#!/usr/bin/env bash
# Picks a JDK that Gradle can actually run on and exports JAVA_HOME.
#
# Ubuntu moved default-java to 25, which the Gradle version in this repo
# refuses with a bare "IllegalArgumentException: 25.0.4" — an unhelpful
# message for a build that worked yesterday. Sourced by the scripts under
# tests/ and tools/; harmless when JAVA_HOME is already a supported JDK.
#
#   . tests/helpers/jdk.sh
set -u

_jdk_major() {
    "$1/bin/java" -version 2>&1 | head -1 |
        sed -E 's/.*version "([0-9]+).*/\1/'
}

_jdk_pick() {
    local candidate major
    if [ -n "${JAVA_HOME:-}" ] && [ -x "${JAVA_HOME}/bin/java" ]; then
        major="$(_jdk_major "$JAVA_HOME")"
        if [ "$major" -ge 17 ] 2>/dev/null && [ "$major" -le 21 ] 2>/dev/null; then
            return 0
        fi
    fi
    for candidate in \
        /usr/lib/jvm/java-21-openjdk-amd64 \
        /usr/lib/jvm/java-17-openjdk-amd64 \
        "$HOME"/jdk-21* \
        "$HOME"/jdk-17*; do
        [ -x "$candidate/bin/java" ] || continue
        export JAVA_HOME="$candidate"
        return 0
    done
    echo "no JDK 17-21 found; Gradle cannot run on $(java -version 2>&1 | head -1)" >&2
    return 1
}

_jdk_pick