Swift code to fetch one or more English Wikipedia articles as plain text without most of the interface text

fetch-wikipedia-text.swift

import Foundation

/// Executes two commands in a pipeline.
///
/// - Parameters:
///   - firstCommand: The first command to execute. This should be a valid
///                   command that you would type into the terminal.
///   - secondCommand: The second command to execute. This should be a valid
///                    command that you would type into the terminal.
///   - args: The command line arguments passed to the script.
/// - Returns: The output of the second command, which is the result of the piped commands.
func executePipedCommands(firstCommand: String, secondCommand: String, args: [String]) -> String {
    // Create two Process objects, one for each command.
    let firstTask = Process()
    let secondTask = Process()

    // Create a Pipe object. This will be used as the input for the second command.
    let pipe = Pipe()

    // Set the standard output of the first command to be the pipe.
    firstTask.standardOutput = pipe

    // Set the arguments for the first command. The "-c" flag tells it to
    // execute the command passed in as a string.
    firstTask.arguments = ["-c", firstCommand]

    // Set the launch path to the zsh shell. This is where the command will be executed.
    firstTask.launchPath = "/bin/zsh"

    // Set the standard input for the second command to be the read end of the pipe.
    secondTask.standardInput = pipe

    // Set the arguments for the second command. The "-c" flag tells it to
    // execute the command passed in as a string.
    secondTask.arguments = ["-c", secondCommand]

    // Set the launch path to the zsh shell. This is where the command will be executed.
    secondTask.launchPath = "/bin/zsh"

    // Create a new Pipe object for the second command's standard output. This
    // will be used to capture the output of the second command.
    let outputPipe = Pipe()

    // Set the standard output of the second command to be the new pipe.
    secondTask.standardOutput = outputPipe

    // Launch the first command.
    firstTask.launch()

    // Launch the second command.
    secondTask.launch()

    // Read the data from the new pipe that was created for the second command's standard output.
    let data = outputPipe.fileHandleForReading.readDataToEndOfFile()

    // Convert the data to a string using UTF8 encoding.
    guard let output = String(data: data, encoding: .utf8) else {
        // If the data could not be converted to a string, return an empty string.
        return ""
    }

    // Return the output of the second command.
    return output
}

// we'll need to convert spaces in the title to underscores
let urls = CommandLine
    .arguments[1...]
    .map { "https://en.wikipedia.org/w/index.php?title=\($0.replacingOccurrences(of: " ", with: "_"))&action=render" }
print(urls)
let pipedCommandOutput = executePipedCommands(
    firstCommand: """
    curl -Z \
        -vs \
        \(urls
            .map { "\"\($0.addingPercentEncoding(withAllowedCharacters: .urlQueryAllowed)!)\"" }
            .joined(separator: " "))
    """,
    secondCommand: """
    textutil \
        -format html \
        -convert txt \
        -stdin \
        -stdout \
        -inputencoding UTF-8
    """,
    args: urls)

print(pipedCommandOutput)