#!/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

# Function to get all locally available image files (including Fedora Rawhide)
get_local_images() {
    find "$IMAGE_DIR" -maxdepth 1 -type f \( -name "*.qcow2" -o -name "*.raw" -o -name "*.img" \) | \
        while read -r image; do
            basename "$image"
        done | sort
}

# Function to check if a local file matches the pattern for a Fedora Rawhide image
is_fedora_rawhide_image() {
    local filename=$1
    # Pattern matching for Fedora Rawhide images that contain "Fedora-Cloud-Base-Generic-Rawhide"
    if [[ "$filename" =~ ^Fedora-Cloud-Base-Generic-Rawhide.*\.qcow2$ ]]; then
        return 0
    fi
    return 1
}

# Function to get the latest Fedora Rawhide image path from local directory
get_latest_fedora_rawhide_path() {
    local latest_file
    latest_file=$(find "$IMAGE_DIR" -maxdepth 1 -name "Fedora-Cloud-Base-Generic-Rawhide*.qcow2" -type f \
        | sort -r \
        | head -1)
    
    if [[ -n "$latest_file" ]]; then
        echo "$latest_file"
    fi
}

# Function to provide a mapping between local files and their original URLs
create_original_url_mapping() {
    # Create a hash-like mapping for known images
    cat << 'EOF'
noble-server-cloudimg-amd64.img=https://cloud-images.ubuntu.com/noble/current/noble-server-cloudimg-amd64.img
Fedora-Cloud-Base-Generic-42-1.1.x86_64.qcow2=https://download.fedoraproject.org/pub/fedora/linux/releases/42/Cloud/x86_64/images/Fedora-Cloud-Base-Generic-42-1.1.x86_64.qcow2
openSUSE-Tumbleweed-Minimal-VM.x86_64-Cloud.qcow2=https://download.opensuse.org/tumbleweed/appliances/openSUSE-Tumbleweed-Minimal-VM.x86_64-Cloud.qcow2
Rocky-10-GenericCloud-Base.latest.x86_64.qcow2=https://dl.rockylinux.org/pub/rocky/10/images/x86_64/Rocky-10-GenericCloud-Base.latest.x86_64.qcow2
debian-13-genericcloud-amd64.raw=https://cloud.debian.org/images/cloud/trixie/latest/debian-13-genericcloud-amd64.raw
CentOS-Stream-GenericCloud-x86_64-10-latest.x86_64.qcow2=https://cloud.centos.org/centos/10-stream/x86_64/images/CentOS-Stream-GenericCloud-x86_64-10-latest.x86_64.qcow2
EOF
}

# 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 "$line" ]]; do
            # Check if the line contains a file:// URL
            if [[ "$line" =~ .*image_location.*=.*\"file://(.*?)\".* ]]; then
                # Extract local path from the file:// URL
                local_file_path="${BASH_REMATCH[1]}"
                local_filename=$(basename "$local_file_path")
                
                # Handle Fedora Rawhide images specially
                if [[ "$local_filename" =~ ^Fedora-Cloud-Base-Generic-Rawhide.*\.qcow2$ ]]; then
                    echo "  Reverting Fedora Rawhide image: $local_filename"
                    
                    # For Rawhide, we'll keep the file:// reference but note that it's a special case
                    if [ "$DRY_RUN" = false ]; then
                        echo "$line" >> "$temp_file"
                    else
                        echo "  Would process Fedora Rawhide image: $local_filename (keeping file:// reference)"
                        echo "$line" >> "$temp_file"
                    fi
                else
                    # For regular images, try to map back to original URL
                    # Create mapping for this specific case
                    mapping=$(create_original_url_mapping)
                    
                    # Find matching original URL
                    found_match=false
                    while IFS= read -r mapping_line; do
                        if [[ -z "$mapping_line" ]] || [[ "$mapping_line" =~ ^#.*$ ]]; then
                            continue
                        fi
                        
                        file_pattern=$(echo "$mapping_line" | cut -d'=' -f1)
                        original_url=$(echo "$mapping_line" | cut -d'=' -f2)
                        
                        if [[ "$file_pattern" == "$local_filename" ]]; then
                            echo "  Found matching original URL: $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" >> "$temp_file"
                            fi
                            found_match=true
                            break
                        fi
                    done <<< "$mapping"
                    
                    if [ "$found_match" = false ]; then
                        echo "  Warning: No matching original URL found for $local_filename"
                        echo "$line" >> "$temp_file"
                    fi
                fi
            else
                # Not a line with image_location, just copy as is
                echo "$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 (including Fedora Rawhide cases)
                local_path="$IMAGE_DIR/$filename"
                
                # Special handling for Fedora Rawhide - check if it's the right pattern
                if [[ "$filename" =~ ^Fedora-Cloud-Base-Generic-Rawhide.*\.qcow2$ ]]; then
                    # For Fedora Rawhide, we need to be more flexible with matching patterns
                    echo "  Checking Fedora Rawhide pattern for: $filename"
                    
                    # Find the most recent Fedora image that matches the pattern but has different timestamp
                    latest_rawhide=$(find "$IMAGE_DIR" -maxdepth 1 -name "Fedora-Cloud-Base-Generic-Rawhide*.qcow2" -type f \
                        | sort -r \
                        | head -1)
                    
                    if [[ -n "$latest_rawhide" ]]; then
                        echo "  Found matching local Fedora Rawhide image: $(basename $latest_rawhide)"
                        
                        if [ "$DRY_RUN" = false ]; then
                            new_line="${line/\"$remote_url\"/\"file://$latest_rawhide\"}"
                            echo "$new_line" >> "$temp_file"
                            echo "  Updated to local file: file://$latest_rawhide"
                        else
                            echo "  Would update Fedora Rawhide to: file://$latest_rawhide"
                            echo "$line" >> "$temp_file"
                        fi
                    else
                        # No matching locally - check if we can find a similar pattern
                        echo "  Checking for any Fedora-Cloud-Base-Generic-Rawhide*.qcow2 files..."
                        # Look for any file with the same prefix but different timestamp
                        local_candidates=$(find "$IMAGE_DIR" -maxdepth 1 -name "*Fedora-Cloud-Base-Generic-Rawhide*" -type f)
                        
                        if [[ -n "$local_candidates" ]]; then
                            most_recent=$(echo "$local_candidates" | sort -r | head -1)
                            echo "  Found matching local Fedora Rawhide image: $(basename $most_recent)"
                            
                            if [ "$DRY_RUN" = false ]; then
                                new_line="${line/\"$remote_url\"/\"file://$most_recent\"}"
                                echo "$new_line" >> "$temp_file"
                                echo "  Updated to local file: file://$most_recent"
                            else
                                echo "  Would update Fedora Rawhide to: file://$most_recent"
                                echo "$line" >> "$temp_file"
                            fi
                        else
                            echo "  Local Fedora Rawhide image not found, using original URL"
                            echo "$line" >> "$temp_file"
                        fi
                    fi
                elif [[ -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