package main

import (
	"context"
	"fmt"

	"google.golang.org/genai"
)

type chatTurn struct {
	Role string `json:"role"` // "user" or "model"
	Text string `json:"text"`
}

const (
	modelGemma  = "gemma-4-26b-a4b-it"
	modelGemini = "gemini-flash-latest"
)

func selectModel(unlockCode, unlockSecret string) string {
	if unlockSecret != "" && unlockCode == unlockSecret {
		return modelGemini
	}
	return modelGemma
}

func buildSystemInstruction(videoTitle, videoDescription string) *genai.Content {
	prompt := fmt.Sprintf(
		"あなたはユーザーと一緒に動画を見ている友達です。タメ口で短く、実況や相槌のように反応してください。\n"+
			"今見ている動画:\nタイトル: %s\n概要: %s",
		videoTitle, videoDescription,
	)
	return genai.NewContentFromText(prompt, genai.RoleUser)
}

func chatReply(ctx context.Context, client *genai.Client, model, videoTitle, videoDescription string, history []chatTurn, message string) (string, error) {
	contents := make([]*genai.Content, 0, len(history)+1)
	for _, h := range history {
		contents = append(contents, genai.NewContentFromText(h.Text, genai.Role(h.Role)))
	}
	contents = append(contents, genai.NewContentFromText(message, genai.RoleUser))

	resp, err := client.Models.GenerateContent(ctx, model, contents, &genai.GenerateContentConfig{
		SystemInstruction: buildSystemInstruction(videoTitle, videoDescription),
	})
	if err != nil {
		return "", err
	}
	return resp.Text(), nil
}