use rig::prelude::*;
use std::fmt::Debug;
use tonic::metadata::MetadataValue;
use tonic::service::Interceptor;
use tonic::transport::{Channel, Endpoint};
use tonic::{Request, Status};

use super::GenerativeServiceClient;
use crate::completion::CompletionModel;
use crate::embedding::EmbeddingModel;

// ================================================================
// Google Gemini gRPC Client
// ================================================================
const GEMINI_GRPC_ENDPOINT: &str = "https://generativelanguage.googleapis.com";

/// User agent identifier for API tracking
const RIG_GRPC_CLIENT_IDENTIFIER: &str = "rig-grpc/0.1.0";

#[derive(Clone)]
pub struct Client {
    api_key: String,
    channel: Channel,
}

impl Debug for Client {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("Client")
            .field("api_key", &"******")
            .field("channel", &"Channel")
            .finish()
    }
}

// Interceptor to add API key and client identification to metadata
#[derive(Clone)]
pub struct ApiKeyInterceptor {
    api_key: MetadataValue<tonic::metadata::Ascii>,
    client_id: MetadataValue<tonic::metadata::Ascii>,
}

impl Interceptor for ApiKeyInterceptor {
    fn call(&mut self, mut request: Request<()>) -> Result<Request<()>, Status> {
        request
            .metadata_mut()
            .insert("x-goog-api-key", self.api_key.clone());
        request
            .metadata_mut()
            .insert("x-goog-api-client", self.client_id.clone());
        Ok(request)
    }
}

impl Client {
    /// Create a gRPC client with the given API key
    pub async fn new(
        api_key: impl Into<String>,
    ) -> Result<Self, Box<dyn std::error::Error + Send + Sync>> {
        let api_key = api_key.into();
        let endpoint = Endpoint::from_static(GEMINI_GRPC_ENDPOINT).tls_config(
            tonic::transport::ClientTlsConfig::new()
                .with_webpki_roots()
                .domain_name("generativelanguage.googleapis.com"),
        )?;

        let channel = endpoint.connect().await?;

        Ok(Self { api_key, channel })
    }

    /// Get a gRPC client with API key interceptor
    pub(crate) fn grpc_client(
        &self,
    ) -> Result<
        GenerativeServiceClient<
            tonic::service::interceptor::InterceptedService<Channel, ApiKeyInterceptor>,
        >,
        Box<dyn std::error::Error + Send + Sync>,
    > {
        let api_key = MetadataValue::try_from(&self.api_key)?;
        let client_id = MetadataValue::try_from(RIG_GRPC_CLIENT_IDENTIFIER)?;
        let interceptor = ApiKeyInterceptor { api_key, client_id };

        Ok(GenerativeServiceClient::with_interceptor(
            self.channel.clone(),
            interceptor,
        ))
    }
}

impl ProviderClient for Client {
    type Input = String;

    /// Create a new Google Gemini gRPC client from the `GEMINI_API_KEY` environment variable.
    /// Panics if the environment variable is not set.
    fn from_env() -> Self {
        let api_key = std::env::var("GEMINI_API_KEY").expect("GEMINI_API_KEY not set");
        tokio::task::block_in_place(|| {
            tokio::runtime::Handle::current()
                .block_on(Self::new(api_key))
                .expect("Failed to create Gemini gRPC client")
        })
    }

    fn from_val(input: Self::Input) -> Self {
        tokio::task::block_in_place(|| {
            tokio::runtime::Handle::current()
                .block_on(Self::new(input))
                .expect("Failed to create Gemini gRPC client")
        })
    }
}

impl CompletionClient for Client {
    type CompletionModel = CompletionModel;

    fn completion_model(&self, model: impl Into<String>) -> Self::CompletionModel {
        CompletionModel::new(self.clone(), model)
    }
}

impl EmbeddingsClient for Client {
    type EmbeddingModel = EmbeddingModel;

    fn embedding_model(&self, model: impl Into<String>) -> Self::EmbeddingModel {
        EmbeddingModel::new(self.clone(), model, None)
    }

    fn embedding_model_with_ndims(
        &self,
        model: impl Into<String>,
        ndims: usize,
    ) -> Self::EmbeddingModel {
        EmbeddingModel::new(self.clone(), model, Some(ndims))
    }
}
