use handlebars::Handlebars;
use serde_json::Value;

use crate::error::{AiError, AiResult};

/// Prompt 模板渲染引擎
pub struct PromptRenderer {
    registry: Handlebars<'static>,
}

impl PromptRenderer {
    pub fn new() -> Self {
        let mut registry = Handlebars::new();
        registry.set_strict_mode(true);
        Self { registry }
    }

    /// 渲染 Prompt 模板 — 使用 Handlebars {{variable}} 语法
    /// JSON 序列化注入，不做字符串拼接，防止 Prompt 注入
    pub fn render(&self, template: &str, data: &Value) -> AiResult<String> {
        self.registry
            .render_template(template, data)
            .map_err(|e| AiError::TemplateError(format!("模板渲染失败: {e}")))
    }
}