#!/bin/bash

# Git Submodule Dependency Tree Generator
# Usage: ./git-submodule-tree.sh <github-repo-url>

set -euo pipefail

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
BLUE='\033[0;34m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

# Function to print usage
usage() {
    echo "Usage: $0 <github-repo-url>"
    echo "Example: $0 https://github.com/user/repo.git"
    exit 1
}

# Check if URL is provided
if [ $# -eq 0 ]; then
    usage
fi

REPO_URL="$1"
TEMP_DIR=$(mktemp -d)
VISITED_REPOS=()

# Clean up on exit
cleanup() {
    rm -rf "$TEMP_DIR"
}
trap cleanup EXIT

# Function to check if repo was already visited
is_visited() {
    local repo="$1"
    for visited in "${VISITED_REPOS[@]}"; do
        if [ "$visited" == "$repo" ]; then
            return 0
        fi
    done
    return 1
}

# Function to extract repo info from .gitmodules
parse_gitmodules() {
    local gitmodules_file="$1"
    local indent="$2"
    
    if [ ! -f "$gitmodules_file" ]; then
        return
    fi
    
    # Parse .gitmodules file
    while IFS= read -r line; do
        if [[ $line =~ ^\[submodule[[:space:]]+\"(.+)\"\] ]]; then
            local name="${BASH_REMATCH[1]}"
            local path=""
            local url=""
            local branch=""
            
            # Read submodule details
            while IFS= read -r subline && ! [[ $subline =~ ^\[submodule ]]; do
                if [[ $subline =~ path[[:space:]]*=[[:space:]]*(.+) ]]; then
                    path="${BASH_REMATCH[1]}"
                elif [[ $subline =~ url[[:space:]]*=[[:space:]]*(.+) ]]; then
                    url="${BASH_REMATCH[1]}"
                elif [[ $subline =~ branch[[:space:]]*=[[:space:]]*(.+) ]]; then
                    branch="${BASH_REMATCH[1]}"
                fi
            done
            
            if [ -n "$url" ]; then
                # Print submodule info
                echo -e "${indent}├── ${GREEN}${name}${NC}"
                echo -e "${indent}│   └── ${BLUE}${url}${NC}"
                
                # Check for commit hash or branch
                if [ -n "$path" ] && [ -d "$(dirname "$gitmodules_file")/$path" ]; then
                    cd "$(dirname "$gitmodules_file")/$path" 2>/dev/null || true
                    local commit=$(git rev-parse HEAD 2>/dev/null || echo "")
                    if [ -n "$commit" ]; then
                        echo -e "${indent}│       └── ${YELLOW}commit: ${commit:0:8}${NC}"
                    fi
                    if [ -n "$branch" ]; then
                        echo -e "${indent}│       └── ${YELLOW}branch: ${branch}${NC}"
                    fi
                    cd - > /dev/null 2>&1 || true
                fi
                
                # Mark as visited
                VISITED_REPOS+=("$url")
                
                # Recursively process submodule if not already visited
                if ! is_visited "$url"; then
                    process_repo "$url" "${indent}│   "
                fi
            fi
        fi
    done < "$gitmodules_file"
}

# Function to process a repository
process_repo() {
    local repo_url="$1"
    local indent="${2:-}"
    
    # Skip if already visited
    if is_visited "$repo_url"; then
        return
    fi
    
    # Create temporary directory for this repo
    local repo_dir=$(mktemp -d -p "$TEMP_DIR")
    
    # Clone the repository (shallow clone for speed)
    echo -e "${indent}${RED}Cloning: ${repo_url}${NC}" >&2
    if ! git clone --depth 1 --recurse-submodules "$repo_url" "$repo_dir" 2>/dev/null; then
        echo -e "${indent}${RED}Failed to clone: ${repo_url}${NC}" >&2
        return
    fi
    
    # Process .gitmodules if it exists
    if [ -f "$repo_dir/.gitmodules" ]; then
        parse_gitmodules "$repo_dir/.gitmodules" "$indent"
    fi
    
    # Clean up this repo
    rm -rf "$repo_dir"
}

# Main execution
echo -e "${GREEN}Git Submodule Dependency Tree${NC}"
echo -e "${GREEN}==============================${NC}"
echo -e "${BLUE}${REPO_URL}${NC}"

# Mark main repo as visited
VISITED_REPOS+=("$REPO_URL")

# Process the main repository
process_repo "$REPO_URL" ""

echo -e "\n${GREEN}Complete!${NC}"