use axum::{
    Json, Router,
    extract::{Path, State},
    http::{Method, StatusCode},
    routing::{get, post},
};
use chrono::Utc;
use sea_orm::{ActiveModelTrait, Database, DatabaseConnection, EntityTrait, QueryOrder, Set};
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use tower_http::cors::{Any, CorsLayer};
use uuid::Uuid;

use crate::agent::Agent;
use crate::entities::task::{self, Entity as Task};
use migration::{Migrator, MigratorTrait};

#[derive(Clone)]
pub struct AppState {
    pub db: DatabaseConnection,
    pub zen_api_key: Option<String>,
    pub tavily_api_key: Option<String>,
}

#[derive(Deserialize)]
pub struct CreateTaskRequest {
    pub goal: String,
}

#[derive(Serialize)]
pub struct TaskResponse {
    pub id: Uuid,
    pub goal: String,
    pub status: String,
    pub logs: String,
    pub answer: Option<String>,
    pub created_at: chrono::DateTime<chrono::FixedOffset>,
}

pub async fn start(db_url: &str) -> Result<(), Box<dyn std::error::Error>> {
    let db = Database::connect(db_url).await?;
    Migrator::up(&db, None).await?;

    let zen_api_key = std::env::var("ZEN_API_KEY").ok();
    let tavily_api_key = std::env::var("TAVILY_API_KEY").ok();

    let state = Arc::new(AppState {
        db,
        zen_api_key,
        tavily_api_key,
    });

    let cors = CorsLayer::new()
        .allow_origin(Any)
        .allow_methods([Method::GET, Method::POST])
        .allow_headers(Any);

    let app = Router::new()
        .route("/tasks", post(create_task).get(list_tasks))
        .route("/tasks/:id", get(get_task))
        .layer(cors)
        .with_state(state);

    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await?;
    println!("Server running on http://localhost:3000");
    axum::serve(listener, app).await?;

    Ok(())
}

async fn list_tasks(
    State(state): State<Arc<AppState>>,
) -> Result<Json<Vec<TaskResponse>>, (StatusCode, String)> {
    let tasks = Task::find()
        .order_by_desc(task::Column::CreatedAt)
        .all(&state.db)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    let response = tasks
        .into_iter()
        .map(|t| TaskResponse {
            id: t.id,
            goal: t.goal,
            status: t.status,
            logs: t.logs,
            answer: t.answer,
            created_at: t.created_at,
        })
        .collect();

    Ok(Json(response))
}

async fn create_task(
    State(state): State<Arc<AppState>>,
    Json(payload): Json<CreateTaskRequest>,
) -> Result<Json<TaskResponse>, (StatusCode, String)> {
    let task_id = Uuid::new_v4();

    // Initial save
    let new_task = task::ActiveModel {
        id: Set(task_id),
        goal: Set(payload.goal.clone()),
        status: Set("running".to_string()),
        logs: Set(String::new()),
        answer: Set(None),
        created_at: Set(Utc::now().into()),
    };

    new_task
        .insert(&state.db)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    // Run agent in the background or synchronously for now as requested
    // "it can be created and executed on the agent with an api. the resulting logs after execution will get returned by the endpoint"
    // This implies we wait for it to finish.

    let mut agent = Agent::new(
        state.zen_api_key.clone(),
        state.tavily_api_key.clone(),
        payload.goal.clone(),
    );

    let (logs, answer) = match agent.run().await {
        Ok((logs, answer)) => (logs, answer),
        Err(e) => (format!("Execution failed: {}", e), None),
    };

    // Update with final logs and status
    let mut task: task::ActiveModel = Task::find_by_id(task_id)
        .one(&state.db)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?
        .ok_or((
            StatusCode::NOT_FOUND,
            "Task not found after insert".to_string(),
        ))?
        .into();

    task.logs = Set(logs.clone());
    task.answer = Set(answer.clone());
    task.status = Set("completed".to_string());

    let updated_task = task
        .update(&state.db)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?;

    Ok(Json(TaskResponse {
        id: updated_task.id,
        goal: updated_task.goal,
        status: updated_task.status,
        logs: updated_task.logs,
        answer: updated_task.answer,
        created_at: updated_task.created_at,
    }))
}

async fn get_task(
    Path(id): Path<Uuid>,
    State(state): State<Arc<AppState>>,
) -> Result<Json<TaskResponse>, (StatusCode, String)> {
    let task = Task::find_by_id(id)
        .one(&state.db)
        .await
        .map_err(|e| (StatusCode::INTERNAL_SERVER_ERROR, e.to_string()))?
        .ok_or((StatusCode::NOT_FOUND, "Task not found".to_string()))?;

    Ok(Json(TaskResponse {
        id: task.id,
        goal: task.goal,
        status: task.status,
        logs: task.logs,
        answer: task.answer,
        created_at: task.created_at,
    }))
}