#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import os
import hashlib
from datetime import datetime
import mysql.connector
from mysql.connector import Error
from dotenv import load_dotenv
from pathlib import Path


# ======================================================
# Load environment
# ======================================================
env_path = Path(__file__).resolve().parent / ".env"
load_dotenv(env_path)


# ======================================================
# MySQL connection
# ======================================================
def get_db_connection():
    conn = mysql.connector.connect(
        host=os.getenv("DB_MYSQL_HOST"),
        user=os.getenv("DB_MYSQL_ROOT"),
        password=os.getenv("DB_MYSQL_ROOT_PASS"),
        port=int(os.getenv("DB_MYSQL_PORT")),
        database="walkfiles",
        auth_plugin="mysql_native_password"
    )
    c = conn.cursor()
    c.execute("SET NAMES utf8mb4 COLLATE utf8mb4_general_ci")
    c.close()
    return conn


# ======================================================
# Helpers
# ======================================================
def file_md5(path, chunk_size=1024 * 1024):
    """Compute content MD5 of a file in chunks."""
    md5 = hashlib.md5()
    with open(path, "rb") as f:
        while chunk := f.read(chunk_size):
            md5.update(chunk)
    return md5.hexdigest()


def parse_size(size_str: str) -> int:
    """
    Convert human input like:
        10MB, 500kB, 2GB
    into bytes. If already numeric, return as-is.
    """
    s = size_str.strip().upper()
    if s.endswith("KB"):
        return int(float(s[:-2]) * 1024)
    if s.endswith("MB"):
        return int(float(s[:-2]) * 1024 * 1024)
    if s.endswith("GB"):
        return int(float(s[:-2]) * 1024 * 1024 * 1024)
    return int(s)  # assume raw bytes


# ======================================================
# MAIN LOGIC
# ======================================================
def run_md5_calculator(device_name=None,
                       device_id=None,
                       extension=".pdf",
                       max_size="50MB",
                       path_prefix=None):
    """
    Accepts:
        device_name="ANY"  -> no device filter
        device_id="ANY"    -> no device filter
        extension="ANY"    -> no extension filter
        max_size="ANY"     -> no size filter
        path_prefix="ANY"  -> no path filter
    """

    # ---------------------------------------------------------
    # Interpret ANY values into boolean filter logic
    # ---------------------------------------------------------

    # DEVICE filter
    filter_by_device = True
    if device_name == "ANY" or device_id == "ANY":
        filter_by_device = False

    elif device_id is None:
        # device_name provided -> resolve device_id
        if device_name is None:
            raise RuntimeError("You must provide device_name or device_id")
        cursor = None
        conn = get_db_connection()
        cursor = conn.cursor(dictionary=True)
        cursor.execute("SELECT id FROM devices WHERE name=%s", (device_name,))
        row = cursor.fetchone()
        cursor.close(); conn.close()
        if not row:
            raise RuntimeError(f"Device '{device_name}' not found")
        device_id = row["id"]

    # EXTENSION filter
    filter_by_extension = (extension != "ANY")

    # SIZE filter
    filter_by_size = (max_size != "ANY")
    if filter_by_size:
        max_bytes = parse_size(max_size)
    else:
        max_bytes = None

    # PATH filter
    filter_by_path = (path_prefix not in [None, "", "ANY"])
    if filter_by_path:
        cleaned_prefix = path_prefix.rstrip("\\/")
    else:
        cleaned_prefix = None

    print(
        f"\n🔍 Filtering:"
        f" device={'ANY' if not filter_by_device else device_id},"
        f" ext={extension},"
        f" max_size={max_size},"
        f" prefix={path_prefix}\n"
    )

    conn, cursor = None, None

    try:
        conn = get_db_connection()
        cursor = conn.cursor(dictionary=True)

        # ---------------------------------------------------------
        # Build WHERE clauses dynamically
        # ---------------------------------------------------------
        where_clauses = ["deleted = 0"]
        params = []

        if filter_by_device:
            where_clauses.append("device_id=%s")
            params.append(device_id)

        if filter_by_extension:
            where_clauses.append("path LIKE %s")
            params.append("%" + extension)

        if filter_by_size:
            where_clauses.append("size <= %s")
            params.append(max_bytes)

        if filter_by_path:
            where_clauses.append("path LIKE %s")
            params.append(cleaned_prefix + "%")

        sql = f"""
            SELECT id, path, size, modified, content_md5, md5_calculated
            FROM files
            WHERE {" AND ".join(where_clauses)}
        """

        cursor.execute(sql, params)
        rows = cursor.fetchall()

        total = len(rows)
        print(f"📁 Files matching criteria: {total}")

        updates = 0

        # ---------------------------------------------------------
        # PROCESS FILES
        # ---------------------------------------------------------
        for row in rows:
            file_id = row["id"]
            path = row["path"]
            modified = row["modified"]
            prev_md5 = row["content_md5"]
            prev_calc = row["md5_calculated"]

            # Skip missing files
            if not os.path.isfile(path):
                print(f"⚠️ Missing on disk, skipping: {path}")
                continue

            need_md5 = (
                prev_md5 is None or
                prev_calc is None or
                prev_calc < modified
            )

            if not need_md5:
                continue

            print(f"🔄 Calculating MD5: {path}")

            new_md5 = file_md5(path)
            now = datetime.now().replace(microsecond=0)

            cursor.execute("""
                UPDATE files
                SET content_md5=%s,
                    md5_calculated=%s
                WHERE id=%s
            """, (new_md5, now, file_id))

            updates += 1

        conn.commit()

        print("\n✅ MD5 calculation finished.")
        print(f"   Updated files: {updates}")
        print(f"   Skipped files: {total - updates}\n")

    except Exception as e:
        print("Error:", e)

    finally:
        if cursor: cursor.close()
        if conn: conn.close()



# ======================================================
# RUN EXAMPLE
# ======================================================
if __name__ == "__main__":
    # Example usage:
    run_md5_calculator(
        device_name="TWW11",
        extension="ANY",
        max_size="ANY",
        path_prefix=r"ANY"
    )