//! LLM provider abstraction layer.
//!
//! Defines the `LlmProvider` trait that all LLM providers implement,
//! along with shared types and the provider factory function.

pub mod anthropic;
pub mod factory;
pub mod gemini;
pub mod openai;
pub mod schema;

use async_trait::async_trait;
use serde_json::Value;

use crate::errors::AppError;

/// Trait defining the contract for LLM provider implementations.
///
/// Each provider (Gemini, OpenAI, Anthropic) implements this trait
/// to provide a unified interface for structured LLM calls.
#[async_trait]
pub trait LlmProvider: Send + Sync {
    /// Returns the provider identifier (e.g., "gemini", "openai", "anthropic").
    fn provider_id(&self) -> &str;

    /// Call the LLM with a prompt and expected JSON schema.
    ///
    /// # Arguments
    /// * `model` — The model identifier (e.g., "gpt-4o-mini")
    /// * `system_prompt` — System-level instructions
    /// * `user_prompt` — The user's prompt
    /// * `response_schema` — JSON Schema defining the expected response structure
    async fn call_llm(
        &self,
        model: &str,
        system_prompt: &str,
        user_prompt: &str,
        response_schema: &Value,
    ) -> Result<Value, AppError>;
}

/// Shared HTTP error mapping for LLM provider responses.
pub fn map_provider_http_error(status: u16, provider_name: &str) -> AppError {
    match status {
        400 => AppError::BadRequest("Invalid request to LLM provider".into()),
        401 => AppError::BadRequest("Invalid or unauthorized API key".into()),
        403 => AppError::BadRequest("Access denied by LLM provider".into()),
        404 => AppError::BadRequest("Model not found or not available".into()),
        429 | 529 => AppError::RateLimited(
            "LLM provider rate limit exceeded. Please try again later.".into(),
        ),
        _ => AppError::Internal(anyhow::anyhow!("{} returned HTTP {}", provider_name, status)),
    }
}