use std::sync::Arc;

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

use matrix_sdk::room::Room;
use opensearch::OpenSearch;

use crate::agent_ux::AgentProgress;
use crate::brain::conversation::ContextMessage;
use crate::brain::personality::Personality;
use crate::config::Config;
use crate::context::ResponseContext;
use crate::conversations::ConversationRegistry;
use crate::memory;
use crate::time_context::TimeContext;
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>,
    opensearch: OpenSearch,
}

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

    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>,
        room: &Room,
        response_ctx: &ResponseContext,
        image_data_uri: Option<&str>,
    ) -> Option<String> {
        // Apply response delay (skip if instant_responses is enabled)
        // Delay happens BEFORE typing indicator — Sol "notices" the message first
        if !self.config.behavior.instant_responses {
            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,
                )
            };
            debug!(delay_ms = delay, is_spontaneous, "Applying response delay");
            sleep(Duration::from_millis(delay)).await;
        }

        // Start typing AFTER the delay — Sol has decided to respond
        let _ = room.typing_notice(true).await;

        // Pre-response memory query
        let memory_notes = self
            .load_memory_notes(response_ctx, trigger_body)
            .await;

        let system_prompt = self.personality.build_system_prompt(
            room_name,
            members,
            memory_notes.as_deref(),
            response_ctx.is_dm,
        );

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

        // Add context messages with timestamps so the model has time awareness
        for msg in context {
            let ts = chrono::DateTime::from_timestamp_millis(msg.timestamp)
                .map(|d| d.format("%H:%M").to_string())
                .unwrap_or_default();
            if msg.sender == self.config.matrix.user_id {
                messages.push(ChatMessage::new_assistant_message(&msg.content, None));
            } else {
                let user_msg = format!("[{}] {}: {}", ts, msg.sender, msg.content);
                messages.push(ChatMessage::new_user_message(&user_msg));
            }
        }

        // Add the triggering message (multimodal if image attached)
        if let Some(data_uri) = image_data_uri {
            use mistralai_client::v1::chat::{ContentPart, ImageUrl};
            let mut parts = vec![];
            if !trigger_body.is_empty() {
                parts.push(ContentPart::Text {
                    text: format!("{trigger_sender}: {trigger_body}"),
                });
            }
            parts.push(ContentPart::ImageUrl {
                image_url: ImageUrl {
                    url: data_uri.to_string(),
                    detail: None,
                },
            });
            messages.push(ChatMessage::new_user_message_with_images(parts));
        } else {
            let trigger = format!("{trigger_sender}: {trigger_body}");
            messages.push(ChatMessage::new_user_message(&trigger));
        }

        let tool_defs = ToolRegistry::tool_definitions(self.tools.has_gitea(), self.tools.has_kratos());
        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) => {
                    let _ = room.typing_notice(false).await;
                    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.text(),
                        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,
                            args = tc.function.arguments.as_str(),
                            "Executing tool call"
                        );

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

                        let result_str = match result {
                            Ok(s) => {
                                let preview: String = s.chars().take(500).collect();
                                info!(
                                    tool = tc.function.name.as_str(),
                                    id = call_id,
                                    result_len = s.len(),
                                    result_preview = preview.as_str(),
                                    "Tool call result"
                                );
                                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 — strip own name prefix if present
            let mut text = choice.message.content.text().trim().to_string();

            // Strip "sol:" or "sol 💕:" or similar prefixes the model sometimes adds
            let lower = text.to_lowercase();
            for prefix in &["sol:", "sol 💕:", "sol💕:"] {
                if lower.starts_with(prefix) {
                    text = text[prefix.len()..].trim().to_string();
                    break;
                }
            }

            if text.is_empty() {
                info!("Generated empty response, skipping send");
                let _ = room.typing_notice(false).await;
                return None;
            }

            let preview: String = text.chars().take(120).collect();
            let _ = room.typing_notice(false).await;
            info!(
                response_len = text.len(),
                response_preview = preview.as_str(),
                is_spontaneous,
                tool_iterations = iteration,
                "Generated response"
            );
            return Some(text);
        }

        let _ = room.typing_notice(false).await;
        warn!("Exceeded max tool iterations");
        None
    }

    /// Generate a response using the Mistral Conversations API.
    /// This path routes through the ConversationRegistry for persistent state,
    /// agent handoffs, and function calling with UX feedback (reactions + threads).
    pub async fn generate_response_conversations(
        &self,
        trigger_body: &str,
        trigger_sender: &str,
        room_id: &str,
        room_name: &str,
        is_dm: bool,
        is_spontaneous: bool,
        mistral: &Arc<mistralai_client::v1::client::Client>,
        room: &Room,
        response_ctx: &ResponseContext,
        conversation_registry: &ConversationRegistry,
        image_data_uri: Option<&str>,
        context_hint: Option<String>,
        event_id: ruma::OwnedEventId,
    ) -> Option<String> {
        // Apply response delay
        if !self.config.behavior.instant_responses {
            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 _ = room.typing_notice(true).await;

        // Pre-response memory query (same as legacy path)
        let memory_notes = self.load_memory_notes(response_ctx, trigger_body).await;

        // Build the input message with dynamic context.
        // Agent instructions are static (set at creation), so per-message context
        // (timestamps, room, members, memory) is prepended to each user message.
        let tc = TimeContext::now();

        let mut context_header = format!(
            "{}\n[room: {} ({})]",
            tc.message_line(),
            room_name,
            room_id,
        );

        if let Some(ref notes) = memory_notes {
            context_header.push('\n');
            context_header.push_str(notes);
        }

        let user_msg = if is_dm {
            trigger_body.to_string()
        } else {
            format!("<{}> {}", response_ctx.matrix_user_id, trigger_body)
        };

        let input_text = format!("{context_header}\n{user_msg}");
        let input = ConversationInput::Text(input_text);

        // Send through conversation registry
        let response = match conversation_registry
            .send_message(room_id, input, is_dm, mistral, context_hint.as_deref())
            .await
        {
            Ok(r) => r,
            Err(e) => {
                error!("Conversation API failed: {e}");
                let _ = room.typing_notice(false).await;
                return None;
            }
        };

        // Check for function calls — execute locally and send results back
        let function_calls = response.function_calls();
        if !function_calls.is_empty() {
            // Agent UX: react with 🔍 and post tool details in a thread
            let mut progress = crate::agent_ux::AgentProgress::new(
                room.clone(),
                event_id.clone(),
            );
            progress.start().await;

            let max_iterations = self.config.mistral.max_tool_iterations;
            let mut current_response = response;

            for iteration in 0..max_iterations {
                let calls = current_response.function_calls();
                if calls.is_empty() {
                    break;
                }

                let mut result_entries = Vec::new();

                for fc in &calls {
                    let call_id = fc.tool_call_id.as_deref().unwrap_or("unknown");
                    info!(
                        tool = fc.name.as_str(),
                        id = call_id,
                        args = fc.arguments.as_str(),
                        "Executing tool call (conversations)"
                    );

                    // Post tool call to thread
                    progress
                        .post_step(&crate::agent_ux::AgentProgress::format_tool_call(
                            &fc.name,
                            &fc.arguments,
                        ))
                        .await;

                    let result = if fc.name == "research" {
                        self.tools
                            .execute_research(
                                &fc.arguments,
                                response_ctx,
                                room,
                                &event_id,
                                0, // depth 0 — orchestrator level
                            )
                            .await
                    } else {
                        self.tools
                            .execute(&fc.name, &fc.arguments, response_ctx)
                            .await
                    };

                    let result_str = match result {
                        Ok(s) => {
                            let preview: String = s.chars().take(500).collect();
                            info!(
                                tool = fc.name.as_str(),
                                id = call_id,
                                result_len = s.len(),
                                result_preview = preview.as_str(),
                                "Tool call result (conversations)"
                            );
                            s
                        }
                        Err(e) => {
                            warn!(tool = fc.name.as_str(), "Tool failed: {e}");
                            format!("Error: {e}")
                        }
                    };

                    result_entries.push(ConversationEntry::FunctionResult(FunctionResultEntry {
                        tool_call_id: call_id.to_string(),
                        result: result_str,
                        id: None,
                        object: None,
                        created_at: None,
                        completed_at: None,
                    }));
                }

                // Send function results back to conversation
                current_response = match conversation_registry
                    .send_function_result(room_id, result_entries, mistral)
                    .await
                {
                    Ok(r) => r,
                    Err(e) => {
                        error!("Failed to send function results: {e}");
                        let _ = room.typing_notice(false).await;
                        return None;
                    }
                };

                debug!(iteration, "Tool iteration complete (conversations)");
            }

            // Done with tool calls
            progress.done().await;

            // Extract final text from the last response
            if let Some(text) = current_response.assistant_text() {
                let text = strip_sol_prefix(&text);
                if text.is_empty() {
                    let _ = room.typing_notice(false).await;
                    return None;
                }
                let _ = room.typing_notice(false).await;
                info!(
                    response_len = text.len(),
                    "Generated response (conversations + tools)"
                );
                return Some(text);
            }

            let _ = room.typing_notice(false).await;
            return None;
        }

        // Simple response — no tools involved
        if let Some(text) = response.assistant_text() {
            let text = strip_sol_prefix(&text);
            if text.is_empty() {
                let _ = room.typing_notice(false).await;
                return None;
            }
            let _ = room.typing_notice(false).await;
            info!(
                response_len = text.len(),
                is_spontaneous,
                "Generated response (conversations)"
            );
            return Some(text);
        }

        let _ = room.typing_notice(false).await;
        None
    }

    async fn load_memory_notes(
        &self,
        ctx: &ResponseContext,
        trigger_body: &str,
    ) -> Option<String> {
        let index = &self.config.opensearch.memory_index;
        let user_id = &ctx.user_id;

        // Search for topically relevant memories
        let mut memories = memory::store::query(
            &self.opensearch,
            index,
            user_id,
            trigger_body,
            5,
        )
        .await
        .unwrap_or_default();

        // Backfill with recent memories if we have fewer than 3
        if memories.len() < 3 {
            let remaining = 5 - memories.len();
            if let Ok(recent) = memory::store::get_recent(
                &self.opensearch,
                index,
                user_id,
                remaining,
            )
            .await
            {
                let existing_ids: std::collections::HashSet<String> =
                    memories.iter().map(|m| m.id.clone()).collect();
                for doc in recent {
                    if !existing_ids.contains(&doc.id) && memories.len() < 5 {
                        memories.push(doc);
                    }
                }
            }
        }

        if memories.is_empty() {
            return None;
        }

        let display = ctx
            .display_name
            .as_deref()
            .unwrap_or(&ctx.matrix_user_id);

        Some(format_memory_notes(display, &memories))
    }
}

/// Strip "sol:" or "sol 💕:" prefixes the model sometimes adds.
fn strip_sol_prefix(text: &str) -> String {
    let trimmed = text.trim();
    let lower = trimmed.to_lowercase();
    for prefix in &["sol:", "sol 💕:", "sol💕:"] {
        if lower.starts_with(prefix) {
            return trimmed[prefix.len()..].trim().to_string();
        }
    }
    trimmed.to_string()
}

/// Format memory documents into a notes block for the system prompt.
pub(crate) fn format_memory_notes(
    display_name: &str,
    memories: &[memory::schema::MemoryDocument],
) -> String {
    let mut lines = vec![format!(
        "## notes about {display_name}\n\n\
         these are your private notes about the person you're talking to.\n\
         use them to inform your responses but don't mention that you have notes.\n"
    )];

    for mem in memories {
        lines.push(format!("- [{}] {}", mem.category, mem.content));
    }

    lines.join("\n")
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::memory::schema::MemoryDocument;

    fn make_mem(id: &str, content: &str, category: &str) -> MemoryDocument {
        MemoryDocument {
            id: id.into(),
            user_id: "sienna@sunbeam.pt".into(),
            content: content.into(),
            category: category.into(),
            created_at: 1710000000000,
            updated_at: 1710000000000,
            source: "auto".into(),
        }
    }

    #[test]
    fn test_format_memory_notes_basic() {
        let memories = vec![
            make_mem("a", "prefers terse answers", "preference"),
            make_mem("b", "working on drive UI", "fact"),
        ];

        let result = format_memory_notes("sienna", &memories);
        assert!(result.contains("## notes about sienna"));
        assert!(result.contains("don't mention that you have notes"));
        assert!(result.contains("- [preference] prefers terse answers"));
        assert!(result.contains("- [fact] working on drive UI"));
    }

    #[test]
    fn test_format_memory_notes_single() {
        let memories = vec![make_mem("x", "birthday is march 12", "context")];
        let result = format_memory_notes("lonni", &memories);
        assert!(result.contains("## notes about lonni"));
        assert!(result.contains("- [context] birthday is march 12"));
    }

    #[test]
    fn test_format_memory_notes_uses_display_name() {
        let memories = vec![make_mem("a", "test", "general")];
        let result = format_memory_notes("Amber", &memories);
        assert!(result.contains("## notes about Amber"));
    }
}