#!/bin/bash

# ==============================================================================
# DETECTION LIBRARY: OS, Hardware, and Environment Detection
# ==============================================================================
# Part of unified bootstrap system for homelab infrastructure
# Provides functions to identify OS family, hardware type, CPU, GPU, and
# deployment environment for intelligent provisioning decisions.
# ==============================================================================

# --- OS DETECTION ---

detect_os_family() {
    # Detect OS family: debian, ubuntu, raspbian, or unknown
    # Returns lowercase OS identifier
    
    if [ -f /etc/os-release ]; then
        . /etc/os-release
        case "${ID,,}" in
            debian)
                echo "debian"
                return 0
                ;;
            ubuntu)
                echo "ubuntu"
                return 0
                ;;
            raspbian)
                echo "raspbian"
                return 0
                ;;
            *)
                echo "unknown"
                return 1
                ;;
        esac
    else
        echo "unknown"
        return 1
    fi
}

detect_os_version() {
    # Get OS version codename (e.g., trixie, bookworm, noble)
    
    if [ -f /etc/os-release ]; then
        . /etc/os-release
        echo "${VERSION_CODENAME:-unknown}"
    else
        echo "unknown"
    fi
}

is_debian_trixie() {
    # Special detection for Debian Trixie (requires Docker repo workaround)
    
    local os_family=$(detect_os_family)
    local os_version=$(detect_os_version)
    
    [[ "$os_family" == "debian" && "$os_version" == "trixie" ]]
}

# --- HARDWARE TYPE DETECTION ---

detect_hardware_type() {
    # Auto-detect hardware deployment type
    # Returns: proxmox, docker-vm, pi, physical-docker, ai-workstation, unknown
    
    # Check for Proxmox VE installation
    if command -v pveversion &>/dev/null; then
        echo "proxmox"
        return 0
    fi
    
    # Check if running inside a VM (common indicators)
    local is_vm=0
    if systemd-detect-virt --vm &>/dev/null; then
        is_vm=1
    elif [ -d /sys/class/dmi/id ]; then
        local product_name=$(cat /sys/class/dmi/id/product_name 2>/dev/null || echo "")
        if [[ "$product_name" =~ (VirtualBox|VMware|KVM|QEMU) ]]; then
            is_vm=1
        fi
    fi
    
    # Check for Raspberry Pi
    if grep -q "Raspberry Pi" /proc/cpuinfo 2>/dev/null; then
        echo "pi"
        return 0
    fi
    
    # Check for Docker installation (distinguishes VM vs physical)
    local has_docker=0
    if command -v docker &>/dev/null || [ -f /usr/bin/docker ]; then
        has_docker=1
    fi
    
    # Check for high-end GPU (indicates AI workstation)
    local gpu_type=$(detect_gpu)
    if [[ "$gpu_type" =~ (nvidia|amd) ]]; then
        local gpu_info=$(lspci 2>/dev/null | grep -i vga | head -n1)
        # High-end NVIDIA cards (RTX, Tesla, Quadro) or AMD (Radeon Pro, Instinct)
        if [[ "$gpu_info" =~ (RTX|Tesla|Quadro|A[0-9]{3,4}|Radeon Pro|Instinct) ]]; then
            echo "ai-workstation"
            return 0
        fi
    fi
    
    # Classify based on VM + Docker
    if [ $is_vm -eq 1 ]; then
        echo "docker-vm"
        return 0
    else
        echo "physical-docker"
        return 0
    fi
}

# --- CPU DETECTION ---

detect_cpu_vendor() {
    # Detect CPU vendor: intel, amd, arm, or unknown
    
    if [ -f /proc/cpuinfo ]; then
        if grep -qi "intel" /proc/cpuinfo; then
            echo "intel"
            return 0
        elif grep -qi "amd" /proc/cpuinfo; then
            echo "amd"
            return 0
        elif grep -qi "arm\|aarch64" /proc/cpuinfo; then
            echo "arm"
            return 0
        fi
    fi
    
    echo "unknown"
    return 1
}

detect_cpu_generation() {
    # Detect Intel CPU generation for kernel parameter tuning
    # Returns generation number (e.g., 12, 13, 14) or "unknown"
    
    local vendor=$(detect_cpu_vendor)
    if [ "$vendor" != "intel" ]; then
        echo "unknown"
        return 1
    fi
    
    local model_name=$(grep "model name" /proc/cpuinfo | head -n1 | cut -d: -f2 | xargs)
    
    # Extract generation from model name patterns
    # Example: "12th Gen Intel(R) Core(TM) i7-12700"
    if [[ "$model_name" =~ ([0-9]{2})th\ Gen ]]; then
        echo "${BASH_REMATCH[1]}"
        return 0
    elif [[ "$model_name" =~ i[3579]-([0-9]{2})[0-9]{2,3} ]]; then
        echo "${BASH_REMATCH[1]}"
        return 0
    fi
    
    echo "unknown"
    return 1
}

needs_intel_hybrid_core_tuning() {
    # 12th Gen+ Intel CPUs with hybrid architecture need special kernel params
    # Returns 0 (true) if tuning required, 1 (false) otherwise
    
    local gen=$(detect_cpu_generation)
    
    # 12th Gen (Alder Lake) and newer have P-cores + E-cores
    if [[ "$gen" =~ ^[0-9]+$ ]] && [ "$gen" -ge 12 ]; then
        return 0
    fi
    
    return 1
}

# --- GPU DETECTION ---

detect_gpu() {
    # Detect GPU vendor: nvidia, amd, intel, or none
    
    if ! command -v lspci &>/dev/null; then
        echo "none"
        return 1
    fi
    
    local gpu_info=$(lspci 2>/dev/null | grep -i vga)
    
    if echo "$gpu_info" | grep -qi nvidia; then
        echo "nvidia"
        return 0
    elif echo "$gpu_info" | grep -qi amd; then
        echo "amd"
        return 0
    elif echo "$gpu_info" | grep -qi intel; then
        echo "intel"
        return 0
    fi
    
    echo "none"
    return 1
}

get_gpu_model() {
    # Get detailed GPU model information
    
    if ! command -v lspci &>/dev/null; then
        echo "unknown"
        return 1
    fi
    
    local gpu_line=$(lspci 2>/dev/null | grep -i "vga\|3d\|display" | head -n1)
    
    if [ -n "$gpu_line" ]; then
        # Extract model after the vendor info
        echo "$gpu_line" | cut -d: -f3 | xargs
    else
        echo "none"
    fi
}

# --- NETWORK INTERFACE DETECTION ---

detect_primary_interface() {
    # Find the primary physical network interface (excludes lo, docker, veth)
    
    # Try to find interface with default route
    local iface=$(ip route show default 2>/dev/null | awk '/^default/ {print $5; exit}')
    
    if [ -n "$iface" ]; then
        echo "$iface"
        return 0
    fi
    
    # Fallback: first non-loopback physical interface
    iface=$(ip -o link show | awk -F': ' '$2 != "lo" && $2 !~ /^(docker|veth|br-)/ {print $2; exit}')
    
    if [ -n "$iface" ]; then
        echo "$iface"
        return 0
    fi
    
    echo "unknown"
    return 1
}

get_current_ip() {
    # Get current IPv4 address of primary interface
    
    local iface=$(detect_primary_interface)
    
    if [ "$iface" == "unknown" ]; then
        echo "unknown"
        return 1
    fi
    
    local ip=$(ip -4 addr show "$iface" 2>/dev/null | grep -oP '(?<=inet\s)\d+(\.\d+){3}' | head -n1)
    
    if [ -n "$ip" ]; then
        echo "$ip"
    else
        echo "unknown"
        return 1
    fi
}

# --- ENVIRONMENT DETECTION ---

is_running_in_container() {
    # Check if running inside a container (Docker, LXC, etc.)
    
    if [ -f /.dockerenv ]; then
        return 0
    fi
    
    if grep -q "lxc\|docker" /proc/1/cgroup 2>/dev/null; then
        return 0
    fi
    
    return 1
}

detect_init_system() {
    # Detect init system: systemd, sysvinit, or unknown
    
    if [ -d /run/systemd/system ]; then
        echo "systemd"
        return 0
    elif [ -f /sbin/init ]; then
        local init_path=$(readlink -f /sbin/init)
        if [[ "$init_path" =~ systemd ]]; then
            echo "systemd"
            return 0
        fi
    fi
    
    echo "unknown"
    return 1
}

# --- PACKAGE MANAGER DETECTION ---

detect_package_manager() {
    # Detect primary package manager: apt, dnf, yum, or unknown
    
    if command -v apt-get &>/dev/null; then
        echo "apt"
        return 0
    elif command -v dnf &>/dev/null; then
        echo "dnf"
        return 0
    elif command -v yum &>/dev/null; then
        echo "yum"
        return 0
    fi
    
    echo "unknown"
    return 1
}

# --- SUMMARY FUNCTION ---

print_detection_summary() {
    # Print comprehensive detection summary to stderr for logging
    
    cat >&2 <<EOF
=== System Detection Summary ===
OS Family:        $(detect_os_family)
OS Version:       $(detect_os_version)
Hardware Type:    $(detect_hardware_type)
CPU Vendor:       $(detect_cpu_vendor)
CPU Generation:   $(detect_cpu_generation)
GPU:              $(detect_gpu) ($(get_gpu_model))
Primary NIC:      $(detect_primary_interface)
Current IP:       $(get_current_ip)
Init System:      $(detect_init_system)
Package Manager:  $(detect_package_manager)
In Container:     $(is_running_in_container && echo "yes" || echo "no")
================================
EOF
}

# Export functions for use in other scripts
export -f detect_os_family
export -f detect_os_version
export -f is_debian_trixie
export -f detect_hardware_type
export -f detect_cpu_vendor
export -f detect_cpu_generation
export -f needs_intel_hybrid_core_tuning
export -f detect_gpu
export -f get_gpu_model
export -f detect_primary_interface
export -f get_current_ip
export -f is_running_in_container
export -f detect_init_system
export -f detect_package_manager
export -f print_detection_summary