http.ab

// Amber-HTTP2 © Karim Vergnes <me@thesola.io>
// Licensed under GNU GPLv2
// Improved HTTP downloader with range support

import { is_command } from "std/env"

/// Downloads a file (or portion of a file) from a given URL to standard output
///
/// ### Arguments
/// - `url`: The URL to download from
/// - `start`: The start offset within the file
/// - `length`: The length of data to download
pub fun file_stream(url: Text, start: Int = 0, length: Int = -1): Text?
{
    let end = ""
    let wget_post = "cat"

    if length >= 0 {
        end = "{length}"
        wget_post = "head -c {length}"
    }

    if {
    is_command("curl"):
        return $ curl -L -r {start}-{end} "{url}" $?
    is_command("wget"):
        return $ wget "{url}" --start-pos {start} -O - | {wget_post} $?
    else:
        fail 1
    }
}

/// Drop-in replacement for Amber's `file_download()` stdlib builtin.
///
/// It downloads a file (or portion of a file) from a given URL to a specified
/// path.
///
/// ### Arguments
/// - `url`: The URL to download from
/// - `path`: The local path to write to
/// - `start`: The start offset within the file
/// - `length`: The length of data to download
pub fun file_download(url: Text, path: Text, start: Int = 0, length: Int = -1): Null?
{
    let end = ""
    let wget_post = "cat"

    if length >= 0 {
        end = "{length}"
        wget_post = "head -c {length}"
    }

    if {
    is_command("curl"):
        $ curl -L -o "{path}" -r {start}-{end} "{url}" $?
    is_command("wget"):
        $ wget "{url}" --start-pos {start} -O - | {wget_post} > {path} $?
    else:
        fail 1
    }

    return
}