#!/bin/bash

# Script to detect locally available OS images and update image_location URLs in main.tf files
# This script updates terraform configurations to use local image paths instead of remote URLs
# It also supports reverting back to original remote URLs using hardcoded values

# Function to display usage
usage() {
    echo "Usage: $0 [options]"
    echo "  options:"
    echo "    -h, --help     Display this help message"
    echo "    -d, --dry-run  Show what would be changed without making modifications"
    echo "    -r, --revert   Revert image_location URLs back to original remote URLs"
    echo ""
    echo "Example:"
    echo "  $0                    # Convert remote URLs to local paths (default)"
    echo "  $0 -d                 # Dry run - show what would be updated"
    echo "  $0 -r                 # Revert to original remote URLs"
    echo "  $0 -r -d              # Dry run revert mode"
    exit 1
}

# Parse command line arguments
DRY_RUN=false
REVERT_MODE=false

while [[ $# -gt 0 ]]; do
    case $1 in
        -h|--help)
            usage
            ;;
        -d|--dry-run)
            DRY_RUN=true
            shift
            ;;
        -r|--revert)
            REVERT_MODE=true
            shift
            ;;
        *)
            echo "Unknown option: $1"
            usage
            ;;
    esac
done

# Define the directory where images are stored
IMAGE_DIR="/var/lib/libvirt/images"

# Check if we have write permissions to the target directory
if [[ ! -d "$IMAGE_DIR" ]]; then
    echo "Error: Directory $IMAGE_DIR does not exist"
    exit 1
fi

# Image URLs (hardcoded original URLs from download_images.sh)
ORIGINAL_IMAGES=(
    "https://cloud.debian.org/images/cloud/trixie/latest/debian-13-genericcloud-amd64.raw"
    "https://download.fedoraproject.org/pub/fedora/linux/releases/42/Cloud/x86_64/images/Fedora-Cloud-Base-Generic-42-1.1.x86_64.qcow2"
    "https://download.opensuse.org/tumbleweed/appliances/openSUSE-Tumbleweed-Minimal-VM.x86_64-Cloud.qcow2"
    "https://dl.rockylinux.org/pub/rocky/10/images/x86_64/Rocky-10-GenericCloud-Base.latest.x86_64.qcow2"
    "https://cloud-images.ubuntu.com/noble/current/noble-server-cloudimg-amd64.img"
    "https://cloud.centos.org/centos/10-stream/x86_64/images/CentOS-Stream-GenericCloud-x86_64-10-latest.x86_64.qcow2"
)

# Function to get filename from URL
get_filename_from_url() {
    local url=$1
    basename "$url"
}

# Find all main.tf files and process them
MAIN_TF_FILES=$(find . -name "main.tf" -type f)

if [ -z "$MAIN_TF_FILES" ]; then
    echo "No main.tf files found!"
    exit 1
fi

echo "Found main.tf files:"
echo "$MAIN_TF_FILES"
echo ""

# Process each file
for file in $MAIN_TF_FILES; do
    echo "Processing $file..."
    
    # Check if the file contains image_location lines
    if ! grep -q "image_location" "$file"; then
        echo "  No image_location found in $file, skipping..."
        continue
    fi
    
    if [ "$REVERT_MODE" = true ]; then
        # Revert operation: change file:// back to original https:// URLs
        temp_file=$(mktemp)
        
        while IFS= read -r line || [[ -n "$line" ]]; do
            if [[ "$line" =~ .*image_location.*=.*\"file://(.*?)\".* ]]; then
                # Extract local path from the file:// URL
                local_file_path="${BASH_REMATCH[1]}"
                local_filename=$(basename "$local_file_path")
                
                # Find matching original URL for this filename
                found_match=false
                for original_url in "${ORIGINAL_IMAGES[@]}"; do
                    if [[ "$(basename "$original_url")" == "$local_filename" ]]; then
                        echo "  Found matching file: $local_filename"
                        
                        if [ "$DRY_RUN" = false ]; then
                            # Use precise string replacement to avoid corrupting the file
                            new_line="${line/\"file:\/\/$local_file_path\"/\"$original_url\"}"
                            echo "$new_line" >> "$temp_file"
                            echo "  Reverted to original URL: $original_url"
                        else
                            echo "  Would revert to: $original_url"
                            echo "$line" >> "$temp_file"
                        fi
                        found_match=true
                        break
                    fi
                done
                
                if [ "$found_match" = false ]; then
                    echo "  Warning: No matching original URL found for $local_filename"
                    echo "$line" >> "$temp_file"
                fi
            else
                # Not a line with image_location, just copy as is
                echo "$line" >> "$temp_file"
            fi
        done < "$file"
        
        if [ "$DRY_RUN" = false ]; then
            mv "$temp_file" "$file"
        else
            rm "$temp_file"
        fi
        
    else
        # Normal operation: convert remote URLs to local paths
        temp_file=$(mktemp)
        
        while IFS= read -r line || [[ -n "$line" ]]; do
            if [[ "$line" =~ .*image_location.*=.*\"(https://.*)\".* ]]; then
                remote_url="${BASH_REMATCH[1]}"
                filename=$(basename "$remote_url")
                
                # Check if the local file exists
                local_path="$IMAGE_DIR/$filename"
                
                if [[ -f "$local_path" ]]; then
                    echo "  Found local image: $filename"
                    
                    if [ "$DRY_RUN" = false ]; then
                        # Use precise string replacement to avoid corrupting the file
                        new_line="${line/\"$remote_url\"/\"file://$local_path\"}"
                        echo "$new_line" >> "$temp_file"
                        echo "  Updated to: file://$local_path"
                    else
                        echo "  Would update to: file://$local_path"
                        echo "$line" >> "$temp_file"
                    fi
                else
                    echo "  Local image not found: $filename"
                    echo "$line" >> "$temp_file"
                fi
            else
                # Not a line with image_location, just copy as is
                echo "$line" >> "$temp_file"
            fi
        done < "$file"
        
        if [ "$DRY_RUN" = false ]; then
            mv "$temp_file" "$file"
        else
            rm "$temp_file"
        fi
    fi
done

echo ""
if [ "$DRY_RUN" = false ]; then
    if [ "$REVERT_MODE" = true ]; then
        echo "Image location URLs have been successfully reverted to original remote URLs!"
    else
        echo "Image location URLs have been successfully updated in all main.tf files!"
    fi
else
    echo "Dry run completed - no changes were made."
fi

# Show a summary of what would be changed
echo ""
echo "Summary of local image availability:"
find "$IMAGE_DIR" -maxdepth 1 -type f -name "*.qcow2" -o -name "*.raw" -o -name "*.img" | \
    while read -r image; do
        filename=$(basename "$image")
        echo "  ✓ $filename"
    done

# If nothing was found, show what images are expected
if ! find "$IMAGE_DIR" -maxdepth 1 -type f -name "*.qcow2" -o -name "*.raw" -o -name "*.img" | grep -q .; then
    echo "  No local images found in $IMAGE_DIR"
    echo "  Run download_images.sh to download required images."
fi