use std::{convert::Infallible, time::Duration};

use axum::{
    extract::Path,
    http::StatusCode,
    response::sse::{Event, KeepAlive, Sse},
    Json,
};
use futures_util::stream;
use serde::{Deserialize, Serialize};
use uuid::Uuid;

use crate::inference::python_bridge::PythonBridge;
use crate::inference::response_validator::{
    AutonomousAgentRolePayload, AutonomousApprovalPayload, AutonomousCheckpointPayload,
    AutonomousSessionPayload, AutonomousTaskPayload, AutonomousTimelineEventPayload,
};

const AUTONOMOUS_STREAM_INTERVAL_MS: u64 = 900;

struct AutonomousStreamState {
    session_id: String,
    active: bool,
    is_first: bool,
}

#[derive(Deserialize)]
pub struct StartSessionRequest {
    pub goal: String,
    pub max_steps: Option<u32>,
    pub persona_id: Option<String>,
    pub session_id: Option<String>,
}

#[derive(Serialize)]
pub struct Task {
    pub id: String,
    pub description: String,
    pub status: String,
    pub result: Option<String>,
    pub created_at: String,
    pub tool: String,
    pub depends_on: Vec<String>,
    pub attempts: u32,
    pub max_attempts: u32,
    pub last_error: Option<String>,
}

#[derive(Serialize)]
pub struct StartSessionResponse {
    pub session_id: String,
    pub goal: String,
    pub status: String,
    pub tasks: Vec<Task>,
    pub progress_percent: u32,
    pub persona_id: String,
    pub persona_title: String,
    pub persona_summary: String,
    pub events: Vec<TimelineEvent>,
    pub checkpoints: Vec<Checkpoint>,
    pub approvals: Vec<Approval>,
    pub agent_roles: Vec<AgentRole>,
    pub replay_cursor: u32,
    pub resume_token: String,
    pub failover_mode: String,
}

#[derive(Serialize)]
pub struct SessionStatus {
    pub session_id: String,
    pub status: String,
    pub tasks: Vec<Task>,
    pub progress_percent: u32,
    pub persona_id: String,
    pub persona_title: String,
    pub persona_summary: String,
    pub events: Vec<TimelineEvent>,
    pub checkpoints: Vec<Checkpoint>,
    pub approvals: Vec<Approval>,
    pub agent_roles: Vec<AgentRole>,
    pub replay_cursor: u32,
    pub resume_token: String,
    pub failover_mode: String,
}

#[derive(Serialize)]
pub struct TimelineEvent {
    pub id: String,
    pub event_type: String,
    pub title: String,
    pub detail: String,
    pub agent_role: String,
    pub level: String,
    pub created_at: String,
    pub task_id: Option<String>,
    pub interruptible: bool,
}

#[derive(Serialize)]
pub struct Checkpoint {
    pub id: String,
    pub label: String,
    pub status: String,
    pub summary: String,
    pub created_at: String,
    pub task_id: Option<String>,
}

#[derive(Serialize)]
pub struct Approval {
    pub id: String,
    pub kind: String,
    pub status: String,
    pub title: String,
    pub summary: String,
    pub created_at: String,
    pub task_id: Option<String>,
    pub resolution_note: Option<String>,
}

#[derive(Serialize)]
pub struct AgentRole {
    pub id: String,
    pub title: String,
    pub responsibility: String,
    pub status: String,
}

fn map_task(task: AutonomousTaskPayload) -> Task {
    Task {
        id: task.id,
        description: task.description,
        status: task.status,
        result: task.result,
        created_at: task.created_at,
        tool: task.tool,
        depends_on: task.depends_on,
        attempts: task.attempts,
        max_attempts: task.max_attempts,
        last_error: task.last_error,
    }
}

fn map_session_status(session_id: String, result: AutonomousSessionPayload) -> SessionStatus {
    SessionStatus {
        session_id,
        status: result.status,
        progress_percent: result.progress_percent,
        tasks: result.tasks.into_iter().map(map_task).collect(),
        persona_id: result.persona_id,
        persona_title: result.persona_title,
        persona_summary: result.persona_summary,
        events: result.events.into_iter().map(map_event).collect(),
        checkpoints: result.checkpoints.into_iter().map(map_checkpoint).collect(),
        approvals: result.approvals.into_iter().map(map_approval).collect(),
        agent_roles: result.agent_roles.into_iter().map(map_agent_role).collect(),
        replay_cursor: result.replay_cursor,
        resume_token: result.resume_token,
        failover_mode: result.failover_mode,
    }
}

fn map_event(event: AutonomousTimelineEventPayload) -> TimelineEvent {
    TimelineEvent {
        id: event.id,
        event_type: event.event_type,
        title: event.title,
        detail: event.detail,
        agent_role: event.agent_role,
        level: event.level,
        created_at: event.created_at,
        task_id: event.task_id,
        interruptible: event.interruptible,
    }
}

fn map_checkpoint(checkpoint: AutonomousCheckpointPayload) -> Checkpoint {
    Checkpoint {
        id: checkpoint.id,
        label: checkpoint.label,
        status: checkpoint.status,
        summary: checkpoint.summary,
        created_at: checkpoint.created_at,
        task_id: checkpoint.task_id,
    }
}

fn map_approval(approval: AutonomousApprovalPayload) -> Approval {
    Approval {
        id: approval.id,
        kind: approval.kind,
        status: approval.status,
        title: approval.title,
        summary: approval.summary,
        created_at: approval.created_at,
        task_id: approval.task_id,
        resolution_note: approval.resolution_note,
    }
}

fn map_agent_role(role: AutonomousAgentRolePayload) -> AgentRole {
    AgentRole {
        id: role.id,
        title: role.title,
        responsibility: role.responsibility,
        status: role.status,
    }
}

async fn fetch_status_payload(session_id: &str) -> Result<SessionStatus, String> {
    let bridge = PythonBridge::new();
    let payload = serde_json::json!({ "session_id": session_id });

    bridge
        .call::<AutonomousSessionPayload>("autonomous/status", &payload)
        .await
        .map(|result| map_session_status(session_id.to_string(), result))
        .map_err(|err| err.to_string())
}

pub async fn start_session(
    Json(req): Json<StartSessionRequest>,
) -> Result<Json<StartSessionResponse>, (StatusCode, Json<serde_json::Value>)> {
    let bridge = PythonBridge::new();
    let session_id = req.session_id.unwrap_or_else(|| Uuid::new_v4().to_string());

    let payload = serde_json::json!({
        "session_id": session_id,
        "goal": req.goal,
        "max_steps": req.max_steps.unwrap_or(10),
        "persona_id": req.persona_id,
    });

    match bridge
        .call::<AutonomousSessionPayload>("autonomous/start", &payload)
        .await
    {
        Ok(result) => {
            let tasks = result.tasks.into_iter().map(map_task).collect();

            Ok(Json(StartSessionResponse {
                session_id,
                goal: req.goal,
                status: result.status,
                tasks,
                progress_percent: result.progress_percent,
                persona_id: result.persona_id,
                persona_title: result.persona_title,
                persona_summary: result.persona_summary,
                events: result.events.into_iter().map(map_event).collect(),
                checkpoints: result.checkpoints.into_iter().map(map_checkpoint).collect(),
                approvals: result.approvals.into_iter().map(map_approval).collect(),
                agent_roles: result.agent_roles.into_iter().map(map_agent_role).collect(),
                replay_cursor: result.replay_cursor,
                resume_token: result.resume_token,
                failover_mode: result.failover_mode,
            }))
        }
        Err(e) => Err((
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(serde_json::json!({ "error": e.to_string() })),
        )),
    }
}

pub async fn get_status(
    Path(session_id): Path<String>,
) -> Result<Json<SessionStatus>, (StatusCode, Json<serde_json::Value>)> {
    match fetch_status_payload(&session_id).await {
        Ok(result) => Ok(Json(result)),
        Err(e) => Err((
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(serde_json::json!({ "error": e.to_string() })),
        )),
    }
}

pub async fn stream_status(
    Path(session_id): Path<String>,
) -> Sse<impl futures_util::Stream<Item = Result<Event, Infallible>>> {
    let stream = stream::unfold(
        AutonomousStreamState {
            session_id,
            active: true,
            is_first: true,
        },
        |state| async move {
            if !state.active {
                return None;
            }

            if !state.is_first {
                tokio::time::sleep(Duration::from_millis(AUTONOMOUS_STREAM_INTERVAL_MS)).await;
            }

            let next_state = match fetch_status_payload(&state.session_id).await {
                Ok(status) => {
                    let is_terminal = matches!(status.status.as_str(), "completed" | "failed");
                    let event = Event::default()
                        .data(serde_json::to_string(&status).unwrap_or_else(|_| "{}".to_string()));
                    Some((
                        Ok(event),
                        AutonomousStreamState {
                            session_id: state.session_id,
                            active: !is_terminal,
                            is_first: false,
                        },
                    ))
                }
                Err(error) => Some((
                    Ok(Event::default().event("maris_error").data(
                        serde_json::json!({
                            "error": error,
                        })
                        .to_string(),
                    )),
                    AutonomousStreamState {
                        session_id: state.session_id,
                        active: false,
                        is_first: false,
                    },
                )),
            };

            next_state
        },
    );

    Sse::new(stream).keep_alive(
        KeepAlive::new()
            .interval(Duration::from_secs(10))
            .text("keepalive"),
    )
}