#!/bin/bash

OS_CODENAME=focal
OS_VERSION=20.04


function get_streams()
{
    if [ -e "$streams" ]; then
        return 0
    fi
    streams="$(mktemp)"
    wget -qO "$streams" https://images.maas.io/ephemeral-v3/stable/streams/v1/com.ubuntu.maas:stable:v3:download.json
}

function get_latest_maas_id()
{
    if [ ! -f "$streams" ]; then
        return 1
    fi
    release_version=$(jq -r '.products[]|select(.version=="'"$OS_VERSION"'" and .arch=="amd64" and .kflavor=="generic" and .subarch=="ga-'"$OS_VERSION"'")|.versions|keys|max' \
        "$streams")
}

function get_checksum()
{
    local release_version="$1"
    local filename="$2"
    if [ ! -f "$streams" ]; then
        return 1
    fi
    checksum=$(jq -r '.products[]|select(.version=="'"$OS_VERSION"'" and .arch=="amd64" and .kflavor=="generic" and .subarch=="ga-'"$OS_VERSION"'").versions."'"$release_version"'".items."'"$filename"'".sha256' \
        "$streams")
}

function file_url()
{
    local release_version="$1"
    local filename="$2"
    local baseurl="https://images.maas.io/ephemeral-v3/stable"

    if [ ! -f "$streams" ]; then
        return 1
    fi
    url=$(jq -r '.products[]|select(.version=="'"$OS_VERSION"'" and .arch=="amd64" and .kflavor=="generic" and .subarch=="ga-'"$OS_VERSION"'").versions."'"$release_version"'".items."'"$filename"'".path' \
        "$streams")
    if [ -n "$MAAS_DOWNLOAD_URL" ]; then
        baseurl="$MAAS_DOWNLOAD_URL"
    fi
    url="$baseurl/$url"
}

function verify_only()
{
    local release_version="$1"
    local fname="$2"
    get_checksum "$release_version" "$fname"
    sha256sum=$(sha256sum "$fname"|cut -d\  -f1)
    if [ "$sha256sum" == "$checksum" ]; then
        return 0
    fi
    return 1
}

function download_and_verify()
{
    local release_version="$1"
    local fname="$2"

    file_url "$release_version" "$fname"

    if [ -f "$fname" ]; then
        if verify_only "$release_version" "$fname"; then
            echo "$fname already downloaded, skipping"
            return 0
        fi
        echo "Deleting $fname"
        rm -f "$fname"
    fi
    wget "$url" -O "$fname"
    if verify_only "$release_version" "$fname"; then
        return 0
    fi
    echo "Checksum fail"
    rm -f "$fname"
    return 1
}

function cleanup_temp()
{
    if [ -f "$streams" ]; then
        rm -f "$streams"
    fi
}

# vim: set ft=sh: