inou/lib/llm.go

package lib

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"strings"
)

var promptsDir string

// InitPrompts sets the directory where prompt files are located.
// This must be called by the main application at startup.
func InitPrompts(path string) {
	promptsDir = path
}

// PromptsDir returns the configured prompts directory.
// This is used by local prompt loading functions in consumer packages.
func PromptsDir() string {
	return promptsDir
}

// GeminiPart represents a single part in the Gemini content, can be text or inline_data.
type GeminiPart struct {
	Text       string            `json:"text,omitempty"`
	InlineData *GeminiInlineData `json:"inline_data,omitempty"`
}

// GeminiInlineData represents inline data for multimodal input.
type GeminiInlineData struct {
	MimeType string `json:"mime_type"`
	Data     string `json:"data"`
}

// GeminiConfig allows overriding default generation parameters.
type GeminiConfig struct {
	Temperature      *float64 `json:"temperature,omitempty"`
	MaxOutputTokens  *int     `json:"maxOutputTokens,omitempty"`
	ResponseMimeType *string  `json:"responseMimeType,omitempty"`
	Model            *string  `json:"model,omitempty"` // Allows specifying a different model
}

// CallGemini sends a text-only request to the Gemini API with default configuration.
// It returns the raw text response from the model.
func CallGemini(prompt string) (string, error) {
	parts := []GeminiPart{
		{Text: prompt},
	}
	return CallGeminiMultimodal(parts, nil)
}

// CallGeminiMultimodal sends a request to the Gemini API with flexible content and configuration.
// It returns the raw text response from the model.
func CallGeminiMultimodal(parts []GeminiPart, config *GeminiConfig) (string, error) {
	if GeminiKey == "" {
		return "", fmt.Errorf("Gemini API key not configured")
	}

	// Default configuration
	defaultTemperature := 0.1
	defaultMaxOutputTokens := 2048
	defaultResponseMimeType := "application/json"
	defaultModel := "gemini-2.0-flash"

	if config == nil {
		config = &GeminiConfig{}
	}

	// Apply defaults if not overridden
	if config.Temperature == nil {
		config.Temperature = &defaultTemperature
	}
	if config.MaxOutputTokens == nil {
		config.MaxOutputTokens = &defaultMaxOutputTokens
	}
	if config.ResponseMimeType == nil {
		config.ResponseMimeType = &defaultResponseMimeType
	}
	if config.Model == nil {
		config.Model = &defaultModel
	}

	reqBody := map[string]interface{}{
		"contents": []map[string]interface{}{
			{
				"parts": parts,
			},
		},
		"systemInstruction": map[string]interface{}{
			"parts": []map[string]string{
				{"text": "You are a JSON-only API. Output raw JSON with no markdown, no code fences, no explanations. Start directly with { and end with }."},
			},
		},
		"generationConfig": map[string]interface{}{
			"temperature":      *config.Temperature,
			"maxOutputTokens":  *config.MaxOutputTokens,
			"responseMimeType": *config.ResponseMimeType,
		},
	}

	jsonBody, err := json.Marshal(reqBody)
	if err != nil {
		return "", fmt.Errorf("marshal request: %w", err)
	}

	url := fmt.Sprintf("https://generativelanguage.googleapis.com/v1beta/models/%s:generateContent?key=%s", *config.Model, GeminiKey)

	resp, err := http.Post(url, "application/json", bytes.NewReader(jsonBody))
	if err != nil {
		return "", fmt.Errorf("API request: %w", err)
	}
	defer resp.Body.Close()

	body, err := io.ReadAll(resp.Body)
	if err != nil {
		return "", fmt.Errorf("read response: %w", err)
	}

	if resp.StatusCode != 200 {
		return "", fmt.Errorf("Gemini API error %d: %s", resp.StatusCode, string(body))
	}

	var geminiResp struct {
		Candidates []struct {
			Content struct {
				Parts []struct {
					Text string `json:"text"`
				} `json:"parts"`
			} `json:"content"`
		} `json:"candidates"`
	}
	if err := json.Unmarshal(body, &geminiResp); err != nil {
		return "", fmt.Errorf("failed to parse Gemini response: %v", err)
	}

	if len(geminiResp.Candidates) == 0 || len(geminiResp.Candidates[0].Content.Parts) == 0 {
		return "", fmt.Errorf("empty response from Gemini")
	}

	finalText := strings.TrimSpace(geminiResp.Candidates[0].Content.Parts[0].Text)
	// The model sometimes still wraps the output in markdown, so we clean it.
	finalText = strings.TrimPrefix(finalText, "```json")
	finalText = strings.TrimPrefix(finalText, "```")
	finalText = strings.TrimSuffix(finalText, "```")

	return finalText, nil
}