#!/bin/bash

# env-update.sh - Update environment variables from .env.example to .env
# Preserves existing values while updating structure and highlighting changes
# Created: April 25, 2025

set -e

# Color definitions
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[0;33m'
BLUE='\033[0;34m'
MAGENTA='\033[0;35m'
CYAN='\033[0;36m'
BOLD='\033[1m'
NC='\033[0m' # No Color

# Files
ENV_FILE=".env"
ENV_EXAMPLE=".env.example"
TIMESTAMP=$(date +"%Y%m%d-%H%M%S")
ENV_BACKUP=".env.${TIMESTAMP}.bak"

# Check if files exist
if [ ! -f "$ENV_FILE" ]; then
    echo -e "${RED}Error: $ENV_FILE doesn't exist${NC}"
    echo -e "Creating a new $ENV_FILE from $ENV_EXAMPLE"
    cp "$ENV_EXAMPLE" "$ENV_FILE"
    echo -e "${GREEN}Done! Please review and fill in required values in $ENV_FILE${NC}"
    exit 0
fi

if [ ! -f "$ENV_EXAMPLE" ]; then
    echo -e "${RED}Error: $ENV_EXAMPLE doesn't exist${NC}"
    exit 1
fi

echo -e "${CYAN}${BOLD}Environment File Update Tool${NC}"
echo -e "${CYAN}============================${NC}"
echo -e "${BLUE}This will update your $ENV_FILE based on the structure in $ENV_EXAMPLE${NC}"
echo -e "${BLUE}Your existing values will be preserved where possible${NC}"
echo -e "${BLUE}Backup will be created as: $ENV_BACKUP${NC}"
echo -e "${YELLOW}Continue? [y/N]:${NC}"
read -r answer
if [[ ! "$answer" =~ ^[Yy]$ ]]; then
    echo -e "${RED}Cancelled.${NC}"
    exit 0
fi

# Create backup of current .env
echo -e "${BLUE}Creating backup of current $ENV_FILE as $ENV_BACKUP...${NC}"
cp "$ENV_FILE" "$ENV_BACKUP"

# Store current env values
echo -e "${BLUE}Reading current environment values...${NC}"
declare -A current_values
declare -A current_keys_present
while IFS='=' read -r key value; do
    # Skip comments and empty lines
    if [[ ! "$key" =~ ^#.*$ ]] && [[ ! -z "$key" ]]; then
        # Clean up any comments after the value
        value=$(echo "$value" | sed 's/[[:space:]]*#.*$//')
        # Trim leading/trailing whitespace
        key=$(echo "$key" | xargs)
        value=$(echo "$value" | xargs)
        # Store in associative array if key is not empty
        if [[ ! -z "$key" ]]; then
            current_values["$key"]="$value"
            # Track that this key existed in original file, regardless of value
            current_keys_present["$key"]=1
        fi
    fi
done < "$ENV_FILE"

# Create new env file from example
echo -e "${BLUE}Creating new $ENV_FILE from $ENV_EXAMPLE...${NC}"
cp "$ENV_EXAMPLE" "$ENV_FILE.new"

# Track which keys from the current env have been used
declare -A used_keys
# Track new keys that need attention
new_keys=()
# Track keys with special warnings
special_keys=()

# Process the template and fill in values from current env
while IFS= read -r line; do
    if [[ "$line" =~ ^([A-Za-z0-9_]+)=(.*)$ ]]; then
        key="${BASH_REMATCH[1]}"
        default_value="${BASH_REMATCH[2]}"
        
        # Mark the key as used if it exists in the original file
        if [[ -n "${current_keys_present[$key]}" ]]; then
            used_keys["$key"]=1
            
            # Replace the line with the current value if one exists
            if [[ -n "${current_values[$key]}" ]]; then
                sed -i "s|^$key=.*$|$key=${current_values[$key]}|" "$ENV_FILE.new"
            fi
        # If key doesn't exist in original file and has empty/placeholder value
        elif [[ -z "$default_value" ]] || [[ "$default_value" == '""' ]] || [[ "$default_value" == "''" ]]; then
            new_keys+=("$key")
            
            # Special attention for Authelia keys
            if [[ "$key" == AUTHELIA_*_SECRET* ]] || [[ "$key" == AUTHELIA_*_KEY* ]]; then
                special_keys+=("$key")
            fi
        fi
    fi
done < "$ENV_FILE.new"

# Create section for unused/deprecated keys at the bottom of the file
echo -e "\n\n# --- DEPRECATED OR UNUSED KEYS (Kept for Reference) ---" >> "$ENV_FILE.new"
echo -e "# Keys below were in your original .env but aren't in the current .env.example" >> "$ENV_FILE.new"
echo -e "# They may be deprecated or renamed. Review and remove if no longer needed\n" >> "$ENV_FILE.new"

unused_keys_count=0
for key in "${!current_values[@]}"; do
    if [[ -z "${used_keys[$key]}" ]]; then
        echo "$key=${current_values[$key]} # DEPRECATED/UNUSED - Review" >> "$ENV_FILE.new"
        unused_keys_count=$((unused_keys_count + 1))
    fi
done

# Replace the old file with the new one
mv "$ENV_FILE.new" "$ENV_FILE"

# Generate summary 
echo -e "\n${GREEN}${BOLD}Update Complete!${NC}"
echo -e "${BLUE}Summary:${NC}"
echo -e "  - ${CYAN}Original config backed up to: $ENV_BACKUP${NC}"
echo -e "  - ${CYAN}Updated .env structure to match .env.example${NC}"
echo -e "  - ${CYAN}Preserved ${#used_keys[@]} existing values${NC}"

if [[ $unused_keys_count -gt 0 ]]; then
    echo -e "  - ${YELLOW}Found $unused_keys_count deprecated/unused keys${NC}"
    echo -e "    ${YELLOW}These have been moved to the bottom of the file with warnings${NC}"
fi

if [[ ${#new_keys[@]} -gt 0 ]]; then
    echo -e "\n${YELLOW}${BOLD}NEW KEYS NEEDING ATTENTION:${NC}"
    echo -e "${YELLOW}The following keys are new and may need values set:${NC}"
    for key in "${new_keys[@]}"; do
        echo -e "  - ${MAGENTA}$key${NC}"
    done
fi

if [[ ${#special_keys[@]} -gt 0 ]]; then
    echo -e "\n${RED}${BOLD}IMPORTANT SECURITY KEYS:${NC}"
    echo -e "${RED}The following keys require secure values:${NC}"
    for key in "${special_keys[@]}"; do
        echo -e "  - ${MAGENTA}$key${NC}" 
        
        # Specific advice for Authelia keys
        if [[ "$key" == AUTHELIA_*_SECRET* ]] || [[ "$key" == AUTHELIA_*_KEY* ]]; then
            echo -e "    ${CYAN}Generate with: ${GREEN}openssl rand -hex 32${NC}"
        fi
    done
fi

echo -e "\n${BLUE}Review your updated $ENV_FILE file and adjust any values as needed.${NC}"