From fb0c6d5f29dcba56a306ecedd8cd6d2f21f32e1e Mon Sep 17 00:00:00 2001
From: Guilherme Henrique <me@gjhenrique.com>
Date: Sun, 15 Jan 2023 20:49:43 +0100
Subject: [PATCH] Add history

---
 store/history.go      | 100 ++++++++++++++++++++++++++++++++++++++++++
 store/history_test.go |  43 ++++++++++++++++++
 2 files changed, 143 insertions(+)
 create mode 100644 store/history_test.go

diff --git a/store/history.go b/store/history.go
index 72440ea..5cedfe0 100644
--- a/store/history.go
+++ b/store/history.go
@@ -1 +1,101 @@
 package store
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"sort"
+	"strconv"
+)
+
+type HistoryStore struct {
+	Dir string
+}
+
+func formatEntry(entryKey []byte, n int) []byte {
+	e := append(entryKey, "\t"...)
+	return append(e, strconv.Itoa(n)...)
+
+}
+
+func (h *HistoryStore) fileName(modeKey string) string {
+	return filepath.Join(h.Dir, fmt.Sprintf("%s_history", modeKey))
+}
+
+func (h *HistoryStore) ListEntries(modeKey string) ([][]byte, error) {
+	fileContent, err := ioutil.ReadFile(h.fileName(modeKey))
+	fields := bytes.Split(fileContent, []byte("\n"))
+	s := make([][]byte, 0)
+
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			return s, nil
+		} else {
+			return nil, err
+		}
+	}
+
+	for _, field := range fields {
+		arr := bytes.Split(field, []byte("\t"))
+		first := arr[0]
+		if len(first) > 0 {
+			s = append(s, first)
+		}
+	}
+
+	return s, nil
+}
+
+func (h *HistoryStore) IncrementEntry(modeKey string, entryKey []byte) error {
+	fileContent, err := ioutil.ReadFile(h.fileName(modeKey))
+
+	if err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			fileContent = make([]byte, 0)
+		} else {
+			return err
+		}
+	}
+
+	fields := bytes.Split(fileContent, []byte("\n"))
+	var found bool
+
+	for i, field := range fields {
+		arr := bytes.Split(field, []byte("\t"))
+		first := arr[0]
+		if bytes.Compare(first, []byte(entryKey)) == 0 {
+			found = true
+
+			last := arr[len(arr)-1]
+			n, err := strconv.Atoi(string(last))
+
+			if err != nil {
+				n = 0
+			}
+
+			fields[i] = formatEntry(entryKey, n+1)
+		}
+	}
+
+	if !found {
+		entry := formatEntry(entryKey, 1)
+		fields = append(fields, entry)
+	}
+
+	sort.SliceStable(fields, func(i, j int) bool {
+		arr1 := bytes.Split(fields[i], []byte("\t"))
+		a, _ := strconv.Atoi(string(arr1[len(arr1)-1]))
+
+		arr2 := bytes.Split(fields[j], []byte("\t"))
+		b, _ := strconv.Atoi(string(arr2[len(arr2)-1]))
+
+		return a > b
+	})
+
+	finalFields := bytes.Join(fields, []byte("\n"))
+
+	return ioutil.WriteFile(h.fileName(modeKey), finalFields, 0644)
+}
diff --git a/store/history_test.go b/store/history_test.go
new file mode 100644
index 0000000..c4a2508
--- /dev/null
+++ b/store/history_test.go
@@ -0,0 +1,43 @@
+package store
+
+import (
+	"testing"
+
+	"github.com/gjhenrique/yafl/internal/test"
+	"github.com/stretchr/testify/require"
+)
+
+func TestOrderIsMaintained(t *testing.T) {
+	workspace := test.SetupWorkspace(t)
+	defer workspace.RemoveWorkspace()
+
+	store := HistoryStore{Dir: workspace.CacheDir}
+
+	err := store.IncrementEntry("key", []byte("a"))
+	require.NoError(t, err)
+	err = store.IncrementEntry("key", []byte("b"))
+	require.NoError(t, err)
+	err = store.IncrementEntry("key", []byte("c"))
+	require.NoError(t, err)
+	err = store.IncrementEntry("key", []byte("b"))
+	require.NoError(t, err)
+
+	entries, err := store.ListEntries("key")
+	require.NoError(t, err)
+
+	require.Len(t, entries, 3)
+	require.Equal(t, string(entries[0]), "b")
+	require.Equal(t, string(entries[1]), "a")
+	require.Equal(t, string(entries[2]), "c")
+}
+
+func TestEmptyArrayWhenFileDoesNotExist(t *testing.T) {
+	workspace := test.SetupWorkspace(t)
+	defer workspace.RemoveWorkspace()
+
+	store := HistoryStore{Dir: workspace.CacheDir}
+
+	entries, err := store.ListEntries("key")
+	require.NoError(t, err)
+	require.Len(t, entries, 0)
+}