#!/usr/bin/env bash

# Open ExampleProject.uproject in Unreal Editor on Linux.

set -Eeuo pipefail

SCRIPT_DIR="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)"
PROJECT_PATH="$SCRIPT_DIR/ExampleProject.uproject"

show_error() {
    local message="$1"

    if command -v zenity >/dev/null 2>&1 && [[ -n "${DISPLAY:-}${WAYLAND_DISPLAY:-}" ]]; then
        zenity --error --title="ExampleProject - Unreal Editor" --width=520 --text="$message"
    else
        printf 'ERROR: %s\n' "$message" >&2
        if [[ -t 0 ]]; then
            read -r -p "Press Enter to close..." _
        fi
    fi
}

if [[ ! -f "$PROJECT_PATH" ]]; then
    show_error "Project file was not found:\n$PROJECT_PATH"
    exit 1
fi

find_editor() {
    local candidate

    # An explicit path takes priority. It may point to the UE root or the binary.
    if [[ -n "${UE_ROOT:-}" ]]; then
        for candidate in \
            "$UE_ROOT" \
            "$UE_ROOT/Engine/Binaries/Linux/UnrealEditor"; do
            if [[ -x "$candidate" && ! -d "$candidate" ]]; then
                printf '%s\n' "$candidate"
                return 0
            fi
        done
    fi

    if command -v UnrealEditor >/dev/null 2>&1; then
        command -v UnrealEditor
        return 0
    fi

    for candidate in \
        "$HOME/Unreal/UE_5.7/Engine/Binaries/Linux/UnrealEditor" \
        "$HOME/UnrealEngine/Engine/Binaries/Linux/UnrealEditor" \
        /opt/UnrealEngine/Engine/Binaries/Linux/UnrealEditor \
        /mnt/UnrealEngine/Engine/Binaries/Linux/UnrealEditor; do
        if [[ -x "$candidate" ]]; then
            printf '%s\n' "$candidate"
            return 0
        fi
    done

    return 1
}

if ! UNREAL_EDITOR="$(find_editor)"; then
    show_error "Unreal Editor was not found.\n\nSet UE_ROOT to the Unreal Engine directory, for example:\nexport UE_ROOT=/home/vysyr/Unreal/UE_5.7"
    exit 1
fi

printf 'Opening project:\n  %s\nwith:\n  %s\n' "$PROJECT_PATH" "$UNREAL_EDITOR"
SDL_VIDEODRIVER=x11 exec "$UNREAL_EDITOR" "$PROJECT_PATH" "$@"