#!/usr/bin/env bash
set -euo pipefail

SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_DIR="$SCRIPT_DIR"
ROOT_DIR="$(cd -- "$SCRIPT_DIR/../.." && pwd)"

# ─── JDK resolution ───
java_major_version() {
    local java_bin="$1"
    local version_line
    version_line="$($java_bin -version 2>&1 | head -n 1)"
    printf '%s\n' "$version_line" | sed -E 's/.*version "([0-9]+)(\.[0-9]+)?.*/\1/'
}

is_supported_java() {
    local java_bin="$1"
    local major
    major="$(java_major_version "$java_bin")"
    [[ "$major" =~ ^[0-9]+$ ]] && [ "$major" -ge 17 ] && [ "$major" -le 21 ]
}

try_set_java_home() {
    local candidate

    if [ -n "${JAVA_HOME:-}" ] && [ -x "$JAVA_HOME/bin/java" ] && is_supported_java "$JAVA_HOME/bin/java"; then
        return 0
    fi

    if command -v /usr/libexec/java_home >/dev/null 2>&1; then
        for candidate in 21 17; do
            if JAVA_HOME_CANDIDATE="$(/usr/libexec/java_home -v "$candidate" 2>/dev/null)" \
                && [ -x "$JAVA_HOME_CANDIDATE/bin/java" ] \
                && is_supported_java "$JAVA_HOME_CANDIDATE/bin/java"; then
                export JAVA_HOME="$JAVA_HOME_CANDIDATE"
                export PATH="$JAVA_HOME/bin:$PATH"
                echo "Using JAVA_HOME=$JAVA_HOME"
                return 0
            fi
        done
    fi

    for candidate in \
        /Library/Java/JavaVirtualMachines/temurin-21.jdk/Contents/Home \
        /Library/Java/JavaVirtualMachines/temurin-17.jdk/Contents/Home \
        /opt/homebrew/opt/openjdk@21/libexec/openjdk.jdk/Contents/Home \
        /opt/homebrew/opt/openjdk@17/libexec/openjdk.jdk/Contents/Home \
        /usr/lib/jvm/java-21-openjdk \
        /usr/lib/jvm/java-17-openjdk \
        /usr/lib/jvm/java-21-openjdk-amd64 \
        /usr/lib/jvm/java-17-openjdk-amd64; do
        if [ -x "$candidate/bin/java" ] && is_supported_java "$candidate/bin/java"; then
            export JAVA_HOME="$candidate"
            export PATH="$JAVA_HOME/bin:$PATH"
            echo "Using JAVA_HOME=$JAVA_HOME"
            return 0
        fi
    done

    return 1
}

if ! try_set_java_home; then
    if ! command -v java >/dev/null 2>&1; then
        cat >&2 <<'EOF'
ERROR: java was not found in PATH.
Please install JDK 17 or JDK 21, then rerun this script.
EOF
        exit 1
    fi
fi

if ! command -v java >/dev/null 2>&1; then
    cat >&2 <<'EOF'
ERROR: java was not found in PATH.
Please install JDK 17 or JDK 21, then rerun this script.
EOF
    exit 1
fi

JAVA_VERSION_OUTPUT="$(java -version 2>&1 | head -n 1)"
JAVA_VERSION="$(java_major_version java)"
if ! [[ "$JAVA_VERSION" =~ ^[0-9]+$ ]]; then
    echo "ERROR: Unable to parse Java version from: $JAVA_VERSION_OUTPUT" >&2
    exit 1
elif [ "$JAVA_VERSION" -lt 17 ] || [ "$JAVA_VERSION" -gt 21 ]; then
    cat >&2 <<EOF
ERROR: This project currently requires JDK 17 or JDK 21.
Found: $JAVA_VERSION_OUTPUT

Kotlin 2.1.0 / this Gradle setup fails with newer Java versions such as 26.0.1.
Install a supported JDK and rerun, for example on macOS:
  brew install --cask temurin@21
  export JAVA_HOME=\$(/usr/libexec/java_home -v 21)

If JDK 17/21 is already installed, set JAVA_HOME before running build.sh.
EOF
    exit 1
fi

# ─── Gradle resolution ───
# 1. Local Gradle at ~/.gradle/gradle-8.5
# 2. Root project gradlew
# 3. System gradle command
find_gradle() {
    # Priority 1: User-provided local Gradle
    if [ -x "$HOME/.gradle/gradle-8.5/bin/gradle" ]; then
        echo "$HOME/.gradle/gradle-8.5/bin/gradle"
        return 0
    fi

    # Priority 2: Root project gradlew
    if [ -x "$ROOT_DIR/gradlew" ]; then
        echo "$ROOT_DIR/gradlew"
        return 0
    fi

    # Priority 3: System gradle
    if command -v gradle >/dev/null 2>&1; then
        echo "gradle"
        return 0
    fi

    return 1
}

if ! GRADLE_CMD="$(find_gradle)"; then
    cat >&2 <<'EOF'
ERROR: Neither local Gradle, root gradlew, nor system gradle was found.

Options:
  1. Place Gradle 8.5 at ~/.gradle/gradle-8.5/
  2. Ensure the project root has gradlew
  3. Install Gradle: brew install gradle
EOF
    exit 1
fi

echo "Using Gradle: $GRADLE_CMD"

cd "$PROJECT_DIR"
"$GRADLE_CMD" --no-configuration-cache build "$@"