#!/usr/bin/env bash

set -euo pipefail

fail() {
  echo "::error::$*" >&2
  exit 1
}

require_command() {
  command -v "$1" >/dev/null 2>&1 || fail "Required command '$1' was not found on the runner."
}

require_environment() {
  [[ -n "${!1:-}" ]] || fail "Required environment variable '$1' is not set."
}

validate_common_inputs() {
  [[ "$GODOT_VERSION" =~ ^4(\.[0-9]+){1,2}(-[0-9A-Za-z][0-9A-Za-z._-]*)?$ ]] || fail "godot-version must be a Godot 4 release tag such as 4.7.2-stable."
  [[ "$GODOT_HOST_OS" == "linux" ]] || fail "host-os must be 'linux' when this action runs on Linux."
  [[ "$GODOT_DOTNET" == "true" || "$GODOT_DOTNET" == "false" ]] || fail "dotnet must be 'true' or 'false'."
  [[ "$GODOT_EXPORT_MODE" == "release" || "$GODOT_EXPORT_MODE" == "debug" ]] || fail "export-mode must be 'release' or 'debug'."
  [[ -n "$GODOT_EXPORT_PRESET" ]] || fail "export-preset must not be empty."
  [[ -n "$GODOT_EXPORT_FILE_NAME" && "$GODOT_EXPORT_FILE_NAME" != "." && "$GODOT_EXPORT_FILE_NAME" != ".." ]] || fail "export-file-name must be a filename."
  [[ "$GODOT_EXPORT_FILE_NAME" != */* && "$GODOT_EXPORT_FILE_NAME" != *\\* ]] || fail "export-file-name must not contain a path separator."
}

actual_architecture() {
  case "$(uname -m)" in
    x86_64|amd64) echo x86_64 ;;
    i?86) echo x86_32 ;;
    aarch64|arm64) echo arm64 ;;
    armv7l|armv6l) echo arm32 ;;
    *) fail "Unsupported Linux runner architecture: $(uname -m)." ;;
  esac
}

download_and_verify() {
  local asset="$1"
  local destination="$2"
  local sum_file="$3"
  local expected
  local actual

  curl --fail --location --retry 3 --silent --show-error "$BASE_URL/$asset" --output "$destination"
  expected="$(awk -v asset="$asset" '$2 == asset || $2 == "*" asset { print $1; exit }' "$sum_file")"
  [[ -n "$expected" ]] || fail "Release checksum manifest does not contain $asset."
  actual="$(sha512sum "$destination" | awk '{ print $1 }')"
  [[ "$actual" == "$expected" ]] || fail "SHA-512 verification failed for $asset."
}

find_editor() {
  find "$EDITOR_DIR" -maxdepth 3 -type f -name 'Godot*' -print -quit
}

install_godot() {
  local sum_file="$CACHE_DIR/SHA512-SUMS.txt"
  local editor_archive="$CACHE_DIR/$EDITOR_ASSET"
  local templates_archive="$CACHE_DIR/$TEMPLATES_ASSET"

  rm -rf "$CACHE_DIR"
  mkdir -p "$EDITOR_DIR" "$TEMPLATE_DIR"
  curl --fail --location --retry 3 --silent --show-error "$BASE_URL/SHA512-SUMS.txt" --output "$sum_file"
  download_and_verify "$EDITOR_ASSET" "$editor_archive" "$sum_file"
  download_and_verify "$TEMPLATES_ASSET" "$templates_archive" "$sum_file"
  unzip -q "$editor_archive" -d "$EDITOR_DIR"
  unzip -q "$templates_archive" -d "$TEMPLATE_DIR"
  EDITOR_EXECUTABLE="$(find_editor)"
  [[ -n "$EDITOR_EXECUTABLE" ]] || fail "The Godot editor archive did not contain an executable."
  [[ -f "$TEMPLATE_DIR/version.txt" ]] || fail "The export-template archive did not contain version.txt."
  printf 'release=%s\neditor=%s\ntemplates=%s\n' "$GODOT_VERSION" "$EDITOR_ASSET" "$TEMPLATES_ASSET" > "$CACHE_DIR/.complete"
}

require_environment GODOT_VERSION
require_environment GODOT_HOST_OS
require_environment GODOT_HOST_ARCH
require_environment GODOT_DOTNET
require_environment GODOT_PROJECT_PATH
require_environment GODOT_EXPORT_PRESET
require_environment GODOT_EXPORT_MODE
require_environment GODOT_EXPORT_FILE_NAME
require_environment GODOT_ACTION_ROOT
require_environment GITHUB_WORKSPACE
require_environment GITHUB_OUTPUT

require_command curl
require_command unzip
require_command sha512sum
validate_common_inputs

[[ "$(uname -s)" == "Linux" ]] || fail "The Linux script was selected on a non-Linux runner."
[[ "$GODOT_HOST_ARCH" == "x86_32" || "$GODOT_HOST_ARCH" == "x86_64" || "$GODOT_HOST_ARCH" == "arm32" || "$GODOT_HOST_ARCH" == "arm64" ]] || fail "Unsupported Linux host-arch '$GODOT_HOST_ARCH'."
[[ "$GODOT_HOST_ARCH" == "$(actual_architecture)" ]] || fail "host-arch '$GODOT_HOST_ARCH' does not match this Linux runner ($(actual_architecture))."

[[ "$GODOT_PROJECT_PATH" != /* && "$GODOT_PROJECT_PATH" != \\* ]] || fail "project-path must be relative to the checked-out workspace."
WORKSPACE_DIR="$(cd "$GITHUB_WORKSPACE" && pwd -P)"
PROJECT_DIR="$(cd "$WORKSPACE_DIR/$GODOT_PROJECT_PATH" 2>/dev/null && pwd -P)" || fail "project-path '$GODOT_PROJECT_PATH' does not exist."
case "$PROJECT_DIR/" in
  "$WORKSPACE_DIR/"*) ;;
  *) fail "project-path must remain inside the checked-out workspace." ;;
esac
[[ -f "$PROJECT_DIR/project.godot" ]] || fail "No project.godot was found in project-path '$GODOT_PROJECT_PATH'."
[[ -f "$PROJECT_DIR/export_presets.cfg" ]] || fail "No export_presets.cfg was found in project-path '$GODOT_PROJECT_PATH'."
grep -Fq "name=\"$GODOT_EXPORT_PRESET\"" "$PROJECT_DIR/export_presets.cfg" || fail "Export preset '$GODOT_EXPORT_PRESET' was not found in export_presets.cfg."

if [[ "$GODOT_DOTNET" == "true" ]]; then
  EDITION=dotnet
  EDITOR_ASSET="Godot_v${GODOT_VERSION}_mono_linux_${GODOT_HOST_ARCH}.zip"
  TEMPLATES_ASSET="Godot_v${GODOT_VERSION}_mono_export_templates.tpz"
else
  EDITION=standard
  EDITOR_ASSET="Godot_v${GODOT_VERSION}_linux.${GODOT_HOST_ARCH}.zip"
  TEMPLATES_ASSET="Godot_v${GODOT_VERSION}_export_templates.tpz"
fi

BASE_URL="https://github.com/godotengine/godot-builds/releases/download/$GODOT_VERSION"
TEMPLATE_VERSION="${GODOT_VERSION//-/.}"
CACHE_DIR="$GODOT_ACTION_ROOT/cache/$GODOT_VERSION/$EDITION/linux-$GODOT_HOST_ARCH"
EDITOR_DIR="$CACHE_DIR/editor"
USER_DATA_DIR="$CACHE_DIR/user-data"
TEMPLATE_DIR="$USER_DATA_DIR/godot/export_templates/$TEMPLATE_VERSION"

if [[ -f "$CACHE_DIR/.complete" && -f "$TEMPLATE_DIR/version.txt" ]]; then
  EDITOR_EXECUTABLE="$(find_editor || true)"
else
  EDITOR_EXECUTABLE=""
fi
if [[ -z "$EDITOR_EXECUTABLE" ]]; then
  install_godot
fi

chmod +x "$EDITOR_EXECUTABLE"
SAFE_PRESET="$(printf '%s' "$GODOT_EXPORT_PRESET" | tr -cs '[:alnum:]_.-' '_')"
BUILD_DIR="$GODOT_ACTION_ROOT/builds/${SAFE_PRESET:-export}-$GODOT_EXPORT_MODE-$$"
OUTPUT_FILE="$BUILD_DIR/$GODOT_EXPORT_FILE_NAME"
mkdir -p "$BUILD_DIR"

export XDG_DATA_HOME="$USER_DATA_DIR"
export XDG_CONFIG_HOME="$CACHE_DIR/config"
"$EDITOR_EXECUTABLE" --headless --path "$PROJECT_DIR" "--export-$GODOT_EXPORT_MODE" "$GODOT_EXPORT_PRESET" "$OUTPUT_FILE"
[[ -e "$OUTPUT_FILE" ]] || fail "Godot completed without creating the expected output '$GODOT_EXPORT_FILE_NAME'."

printf 'build-directory=%s\n' "$BUILD_DIR" >> "$GITHUB_OUTPUT"