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import Foundation
/// A named, self-updating unit of the bar.
///
/// Each block runs a shell command on an optional timer,
/// splits its stdout into ``Cell`` values, and publishes
/// them for rendering. Blocks are identified by ``name``
/// so they can be refreshed on demand via Darwin
/// notifications (see ``Notifier``).
@MainActor
final class Block: ObservableObject, Identifiable {
/// Stable identity for SwiftUI diffing.
let id = UUID()
/// Identifier used for manual updates via Darwin
/// notifications.
///
/// Multiple blocks can share the same name.
/// In such case, a single notification will refresh
/// all of them.
let name: String
/// Whether the block is anchored to the left or right
/// side of the bar.
let placement: Config.Block.Placement
/// The shell command to execute for producing the cells.
///
/// Can be an inline expression or a path to an executable
/// script. Inherits the environment of the phbar process.
let command: String
/// Refresh interval in seconds, or `nil` for a one-shot block.
///
/// A one-shot block can still be manually refreshed via
/// a Darwin notification (see ``Notifier``).
let interval: Double?
/// The current cells produced by the last command execution.
///
/// SwiftUI observes this `@Published` property and re-renders
/// the view tree automatically.
@Published var cells: [Cell] = []
private var tick: Task<Void, Never>?
init(name: String, placement: Config.Block.Placement, command: String, interval: Double? = nil) {
self.name = name
self.placement = placement
self.command = command
self.interval = interval
}
/// Initial paint + interval timer.
func start() {
runScript()
startTick()
}
/// Re-run the command and update the cells on the main actor.
func runScript() {
let command = self.command
Task.detached(priority: .utility) { [weak self] in
let lines = Runner.run(command)
await self?.apply(lines)
}
}
/// Stop the interval timer.
func stop() {
tick?.cancel()
}
/// Replace the current cells with freshly parsed lines.
///
/// Each line becomes a ``Cell``. This is always called
/// on the main actor so SwiftUI sees the update immediately.
@MainActor
private func apply(_ lines: [String]) {
self.cells = lines.map { Cell(rawValue: $0) }
}
/// Start the interval timer that re-runs the command periodically.
///
/// Does nothing when ``interval`` is `nil` or ≤ 0.
private func startTick() {
guard let interval, interval > 0 else { return }
tick = Task { [weak self] in
while !Task.isCancelled {
try? await Task.sleep(for: .seconds(interval))
if Task.isCancelled { break }
self?.runScript()
}
}
}
}
extension Config.Block {
@MainActor
var resolved: phbar.Block {
.init(name: name, placement: placement, command: command, interval: interval)
}
}
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