use std::sync::Arc;

use async_trait::async_trait;
use codex_protocol::models::ShellToolCallParams;
use codex_protocol::user_input::UserInput;
use tokio::sync::Mutex;
use tokio_util::sync::CancellationToken;
use tracing::error;
use uuid::Uuid;

use crate::codex::TurnContext;
use crate::protocol::EventMsg;
use crate::protocol::TaskStartedEvent;
use crate::state::TaskKind;
use crate::tools::context::ToolPayload;
use crate::tools::parallel::ToolCallRuntime;
use crate::tools::router::ToolCall;
use crate::tools::router::ToolRouter;
use crate::turn_diff_tracker::TurnDiffTracker;

use super::SessionTask;
use super::SessionTaskContext;

const USER_SHELL_TOOL_NAME: &str = "local_shell";

#[derive(Clone)]
pub(crate) struct UserShellCommandTask {
    command: String,
}

impl UserShellCommandTask {
    pub(crate) fn new(command: String) -> Self {
        Self { command }
    }
}

#[async_trait]
impl SessionTask for UserShellCommandTask {
    fn kind(&self) -> TaskKind {
        TaskKind::Regular
    }

    async fn run(
        self: Arc<Self>,
        session: Arc<SessionTaskContext>,
        turn_context: Arc<TurnContext>,
        _input: Vec<UserInput>,
        cancellation_token: CancellationToken,
    ) -> Option<String> {
        let event = EventMsg::TaskStarted(TaskStartedEvent {
            model_context_window: turn_context.client.get_model_context_window(),
        });
        let session = session.clone_session();
        session.send_event(turn_context.as_ref(), event).await;

        // Execute the user's script under their default shell when known; this
        // allows commands that use shell features (pipes, &&, redirects, etc.).
        // We do not source rc files or otherwise reformat the script.
        let shell_invocation = match session.user_shell() {
            crate::shell::Shell::Zsh(zsh) => vec![
                zsh.shell_path.clone(),
                "-lc".to_string(),
                self.command.clone(),
            ],
            crate::shell::Shell::Bash(bash) => vec![
                bash.shell_path.clone(),
                "-lc".to_string(),
                self.command.clone(),
            ],
            crate::shell::Shell::PowerShell(ps) => vec![
                ps.exe.clone(),
                "-NoProfile".to_string(),
                "-Command".to_string(),
                self.command.clone(),
            ],
            crate::shell::Shell::Unknown => {
                shlex::split(&self.command).unwrap_or_else(|| vec![self.command.clone()])
            }
        };

        let params = ShellToolCallParams {
            command: shell_invocation,
            workdir: None,
            timeout_ms: None,
            with_escalated_permissions: None,
            justification: None,
        };

        let tool_call = ToolCall {
            tool_name: USER_SHELL_TOOL_NAME.to_string(),
            call_id: Uuid::new_v4().to_string(),
            payload: ToolPayload::LocalShell { params },
        };

        let router = Arc::new(ToolRouter::from_config(&turn_context.tools_config, None));
        let tracker = Arc::new(Mutex::new(TurnDiffTracker::new()));
        let runtime = ToolCallRuntime::new(
            Arc::clone(&router),
            Arc::clone(&session),
            Arc::clone(&turn_context),
            Arc::clone(&tracker),
        );

        if let Err(err) = runtime
            .handle_tool_call(tool_call, cancellation_token)
            .await
        {
            error!("user shell command failed: {err:?}");
        }
        None
    }
}