#!/bin/sh
set -eu

CONFIG_FILE="${1:-}"
EXPECTED_FILE="${2:-}"

if [ -z "$CONFIG_FILE" ] || [ -z "$EXPECTED_FILE" ]; then
    echo "usage: $0 <resolved-.config> <expected-fragment.config>" >&2
    exit 2
fi

if [ ! -f "$CONFIG_FILE" ]; then
    echo "error: config file not found: $CONFIG_FILE" >&2
    exit 2
fi

if [ ! -f "$EXPECTED_FILE" ]; then
    echo "error: expected config fragment not found: $EXPECTED_FILE" >&2
    exit 2
fi

failed=0

normalize_expected_line() {
    line="$1"

    case "$line" in
        CONFIG_*=y|CONFIG_*=m)
            echo "$line"
            ;;
        CONFIG_*=n)
            sym="${line%%=*}"
            echo "# $sym is not set"
            ;;
        "# CONFIG_"*" is not set")
            echo "$line"
            ;;
        CONFIG_*=*)
            echo "$line"
            ;;
        *)
            return 1
            ;;
    esac
}

is_disabled_expected() {
    expected="$1"

    case "$expected" in
        "# CONFIG_"*" is not set")
            return 0
            ;;
        *)
            return 1
            ;;
    esac
}

symbol_from_expected() {
    expected="$1"

    case "$expected" in
        CONFIG_*=*)
            echo "${expected%%=*}"
            ;;
        "# CONFIG_"*" is not set")
            printf '%s\n' "$expected" | sed 's/^# \(CONFIG_[^ ]*\) is not set$/\1/'
            ;;
        *)
            return 1
            ;;
    esac
}

check_expected_line() {
    expected="$1"
    sym="$(symbol_from_expected "$expected")"

    actual="$(grep -E "^${sym}=|^# ${sym} is not set$" "$CONFIG_FILE" || true)"

    if [ "$actual" = "$expected" ]; then
        return 0
    fi

    # For disabled symbols, absence from the final .config is acceptable.
    # Some Kconfig symbols do not exist on this arch/tree, and missing still means "not enabled".
    if is_disabled_expected "$expected" && [ -z "$actual" ]; then
        return 0
    fi

    echo "kconfig mismatch: $sym" >&2
    echo "  expected: $expected" >&2
    if [ -n "$actual" ]; then
        echo "  actual:   $actual" >&2
    else
        echo "  actual:   <missing>" >&2
    fi

    failed=1
}

while IFS= read -r raw || [ -n "$raw" ]; do
    # Strip leading/trailing whitespace.
    line="$(printf '%s\n' "$raw" | sed 's/^[[:space:]]*//; s/[[:space:]]*$//')"

    # Ignore blanks.
    [ -z "$line" ] && continue

    # Ignore normal comments, but keep '# CONFIG_FOO is not set'.
    case "$line" in
        "# CONFIG_"*" is not set") ;;
        "#"*) continue ;;
    esac

    expected="$(normalize_expected_line "$line" || true)"
    [ -z "${expected:-}" ] && continue

    check_expected_line "$expected"
done < "$EXPECTED_FILE"

if [ "$failed" -ne 0 ]; then
    echo "error: resolved kernel config does not satisfy $EXPECTED_FILE" >&2
    exit 1
fi

echo "kernel config satisfies $EXPECTED_FILE"