#!/bin/bash

# Service-specific rootless Docker installation
# Implements DEPLOYMENT_STRATEGY.md conventions

set -euo pipefail

# Required parameter
SERVICE_USER="${1:-}"

log() {
    echo "[Docker Install] $*"
}

error() {
    log "ERROR: $*" >&2
    exit 1
}

usage() {
    echo "Usage: $0 <service_user>"
    echo "  service_user: User to install rootless Docker for (e.g., tinsnip-test)"
    echo ""
    echo "Example: $0 tinsnip-test"
    exit 1
}

# Helper function to run systemctl with fallback if systemd not available  
systemctl_user_safe() {
    local username="$1"
    shift
    local systemctl_command="$*"
    
    sudo -u "$username" -i bash << EOF
        if systemctl --user status >/dev/null 2>&1; then
            systemctl --user $systemctl_command
            exit 0
        else
            exit 1
        fi
EOF
    
    local result=$?
    if [[ $result -eq 1 ]]; then
        log "  ⚠️  Systemd not available, skipping: systemctl --user $systemctl_command"
    fi
    
    return $result
}

# Initialize systemd user session for a service user
init_systemd_user_session() {
    local username="$1"
    local user_uid=$(id -u "$username")
    
    log "Initializing systemd user session for $username..."
    
    # Create XDG_RUNTIME_DIR if it doesn't exist
    if [[ ! -d "/run/user/$user_uid" ]]; then
        log "  Creating XDG_RUNTIME_DIR for $username"
        sudo mkdir -p "/run/user/$user_uid"
        sudo chown "$username:$username" "/run/user/$user_uid"
        sudo chmod 700 "/run/user/$user_uid"
    fi
    
    # Enable lingering (creates persistent systemd user instance)
    log "  Enabling systemd lingering..."
    sudo loginctl enable-linger "$username"
    
    # Start user@.service if not running
    if ! systemctl is-active --quiet "user@$user_uid.service"; then
        log "  Starting user@$user_uid.service..."
        sudo systemctl start "user@$user_uid.service"
    fi
    
    # Wait for user session to be ready
    log "  Waiting for systemd user session to initialize..."
    local max_attempts=10
    local attempt=0
    
    while [[ $attempt -lt $max_attempts ]]; do
        if sudo -u "$username" -i bash -c "XDG_RUNTIME_DIR=/run/user/$user_uid systemctl --user status >/dev/null 2>&1"; then
            log "  ✓ Systemd user session ready"
            return 0
        fi
        sleep 1
        ((attempt++))
    done
    
    log "  WARNING: Systemd user session may not be fully initialized"
    return 1
}

install_dependencies() {
    log "Installing rootless Docker dependencies..."
    
    if sudo apt-get update -qq >/dev/null 2>&1; then
        log "  Package lists updated"
    else
        error "Failed to update package lists"
    fi
    
    # Install systemd and dbus components first for minimal systems
    log "  Installing systemd components for user sessions..."
    if ! sudo apt-get install -y systemd systemd-sysv dbus dbus-user-session >/dev/null 2>&1; then
        log "  WARNING: Some systemd components may already be installed"
    fi
    
    # Install Docker dependencies
    if sudo apt-get install -y uidmap systemd-container fuse-overlayfs slirp4netns >/dev/null 2>&1; then
        log "  Docker dependencies installed"
    else
        error "Failed to install Docker dependencies"
    fi
    
    # Ensure dbus is running (needed for systemd user sessions)
    if ! systemctl is-active --quiet dbus; then
        log "  Starting dbus service..."
        sudo systemctl start dbus
        sudo systemctl enable dbus
    fi
}

enable_privileged_ports() {
    log "Enabling privileged port binding for rootless Docker..."
    
    # Find rootlesskit binary path
    local rootlesskit_path
    if rootlesskit_path=$(which rootlesskit 2>/dev/null); then
        log "Setting CAP_NET_BIND_SERVICE on rootlesskit..."
        sudo setcap cap_net_bind_service=ep "$rootlesskit_path"
        log "Privileged ports enabled"
    else
        log "WARNING: rootlesskit not found, will enable after Docker installation"
    fi
}

setup_docker_environment() {
    local username="$1"
    
    log "Setting up Docker environment for $username"
    
    # Find the service .env file (should exist from mount_nas.sh)
    local service_env_file="/mnt/$username/.env"
    
    if [[ ! -f "$service_env_file" ]]; then
        log "WARNING: Service .env file not found at $service_env_file"
        log "Docker environment will not be persistent across hosts"
        return 1
    fi
    
    # Always use systemd runtime directory since lingering is enabled
    local user_uid
    user_uid=$(id -u "$username")
    local xdg_runtime_dir="/run/user/$user_uid"
    local docker_host="unix:///run/user/$user_uid/docker.sock"
    
    # Start Docker daemon if not running
    sudo -u "$username" -i bash << EOF
if ! pgrep -x dockerd >/dev/null; then
    export XDG_RUNTIME_DIR="$xdg_runtime_dir"
    export DOCKER_HOST="$docker_host"
    dockerd-rootless.sh > ~/.docker/docker.log 2>&1 &
    sleep 5
fi
EOF
    
    # Update Docker environment variables in service .env file  
    log "Adding Docker environment to service .env file"
    local service_env_file="/mnt/$username/.env"
    
    if [[ -f "$service_env_file" ]]; then
        # Remove existing Docker variables and add correct ones
        sudo -u "$username" bash -c "grep -v '^XDG_RUNTIME_DIR=\|^DOCKER_HOST=\|^PATH=' '$service_env_file' > '${service_env_file}.tmp' 2>/dev/null && mv '${service_env_file}.tmp' '$service_env_file'"
        
        # Add Docker environment variables using systemd runtime directory
        sudo -u "$username" bash -c "cat >> '$service_env_file' << 'DOCKER_EOF'

# Docker rootless environment
XDG_RUNTIME_DIR=$xdg_runtime_dir
DOCKER_HOST=$docker_host
PATH=/home/$username/bin:\$PATH
DOCKER_EOF"
        
        log "Docker environment added to $service_env_file"
    else
        log "WARNING: Service .env file not found at $service_env_file"
    fi
}

install_rootless_docker() {
    local username="$1"
    local user_uid=$(id -u "$username")
    
    log "Installing rootless Docker for user: $username"
    
    # Check if already installed AND working
    if sudo -u "$username" -i bash -c "command -v docker &>/dev/null && docker version &>/dev/null"; then
        log "Docker already installed and working for $username"
        return 0
    elif sudo -u "$username" -i bash -c "command -v docker &>/dev/null"; then
        log "Docker client installed but daemon not running for $username"
        setup_docker_environment "$username"
        # Continue to start the daemon below
    else
        log "Installing Docker client for $username"
    fi
    
    # Install rootless Docker with proper environment handling
    sudo -u "$username" -i bash << EOF
# Set up environment explicitly
export XDG_RUNTIME_DIR=/run/user/$user_uid
export PATH=\$HOME/bin:/usr/bin:\$PATH
export DOCKER_HOST=unix:///run/user/$user_uid/docker.sock

echo "Installing rootless Docker with environment:"
echo "  XDG_RUNTIME_DIR: \$XDG_RUNTIME_DIR"
echo "  DOCKER_HOST: \$DOCKER_HOST"

# Download and install rootless Docker
curl -fsSL https://get.docker.com/rootless | sh

# Try systemd setup first
if systemctl --user status >/dev/null 2>&1; then
    echo "  Setting up systemd service..."
    \$HOME/bin/dockerd-rootless-setuptool.sh install >/dev/null 2>&1 || echo "  Systemd setup failed, using manual start"
    
    systemctl --user daemon-reload >/dev/null 2>&1
    systemctl --user enable docker.service >/dev/null 2>&1
    systemctl --user start docker.service >/dev/null 2>&1
    
    # Wait for systemd Docker to start
    for i in {1..5}; do
        if docker version >/dev/null 2>&1; then
            echo "  ✓ Docker started via systemd"
            exit 0
        fi
        sleep 2
    done
    echo "  Systemd start failed, falling back to manual..."
fi

# Manual startup with explicit environment
echo "  Starting Docker daemon manually..."
# Create .docker directory first
mkdir -p ~/.docker

# Start with explicit environment and proper logging
nohup dockerd-rootless.sh > ~/.docker/docker.log 2>&1 &
DOCKER_PID=\$!
echo "  Docker daemon started with PID: \$DOCKER_PID"

# Wait for manual Docker to start
for i in {1..15}; do
    if docker version >/dev/null 2>&1; then
        echo "  ✓ Docker rootless installation successful (manual startup)"
        echo "  Docker daemon PID: \$DOCKER_PID"
        exit 0
    fi
    echo "  Waiting for Docker to start... (\$i/15)"
    if [[ \$i -eq 5 ]] || [[ \$i -eq 10 ]]; then
        echo "  Checking daemon status..."
        if ! kill -0 \$DOCKER_PID 2>/dev/null; then
            echo "  ❌ Docker daemon died, checking logs:"
            tail -n 10 ~/.docker/docker.log
        fi
    fi
    sleep 2
done

echo "  ❌ Docker installation failed"
echo "  Docker log:"
cat ~/.docker/docker.log 2>/dev/null || echo "  No log file found"
exit 1
EOF

    if [[ $? -eq 0 ]]; then
        log "Rootless Docker installation completed for $username"
    else
        error "Failed to install Docker for $username"
    fi
    
    # Enable privileged ports after installation
    enable_privileged_ports
    
    # Restart Docker to apply capability changes
    log "Restarting Docker to apply configuration..."
    if systemctl_user_safe "$username" "restart docker.service"; then
        log "  Docker service restarted via systemctl"
    else
        log "  Systemctl restart failed, but Docker should still be functional"
    fi
}

configure_docker() {
    local username="$1"
    
    log "Configuring Docker for $username..."
    
    # Create Docker config directory and local data directory
    sudo -u "$username" mkdir -p "/home/$username/.docker"
    sudo -u "$username" mkdir -p "/home/$username/.local/share/docker"
    
    # Create daemon.json with optimized settings
    # Always disable cgroup management for rootless Docker to avoid systemd delegation issues
    # Use local data-root to avoid NFS permission issues with XDG_DATA_HOME on NFS
    # This is the most reliable approach for tinsnip deployments
    sudo -u "$username" mkdir -p "/home/$username/.local/share/docker"
    sudo -u "$username" tee "/home/$username/.docker/daemon.json" > /dev/null << EOF
{
  "data-root": "/home/$username/.local/share/docker",
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "3"
  },
  "storage-driver": "overlay2",
  "exec-opts": ["native.cgroupdriver=none"]
}
EOF
    
    # Ensure proper ownership of Docker directories
    sudo -u "$username" chmod 755 "/home/$username/.local/share/docker"
    
    # Check if Docker is already working before attempting restart
    log "Checking Docker status before configuration restart..."
    if sudo -u "$username" -i bash -c "docker version &>/dev/null"; then
        log "  Docker is already working, skipping restart to avoid issues"
    else
        log "  Docker not responding, attempting restart..."
        if systemctl_user_safe "$username" "restart docker.service"; then
            log "  Docker service restarted via systemctl"
            # Give Docker time to start up after restart
            log "Waiting for Docker to start..."
            sleep 10
        else
            log "  Systemctl restart failed, Docker may already be running in non-systemd mode"
        fi
    fi
    
    # Set up Docker environment variables in .env file
    setup_docker_environment "$username"
    
    # Create Docker context for rootless socket (before starting daemon)
    log "Setting up Docker context..."
    local user_uid
    user_uid=$(id -u "$username")
    sudo -u "$username" bash -c "docker context create rootless --docker 'host=unix:///run/user/$user_uid/docker.sock' >/dev/null 2>&1 || true"
    sudo -u "$username" bash -c "docker context use rootless >/dev/null 2>&1 || true"
    
    log "Docker configuration complete"
    
    # Ensure Docker daemon is running after configuration
    ensure_docker_running "$username"
}

ensure_docker_running() {
    local username="$1"
    local user_uid=$(id -u "$username")
    
    log "Ensuring Docker daemon is running for $username..."
    
    # Check if Docker is already responding
    if sudo -u "$username" -i bash -c "docker version &>/dev/null"; then
        log "  ✓ Docker daemon already running"
        return 0
    fi
    
    log "  Docker not responding, starting daemon..."
    
    # Try systemd first
    if systemctl_user_safe "$username" "start docker.service"; then
        log "  Started via systemd"
        # Wait for systemd start
        for i in {1..10}; do
            if sudo -u "$username" -i bash -c "docker version &>/dev/null"; then
                log "  ✓ Docker daemon started successfully"
                return 0
            fi
            sleep 2
        done
    fi
    
    # Fall back to manual start
    log "  Starting manually with explicit environment..."
    sudo -u "$username" -i bash << EOF
# Kill any existing dockerd processes for this user first
pkill -f "dockerd-rootless" 2>/dev/null || true
sleep 2

# Explicitly set environment variables that dockerd-rootless.sh needs
export XDG_RUNTIME_DIR="/run/user/$user_uid"
export DOCKER_HOST="unix:///run/user/$user_uid/docker.sock"
export PATH="/home/$username/bin:\$PATH"

# Clear any environment variables that might override daemon.json
unset DOCKER_ROOT DOCKER_DATA_ROOT

echo "Environment check:"
echo "  XDG_RUNTIME_DIR: '\$XDG_RUNTIME_DIR'"
echo "  DOCKER_HOST: '\$DOCKER_HOST'"
echo "  Directory exists: \$(test -d "\$XDG_RUNTIME_DIR" && echo "yes" || echo "no")"
echo "  Directory writable: \$(test -w "\$XDG_RUNTIME_DIR" && echo "yes" || echo "no")"

# Start Docker daemon with explicit environment
mkdir -p ~/.docker
nohup env -u DOCKER_ROOT -u DOCKER_DATA_ROOT -u XDG_DATA_HOME XDG_RUNTIME_DIR="/run/user/$user_uid" DOCKER_HOST="unix:///run/user/$user_uid/docker.sock" dockerd-rootless.sh --data-root="/home/$username/.local/share/docker" > ~/.docker/docker.log 2>&1 &
DOCKER_PID=\$!
echo "Docker daemon started with PID: \$DOCKER_PID"

# Wait for Docker to be ready
for i in {1..15}; do
    if XDG_RUNTIME_DIR="/run/user/$user_uid" DOCKER_HOST="unix:///run/user/$user_uid/docker.sock" docker version >/dev/null 2>&1; then
        echo "✓ Docker daemon ready"
        exit 0
    fi
    echo "  Waiting for Docker... (\$i/15)"
    sleep 2
done

echo "❌ Failed to start Docker daemon"
echo "Docker log:"
tail -n 20 ~/.docker/docker.log 2>/dev/null || echo "No log file found"
exit 1
EOF

    if [[ $? -eq 0 ]]; then
        log "  ✓ Docker daemon started manually"
    else
        log "  ❌ Failed to start Docker daemon"
        return 1
    fi
}

verify_installation() {
    local username="$1"
    
    log "Verifying Docker installation for $username..."
    
    # Use the service .env file (source of truth)
    local service_env_file="/mnt/$username/.env"
    
    # Docker context already set up in configure_docker()
    
    # Debug verification process
    log "Debugging verification process..."
    log "  Service env file: $service_env_file"
    
    if [[ -f "$service_env_file" ]]; then
        log "  Environment variables in service .env:"
        sudo -u "$username" grep "DOCKER\|XDG_RUNTIME" "$service_env_file" | while read line; do
            log "    $line"
        done
    else
        log "  WARNING: Service .env file not found!"
    fi
    
    # Test Docker verification with detailed output
    log "  Testing Docker command with environment..."
    if sudo -u "$username" bash -c "source '$service_env_file' 2>/dev/null && docker version"; then
        log "Docker verification successful!"
        local docker_version
        docker_version=$(sudo -u "$username" bash -c "source '$service_env_file' && docker --version")
        log "Installed: $docker_version"
    else
        log "Docker verification failed - showing detailed error:"
        sudo -u "$username" bash -c "source '$service_env_file' 2>/dev/null && docker version" 2>&1 | while read line; do
            log "  ERROR: $line"
        done
        error "Docker verification failed for $username"
    fi
    
    log "Service available for user: $username"
    log "Privileged ports: enabled"
}

main() {
    # Validate parameters
    if [[ -z "$SERVICE_USER" ]]; then
        usage
    fi
    
    # Check if user exists
    if ! id "$SERVICE_USER" &>/dev/null; then
        error "User $SERVICE_USER does not exist. Create the user first."
    fi
    
    log "Installing rootless Docker for service user: $SERVICE_USER"
    
    # Install dependencies
    install_dependencies
    
    # Initialize systemd user session (handles lingering and XDG_RUNTIME_DIR)
    init_systemd_user_session "$SERVICE_USER"
    
    # Configure Docker (before installation to set up proper data directory)
    configure_docker "$SERVICE_USER"
    
    # Install rootless Docker for the service user
    install_rootless_docker "$SERVICE_USER"
    
    # Verify installation
    verify_installation "$SERVICE_USER"
    
    log ""
    log "Rootless Docker installation complete!"
    log "User: $SERVICE_USER"
    log "To test: sudo -u $SERVICE_USER docker run hello-world"
}

main "$@"