video2document/services/modules/llm-gemini/gemini.js

const outputDir = path.join(__dirname, "../../../storage/documents"); //  path for output directory

if (!fs.existsSync(outputDir)) {
    fs.mkdirSync(outputDir, { recursive: true }); // Create output directory if it doesn't exist
}

// Ensure Google API key is set in environment variables: export GOOGLE_API_KEY="your_api_key_here"

const GEMINI_API_KEY = process.env.GOOGLE_API_KEY; // Ensure Google API key is set in environment variables: export GOOGLE_API_KEY="your_api_key_here"
const GEMINI_URL = "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.5-flash:generateContent"; //URL for the REST call, used model and action

module.exports = {
    name: "llm-gemini",
    type: "llm",
    displayname: "Gemini LLM",
    description: "Generates documents using Google Gemini LLM",

    async function(parameter) {
        try {
            console.log("Gemini LLM module invoked with parameters:", parameter);

            await this.createDocumentFromTranscript( //Call the function to create document with transcript, document type and language
                parameter.inputTranscriptPath, // Path to input transcript file
                parameter.documentTypePath, // Path to document type file which is chosen in the front end by the user
                parameter.language // Language for the document which is chosen in the front end by the user
            );

        } catch (error) {
            console.error("Error in Gemini LLM module:", error);
        }
    },

    createDocumentFromTranscript: async function(transcriptPath, documentTypePath, language = "en") { // default language is English
        try {
            const transcript = await fs.promises.readFile(transcriptPath, "utf-8"); //read transcript file from Path
            const documentType = await fs.promises.readFile(documentTypePath, "utf-8"); //read document type from Path
            const promptText = `${documentType}, in language ${language}, transcript:\n\n${transcript}`; //combine doc type, language and transcript - Change prompt here if needed

            // --- REST CALL ---
            const response = await fetch(`${GEMINI_URL}?key=${GEMINI_API_KEY}`, { //safe model response in variable
                method: "POST",
                headers: {
                    "Content-Type": "application/json"
                },
                body: JSON.stringify({
                    contents: [
                        {
                            parts: [
                                { text: promptText } // Input prompt for content generation
                            ]
                        }
                    ]
                })
            });

            if (!response.ok) { //ok is true when a responce was successfull
                const text = await response.text();
                throw new Error(`Gemini API error (${response.status}): ${text}`);
            }

            const data = await response.json();

            // Get generated text from response or default to empty string (if null)
            const output = data?.candidates?.[0]?.content?.parts?.[0]?.text || "";
            let inputTranscriptName = path.basename(transcriptPath, path.extname(transcriptPath)); // Name for the output file 
            console.log(inputTranscriptName);
            const outPath = path.join(outputDir, `${inputTranscriptName}.md`); // Output file path & name to make naming dynamic. Pulled from input transcript name
            fs.writeFileSync(outPath, output, "utf8"); // Write output to file

            console.log("Generated document written to:", outPath);

        } catch (error) {
            console.error("Error generating Gemini content:", error);
        }
    }
};