// SPDX-FileCopyrightText: 2025 The Project Pterodactyl Developers
//
// SPDX-License-Identifier: MPL-2.0

import Foundation
import llbuild2fx

extension Keys.SourceTree {
	/// Narrows a source tree to just the transitive dependencies of a given unit
	struct NarrowToUnit: BuildKey {
		let sourceTreeId: LLBDataID
		let unitName: UnitName

		typealias ValueType = LLBDataID

		static let versionDependencies: [any FXVersioning.Type] = [GetDependencies.self, GetUnitMap.self]

		func computeValue(_ ctx: BuildContext<Self>) async throws -> ValueType {
			let dependencies = try await ctx.request(GetDependencies(sourceTreeId: sourceTreeId, unitName: unitName))
			let unitMap = try await ctx.request(GetUnitMap(sourceTreeId: sourceTreeId))

			var sourceTree = try await LLBCASFileTree.load(id: sourceTreeId, in: ctx)
			for (unitName, unitInfo) in unitMap.units {
				if !dependencies.contains(unitName) {
					sourceTree = try await sourceTree.remove(path: unitInfo.path, in: ctx)
				}
			}

			return sourceTree.id
		}
	}
}