#!/bin/bash
# resolve-module-dependencies.sh - Automatically resolve kernel module dependencies using modinfo
# This script builds a complete dependency tree for specified kernel modules

# Don't exit on errors - we want to handle missing modules gracefully
set -o pipefail

# Configuration
KERNEL_BUILD_DIR=""
MODULES_DIR=""
KERNEL_VERSION=""
VERBOSE=${VERBOSE:-0}

# Global arrays for tracking
declare -A RESOLVED_MODULES=()    # Track resolved modules to avoid duplicates
declare -A PROCESSING_MODULES=()  # Track modules being processed to detect cycles
declare -a DEPENDENCY_ORDER=()    # Final ordered list of modules

usage() {
    echo "Usage: $0 [OPTIONS] MODULE [MODULE...]"
    echo ""
    echo "Resolve kernel module dependencies using modinfo and copy to initramfs"
    echo ""
    echo "Options:"
    echo "  -k DIR     Kernel build directory (e.g., /build/kernel/linux-6.12.41)"
    echo "  -m DIR     Target modules directory (e.g., /build/initramfs/lib/modules/6.12.41-Zero-OS)"
    echo "  -v VER     Kernel version (e.g., 6.12.41-Zero-OS)"
    echo "  -V         Verbose output"
    echo "  -h         Show this help"
    echo ""
    echo "Examples:"
    echo "  $0 -k /build/kernel/linux-6.12.41 -m /build/initramfs/lib/modules/6.12.41-Zero-OS -v 6.12.41-Zero-OS tun e1000e"
    echo "  $0 -k /build/kernel/linux-6.12.41 -m /build/initramfs/lib/modules/6.12.41-Zero-OS -v 6.12.41-Zero-OS mycelium-modules.list"
}

log() {
    if [ "$VERBOSE" -eq 1 ]; then
        echo "[INFO] $*" >&2
    fi
}

warn() {
    echo "[WARN] $*" >&2
}

error() {
    echo "[ERROR] $*" >&2
    exit 1
}

# Find a kernel module file in the build directory
find_module() {
    local module_name="$1"
    
    # Try with .ko extension
    local ko_file=$(find "$KERNEL_BUILD_DIR" -name "${module_name}.ko" -type f 2>/dev/null | head -1)
    if [ -n "$ko_file" ]; then
        echo "$ko_file"
        return 0
    fi
    
    # Try without extension (in case it was passed with .ko)
    local base_name="${module_name%.ko}"
    ko_file=$(find "$KERNEL_BUILD_DIR" -name "${base_name}.ko" -type f 2>/dev/null | head -1)
    if [ -n "$ko_file" ]; then
        echo "$ko_file"
        return 0
    fi
    
    return 1
}

# Get dependencies for a module using modinfo
get_module_dependencies() {
    local module_file="$1"
    local module_name=$(basename "$module_file" .ko)
    
    if [ ! -f "$module_file" ]; then
        warn "Module file not found: $module_file"
        return 0  # Continue processing, just no dependencies
    fi
    
    # Use modinfo to get dependencies
    local deps=$(modinfo -F depends "$module_file" 2>/dev/null | tr ',' ' ')
    
    if [ -n "$deps" ]; then
        log "Dependencies for $module_name: $deps"
        echo "$deps"
    else
        log "No dependencies for $module_name"
    fi
}

# Recursively resolve module dependencies
resolve_dependencies() {
    local module_name="$1"
    local depth="$2"
    local indent=""
    
    # Create indentation for visual tree
    for i in $(seq 1 $depth); do
        indent="  $indent"
    done
    
    log "${indent}Resolving: $module_name (depth: $depth)"
    
    # Check if we're already processing this module (circular dependency)
    if [ "${PROCESSING_MODULES[$module_name]}" = "1" ]; then
        warn "${indent}Circular dependency detected for: $module_name"
        return 0
    fi
    
    # Check if already resolved
    if [ "${RESOLVED_MODULES[$module_name]}" = "1" ]; then
        log "${indent}Already resolved: $module_name"
        return 0
    fi
    
    # Mark as being processed
    PROCESSING_MODULES[$module_name]=1
    
    # Find the module file
    local module_file=$(find_module "$module_name")
    if [ -z "$module_file" ]; then
        warn "${indent}Module not found: $module_name (skipping)"
        unset PROCESSING_MODULES[$module_name]
        # Don't mark as resolved since we couldn't find it
        return 0  # Continue processing other modules
    fi
    
    # Get dependencies
    local deps=$(get_module_dependencies "$module_file")
    
    # Recursively resolve dependencies first
    for dep in $deps; do
        if [ -n "$dep" ]; then
            resolve_dependencies "$dep" $((depth + 1))
        fi
    done
    
    # Mark as resolved and add to ordered list
    RESOLVED_MODULES[$module_name]=1
    DEPENDENCY_ORDER+=("$module_name")
    log "${indent}Resolved: $module_name"
    
    # Remove from processing list
    unset PROCESSING_MODULES[$module_name]
}

# Copy module to target directory
copy_module() {
    local module_name="$1"
    local module_file=$(find_module "$module_name")
    
    if [ -z "$module_file" ]; then
        warn "Cannot copy module, file not found: $module_name"
        return 1
    fi
    
    # Determine target subdirectory based on module path
    local rel_path=$(echo "$module_file" | sed "s|^$KERNEL_BUILD_DIR/||")
    local target_dir="$MODULES_DIR/$(dirname "$rel_path")"
    local target_file="$target_dir/$(basename "$module_file")"
    
    # Create target directory
    mkdir -p "$target_dir"
    
    # Copy module
    cp "$module_file" "$target_file"
    log "Copied: $module_name -> $target_file"
}

# Parse command line arguments
while getopts "k:m:v:Vh" opt; do
    case $opt in
        k) KERNEL_BUILD_DIR="$OPTARG" ;;
        m) MODULES_DIR="$OPTARG" ;;
        v) KERNEL_VERSION="$OPTARG" ;;
        V) VERBOSE=1 ;;
        h) usage; exit 0 ;;
        *) usage; exit 1 ;;
    esac
done

shift $((OPTIND-1))

# Validate required parameters
if [ -z "$KERNEL_BUILD_DIR" ] || [ -z "$MODULES_DIR" ] || [ -z "$KERNEL_VERSION" ]; then
    error "Missing required parameters. Use -h for help."
fi

if [ ! -d "$KERNEL_BUILD_DIR" ]; then
    error "Kernel build directory not found: $KERNEL_BUILD_DIR"
fi

if [ $# -eq 0 ]; then
    error "No modules specified. Use -h for help."
fi

# Parse module list (can be individual modules or a file containing module names)
REQUIRED_MODULES=()
for arg in "$@"; do
    if [ -f "$arg" ]; then
        # Read modules from file
        log "Reading modules from file: $arg"
        while IFS= read -r line; do
            # Skip empty lines and comments
            line=$(echo "$line" | sed 's/#.*//' | xargs)
            if [ -n "$line" ]; then
                REQUIRED_MODULES+=("$line")
            fi
        done < "$arg"
    else
        # Individual module name
        REQUIRED_MODULES+=("$arg")
    fi
done

if [ ${#REQUIRED_MODULES[@]} -eq 0 ]; then
    error "No valid modules found to process"
fi

log "Processing ${#REQUIRED_MODULES[@]} required modules: ${REQUIRED_MODULES[*]}"

# Resolve dependencies for all required modules
echo "Resolving dependencies for: ${REQUIRED_MODULES[*]}"
for module in "${REQUIRED_MODULES[@]}"; do
    echo "Processing: $module"
    resolve_dependencies "$module" 0
done

# Report results
echo ""
echo "Dependency resolution complete!"
echo "Total modules required: ${#DEPENDENCY_ORDER[@]}"
echo ""
echo "Dependency order:"
for i in "${!DEPENDENCY_ORDER[@]}"; do
    printf "%3d. %s\n" $((i+1)) "${DEPENDENCY_ORDER[$i]}"
done

# Copy all modules
echo ""
echo "Copying modules to: $MODULES_DIR"
mkdir -p "$MODULES_DIR"

COPIED_COUNT=0
FAILED_COUNT=0

for module in "${DEPENDENCY_ORDER[@]}"; do
    if copy_module "$module"; then
        ((COPIED_COUNT++))
    else
        ((FAILED_COUNT++))
    fi
done

# Summary
echo ""
echo "Module installation summary:"
echo "  Successfully copied: $COPIED_COUNT modules"
echo "  Failed to copy: $FAILED_COUNT modules"
echo "  Target directory: $MODULES_DIR"

# Exit with appropriate code
if [ $COPIED_COUNT -gt 0 ]; then
    echo "SUCCESS: At least some modules were installed successfully"
    exit 0
elif [ $FAILED_COUNT -gt 0 ]; then
    echo "ERROR: All module installations failed"
    exit 1
else
    echo "ERROR: No modules were processed"
    exit 1
fi