#!/bin/sh

set -eu

fail() {
    printf 'Genesis report: %s\n' "$*" >&2
    exit 1
}

file_size() {
    wc -c <"$1" | tr -d '[:space:]'
}

read_value() {
    value_file=$1
    value_name=$2

    while IFS='=' read -r name value; do
        if [ "$name" = "$value_name" ]; then
            printf '%s\n' "$value"
            return 0
        fi
    done <"$value_file"
    return 1
}

require_uint() {
    value_name=$1
    value=$2

    case "$value" in
        ''|*[!0-9]*) fail "invalid $value_name value: $value" ;;
    esac
}

runtime_file=
baseline_file=
while [ "$#" -gt 0 ]; do
    case "$1" in
        --runtime)
            [ "$#" -ge 2 ] || fail 'missing --runtime value'
            runtime_file=$2
            shift 2
            ;;
        --baseline)
            [ "$#" -ge 2 ] || fail 'missing --baseline value'
            baseline_file=$2
            shift 2
            ;;
        --) shift; break ;;
        -*) fail "unknown option: $1" ;;
        *) break ;;
    esac
done

[ "$#" -eq 2 ] \
    || fail 'usage: report [--runtime FILE] [--baseline FILE] ARCHITECTURE IMAGE_DIRECTORY'

architecture=$1
image_dir=${2%/}
case "$architecture" in
    aarch64|armv7hf|riscv64|s390x|x86|x86_64|ppc64|ppc64le) ;;
    *) fail "unsupported architecture: $architecture" ;;
esac

[ -d "$image_dir" ] && [ ! -L "$image_dir" ] \
    || fail "invalid image directory: $image_dir"
kernel=$image_dir/kernel
initramfs=$image_dir/initramfs.cpio.gz
[ -f "$kernel" ] && [ ! -L "$kernel" ] \
    || fail "missing artifact: $kernel"
[ -f "$initramfs" ] && [ ! -L "$initramfs" ] \
    || fail "missing artifact: $initramfs"

gzip -t -- "$initramfs" || fail "invalid initramfs: $initramfs"
kernel_bytes=$(file_size "$kernel")
compressed_bytes=$(file_size "$initramfs")
unpacked_bytes=$(gzip -dc -- "$initramfs" | wc -c | tr -d '[:space:]')

printf 'SCHEMA=1\n'
printf 'ARCHITECTURE=%s\n' "$architecture"
printf 'KERNEL_BYTES=%s\n' "$kernel_bytes"
printf 'COMPRESSED_INITRAMFS_BYTES=%s\n' "$compressed_bytes"
printf 'UNPACKED_INITRAMFS_BYTES=%s\n' "$unpacked_bytes"

if [ -n "$runtime_file" ]; then
    [ -f "$runtime_file" ] && [ ! -L "$runtime_file" ] \
        || fail "invalid runtime report: $runtime_file"
    boot_ready_seconds=$(read_value "$runtime_file" BOOT_READY_SECONDS) \
        || fail 'runtime report lacks BOOT_READY_SECONDS'
    capture_uptime_seconds=$(read_value "$runtime_file" CAPTURE_UPTIME_SECONDS) \
        || fail 'runtime report lacks CAPTURE_UPTIME_SECONDS'
    memory_total_kib=$(read_value "$runtime_file" MEMORY_TOTAL_KIB) \
        || fail 'runtime report lacks MEMORY_TOTAL_KIB'
    memory_available_kib=$(read_value "$runtime_file" MEMORY_AVAILABLE_KIB) \
        || fail 'runtime report lacks MEMORY_AVAILABLE_KIB'
    memory_used_kib=$(read_value "$runtime_file" MEMORY_USED_KIB) \
        || fail 'runtime report lacks MEMORY_USED_KIB'

    require_uint BOOT_READY_SECONDS "$boot_ready_seconds"
    require_uint CAPTURE_UPTIME_SECONDS "$capture_uptime_seconds"
    require_uint MEMORY_TOTAL_KIB "$memory_total_kib"
    require_uint MEMORY_AVAILABLE_KIB "$memory_available_kib"
    require_uint MEMORY_USED_KIB "$memory_used_kib"

    printf 'BOOT_READY_SECONDS=%s\n' "$boot_ready_seconds"
    printf 'CAPTURE_UPTIME_SECONDS=%s\n' "$capture_uptime_seconds"
    printf 'MEMORY_TOTAL_KIB=%s\n' "$memory_total_kib"
    printf 'MEMORY_AVAILABLE_KIB=%s\n' "$memory_available_kib"
    printf 'MEMORY_USED_KIB=%s\n' "$memory_used_kib"
fi

[ -n "$baseline_file" ] || exit 0
[ -f "$baseline_file" ] && [ ! -L "$baseline_file" ] \
    || fail "invalid baseline report: $baseline_file"
baseline_architecture=$(read_value "$baseline_file" ARCHITECTURE) \
    || fail 'baseline report lacks ARCHITECTURE'
[ "$baseline_architecture" = "$architecture" ] \
    || fail "baseline architecture is $baseline_architecture, expected $architecture"

compare_metric() {
    metric_name=$1
    current_value=$2
    baseline_value=$(read_value "$baseline_file" "$metric_name") \
        || fail "baseline report lacks $metric_name"
    require_uint "$metric_name" "$baseline_value"
    printf '%s_DELTA=%s\n' "$metric_name" "$((current_value - baseline_value))"
}

compare_metric KERNEL_BYTES "$kernel_bytes"
compare_metric COMPRESSED_INITRAMFS_BYTES "$compressed_bytes"
compare_metric UNPACKED_INITRAMFS_BYTES "$unpacked_bytes"
if [ -n "$runtime_file" ]; then
    compare_metric BOOT_READY_SECONDS "$boot_ready_seconds"
    compare_metric MEMORY_USED_KIB "$memory_used_kib"
fi