feat(ai): add Gemini client wrapper

internal/ai/gemini.go

@@ -0,0 +1,64 @@
+package ai
+
+import (
+	"context"
+	"fmt"
+	"io"
+
+	"google.golang.org/genai"
+)
+
+type GeminiModel string
+
+const (
+	GeminiModel1p5Flash     GeminiModel = "gemini-1.5-flash"
+	GeminiModel20FlashExp   GeminiModel = "gemini-2.0-flash-exp"
+	GeminiModel2p5Flash     GeminiModel = "gemini-2.5-flash"
+	GeminiModel2p5FlashLite GeminiModel = "gemini-2.5-flash-lite"
+)
+
+type GeminiProvider struct {
+	client *genai.Client
+	model  GeminiModel
+	config *genai.GenerateContentConfig
+}
+
+func NewGeminiProvider(ctx context.Context, apiKey string, modelName GeminiModel, config *genai.GenerateContentConfig) (*GeminiProvider, error) {
+	cc := genai.ClientConfig{
+		APIKey: apiKey,
+	}
+	client, err := genai.NewClient(ctx, &cc)
+	if err != nil {
+		return nil, err
+	}
+
+	return &GeminiProvider{client: client, model: modelName, config: config}, nil
+}
+
+func (p *GeminiProvider) Summarize(ctx context.Context, reader io.Reader, writer io.Writer) error {
+
+	inputBytes, err := io.ReadAll(reader)
+	if err != nil {
+		return fmt.Errorf("failed to read input: %w", err)
+	}
+
+	prompt := fmt.Sprintf("Summarize the following:\n%s", string(inputBytes))
+	stream := p.client.Models.GenerateContentStream(
+		ctx,
+		string(p.model),
+		genai.Text(prompt),
+		p.config,
+	)
+
+	for chunk, err := range stream {
+		if err != nil {
+			return fmt.Errorf("failed to generate content: %w", err)
+		}
+		part := chunk.Candidates[0].Content.Parts[0]
+		_, err = writer.Write([]byte(part.Text))
+		if err != nil {
+			return fmt.Errorf("failed to write output: %w", err)
+		}
+	}
+	return nil
+}