use std::sync::Arc;

use mistralai_client::v1::{
    chat::{ChatMessage, ChatParams, ChatResponse, ChatResponseChoiceFinishReason},
    constants::Model,
    error::ApiError,
    tool::ToolChoice,
};
use rand::Rng;
use tokio::time::{sleep, Duration};
use tracing::{debug, error, info, warn};

use crate::brain::conversation::ContextMessage;
use crate::brain::personality::Personality;
use crate::config::Config;
use crate::tools::ToolRegistry;

/// Run a Mistral chat completion on a blocking thread.
///
/// The mistral client's `chat_async` holds a `std::sync::MutexGuard` across an
/// `.await` point, making the future !Send. We use the synchronous `chat()`
/// method via `spawn_blocking` instead.
pub(crate) async fn chat_blocking(
    client: &Arc<mistralai_client::v1::client::Client>,
    model: Model,
    messages: Vec<ChatMessage>,
    params: ChatParams,
) -> Result<ChatResponse, ApiError> {
    let client = Arc::clone(client);
    tokio::task::spawn_blocking(move || client.chat(model, messages, Some(params)))
        .await
        .map_err(|e| ApiError {
            message: format!("spawn_blocking join error: {e}"),
        })?
}

pub struct Responder {
    config: Arc<Config>,
    personality: Arc<Personality>,
    tools: Arc<ToolRegistry>,
}

impl Responder {
    pub fn new(
        config: Arc<Config>,
        personality: Arc<Personality>,
        tools: Arc<ToolRegistry>,
    ) -> Self {
        Self {
            config,
            personality,
            tools,
        }
    }

    pub async fn generate_response(
        &self,
        context: &[ContextMessage],
        trigger_body: &str,
        trigger_sender: &str,
        room_name: &str,
        members: &[String],
        is_spontaneous: bool,
        mistral: &Arc<mistralai_client::v1::client::Client>,
    ) -> Option<String> {
        // Apply response delay
        let delay = if is_spontaneous {
            rand::thread_rng().gen_range(
                self.config.behavior.spontaneous_delay_min_ms
                    ..=self.config.behavior.spontaneous_delay_max_ms,
            )
        } else {
            rand::thread_rng().gen_range(
                self.config.behavior.response_delay_min_ms
                    ..=self.config.behavior.response_delay_max_ms,
            )
        };
        sleep(Duration::from_millis(delay)).await;

        let system_prompt = self.personality.build_system_prompt(room_name, members);

        let mut messages = vec![ChatMessage::new_system_message(&system_prompt)];

        // Add context messages
        for msg in context {
            if msg.sender == self.config.matrix.user_id {
                messages.push(ChatMessage::new_assistant_message(&msg.content, None));
            } else {
                let user_msg = format!("{}: {}", msg.sender, msg.content);
                messages.push(ChatMessage::new_user_message(&user_msg));
            }
        }

        // Add the triggering message
        let trigger = format!("{trigger_sender}: {trigger_body}");
        messages.push(ChatMessage::new_user_message(&trigger));

        let tool_defs = ToolRegistry::tool_definitions();
        let model = Model::new(&self.config.mistral.default_model);
        let max_iterations = self.config.mistral.max_tool_iterations;

        for iteration in 0..=max_iterations {
            let params = ChatParams {
                tools: if iteration < max_iterations {
                    Some(tool_defs.clone())
                } else {
                    None
                },
                tool_choice: if iteration < max_iterations {
                    Some(ToolChoice::Auto)
                } else {
                    None
                },
                ..Default::default()
            };

            let response = match chat_blocking(mistral, model.clone(), messages.clone(), params).await {
                Ok(r) => r,
                Err(e) => {
                    error!("Mistral chat failed: {e}");
                    return None;
                }
            };

            let choice = &response.choices[0];

            if choice.finish_reason == ChatResponseChoiceFinishReason::ToolCalls {
                if let Some(tool_calls) = &choice.message.tool_calls {
                    // Add assistant message with tool calls
                    messages.push(ChatMessage::new_assistant_message(
                        &choice.message.content,
                        Some(tool_calls.clone()),
                    ));

                    for tc in tool_calls {
                        let call_id = tc.id.as_deref().unwrap_or("unknown");
                        info!(
                            tool = tc.function.name.as_str(),
                            id = call_id,
                            "Executing tool call"
                        );

                        let result = self
                            .tools
                            .execute(&tc.function.name, &tc.function.arguments)
                            .await;

                        let result_str = match result {
                            Ok(s) => s,
                            Err(e) => {
                                warn!(tool = tc.function.name.as_str(), "Tool failed: {e}");
                                format!("Error: {e}")
                            }
                        };

                        messages.push(ChatMessage::new_tool_message(
                            &result_str,
                            call_id,
                            Some(&tc.function.name),
                        ));
                    }

                    debug!(iteration, "Tool iteration complete, continuing");
                    continue;
                }
            }

            // Final text response
            let text = choice.message.content.trim().to_string();
            if text.is_empty() {
                return None;
            }
            return Some(text);
        }

        warn!("Exceeded max tool iterations");
        None
    }
}