#!/usr/bin/env bash

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_DIR="$SCRIPT_DIR"
TMP_DIR="$PROJECT_DIR/.tmp-android-build"
SDK_DIR="$PROJECT_DIR/android-sdk"
JDK_DIR="$PROJECT_DIR/jdk"
GRADLE_USER_HOME_DIR="$PROJECT_DIR/.gradle-user-home"
STATE_FILE="$PROJECT_DIR/.android-project-tooling.state"
LEGACY_STATE_FILE="$PROJECT_DIR/.setup-build-environment.state"
COMMIT_SUMMARY_FILE="$PROJECT_DIR/commit-summary.txt"
CMDLINE_TOOLS_DIR="$SDK_DIR/cmdline-tools"
CMDLINE_TOOLS_LATEST_DIR="$CMDLINE_TOOLS_DIR/latest"
WRAPPER_JAR_PATH="$PROJECT_DIR/gradle/wrapper/gradle-wrapper.jar"
LOCAL_PROPERTIES_PATH="$PROJECT_DIR/local.properties"
HOST_GIT_BINARY="$PROJECT_DIR/build/host-git/libgit.so"
GIT_SRC_DIR="$TMP_DIR/git-src"
HOST_GIT_DIR="$PROJECT_DIR/build/host-git"
HOST_GIT_STAMP="$HOST_GIT_DIR/.source-fingerprint"
ANDROID_JNI_DIR="$PROJECT_DIR/app/src/main/jniLibs"
ANDROID_ASSET_MANPAGE_DIR="$PROJECT_DIR/app/src/main/assets/manpages"
ANDROID_API=24

ANDROID_CMDLINE_TOOLS_URL="https://dl.google.com/android/repository/commandlinetools-linux-11076708_latest.zip"
GRADLE_DIST_URL="https://services.gradle.org/distributions/gradle-8.7-bin.zip"
JDK_DIST_URL="https://api.adoptium.net/v3/binary/latest/17/ga/linux/x64/jdk/hotspot/normal/eclipse"
ANDROID_NDK_PACKAGE="ndk;27.2.12479018"
ANDROID_CMAKE_PACKAGE="cmake;3.22.1"
ANDROID_NDK_DIR="$SDK_DIR/ndk/27.2.12479018"
ANDROID_CMAKE_DIR="$SDK_DIR/cmake/3.22.1"
ANDROID_TOOLBIN="$ANDROID_NDK_DIR/toolchains/llvm/prebuilt/linux-x86_64/bin"
STATE_TTL_SECONDS=86400

log() {
  printf '\n[%s] %s\n' "tooling" "$1"
}

require_tool() {
  if ! command -v "$1" >/dev/null 2>&1; then
    echo "Missing required tool: $1" >&2
    exit 1
  fi
}

ensure_dir() {
  mkdir -p "$1"
}

current_epoch() {
  date +%s
}

have_recent_success_marker() {
  local marker_file="$STATE_FILE"
  if [ ! -f "$marker_file" ] && [ -f "$LEGACY_STATE_FILE" ]; then
    marker_file="$LEGACY_STATE_FILE"
  fi

  if [ ! -f "$marker_file" ]; then
    return 1
  fi

  local recorded_epoch
  recorded_epoch="$(cat "$marker_file" 2>/dev/null || true)"
  if ! printf '%s' "$recorded_epoch" | grep -Eq '^[0-9]+$'; then
    return 1
  fi

  local now
  now="$(current_epoch)"
  [ $((now - recorded_epoch)) -lt "$STATE_TTL_SECONDS" ]
}

mark_successful_check() {
  current_epoch > "$STATE_FILE"
}

required_sdk_packages_present() {
  [ -d "$SDK_DIR/platform-tools" ] \
    && [ -d "$SDK_DIR/platforms/android-35" ] \
    && [ -d "$SDK_DIR/build-tools/35.0.0" ] \
    && [ -d "$ANDROID_NDK_DIR" ] \
    && [ -d "$ANDROID_CMAKE_DIR" ]
}

auto_commit_if_needed() {
  if ! command -v git >/dev/null 2>&1; then
    log "Git is not available; skipping automatic commit"
    return
  fi

  if ! git -C "$PROJECT_DIR" rev-parse --is-inside-work-tree >/dev/null 2>&1; then
    log "Project is not inside a git work tree; skipping automatic commit"
    return
  fi

  git -C "$PROJECT_DIR" add -A

  # Defense in depth: never allow signing material or local signing config to be
  # included in the automatic commit, even if a file was force-added manually.
  git -C "$PROJECT_DIR" reset -q HEAD -- \
    keystore.properties \
    commit-summary.txt \
    '*.keystore' \
    '*.jks' 2>/dev/null || true

  if git -C "$PROJECT_DIR" diff --cached --quiet; then
    log "No source changes to commit after successful build"
    return
  fi

  log "Creating git commit for the latest successful build"
  if [ -s "$COMMIT_SUMMARY_FILE" ] && grep -q '[^[:space:]]' "$COMMIT_SUMMARY_FILE"; then
    git -C "$PROJECT_DIR" commit -F "$COMMIT_SUMMARY_FILE"
  else
    git -C "$PROJECT_DIR" commit -m "Misc Changes"
  fi
  : > "$COMMIT_SUMMARY_FILE"
  git push
}

download_if_missing() {
  local url="$1"
  local output="$2"
  if [ -f "$output" ]; then
    log "Using existing download: ${output#$PROJECT_DIR/}"
  else
    log "Downloading $(basename "$output")"
    curl -L "$url" -o "$output"
  fi
}

ensure_cmdline_tools() {
  if [ -x "$CMDLINE_TOOLS_LATEST_DIR/bin/sdkmanager" ]; then
    log "Android command-line tools already present"
    return
  fi

  ensure_dir "$CMDLINE_TOOLS_DIR"
  ensure_dir "$TMP_DIR"
  local zip_path="$TMP_DIR/commandlinetools.zip"
  download_if_missing "$ANDROID_CMDLINE_TOOLS_URL" "$zip_path"

  log "Extracting Android command-line tools"
  rm -rf "$CMDLINE_TOOLS_LATEST_DIR"
  unzip -q -o "$zip_path" -d "$CMDLINE_TOOLS_DIR"
  if [ -d "$CMDLINE_TOOLS_DIR/cmdline-tools" ]; then
    mv "$CMDLINE_TOOLS_DIR/cmdline-tools" "$CMDLINE_TOOLS_LATEST_DIR"
  fi
}

ensure_wrapper_jar() {
  if [ -f "$WRAPPER_JAR_PATH" ]; then
    log "Gradle wrapper jar already present"
    return
  fi

  ensure_dir "$TMP_DIR"
  local zip_path="$TMP_DIR/gradle-8.7-bin.zip"
  local gradle_extract_dir="$TMP_DIR/gradle-8.7"
  local plugin_wrapper_jar="$gradle_extract_dir/lib/plugins/gradle-wrapper-8.7.jar"
  download_if_missing "$GRADLE_DIST_URL" "$zip_path"

  log "Extracting Gradle wrapper jar"
  rm -rf "$gradle_extract_dir"
  unzip -q -o "$zip_path" -d "$TMP_DIR"
  python - <<PY
import zipfile
src = r'''$plugin_wrapper_jar'''
dst = r'''$WRAPPER_JAR_PATH'''
with zipfile.ZipFile(src) as zf:
    data = zf.read('gradle-wrapper.jar')
with open(dst, 'wb') as f:
    f.write(data)
PY
}

ensure_jdk17() {
  if [ -x "$JDK_DIR/bin/java" ]; then
    log "Project-local JDK already present"
    return
  fi

  ensure_dir "$TMP_DIR"
  local archive_path="$TMP_DIR/jdk17.tar.gz"
  local extract_dir="$TMP_DIR/jdk17-extract"
  rm -f "$archive_path"
  download_if_missing "$JDK_DIST_URL" "$archive_path"

  log "Extracting project-local JDK"
  rm -rf "$extract_dir" "$JDK_DIR"
  mkdir -p "$extract_dir"
  if ! file "$archive_path" | grep -qiE 'gzip compressed|tar archive'; then
    echo "Downloaded JDK archive is not a valid tar.gz: $archive_path" >&2
    exit 1
  fi
  tar -xzf "$archive_path" -C "$extract_dir"
  local extracted_root
  extracted_root="$(find "$extract_dir" -mindepth 1 -maxdepth 1 -type d | head -n 1)"
  if [ -z "$extracted_root" ]; then
    echo "Unable to locate extracted JDK directory" >&2
    exit 1
  fi
  mv "$extracted_root" "$JDK_DIR"
}

setup_java_env() {
  export JAVA_HOME="$JDK_DIR"
  export PATH="$JAVA_HOME/bin:$PATH"
}

write_local_properties() {
  log "Writing local.properties"
  cat > "$LOCAL_PROPERTIES_PATH" <<EOF_INNER
sdk.dir=$SDK_DIR
EOF_INNER
}

bump_android_version() {
  local gradle_file="$PROJECT_DIR/app/build.gradle.kts"
  if [ ! -f "$gradle_file" ]; then
    log "No app/build.gradle.kts found; skipping version bump"
    return
  fi

  log "Bumping Android app version before build"
  python - <<PY
from pathlib import Path
import re

path = Path(r'''$gradle_file''')
text = path.read_text()

version_code_match = re.search(r'versionCode\s*=\s*(\d+)', text)
version_name_match = re.search(r'versionName\s*=\s*"(\d+)\.(\d+)\.(\d+)"', text)

if not version_code_match or not version_name_match:
    raise SystemExit('Could not find versionCode/versionName in app/build.gradle.kts')

current_code = int(version_code_match.group(1))
major, minor, patch = map(int, version_name_match.groups())

new_code = current_code + 1
new_name = f'{major}.{minor}.{patch + 1}'

text = re.sub(r'versionCode\s*=\s*\d+', f'versionCode = {new_code}', text, count=1)
text = re.sub(r'versionName\s*=\s*"\d+\.\d+\.\d+"', f'versionName = "{new_name}"', text, count=1)

path.write_text(text)
print(f'Updated versionCode to {new_code} and versionName to {new_name}')
PY
}

setup_env() {
  setup_java_env
  export ANDROID_HOME="$SDK_DIR"
  export ANDROID_SDK_ROOT="$SDK_DIR"
  export GRADLE_USER_HOME="$GRADLE_USER_HOME_DIR"
}

require_path() {
  if [ ! -e "$1" ]; then
    echo "Required path not found: $1" >&2
    exit 1
  fi
}

ensure_git_source() {
  mkdir -p "$TMP_DIR"
  if [ ! -d "$GIT_SRC_DIR/.git" ]; then
    log "Cloning Git source"
    git clone --depth 1 https://github.com/git/git.git "$GIT_SRC_DIR"
  else
    log "Using existing Git source checkout"
  fi
}

common_git_make_args() {
  printf '%s\n' \
    NO_OPENSSL=YesPlease \
    NO_CURL=YesPlease \
    NO_EXPAT=YesPlease \
    NO_GETTEXT=YesPlease \
    NO_TCLTK=YesPlease \
    NO_PERL=YesPlease \
    NO_PYTHON=YesPlease \
    NO_INSTALL_HARDLINKS=YesPlease \
    NO_ICONV=YesPlease \
    NO_REGEX=NeedsStartEnd \
    HAVE_ALLOCA_H=YesPlease \
    HAVE_PATHS_H=YesPlease \
    HAVE_CLOCK_GETTIME=YesPlease \
    HAVE_CLOCK_MONOTONIC=YesPlease \
    HAVE_GETDELIM=YesPlease \
    FREAD_READS_DIRECTORIES=UnfortunatelyYes \
    CSPRNG_METHOD=
}

bundle_git_manpages() {
  require_path "$GIT_SRC_DIR/Documentation"

  log "Bundling full Git manpage sources"
  mkdir -p "$ANDROID_ASSET_MANPAGE_DIR"
  find "$ANDROID_ASSET_MANPAGE_DIR" -type f -name '*.txt' -delete
  while IFS= read -r manpage_source; do
    local manpage_name
    manpage_name="$(basename "$manpage_source")"
    cp "$manpage_source" "$ANDROID_ASSET_MANPAGE_DIR/${manpage_name%.*}.txt"
  done < <(find "$GIT_SRC_DIR/Documentation" -maxdepth 1 -type f \( -name 'git*.txt' -o -name 'git*.adoc' -o -name 'gitignore.txt' -o -name 'gitignore.adoc' \))
}

git_source_fingerprint() {
  ensure_git_source

  local head
  local tracked_changes
  head="$(git -C "$GIT_SRC_DIR" rev-parse HEAD)"
  tracked_changes="$(git -C "$GIT_SRC_DIR" diff --binary HEAD -- | git hash-object --stdin)"
  printf '%s:%s\n' "$head" "$tracked_changes"
}

target_is_current() {
  local output="$1"
  local stamp="$2"
  local fingerprint="$3"

  [ -x "$output" ] \
    && [ -f "$stamp" ] \
    && [ "$(cat "$stamp" 2>/dev/null || true)" = "$fingerprint" ]
}

mark_target_current() {
  local stamp="$1"
  local fingerprint="$2"

  mkdir -p "$(dirname "$stamp")"
  printf '%s\n' "$fingerprint" > "$stamp"
}

build_host_git() {
  ensure_git_source
  bundle_git_manpages

  local fingerprint
  fingerprint="$(git_source_fingerprint):host"
  if target_is_current "$HOST_GIT_BINARY" "$HOST_GIT_STAMP" "$fingerprint"; then
    log "Host Git binary is current; skipping rebuild"
    "$HOST_GIT_BINARY" --version
    return
  fi

  log "Building Git for development host"
  cd "$GIT_SRC_DIR"
  make clean >/dev/null 2>&1 || true
  mapfile -t make_args < <(common_git_make_args)
  make -j"$(nproc 2>/dev/null || printf 4)" "${make_args[@]}" git

  mkdir -p "$HOST_GIT_DIR"
  cp git "$HOST_GIT_BINARY"
  chmod 755 "$HOST_GIT_BINARY"
  mark_target_current "$HOST_GIT_STAMP" "$fingerprint"

  log "Host test Git binary: $HOST_GIT_BINARY"
  "$HOST_GIT_BINARY" --version
  cd "$PROJECT_DIR"
}

build_android_git_for_abi() {
  local abi="$1"
  local cc="$2"
  local output_dir="$ANDROID_JNI_DIR/$abi"
  local output_binary="$output_dir/libgit.so"
  local stamp="$output_dir/.source-fingerprint"
  local fingerprint="$3:android:$abi:$cc:$ANDROID_API"

  require_path "$ANDROID_TOOLBIN/$cc"

  if target_is_current "$output_binary" "$stamp" "$fingerprint"; then
    log "Android $abi Git binary is current; skipping rebuild"
    ls -lh "$output_binary"
    return
  fi

  log "Building Git for Android $abi"
  cd "$GIT_SRC_DIR"
  make clean >/dev/null 2>&1 || true
  mapfile -t make_args < <(common_git_make_args)
  make -j"$(nproc 2>/dev/null || printf 4)" \
    uname_S=Android \
    uname_O=Android \
    NO_PTHREADS=YesPlease \
    NO_LIBGEN_H=YesPlease \
    HAVE_DEV_TTY=YesPlease \
    CC="$cc" \
    AR=llvm-ar \
    RANLIB=llvm-ranlib \
    STRIP=llvm-strip \
    "${make_args[@]}" \
    git

  log "Validating Android $abi binary"
  file git
  readelf -h git | sed -n '1,12p'

  mkdir -p "$output_dir"
  llvm-strip -s git -o "$output_binary"
  chmod 755 "$output_binary"
  mark_target_current "$stamp" "$fingerprint"
  ls -lh "$output_binary"
  cd "$PROJECT_DIR"
}

build_android_git() {
  ensure_git_source
  bundle_git_manpages
  require_path "$ANDROID_NDK_DIR"
  export PATH="$ANDROID_TOOLBIN:$PATH"

  local fingerprint
  fingerprint="$(git_source_fingerprint)"

  build_android_git_for_abi "arm64-v8a" "aarch64-linux-android${ANDROID_API}-clang" "$fingerprint"
  build_android_git_for_abi "armeabi-v7a" "armv7a-linux-androideabi${ANDROID_API}-clang" "$fingerprint"
  build_android_git_for_abi "x86" "i686-linux-android${ANDROID_API}-clang" "$fingerprint"
  build_android_git_for_abi "x86_64" "x86_64-linux-android${ANDROID_API}-clang" "$fingerprint"
}

build_all_git_targets() {
  build_host_git
  build_android_git
}

ensure_sdk_packages() {
  setup_env

  if required_sdk_packages_present; then
    if have_recent_success_marker; then
      log "Skipping SDK verification/install because all components were confirmed within the last 24 hours"
    else
      log "Required SDK packages are already installed locally"
      mark_successful_check
    fi
    return
  fi

  if have_recent_success_marker; then
    log "Skipping SDK verification/install because all components were confirmed within the last 24 hours"
    return
  fi

  log "Accepting Android SDK licenses"
  set +e
  set +o pipefail
  yes | "$CMDLINE_TOOLS_LATEST_DIR/bin/sdkmanager" --sdk_root="$SDK_DIR" --licenses >/dev/null
  local license_status=$?
  set -o pipefail
  set -e
  if [ "$license_status" -ne 0 ]; then
    echo "sdkmanager --licenses failed with exit code $license_status" >&2
    exit "$license_status"
  fi

  log "Installing required Android SDK packages"
  "$CMDLINE_TOOLS_LATEST_DIR/bin/sdkmanager" --sdk_root="$SDK_DIR" \
    "platform-tools" \
    "platforms;android-35" \
    "build-tools;35.0.0" \
    "$ANDROID_NDK_PACKAGE" \
    "$ANDROID_CMAKE_PACKAGE"

  mark_successful_check
}

maybe_run_operation() {
  local mode="${1:-}"
  local gradle_task=""
  local artifact_label=""
  local artifact_source=""
  local artifact_target=""
  local should_bump_version="false"
  local should_auto_commit="false"
  local should_compile_host_git="false"
  local should_bundle_manpages="false"

  case "$mode" in
    --build)
      gradle_task="assembleDebug"
      artifact_label="debug APK"
      artifact_source="$PROJECT_DIR/app/build/outputs/apk/debug/app-debug.apk"
      artifact_target="$PROJECT_DIR/app/build/outputs/apk/debug/githug-android-debug.apk"
      should_bump_version="true"
      should_auto_commit="true"
      should_bundle_manpages="true"
      ;;
    --build-release-aab)
      gradle_task="bundleRelease"
      artifact_label="release AAB"
      artifact_source="$PROJECT_DIR/app/build/outputs/bundle/release/app-release.aab"
      artifact_target="$PROJECT_DIR/app/build/outputs/bundle/release/githug-android-release.aab"
      should_bump_version="true"
      should_auto_commit="true"
      should_bundle_manpages="true"
      ;;
    --test)
      gradle_task="testDebugUnitTest"
      artifact_label="debug unit tests"
      should_compile_host_git="true"
      ;;
    --compile-git)
      build_all_git_targets
      return
      ;;
    *)
      return
      ;;
  esac

  setup_env
  if [ "$should_bump_version" = "true" ]; then
    bump_android_version
  fi
  if [ "$should_compile_host_git" = "true" ]; then
    build_host_git
    export GITHUG_TEST_GIT_BINARY="$HOST_GIT_BINARY"
  fi
  if [ "$should_bundle_manpages" = "true" ]; then
    ensure_git_source
    bundle_git_manpages
  fi

  log "Running $artifact_label with --no-daemon"
  "$PROJECT_DIR/gradlew" --no-daemon "$gradle_task"

  if [ -n "$artifact_source" ] && [ -f "$artifact_source" ]; then
    log "Renaming $(basename "$artifact_source") to $(basename "$artifact_target")"
    mv -f "$artifact_source" "$artifact_target"
  elif [ -n "$artifact_source" ]; then
    log "Expected build output not found for rename: ${artifact_source#$PROJECT_DIR/}"
  fi

  if [ "$should_auto_commit" = "true" ]; then
    auto_commit_if_needed
  fi

  log "Stopping any Gradle daemons just in case"
  "$PROJECT_DIR/gradlew" --stop >/dev/null 2>&1 || true
}

print_usage() {
  cat <<EOF_USAGE
Usage: bash ./AndroidProjectTooling.sh [--build | --build-release-aab | --test | --compile-git]

  --build      Set up the environment and build the debug APK
  --build-release-aab  Set up the environment and build a release Android App Bundle (AAB)
  --test       Set up the environment, compile host Git, and run the debug JVM unit tests with it
  --compile-git  Compile Git for the development host and all Android target ABIs
EOF_USAGE
}

validate_args() {
  case "${1:-}" in
    ""|--build|--build-release-aab|--test|--compile-git)
      ;;
    *)
      echo "Unknown argument: $1" >&2
      print_usage >&2
      exit 1
      ;;
  esac
}

main() {
  validate_args "${1:-}"

  require_tool curl
  require_tool unzip
  require_tool tar
  require_tool git
  require_tool perl
  require_tool make
  require_tool clang
  require_tool pkg-config
  require_tool readelf
  require_tool file

  ensure_dir "$TMP_DIR"
  ensure_dir "$SDK_DIR"
  ensure_dir "$GRADLE_USER_HOME_DIR"

  ensure_jdk17
  ensure_cmdline_tools
  ensure_wrapper_jar
  write_local_properties
  ensure_sdk_packages
  maybe_run_operation "${1:-}"

  log "Environment ready"
  log "Project dir: $PROJECT_DIR"
  log "JDK dir: $JDK_DIR"
  log "SDK dir: $SDK_DIR"
  log "NDK dir: $ANDROID_NDK_DIR"
  log "CMake dir: $ANDROID_CMAKE_DIR"
  log "To compile Git for host and Android ABIs: bash ./AndroidProjectTooling.sh --compile-git"
  log "To build without a background Gradle daemon: ./gradlew --no-daemon assembleDebug"
  log "To set up and build in one step: bash ./AndroidProjectTooling.sh --build"
  log "To set up and build a release AAB in one step: bash ./AndroidProjectTooling.sh --build-release-aab"
  log "To set up and run unit tests with compiled host Git: bash ./AndroidProjectTooling.sh --test"
}

main "$@"