From d97741966a6c97b5db7df62873bd2ee9d99f0565 Mon Sep 17 00:00:00 2001
From: Paul Buetow <paul@buetow.org>
Date: Sun, 19 Apr 2026 23:13:06 +0300
Subject: y4: wire ComicForge CLI providers and config

---
 internal/text/gemini.go | 110 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)
 create mode 100644 internal/text/gemini.go

(limited to 'internal/text')

diff --git a/internal/text/gemini.go b/internal/text/gemini.go
new file mode 100644
index 0000000..94a8c16
--- /dev/null
+++ b/internal/text/gemini.go
@@ -0,0 +1,110 @@
+package text
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"google.golang.org/genai"
+
+	"codeberg.org/snonux/comicforge/internal/httpctx"
+	"codeberg.org/snonux/comicforge/internal/provider"
+)
+
+const (
+	// DefaultModel is the Gemini text model used for story generation.
+	DefaultModel = "gemini-2.5-flash"
+)
+
+// GeminiConfig holds the settings needed to build a Gemini-backed text provider.
+type GeminiConfig struct {
+	APIKey string
+	Model  string
+}
+
+// GeminiProvider implements TextProvider for Google Gemini text generation.
+type GeminiProvider struct {
+	client *genai.Client
+	model  string
+	err    error
+}
+
+var _ provider.TextProvider = (*GeminiProvider)(nil)
+
+var newGeminiClient = httpctx.NewGenAIClient
+var geminiGenerateText = func(ctx context.Context, p *GeminiProvider, prompt string) (string, error) {
+	return p.generateText(ctx, prompt)
+}
+
+// NewGeminiProvider creates a Gemini text provider.
+func NewGeminiProvider(cfg *GeminiConfig) *GeminiProvider {
+	g := &GeminiProvider{model: DefaultModel}
+	if cfg == nil {
+		g.err = fmt.Errorf("text config is required")
+		return g
+	}
+	g.model = defaultOr(cfg.Model, DefaultModel)
+	if strings.TrimSpace(cfg.APIKey) == "" {
+		g.err = fmt.Errorf("Google API key is required for text generation")
+		return g
+	}
+	client, err := newGeminiClient(context.Background(), &genai.ClientConfig{
+		APIKey:  cfg.APIKey,
+		Backend: genai.BackendGeminiAPI,
+	})
+	if err != nil {
+		g.err = fmt.Errorf("create Gemini client: %w", err)
+		return g
+	}
+	g.client = client
+	return g
+}
+
+// Name returns the provider name.
+func (g *GeminiProvider) Name() string { return provider.Gemini }
+
+// IsAvailable reports whether the provider was initialized successfully.
+func (g *GeminiProvider) IsAvailable() error {
+	if g == nil {
+		return fmt.Errorf("text provider is nil")
+	}
+	return g.err
+}
+
+// GenerateText generates a text response for the provided prompt.
+func (g *GeminiProvider) GenerateText(ctx context.Context, prompt string) (string, error) {
+	if g == nil {
+		return "", fmt.Errorf("text provider is nil")
+	}
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	if g.err != nil {
+		return "", g.err
+	}
+	if strings.TrimSpace(prompt) == "" {
+		return "", fmt.Errorf("prompt is required")
+	}
+	return geminiGenerateText(ctx, g, prompt)
+}
+
+func (g *GeminiProvider) generateText(ctx context.Context, prompt string) (string, error) {
+	resp, err := g.client.Models.GenerateContent(ctx, g.model, []*genai.Content{
+		genai.NewContentFromText(prompt, genai.RoleUser),
+	}, nil)
+	if err != nil {
+		return "", fmt.Errorf("generate text: %w", err)
+	}
+	text := strings.TrimSpace(resp.Text())
+	if text == "" {
+		return "", fmt.Errorf("no text content returned")
+	}
+	return text, nil
+}
+
+func defaultOr(value, fallback string) string {
+	if strings.TrimSpace(value) != "" {
+		return value
+	}
+	return fallback
+}
-- 
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