import os
import csv
from datetime import datetime

def search_in_file(file_path: str, needle: str, case_sensitive: bool = True):
    """Search for a string in a file.
    Returns a list of (line_number, line_text) for each match."""
    matches = []
    try:
        with open(file_path, "r", encoding="utf-8", errors="ignore") as f:
            text = f.read()
    except (OSError, UnicodeDecodeError):
        # Skip files that cannot be read as text
        return matches

    if not text or not needle:
        return matches

    # Prepare for case (in)sensitive search
    if case_sensitive:
        haystack = text
        needle_cmp = needle
    else:
        haystack = text.lower()
        needle_cmp = needle.lower()

    start = 0
    while True:
        idx = haystack.find(needle_cmp, start)
        if idx == -1:
            break

        # Line number = number of '\n' before the match + 1
        line_number = text.count("\n", 0, idx) + 1

        # Get the full line where the match begins (for display)
        line_start = text.rfind("\n", 0, idx)
        line_end = text.find("\n", idx)
        if line_start == -1:
            line_start = 0
        else:
            line_start += 1
        if line_end == -1:
            line_end = len(text)

        line_text = text[line_start:line_end].strip()
        matches.append((line_number, line_text))

        # Move past this match to find others
        start = idx + 1

    return matches


def scan(root: str, needle: str, case_sensitive: bool = True):
    """Recursively scan root folder and search in all files."""
    results = []

    for dirpath, dirnames, filenames in os.walk(root):
        for filename in filenames:
            full_path = os.path.join(dirpath, filename)
            file_matches = search_in_file(full_path, needle, case_sensitive)
            for line_number, line_text in file_matches:
                results.append({
                    "file_path": full_path,
                    "folder": dirpath,
                    "line_number": line_number,
                    "line_text": line_text,
                })

    return results


def choose_folder(base_dir: str) -> str:
    """List subfolders of base_dir and let user pick one (or base_dir itself)."""
    print(f"Base directory: {base_dir}\n")

    # Find direct subdirectories
    entries = os.listdir(base_dir)
    subfolders = [d for d in entries if os.path.isdir(os.path.join(base_dir, d))]
    subfolders.sort()

    # Always include option 0 = current/base directory
    print("Select which folder to scan:")
    print("  0) (this folder and all subfolders)")

    if subfolders:
        for idx, folder in enumerate(subfolders, start=1):
            print(f"  {idx}) {folder}")
    else:
        print("  (no subfolders found, only option is 0)")

    while True:
        choice = input("\nEnter the number of the folder to scan: ").strip()
        if not choice.isdigit():
            print("Please enter a valid number.")
            continue

        idx = int(choice)

        if idx == 0:
            return base_dir

        if 1 <= idx <= len(subfolders):
            return os.path.join(base_dir, subfolders[idx - 1])

        print("Invalid choice, try again.")


def write_results_to_csv(results, csv_path: str):
    """Write all results to a CSV file."""
    fieldnames = ["file_path", "folder", "line_number", "line_text"]
    try:
        # newline='' is important on Windows to avoid blank lines
        with open(csv_path, "w", encoding="utf-8", newline="") as csvfile:
            writer = csv.DictWriter(csvfile, fieldnames=fieldnames)
            writer.writeheader()
            for row in results:
                writer.writerow(row)
    except OSError as e:
        print(f"Error writing CSV file: {e}")
        return False
    return True


if __name__ == "__main__":
    # Use the directory where this script is located as the base
    script_dir = os.path.dirname(os.path.abspath(__file__))

    # Step 1: Choose folder
    target_root = choose_folder(script_dir)
    print(f"\nScanning in: {target_root}\n")

    # Step 2: Ask what code/text to search
    pattern = input("Enter the exact code/text to search for: ")

    # Step 3: Case sensitivity
    case_input = input("Case-sensitive search? (y/n, default: y): ").strip().lower()
    case_sensitive = (case_input != "n")

    print("\nSearching... this may take a moment on large folders.\n")

    results = scan(target_root, pattern, case_sensitive=case_sensitive)

    if not results:
        print("No matches found.")
    else:
        print(f"Total matches found: {len(results)}")

        # Default CSV file name with timestamp
        default_name = f"search_results_{datetime.now().strftime('%Y%m%d_%H%M%S')}.csv"
        user_name = input(
            f"Enter CSV file name to save results "
            f"(press Enter for default '{default_name}'): "
        ).strip()

        if not user_name:
            csv_name = default_name
        else:
            # Ensure it ends with .csv
            if not user_name.lower().endswith(".csv"):
                csv_name = user_name + ".csv"
            else:
                csv_name = user_name

        csv_path = os.path.join(script_dir, csv_name)

        if write_results_to_csv(results, csv_path):
            print(f"\nResults saved to CSV: {csv_path}")
        else:
            print("\nFailed to save results to CSV.")