7 files changed, 398 insertions, 0 deletions
diff --git a/internal/api/handler.go b/internal/api/handler.go
new file mode 100644
index 0000000..0e51807
--- /dev/null
+++ b/internal/api/handler.go
@@ -0,0 +1,155 @@
+package api
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"go.neonxp.dev/djson/internal/model"
+	"go.neonxp.dev/djson/internal/tree"
+	"go.neonxp.dev/json"
+)
+
+func NewHandler(tree *tree.Engine) *Handler {
+	return &Handler{tree: tree}
+}
+
+type Handler struct {
+	tree *tree.Engine
+}
+
+func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodGet:
+		res, err := h.get(r.Context(), r.URL.Path)
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			log.Println(err.Error())
+			return
+		}
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			log.Println(err.Error())
+			return
+		}
+		result, err := res.MarshalJSON()
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			log.Println(err.Error())
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write(result)
+	case http.MethodPost:
+		jsonBody, err := io.ReadAll(r.Body)
+		r.Body.Close()
+
+		if err := h.post(r.Context(), r.URL.Path, jsonBody); err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			log.Println(err.Error())
+			return
+		}
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			log.Println(err.Error())
+			return
+		}
+		w.WriteHeader(http.StatusCreated)
+	case http.MethodPatch:
+		jsonBody, err := io.ReadAll(r.Body)
+		r.Body.Close()
+
+		if err := h.patch(r.Context(), r.URL.Path, jsonBody); err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			log.Println(err.Error())
+			return
+		}
+		if err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			log.Println(err.Error())
+			return
+		}
+		w.WriteHeader(http.StatusOK)
+	case http.MethodDelete:
+		if err := h.remove(r.Context(), r.URL.Path); err != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			log.Println(err.Error())
+			return
+		}
+		w.WriteHeader(http.StatusNoContent)
+	default:
+		w.WriteHeader(http.StatusMethodNotAllowed)
+		_, _ = w.Write([]byte(fmt.Sprintf("Unknown method: %s", r.Method)))
+	}
+}
+
+func (h *Handler) get(ctx context.Context, p string) (Marshaller, error) {
+	return h.tree.Get(parsePath(p))
+}
+
+func (h *Handler) post(ctx context.Context, p string, jsonBody []byte) error {
+	node, err := json.Unmarshal(jsonBody)
+	if err != nil {
+		return err
+	}
+
+	return h.tree.Mutation(ctx, &model.Mutation{
+		Date: time.Now(),
+		Type: model.Create,
+		Path: parsePath(p),
+		Body: *node,
+	})
+}
+
+func (h *Handler) patch(ctx context.Context, p string, jsonBody []byte) error {
+	node, err := json.Unmarshal(jsonBody)
+	if err != nil {
+		return err
+	}
+
+	return h.tree.Mutation(ctx, &model.Mutation{
+		Date: time.Now(),
+		Type: model.Merge,
+		Path: parsePath(p),
+		Body: *node,
+	})
+}
+
+func (h *Handler) remove(ctx context.Context, p string) error {
+	return h.tree.Mutation(ctx, &model.Mutation{
+		Date: time.Now(),
+		Type: model.Remove,
+		Path: parsePath(p),
+	})
+}
+
+type ErrorStruct struct {
+	Error string `json:"error"`
+}
+
+func newError(err error) *ErrorStruct {
+	return &ErrorStruct{
+		Error: err.Error(),
+	}
+}
+
+type Marshaller interface {
+	MarshalJSON() ([]byte, error)
+}
+
+func parsePath(nodePath string) []string {
+	nodePath = filepath.Clean(nodePath)
+	nodePath = strings.Trim(nodePath, "/")
+	arr := []string{}
+	for _, v := range strings.Split(nodePath, "/") {
+		if v != "" {
+			arr = append(arr, v)
+		}
+	}
+	return arr
+}
diff --git a/internal/model/commandtype_string.go b/internal/model/commandtype_string.go
new file mode 100644
index 0000000..1ad4635
--- /dev/null
+++ b/internal/model/commandtype_string.go
@@ -0,0 +1,25 @@
+// Code generated by "stringer -type=CommandType"; DO NOT EDIT.
+
+package model
+
+import "strconv"
+
+func _() {
+	// An "invalid array index" compiler error signifies that the constant values have changed.
+	// Re-run the stringer command to generate them again.
+	var x [1]struct{}
+	_ = x[Create-0]
+	_ = x[Merge-1]
+	_ = x[Remove-2]
+}
+
+const _CommandType_name = "CreateMergeRemove"
+
+var _CommandType_index = [...]uint8{0, 6, 11, 17}
+
+func (i CommandType) String() string {
+	if i < 0 || i >= CommandType(len(_CommandType_index)-1) {
+		return "CommandType(" + strconv.FormatInt(int64(i), 10) + ")"
+	}
+	return _CommandType_name[_CommandType_index[i]:_CommandType_index[i+1]]
+}
diff --git a/internal/model/mutations.go b/internal/model/mutations.go
new file mode 100644
index 0000000..6463823
--- /dev/null
+++ b/internal/model/mutations.go
@@ -0,0 +1,36 @@
+package model
+
+import (
+	"fmt"
+	"strings"
+	"time"
+
+	"go.neonxp.dev/json/model"
+)
+
+type Mutation struct {
+	Date time.Time
+	Type CommandType
+	Path []string
+	Body model.Node
+}
+
+func (m *Mutation) String() string {
+	body, _ := m.Body.MarshalJSON()
+	return fmt.Sprintf(
+		"Date=%s Type=%s Path='%s' Body=%s",
+		m.Date.Format(time.RFC3339),
+		m.Type,
+		strings.Join(m.Path, "/"),
+		string(body),
+	)
+}
+
+//go:generate stringer -type=CommandType
+type CommandType int
+
+const (
+	Create CommandType = iota
+	Merge
+	Remove
+)
diff --git a/internal/storage/file.go b/internal/storage/file.go
new file mode 100644
index 0000000..7619e32
--- /dev/null
+++ b/internal/storage/file.go
@@ -0,0 +1,66 @@
+package storage
+
+import (
+	"context"
+	"encoding/gob"
+	"fmt"
+	"io"
+	"log"
+	"os"
+
+	"go.neonxp.dev/djson/internal/model"
+)
+
+type FileStorage struct {
+	enc          *gob.Encoder
+	dec          *gob.Decoder
+	fh           *os.File
+	fileName     string
+	mutationsLog []model.Mutation
+}
+
+func NewFileStorage(fileName string) (*FileStorage, error) {
+	fh, err := os.OpenFile(fileName, os.O_CREATE|os.O_APPEND|os.O_RDWR, 0o666)
+	if err != nil {
+		return nil, err
+	}
+
+	return &FileStorage{
+		fileName:     fileName,
+		fh:           fh,
+		enc:          gob.NewEncoder(fh),
+		dec:          gob.NewDecoder(fh),
+		mutationsLog: []model.Mutation{},
+	}, nil
+}
+
+func (fs *FileStorage) Commit(ctx context.Context, mut model.Mutation) error {
+	if fs.enc == nil {
+		return fmt.Errorf("file storage not initiated")
+	}
+	return fs.enc.Encode(mut)
+}
+
+func (fs *FileStorage) Load() chan model.Mutation {
+	ch := make(chan model.Mutation)
+	go func() {
+		for {
+			m := model.Mutation{}
+			if err := fs.dec.Decode(&m); err != nil {
+				if err != io.EOF {
+					log.Println(err.Error())
+				}
+				close(ch)
+				return
+			}
+			log.Println("Loaded from fs", m.String())
+			fs.mutationsLog = append(fs.mutationsLog, m)
+			ch <- m
+		}
+	}()
+	return ch
+}
+
+func (fs *FileStorage) Close() error {
+	return fs.fh.Close()
+}
diff --git a/internal/storage/storage.go b/internal/storage/storage.go
new file mode 100644
index 0000000..5847bcc
--- /dev/null
+++ b/internal/storage/storage.go
@@ -0,0 +1,14 @@
+package storage
+
+import (
+	"context"
+	"io"
+
+	"go.neonxp.dev/djson/internal/model"
+)
+
+type Storage interface {
+	io.Closer
+	Commit(ctx context.Context, mut model.Mutation) error
+	Load() chan model.Mutation
+}
diff --git a/internal/tree/engine.go b/internal/tree/engine.go
new file mode 100644
index 0000000..0f28eb7
--- /dev/null
+++ b/internal/tree/engine.go
@@ -0,0 +1,42 @@
+package tree
+
+import (
+	"context"
+	"sync"
+
+	"go.neonxp.dev/djson/internal/storage"
+	"go.neonxp.dev/json/model"
+)
+
+type Engine struct {
+	Root    model.Node
+	mu      sync.RWMutex
+	storage storage.Storage
+}
+
+func New(storage storage.Storage) *Engine {
+	return &Engine{
+		Root:    model.Node{},
+		mu:      sync.RWMutex{},
+		storage: storage,
+	}
+}
+
+func (t *Engine) Run(ctx context.Context) error {
+	// Load initial mutations
+	for m := range t.storage.Load() {
+		if err := t.execute(&m); err != nil {
+			return err
+		}
+	}
+
+	<-ctx.Done()
+	return nil
+}
+
+func (t *Engine) Get(nodes []string) (*model.Node, error) {
+	if len(nodes) == 0 {
+		return &t.Root, nil
+	}
+	return t.Root.Query(nodes)
+}
diff --git a/internal/tree/mutations.go b/internal/tree/mutations.go
new file mode 100644
index 0000000..ec80ebd
--- /dev/null
+++ b/internal/tree/mutations.go
@@ -0,0 +1,60 @@
+package tree
+
+import (
+	"context"
+	"fmt"
+
+	"go.neonxp.dev/djson/internal/model"
+)
+
+func (t *Engine) Mutation(ctx context.Context, mut *model.Mutation) error {
+	t.mu.Lock()
+	defer t.mu.Unlock()
+	if err := t.execute(mut); err != nil {
+		return err
+	}
+	return t.storage.Commit(ctx, *mut)
+}
+
+func (t *Engine) execute(mut *model.Mutation) error {
+	switch mut.Type {
+	case model.Create:
+		if len(mut.Path) == 0 {
+			// create root node
+			t.Root = mut.Body
+			return nil
+		}
+		key := mut.Path[len(mut.Path)-1]
+		path := mut.Path[:len(mut.Path)-1]
+		target, err := t.Root.Query(path)
+		if err != nil {
+			return err
+		}
+		return target.Set(key, mut.Body)
+	case model.Merge:
+		if len(mut.Path) == 0 {
+			// patch root node
+			return t.Root.Merge(&mut.Body)
+		}
+		target, err := t.Root.Query(mut.Path)
+		if err != nil {
+			return err
+		}
+		return target.Merge(&mut.Body)
+	case model.Remove:
+		if len(mut.Path) == 0 {
+			return fmt.Errorf("can't remove root node. Only replace or create avaliable")
+		}
+		key := mut.Path[len(mut.Path)-1]
+		if len(mut.Path) == 1 {
+			return t.Root.Remove(key)
+		}
+		path := mut.Path[:len(mut.Path)-1]
+		target, err := t.Root.Query(path)
+		if err != nil {
+			return err
+		}
+		return target.Remove(key)
+	}
+	return fmt.Errorf("invalid command type: %d", mut.Type)
+}