#!/bin/bash
# ==============================================================================
# WALLARM PREFLIGHT CHECK SCRIPT - V1.0 (Native deployment)
# ==============================================================================
# Purpose: Validate system readiness for native (no-Docker) Wallarm deployment
# Features:
# - Non-interactive system validation (sudo, OS, architecture, init system)
# - Network connectivity testing (US/EU cloud + Wallarm all-in-one installer)
# - Resource availability assessment
# - Outputs results to .env file for deployment script
# - DAU-friendly error messages with remediation
# ==============================================================================

# Script location and shared library (colors, logging, validation, detection, connectivity)
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
# shellcheck source=../common/wallarm-lib.sh
source "$SCRIPT_DIR/../common/wallarm-lib.sh"

# Strict error handling
set -euo pipefail
trap early_error_handler ERR

# Configuration
ENV_FILE=".env"
LOG_FILE="${HOME:-.}/logs/wallarm-check-native.log"

# Native install artifacts (Wallarm all-in-one installer)
WALLARM_VERSION="${WALLARM_VERSION:-6.12.7}"
INSTALLER_BASE_URL="https://meganode.wallarm.com/${WALLARM_VERSION%.*}"
INSTALLER_NAME="wallarm-${WALLARM_VERSION}.x86_64-glibc.sh"
INSTALLER_URL="${INSTALLER_BASE_URL}/${INSTALLER_NAME}"

# Cloud endpoints (from Wallarm documentation)
EU_DATA_NODES=("api.wallarm.com" "node-data0.eu1.wallarm.com" "node-data1.eu1.wallarm.com")
US_DATA_NODES=("us1.api.wallarm.com" "node-data0.us1.wallarm.com" "node-data1.us1.wallarm.com")

# Global result tracking
CHECK_RESULT="pass"
CHECK_ERRORS=()
INSTALLER_REACHABLE="false"

# ==============================================================================
# RESULT TRACKING & ENV FILE
# ==============================================================================

add_error() {
    local error_msg="$1"
    CHECK_ERRORS+=("$error_msg")
    CHECK_RESULT="fail"
    log_message "ERROR" "$error_msg"
}

write_env_file() {
    local os_name="$1"
    local os_version="$2"
    local architecture="$3"
    local init_system="$4"
    local us_cloud_reachable="$5"
    local eu_cloud_reachable="$6"
    local installer_reachable="${7:-false}"

    cat > "$ENV_FILE" << EOF
# Wallarm Preflight Check Results (Native deployment)
# Generated: $(date '+%Y-%m-%d %H:%M:%S')
# Script: $0

result=$CHECK_RESULT
os_name=$os_name
os_version=$os_version
architecture=$architecture
init_system=$init_system
us_cloud_reachable=$us_cloud_reachable
eu_cloud_reachable=$eu_cloud_reachable
installer_reachable=$installer_reachable

EOF

    if [ ${#CHECK_ERRORS[@]} -gt 0 ]; then
        echo "# Errors:" >> "$ENV_FILE"
        for i in "${!CHECK_ERRORS[@]}"; do
            echo "error_$i=\"${CHECK_ERRORS[$i]}\"" >> "$ENV_FILE"
        done
    fi

    log_message "SUCCESS" "Check results written to $ENV_FILE"
}

# ==============================================================================
# PRE-FLIGHT VALIDATION FUNCTIONS
# ==============================================================================

validate_sudo_access() {
    log_message "INFO" "Validating sudo access..."

    local os_name
    os_name=$(uname -s | tr '[:upper:]' '[:lower:]')

    if ! command -v sudo >/dev/null 2>&1; then
        add_error "sudo command not found"
        return 1
    fi

    if [ "$os_name" = "darwin" ]; then
        log_message "WARNING" "macOS detected: sudo authentication test skipped (may prompt during deployment)"
        log_message "INFO" "Note: macOS is not a supported deployment target. This check is for Linux servers."
        return 0
    fi

    if ! sudo -v; then
        add_error "sudo authentication failed"
        return 1
    fi

    log_message "SUCCESS" "Sudo access validated"
    return 0
}

validate_required_commands() {
    log_message "INFO" "Validating required system commands..."

    local missing_commands=()

    local os_name
    os_name=$(uname -s | tr '[:upper:]' '[:lower:]')

    # Core commands required for native check and deployment scripts
    local core_commands=(
        "curl"     # Required for downloading the all-in-one installer
        "grep"     # Used extensively
        "cut"      # Used for parsing output
        "tr"       # Used for text transformations
        "sed"      # Used for text processing
        "head"     # Used for limiting output
        "tail"     # Used for limiting output
        "ls"       # Used for file listing
        "date"     # Used for logging timestamps
        "mkdir"    # Used for creating directories
        "chmod"    # Used for permission changes
        "tee"      # Required for writing configuration files
        "rm"       # Required for cleanup operations
    )

    # Check each core command (command_exists comes from common library)
    local cmd
    for cmd in "${core_commands[@]}"; do
        if ! command_exists "$cmd"; then
            missing_commands+=("$cmd")
        fi
    done

    # Check for port checking utility (ss or netstat)
    if [ "$os_name" != "darwin" ]; then
        if ! command_exists ss && ! command_exists netstat; then
            missing_commands+=("ss or netstat")
        fi
    fi

    # Detect init system and validate its control command
    if [ "$os_name" != "darwin" ]; then
        local init_system
        init_system=$(detect_init_system)

        case "$init_system" in
            "systemd")
                if ! command_exists systemctl; then
                    missing_commands+=("systemctl")
                fi
                ;;
            "openrc")
                if ! command_exists rc-service; then
                    missing_commands+=("rc-service")
                fi
                ;;
            "sysvinit")
                if ! command_exists service; then
                    missing_commands+=("service")
                fi
                ;;
            "upstart")
                if ! command_exists initctl; then
                    missing_commands+=("initctl")
                fi
                ;;
            *)
                log_message "WARNING" "Unknown init system '$init_system', cannot validate init command"
                ;;
        esac
    else
        log_message "INFO" "Skipping init system validation on macOS (not a deployment target)"
    fi

    if [ ${#missing_commands[@]} -gt 0 ]; then
        local missing_list
        missing_list=$(IFS=', '; echo "${missing_commands[*]}")
        add_error "Missing required commands: $missing_list"
        log_message "ERROR" "Please install missing commands and run the check again."
        return 1
    fi

    log_message "SUCCESS" "All required system commands are available"
    return 0
}

# ==============================================================================
# NETWORK CONNECTIVITY TESTING
# ==============================================================================

perform_network_tests() {
    log_message "INFO" "=== NETWORK CONNECTIVITY TESTING ==="

    # Test US cloud endpoints
    local us_reachable
    us_reachable=$(test_cloud_endpoints "US" "${US_DATA_NODES[@]}")

    # Test EU cloud endpoints
    local eu_reachable
    eu_reachable=$(test_cloud_endpoints "EU" "${EU_DATA_NODES[@]}")

    # Test Wallarm all-in-one installer reachability (needed for native install)
    log_message "INFO" "Testing Wallarm all-in-one installer availability..."
    if test_connectivity "$INSTALLER_URL" "Wallarm all-in-one installer"; then
        INSTALLER_REACHABLE="true"
        log_message "SUCCESS" "Wallarm installer is reachable (version $WALLARM_VERSION)"
    else
        log_message "WARNING" "Wallarm installer is not reachable at $INSTALLER_URL"
        log_message "INFO" "Check https://docs.wallarm.com/updating-migrating/node-artifact-versions/ for the latest version."
    fi

    echo "$us_reachable:$eu_reachable:$INSTALLER_REACHABLE"
}

# ==============================================================================
# MAIN FUNCTION
# ==============================================================================

main() {
    clear
    echo -e "${BLUE}${BOLD}"
    echo "╔══════════════════════════════════════════════════════════════╗"
    echo "║       WALLARM PREFLIGHT CHECK SCRIPT (Native) - V1.0         ║"
    echo "║      System Readiness Validation for Deployment             ║"
    echo "╚══════════════════════════════════════════════════════════════╝${NC}"
    echo -e "\n${YELLOW}Starting preflight check at: $(date)${NC}"

    # Initialize logging
    local log_dir="${HOME:-.}/logs"
    if [ ! -d "$log_dir" ]; then
        if ! mkdir -p "$log_dir"; then
            echo -e "${YELLOW}Cannot create log directory $log_dir, falling back to current directory...${NC}"
            log_dir="."
        fi
    fi

    LOG_FILE="$log_dir/wallarm-check-native.log"
    if ! : > "$LOG_FILE"; then
        echo -e "${RED}Cannot create log file at $LOG_FILE${NC}"
        echo -e "${YELLOW}Falling back to current directory...${NC}"
        LOG_FILE="./wallarm-check-native.log"
        : > "$LOG_FILE" 2>/dev/null || true
    fi
    if ! chmod 644 "$LOG_FILE" 2>/dev/null; then
        echo -e "${YELLOW}Warning: Could not set permissions on log file${NC}"
    fi

    log_message "INFO" "=== Wallarm Preflight Check (Native) Started ==="

    if [ "$INSECURE_SSL" = "1" ]; then
        log_message "WARNING" "SSL certificate validation is DISABLED (insecure). Set WALLARM_INSECURE_SSL=0 to enable validation."
    fi

    # Phase 1: System validation
    log_message "INFO" "=== PHASE 1: SYSTEM VALIDATION ==="

    if ! validate_required_commands; then
        add_error "Required system commands validation failed"
    fi

    if ! validate_sudo_access; then
        add_error "Sudo access validation failed"
    fi

    local os_info
    os_info=$(detect_os_and_version)
    local os_name
    os_name=$(echo "$os_info" | cut -d: -f1)
    local os_version
    os_version=$(echo "$os_info" | cut -d: -f2)

    local architecture
    architecture=$(detect_architecture)
    if [ "$architecture" = "unknown" ]; then
        add_error "Unsupported architecture detected"
    fi

    local init_system
    init_system=$(detect_init_system)

    log_message "SUCCESS" "System validation completed:"
    log_message "SUCCESS" "  OS: $os_name $os_version"
    log_message "SUCCESS" "  Architecture: $architecture"
    log_message "SUCCESS" "  Init System: $init_system"

    # Phase 2: Network connectivity testing
    log_message "INFO" "=== PHASE 2: NETWORK CONNECTIVITY TESTING ==="

    local network_results
    network_results=$(perform_network_tests)
    local us_reachable
    us_reachable=$(echo "$network_results" | cut -d: -f1)
    local eu_reachable
    eu_reachable=$(echo "$network_results" | cut -d: -f2)
    local installer_reachable
    installer_reachable=$(echo "$network_results" | cut -d: -f3)

    log_message "SUCCESS" "Network testing completed:"
    log_message "SUCCESS" "  US Cloud Reachable: $us_reachable"
    log_message "SUCCESS" "  EU Cloud Reachable: $eu_reachable"
    log_message "SUCCESS" "  Wallarm Installer Reachable: $installer_reachable"

    # Phase 3: Write results
    log_message "INFO" "=== PHASE 3: WRITING RESULTS ==="

    write_env_file "$os_name" "$os_version" "$architecture" "$init_system" \
                   "$us_reachable" "$eu_reachable" "$installer_reachable"

    # Final summary
    if [ "$CHECK_RESULT" = "pass" ]; then
        log_message "SUCCESS" "=== PREFLIGHT CHECK PASSED ==="
        echo -e "\n${GREEN}${BOLD}╔══════════════════════════════════════════════════════════════╗${NC}"
        echo -e "${GREEN}${BOLD}║           PREFLIGHT CHECK PASSED - SYSTEM READY              ║${NC}"
        echo -e "${GREEN}${BOLD}╚══════════════════════════════════════════════════════════════╝${NC}"
        echo -e "\n${CYAN}System is ready for native Wallarm deployment.${NC}"
        echo -e "${YELLOW}Check results: $ENV_FILE${NC}"
        echo -e "${YELLOW}Full log: $LOG_FILE${NC}"
        echo -e "\n${GREEN}Next step: Run ./native/wallarm-ct-deploy.sh to proceed with deployment${NC}"
        exit 0
    else
        log_message "ERROR" "=== PREFLIGHT CHECK FAILED ==="
        echo -e "\n${RED}${BOLD}╔══════════════════════════════════════════════════════════════╗${NC}"
        echo -e "${RED}${BOLD}║           PREFLIGHT CHECK FAILED - SYSTEM NOT READY          ║${NC}"
        echo -e "${RED}${BOLD}╚══════════════════════════════════════════════════════════════╝${NC}"
        echo -e "\n${YELLOW}${BOLD}Issues found:${NC}"
        for error in "${CHECK_ERRORS[@]}"; do
            echo -e "  ${RED}•${NC} $error"
        done
        echo -e "\n${YELLOW}Check results: $ENV_FILE${NC}"
        echo -e "${YELLOW}Full log: $LOG_FILE${NC}"
        echo -e "\n${CYAN}Please fix the issues above and run the check again.${NC}"
        exit 1
    fi
}

# ==============================================================================
# SCRIPT EXECUTION
# ==============================================================================

# Ensure we're in bash
if [ -z "$BASH_VERSION" ]; then
    echo "Error: This script must be run with bash" >&2
    exit 1
fi

# Run main function
main "$@"