xa11y-core 0.6.2

use std::sync::Arc;
use std::time::{Duration, Instant};

use crate::element::{Element, ElementData};
use crate::error::{Error, Result};
use crate::event_provider::Subscription;
use crate::locator::Locator;
use crate::provider::Provider;
use crate::selector::Selector;

/// Polling interval shared by all `*_with_timeout` lookups.
const LOOKUP_POLL_INTERVAL: Duration = Duration::from_millis(100);

/// Run `attempt` repeatedly until it succeeds or `timeout` elapses, treating
/// `SelectorNotMatched` as a "not yet" signal. All other errors short-circuit.
///
/// `Duration::ZERO` performs exactly one attempt — identical to a non-polling
/// call. On timeout, returns the last `SelectorNotMatched` error.
fn poll_lookup<F>(timeout: Duration, mut attempt: F) -> Result<App>
where
    F: FnMut() -> Result<App>,
{
    let start = Instant::now();
    loop {
        match attempt() {
            Ok(app) => return Ok(app),
            Err(e @ Error::SelectorNotMatched { .. }) => {
                if start.elapsed() >= timeout {
                    return Err(e);
                }
            }
            Err(e) => return Err(e),
        }
        std::thread::sleep(LOOKUP_POLL_INTERVAL);
    }
}

/// A running application, the entry point for accessibility queries.
///
/// `App` is **not** an [`Element`] — it represents the application as a whole
/// and provides a [`locator`](App::locator) to search its accessibility tree.
pub struct App {
    /// Application name.
    pub name: String,
    /// Process ID.
    pub pid: Option<u32>,
    /// The underlying element data for this application.
    pub data: ElementData,
    provider: Arc<dyn Provider>,
}

impl App {
    /// Find an application by exact name, using an explicit provider.
    ///
    /// Prefer `App::by_name` from the `xa11y` crate which uses the global
    /// singleton provider. Use this variant when you need to supply a specific
    /// provider (e.g. a mock in unit tests).
    ///
    /// Returns [`Error::PermissionDenied`] if the platform provider was created
    /// without required permissions.
    pub fn by_name_with(provider: Arc<dyn Provider>, name: &str) -> Result<Self> {
        // Try application role first (Linux/macOS), then window role (Windows —
        // UIA has no Application node at the top level).
        let app_selector = format!(r#"application[name="{}"]"#, name);
        if let Ok(results) =
            provider.find_elements(None, &Selector::parse(&app_selector)?, Some(1), Some(0))
        {
            if let Some(data) = results.into_iter().next() {
                return Ok(Self::from_data(provider, data));
            }
        }
        let win_selector = format!(r#"window[name="{}"]"#, name);
        let results =
            provider.find_elements(None, &Selector::parse(&win_selector)?, Some(1), Some(0))?;
        let data = results
            .into_iter()
            .next()
            .ok_or(Error::SelectorNotMatched {
                selector: app_selector,
            })?;
        Ok(Self::from_data(provider, data))
    }

    /// Like [`by_name_with`](Self::by_name_with), but polls until the app
    /// appears or `timeout` elapses.
    ///
    /// Useful when the app may not yet be registered with the platform
    /// accessibility API (e.g. just-launched test apps). Only
    /// [`Error::SelectorNotMatched`] triggers a retry; other errors
    /// (permission, parse, platform) short-circuit immediately.
    ///
    /// `Duration::ZERO` is equivalent to [`by_name_with`](Self::by_name_with).
    pub fn by_name_with_timeout(
        provider: Arc<dyn Provider>,
        name: &str,
        timeout: Duration,
    ) -> Result<Self> {
        poll_lookup(timeout, || Self::by_name_with(Arc::clone(&provider), name))
    }

    /// Find an application by process ID, using an explicit provider.
    ///
    /// Prefer `App::by_pid` from the `xa11y` crate which uses the global
    /// singleton provider.
    pub fn by_pid_with(provider: Arc<dyn Provider>, pid: u32) -> Result<Self> {
        // Try application role first, then window role (Windows fallback).
        for role in ["application", "window"] {
            let selector = Selector::parse(role)?;
            if let Ok(results) = provider.find_elements(None, &selector, None, Some(0)) {
                if let Some(data) = results.into_iter().find(|d| d.pid == Some(pid)) {
                    return Ok(Self::from_data(provider, data));
                }
            }
        }
        Err(Error::SelectorNotMatched {
            selector: format!("application with pid={}", pid),
        })
    }

    /// Like [`by_pid_with`](Self::by_pid_with), but polls until the app
    /// appears or `timeout` elapses. See [`by_name_with_timeout`](Self::by_name_with_timeout)
    /// for the retry semantics.
    pub fn by_pid_with_timeout(
        provider: Arc<dyn Provider>,
        pid: u32,
        timeout: Duration,
    ) -> Result<Self> {
        poll_lookup(timeout, || Self::by_pid_with(Arc::clone(&provider), pid))
    }

    /// List all running applications, using an explicit provider.
    ///
    /// Prefer `App::list` from the `xa11y` crate which uses the global
    /// singleton provider.
    pub fn list_with(provider: Arc<dyn Provider>) -> Result<Vec<Self>> {
        // Collect application role elements (Linux/macOS), then add window
        // role elements (Windows fallback) for any not already found by PID.
        let mut apps = Vec::new();
        let mut seen_pids = std::collections::HashSet::new();

        for role in ["application", "window"] {
            let selector = Selector::parse(role)?;
            if let Ok(results) = provider.find_elements(None, &selector, None, Some(0)) {
                for d in results {
                    if let Some(pid) = d.pid {
                        if !seen_pids.insert(pid) {
                            continue; // already found via application role
                        }
                    }
                    apps.push(Self::from_data(Arc::clone(&provider), d));
                }
            }
        }

        Ok(apps)
    }

    fn from_data(provider: Arc<dyn Provider>, data: ElementData) -> Self {
        let name = data.name.clone().unwrap_or_default();
        let pid = data.pid;
        Self {
            name,
            pid,
            data,
            provider,
        }
    }

    /// Create a [`Locator`] to search this application's accessibility tree.
    pub fn locator(&self, selector: &str) -> Locator {
        Locator::new(
            Arc::clone(&self.provider),
            Some(self.data.clone()),
            selector,
        )
    }

    /// Subscribe to accessibility events from this application.
    pub fn subscribe(&self) -> Result<Subscription> {
        self.provider.subscribe(&self.data)
    }

    /// Get direct children (typically windows) of this application.
    pub fn children(&self) -> Result<Vec<Element>> {
        let children = self.provider.get_children(Some(&self.data))?;
        Ok(children
            .into_iter()
            .map(|d| Element::new(d, Arc::clone(&self.provider)))
            .collect())
    }

    /// Get the provider reference.
    pub fn provider(&self) -> &Arc<dyn Provider> {
        &self.provider
    }
}

impl std::fmt::Display for App {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "application \"{}\"", self.name)
    }
}

impl std::fmt::Debug for App {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("App")
            .field("name", &self.name)
            .field("pid", &self.pid)
            .finish()
    }
}