1 files changed, 67 insertions, 0 deletions
diff --git a/internal/factgiver/factgiver.go b/internal/factgiver/factgiver.go
new file mode 100644
index 0000000..6f77403
--- /dev/null
+++ b/internal/factgiver/factgiver.go
@@ -0,0 +1,67 @@
+package factgiver
+
+import (
+	"fmt"
+	"math/rand"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/SayaAndy/saya-today-web/config"
+	"github.com/SayaAndy/saya-today-web/internal/b2"
+)
+
+type FactGiver struct {
+	b2Client      *b2.B2Client
+	cache         map[string][]string
+	langs         []string
+	factsFileName string
+	nlRe          *regexp.Regexp
+	randGen       *rand.Rand
+}
+
+func NewFactGiver(cfg *config.FactGiverConfig, langs []string) (*FactGiver, error) {
+	b2Client, err := b2.NewB2Client(&cfg.Storage.Config)
+	if err != nil {
+		return nil, fmt.Errorf("fail to init b2 client for a new fact giver: %s", err.Error())
+	}
+
+	factGiver := &FactGiver{
+		b2Client:      b2Client,
+		cache:         make(map[string][]string, len(langs)),
+		langs:         langs,
+		factsFileName: cfg.FactsFileName,
+		nlRe:          regexp.MustCompile(`\r?\n`),
+		randGen:       rand.New(rand.NewSource(time.Now().UnixNano())),
+	}
+	if err = factGiver.initCache(); err != nil {
+		return nil, fmt.Errorf("fail to init cache for a new fact giver: %s", err.Error())
+	}
+
+	return factGiver, nil
+}
+
+func (g *FactGiver) Give(lang string) [3]string {
+	factSlice := make([]string, len(g.cache[lang]))
+	copy(factSlice, g.cache[lang])
+	g.randGen.Shuffle(len(factSlice), func(i, j int) {
+		factSlice[i], factSlice[j] = factSlice[j], factSlice[i]
+	})
+	return [3]string{factSlice[0], factSlice[1], factSlice[2]}
+}
+
+func (g *FactGiver) initCache() error {
+	for _, lang := range g.langs {
+		localFacts := strings.Replace(g.factsFileName, "*", lang, 1)
+		factsContentBytes, err := g.b2Client.ReadAll(localFacts)
+		if err != nil {
+			return fmt.Errorf("fail to read '%s' facts file: %s", lang, err.Error())
+		}
+		factsContent := string(factsContentBytes)
+		g.cache[lang] = g.nlRe.Split(factsContent, -1)
+		if g.cache[lang][len(g.cache[lang])-1] == "" {
+			g.cache[lang] = g.cache[lang][:len(g.cache[lang])-1]
+		}
+	}
+	return nil
+}