#!/usr/bin/env bash

set -Eeuo pipefail

# ============================================================
# Linux Parental Control Installer
# ============================================================

APP_NAME="Parental Control"
SERVICE_NAME="parental-control.service"
DESKTOP_ID="parental-control.desktop"

INSTALL_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
VENV_DIR="$INSTALL_DIR/.venv"
PYTHON="$VENV_DIR/bin/python"

SERVICE_FILE="/etc/systemd/system/$SERVICE_NAME"
DESKTOP_FILE="/usr/share/applications/$DESKTOP_ID"

POLKIT_ACTION="org.parentalcontrol.modify"
POLKIT_SOURCE="$INSTALL_DIR/$POLKIT_ACTION.policy"
POLKIT_DEST="/etc/polkit-1/actions/$POLKIT_ACTION.policy"

SOCKET_PATH="/run/parental-control.sock"

INSTALL_USER=""
INSTALL_GROUP=""
PACKAGE_MANAGER=""
POLKIT_AGENT=""

# ============================================================
# Output helpers
# ============================================================

info() {
    echo
    echo "==> $1"
}

success() {
    echo "    $1"
}

warning() {
    echo "    WARNING: $1"
}

error() {
    echo
    echo "ERROR: $1"
    echo
    exit 1
}

# ============================================================
# Error handling
# ============================================================

on_error() {
    echo
    echo "Installation failed."
    echo "Line: $1"
    echo "Command: $2"
    echo
}

trap 'on_error "$LINENO" "$BASH_COMMAND"' ERR

# ============================================================
# Root check
# ============================================================

if [ "$EUID" -ne 0 ]; then
    error "Run this installer with sudo:

    sudo ./install.sh"
fi

# ============================================================
# Find original user
# ============================================================

if [ -n "${SUDO_USER:-}" ] && [ "$SUDO_USER" != "root" ]; then
    INSTALL_USER="$SUDO_USER"
else
    INSTALL_USER="$(stat -c '%U' "$INSTALL_DIR")"
fi

if ! id "$INSTALL_USER" >/dev/null 2>&1; then
    error "Could not determine the normal installation user."
fi

INSTALL_GROUP="$(id -gn "$INSTALL_USER")"

INSTALL_USER_HOME="$(getent passwd "$INSTALL_USER" | cut -d: -f6)"

if [ -z "$INSTALL_USER_HOME" ] || [ ! -d "$INSTALL_USER_HOME" ]; then
    error "Could not determine the home directory of $INSTALL_USER."
fi

# ============================================================
# Header
# ============================================================

clear 2>/dev/null || true

echo
echo "=========================================="
echo " Linux Parental Control Installer"
echo "=========================================="
echo
echo "Application:"
echo "  $APP_NAME"
echo
echo "Installation directory:"
echo "  $INSTALL_DIR"
echo
echo "Installation user:"
echo "  $INSTALL_USER"
echo

# ============================================================
# Check project files
# ============================================================

info "Checking project files"

REQUIRED_FILES=(
    "requirements.txt"
    "parental-control.service"
    "$POLKIT_ACTION.policy"

    "app/__init__.py"
    "app/main.py"
    "app/config.py"
    "app/enforcement.py"
    "app/scheduler.py"
    "app/users.py"
    "app/ipc.py"

    "desktop/__init__.py"
    "desktop/main.py"
    "desktop/client.py"

    "config/users.yaml"
    "config/state.json"
)

for file in "${REQUIRED_FILES[@]}"; do
    if [ ! -f "$INSTALL_DIR/$file" ]; then
        error "Required file not found: $file"
    fi
done

success "All required project files found."

# ============================================================
# Detect operating system
# ============================================================

info "Detecting operating system"

if [ ! -f /etc/os-release ]; then
    error "/etc/os-release was not found."
fi

# shellcheck disable=SC1091
source /etc/os-release

OS_ID="${ID:-unknown}"
OS_NAME="${NAME:-Unknown Linux}"
OS_VERSION="${VERSION_ID:-unknown}"

echo "    Distribution: $OS_NAME"
echo "    Version:      $OS_VERSION"

# ============================================================
# Check systemd
# ============================================================

info "Checking systemd"

if ! command -v systemctl >/dev/null 2>&1; then
    error "systemd is required for this version of the application.

This installer does not support non-systemd distributions."
fi

if [ ! -d /run/systemd/system ]; then
    error "systemd is installed but is not currently running."
fi

if ! command -v loginctl >/dev/null 2>&1; then
    error "loginctl was not found.

The application requires systemd-logind."
fi

success "systemd and loginctl detected."

# ============================================================
# Detect package manager
# ============================================================

info "Detecting package manager"

if command -v pacman >/dev/null 2>&1; then
    PACKAGE_MANAGER="pacman"

elif command -v apt-get >/dev/null 2>&1; then
    PACKAGE_MANAGER="apt"

elif command -v dnf >/dev/null 2>&1; then
    PACKAGE_MANAGER="dnf"

elif command -v zypper >/dev/null 2>&1; then
    PACKAGE_MANAGER="zypper"

else
    error "No supported package manager was detected.

Supported package managers:
  pacman
  apt
  dnf
  zypper

You can install the required dependencies manually,
then run the installer again."
fi

success "Package manager: $PACKAGE_MANAGER"

# ============================================================
# Install system dependencies
# ============================================================

info "Installing system dependencies"

case "$PACKAGE_MANAGER" in

    pacman)
        pacman -S --needed --noconfirm \
            python \
            python-pip \
            polkit \
            polkit-gnome \
            desktop-file-utils \
            systemd
        ;;

    apt)
        export DEBIAN_FRONTEND=noninteractive

        apt-get update

        apt-get install -y \
            python3 \
            python3-pip \
            python3-venv \
            polkitd \
            policykit-1 \
            policykit-1-gnome \
            desktop-file-utils \
            systemd
        ;;

    dnf)
        dnf install -y \
            python3 \
            python3-pip \
            python3-virtualenv \
            polkit \
            polkit-gnome \
            desktop-file-utils \
            systemd
        ;;

    zypper)
        zypper --non-interactive install \
            python3 \
            python3-pip \
            python3-virtualenv \
            polkit \
            polkit-gnome \
            desktop-file-utils \
            systemd
        ;;

esac

success "System dependencies installed."

# ============================================================
# Find Python
# ============================================================

info "Checking Python"

SYSTEM_PYTHON=""

for candidate in python3 python; do
    if command -v "$candidate" >/dev/null 2>&1; then
        SYSTEM_PYTHON="$(command -v "$candidate")"
        break
    fi
done

if [ -z "$SYSTEM_PYTHON" ]; then
    error "Python 3 could not be found."
fi

PYTHON_MAJOR="$(
    "$SYSTEM_PYTHON" -c \
    'import sys; print(sys.version_info.major)'
)"

PYTHON_MINOR="$(
    "$SYSTEM_PYTHON" -c \
    'import sys; print(sys.version_info.minor)'
)"

PYTHON_VERSION="$(
    "$SYSTEM_PYTHON" -c \
    'import sys; print(".".join(map(str, sys.version_info[:3])))'
)"

if [ "$PYTHON_MAJOR" -ne 3 ]; then
    error "Python 3 is required.

Found Python $PYTHON_VERSION."
fi

if [ "$PYTHON_MINOR" -lt 9 ]; then
    error "Python $PYTHON_VERSION is too old.

Python 3.9 or newer is required."
fi

echo "    Python: $SYSTEM_PYTHON"
echo "    Version: $PYTHON_VERSION"

success "Python version is supported."

# ============================================================
# Create virtual environment
# ============================================================

info "Preparing Python virtual environment"

if [ -x "$PYTHON" ]; then
    success "Existing virtual environment found."

else
    if [ -d "$VENV_DIR" ]; then
        warning "Existing virtual environment is incomplete."
        warning "Removing it."

        rm -rf "$VENV_DIR"
    fi

    echo "    Creating virtual environment..."

    if ! "$SYSTEM_PYTHON" -m venv "$VENV_DIR"; then
        error "Could not create the Python virtual environment.

Install your distribution's Python venv package."
    fi

    success "Virtual environment created."
fi

# ============================================================
# Install Python dependencies
# ============================================================

info "Installing Python dependencies"

"$PYTHON" -m pip install \
    --disable-pip-version-check \
    --upgrade pip

"$PYTHON" -m pip install \
    --disable-pip-version-check \
    -r "$INSTALL_DIR/requirements.txt"

success "Python dependencies installed."

# ============================================================
# Validate Python source
# ============================================================

info "Checking Python source files"

"$PYTHON" -m compileall \
    -q \
    "$INSTALL_DIR/app" \
    "$INSTALL_DIR/desktop"

success "Python source validation passed."

# ============================================================
# Validate configuration
# ============================================================

info "Checking application configuration"

if [ ! -f "$INSTALL_DIR/config/users.yaml" ]; then
    error "users.yaml was not found."
fi

if [ ! -f "$INSTALL_DIR/config/state.json" ]; then
    error "state.json was not found."
fi

success "Configuration files found."

# ============================================================
# Install systemd service
# ============================================================

info "Installing systemd service"

SERVICE_TEMP="$(mktemp)"

sed \
    "s|%INSTALL_DIR%|$INSTALL_DIR|g" \
    "$INSTALL_DIR/parental-control.service" \
    > "$SERVICE_TEMP"

if ! grep -q '^Environment=PYTHONDONTWRITEBYTECODE=' "$SERVICE_TEMP"; then
    sed -i \
        '/^\[Service\]/a Environment=PYTHONDONTWRITEBYTECODE=1' \
        "$SERVICE_TEMP"
fi

install \
    -o root \
    -g root \
    -m 644 \
    "$SERVICE_TEMP" \
    "$SERVICE_FILE"

rm -f "$SERVICE_TEMP"

success "Systemd service installed."

# ============================================================
# Install polkit policy
# ============================================================

info "Installing polkit policy"

if [ ! -f "$POLKIT_SOURCE" ]; then
    error "Polkit policy file was not found:

$POLKIT_SOURCE"
fi

mkdir -p /etc/polkit-1/actions

install \
    -o root \
    -g root \
    -m 644 \
    "$POLKIT_SOURCE" \
    "$POLKIT_DEST"

success "Polkit policy installed."

# ============================================================
# Detect polkit authentication agent
# ============================================================

info "Detecting polkit authentication agent"

POLKIT_AGENT=""

POLKIT_AGENT_CANDIDATES=(
    "/usr/lib/polkit-gnome/polkit-gnome-authentication-agent-1"
    "/usr/libexec/polkit-gnome-authentication-agent-1"
    "/usr/lib/polkit-1-gnome/polkit-gnome-authentication-agent-1"
)

for candidate in "${POLKIT_AGENT_CANDIDATES[@]}"; do
    if [ -x "$candidate" ]; then
        POLKIT_AGENT="$candidate"
        break
    fi
done

if [ -n "$POLKIT_AGENT" ]; then
    success "Authentication agent found:"
    success "$POLKIT_AGENT"
else
    warning "A polkit authentication agent was not found."
    warning "GUI administrative actions may require manual configuration."
fi

# ============================================================
# Configure Sway polkit authentication agent
# ============================================================

configure_sway_polkit() {
    local user_home="$1"
    local sway_config="$user_home/.config/sway/config"
    local marker="parental-control-polkit-agent"

    if [ -z "$POLKIT_AGENT" ]; then
        return 0
    fi

    if [ ! -f "$sway_config" ]; then
        warning "Sway configuration not found:"
        warning "$sway_config"
        return 0
    fi

    if grep -Fq "$marker" "$sway_config"; then
        success "Sway polkit authentication agent is already configured."
        return 0
    fi

    cp -a \
        "$sway_config" \
        "$sway_config.parental-control-backup"

    cat >> "$sway_config" <<EOF

# $marker
exec_always --no-startup-id $POLKIT_AGENT
EOF

    chown \
        "$INSTALL_USER:$INSTALL_GROUP" \
        "$sway_config"

    success "Sway polkit authentication agent configured."
}

if [ -n "$POLKIT_AGENT" ]; then
    configure_sway_polkit "$INSTALL_USER_HOME"
fi

# ============================================================
# Install desktop launcher
# ============================================================

info "Installing desktop launcher"

cat > "$DESKTOP_FILE" <<EOF
[Desktop Entry]
Name=$APP_NAME
Comment=Linux Parental Control Manager
Exec=$PYTHON -m desktop.main
Path=$INSTALL_DIR
Icon=preferences-system-parental-controls
Terminal=false
Type=Application
Categories=Settings;
StartupNotify=true
EOF

chmod 644 "$DESKTOP_FILE"

success "Desktop launcher installed."

# ============================================================
# Validate desktop launcher
# ============================================================

if command -v desktop-file-validate >/dev/null 2>&1; then

    info "Validating desktop launcher"

    if ! desktop-file-validate "$DESKTOP_FILE"; then
        error "Desktop launcher validation failed."
    fi

    success "Desktop launcher is valid."

else
    warning "desktop-file-validate is not available."
fi

# ============================================================
# Update desktop database
# ============================================================

if command -v update-desktop-database >/dev/null 2>&1; then
    update-desktop-database \
        /usr/share/applications \
        >/dev/null 2>&1 || true
fi

# ============================================================
# Restore source ownership
# ============================================================

info "Fixing source ownership"

chown -R \
    "$INSTALL_USER:$INSTALL_GROUP" \
    "$INSTALL_DIR"

success "Source tree owned by $INSTALL_USER."

# ============================================================
# Reload systemd
# ============================================================

info "Reloading systemd"

systemctl daemon-reload

success "Systemd reloaded."

# ============================================================
# Remove stale IPC socket
# ============================================================

info "Cleaning stale IPC socket"

if [ -e "$SOCKET_PATH" ]; then

    if [ -S "$SOCKET_PATH" ]; then
        rm -f "$SOCKET_PATH"
        success "Removed stale IPC socket."
    else
        warning "$SOCKET_PATH exists but is not a socket."
        warning "Leaving it untouched."
    fi

fi

# ============================================================
# Enable service
# ============================================================

info "Enabling parental control service"

systemctl enable "$SERVICE_NAME"

success "Service enabled."

# ============================================================
# Restart service
# ============================================================

info "Starting parental control service"

systemctl restart "$SERVICE_NAME"

# ============================================================
# Wait for service
# ============================================================

info "Waiting for service startup"

SERVICE_READY=0

for _ in $(seq 1 15); do

    if systemctl is-active --quiet "$SERVICE_NAME"; then
        SERVICE_READY=1
        break
    fi

    sleep 1

done

if [ "$SERVICE_READY" -ne 1 ]; then

    echo
    echo "=========================================="
    echo " Service startup failed"
    echo "=========================================="
    echo

    systemctl status \
        "$SERVICE_NAME" \
        --no-pager || true

    echo
    echo "Recent service logs:"
    echo

    journalctl \
        -u "$SERVICE_NAME" \
        -n 50 \
        --no-pager || true

    exit 1
fi

success "Service is running."

# ============================================================
# Verify IPC socket
# ============================================================

info "Checking IPC socket"

if [ ! -S "$SOCKET_PATH" ]; then
    warning "IPC socket was not created:"
    warning "$SOCKET_PATH"
else
    success "IPC socket is active."
fi

# ============================================================
# Final verification
# ============================================================

info "Running final checks"

CHECK_FAILED=0

if systemctl is-active --quiet "$SERVICE_NAME"; then
    echo "    Service:     OK"
else
    echo "    Service:     FAILED"
    CHECK_FAILED=1
fi

if [ -x "$PYTHON" ]; then
    echo "    Python:      OK"
else
    echo "    Python:      FAILED"
    CHECK_FAILED=1
fi

if [ -f "$DESKTOP_FILE" ]; then
    echo "    Desktop:     OK"
else
    echo "    Desktop:     FAILED"
    CHECK_FAILED=1
fi

if [ -S "$SOCKET_PATH" ]; then
    echo "    IPC:         OK"
else
    echo "    IPC:         WARNING"
fi

if [ -f "$POLKIT_DEST" ]; then
    echo "    Polkit:      OK"
else
    echo "    Polkit:      FAILED"
    CHECK_FAILED=1
fi

if [ -f "$INSTALL_DIR/config/users.yaml" ]; then
    echo "    Users:       OK"
else
    echo "    Users:       FAILED"
    CHECK_FAILED=1
fi

if [ -f "$INSTALL_DIR/config/state.json" ]; then
    echo "    State:       OK"
else
    echo "    State:       FAILED"
    CHECK_FAILED=1
fi

if [ "$CHECK_FAILED" -ne 0 ]; then
    error "One or more required installation checks failed."
fi

# ============================================================
# Finished
# ============================================================

echo
echo "=========================================="
echo " Installation complete"
echo "=========================================="
echo
echo "Application:"
echo "  $APP_NAME"
echo
echo "Launch:"
echo "  Application menu"
echo "  Rofi"
echo
echo "Service:"
echo "  systemctl status $SERVICE_NAME"
echo
echo "Logs:"
echo "  journalctl -u $SERVICE_NAME"
echo
echo "IPC:"
echo "  $SOCKET_PATH"
echo
echo "Configuration:"
echo "  $INSTALL_DIR/config/users.yaml"
echo "  $INSTALL_DIR/config/state.json"
echo
echo "Installation:"
echo "  $INSTALL_DIR"
echo
echo "Polkit agent:"
if [ -n "$POLKIT_AGENT" ]; then
    echo "  $POLKIT_AGENT"
else
    echo "  Not detected"
fi
echo
echo "=========================================="
echo