import Foundation
import TOML

extension PHLayout {
	/// Load the specified layouts from the resolved config directory (see `PHPaths`).
	/// If any of theme doesn't exist or fails to parse, the execution is interrupted.
	static func load(_ layouts: Set<String>) throws -> [String: PHLayout] {
		var dictionary = [String: PHLayout]()

		for layout in layouts {
			dictionary.updateValue(try load(layout), forKey: layout)
		}

		return dictionary
	}

	/// Load a layout from the resolved config directory (see `PHPaths`).
	/// If the file doesn't exist or fails to parse, the execution is interrupted.
	static func load(_ layout: String) throws -> PHLayout {
		let url = PHPaths.layoutsDirectory.appending(path: "\(layout).toml")

		if FileManager.default.fileExists(atPath: url.relativePath) {
			return try load(from: url)
		} else {
			let layout = url.lastPathComponent
			throw PHBar.Error(
				"""
				Layout file not found.
				       Make sure to have a file named `\(layout)` inside the
				       directory: `\(PHPaths.layoutsDirectory.relativePath)`

				Tip: If you've never used phbar before, run `phbar generate config`
				     to automatically generate the required configuration files.
				"""
			)
		}
	}

	/// Load a layout from the file at URL.
	/// If the file doesn't exist or fails to parse, the execution is interrupted.
	static private func load(from url: URL) throws -> PHLayout {
		do {
			let data = try Data(contentsOf: url)
			guard let contents = String(data: data, encoding: .utf8) else {
				throw PHBar.Error("content is not UTF8 encoded.")
			}
			let decoder = TOMLDecoder()
			let layoutFile = contents.expanded(from: ProcessInfo.processInfo.environment)
			return try decoder.decode(PHLayout.self, from: layoutFile)
		} catch {
			let layout = url.lastPathComponent
			throw PHBar.Error("Layout file `\(layout)` not readable", underlyingError: error)
		}
	}
}