement the IIdentifiable interface. The prefix
+// will be used for the key for every entry using the created repository. The
+// prefix should be not yet be in use in the given datastore and not contain a
+// ':' character.
+func NewDefaultRepository[T IIdentifiable](ds IDatastore, prefix string) (*DefaultRepository[T], error) {
+    if strings.Contains(prefix, ":") { return nil, errors.New("prefix should not contain ':'") }
+    return &DefaultRepository[T]{ ds: ds, prefix: prefix }, nil
 }
 
 // Creates a new entry in the repository with the given object t. Throws an
@@ -25,7 +30,7 @@ func (repo *DefaultRepository[T]) Create(t T) error {
     key := repo.prefix + ":" + strconv.FormatUint(uint64(t.Id()), 10)
     exists, err := repo.ds.KeyExists(key)
     if err != nil { return err }
-    if exists { return errors.New("key already exits") }
+    if exists { return errors.New("entry with given id already exists") }
 
     d, err := json.Marshal(t)
     if err != nil { return err }
@@ -43,7 +48,7 @@ func (repo *DefaultRepository[T]) Update(t T) error {
     key := repo.prefix + ":" + strconv.FormatUint(uint64(t.Id()), 10)
     exists, err := repo.ds.KeyExists(key)
     if err != nil { return err }
-    if !exists { return errors.New("key does not exits") }
+    if !exists { return errors.New("no entry with given id") }
 
     d, err := json.Marshal(t)
     if err != nil { return err }
@@ -54,19 +59,61 @@ func (repo *DefaultRepository[T]) Update(t T) error {
     return nil
 }
 
+// Delete the entry with the same id as t in the repository. Trows an error if
+// the connection to the IDatastore fails or the key of t does not exist.
 func (repo *DefaultRepository[T]) Delete(t T) error {
-    // TODO
+    key := repo.prefix + ":" + strconv.FormatUint(uint64(t.Id()), 10)
+
+    exists, err := repo.ds.KeyExists(key)
+    if err != nil { return err }
+    if !exists { return errors.New("no entry with given id") }
+
+    err = repo.ds.Delete(key)
+    if err != nil { return err }
+
     return nil
 }
 
+// Get all the objects of type T from the repository as a list. Trows an error
+// if the connection to the IDatastore fails.
 func (repo *DefaultRepository[T]) GetAll() ([]T, error) {
-    // TODO
-    return nil, nil
+    out := make([]T, 0)
+    
+    allkeys, err := repo.ds.GetAllKeys()
+    if err != nil { return nil, err }
+
+    for key, _ := range allkeys {
+        splitkey := strings.Split(key, ":")
+        if splitkey[0] == repo.prefix {
+
+            // convert id to an int
+            id, err := strconv.ParseUint(splitkey[1], 10, 0)
+            if err != nil { return nil, err }
+
+            // retrieve the object
+            obj, err := repo.GetById(uint(id))
+            if err != nil { return nil, err }
+            out = append(out, obj)
+
+        }
+    }
+
+    return out, nil
 }
 
+// Get the objects of type T from the repository that has the given id. Trows an error
+// if the connection to the IDatastore or the decoding process fails.
 func (repo *DefaultRepository[T]) GetById(id uint) (T, error) {
-    // TODO
-    return *new(T), nil
+    var obj T
+
+    key := repo.prefix + ":" + strconv.FormatUint(uint64(id), 10)
+    value, err := repo.ds.Get(key)
+    if err != nil { return obj, err }
+    
+    err = json.Unmarshal([]byte(value), &obj)
+    if err != nil { return obj, err }
+
+    return obj, nil
 }
 
 func (repo *DefaultRepository[T]) GetByCriteria(c ISearchCriteria[T]) ([]T, error) {