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

import os
import hashlib
from datetime import datetime
import mysql.connector
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"):
    """
    device_name OR device_id must be provided.
    extension: ".pdf", ".jpg", etc.
    max_size: "10MB", "500KB", "1GB" or number of bytes
    """

    max_bytes = parse_size(max_size)

    conn, cursor = None, None

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

        # ------------------------------------------
        # Resolve device_id if only device_name given
        # ------------------------------------------
        if device_id is None:
            if device_name is None:
                raise RuntimeError("You must provide device_name or device_id")
            cursor.execute("SELECT id FROM devices WHERE name=%s", (device_name,))
            row = cursor.fetchone()
            if not row:
                raise RuntimeError(f"Device '{device_name}' not found")
            device_id = row["id"]

        print(f"\n🔍 Filtering: device={device_id}, ext={extension}, max_size={max_bytes} bytes\n")

        # ------------------------------------------
        # SELECT only files that need MD5 calculation
        # ------------------------------------------
        cursor.execute("""
            SELECT id, path, size, modified, content_md5, md5_calculated
            FROM files
            WHERE device_id=%s
              AND deleted = 0
              AND path LIKE %s
              AND size <= %s
        """, (device_id, "%" + extension, max_bytes))

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

        updates = 0

        for row in rows:

            file_id = row["id"]
            path = row["path"]
            size = row["size"]
            modified = row["modified"]
            prev_md5 = row["content_md5"]
            prev_calc = row["md5_calculated"]

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

            # -------------------------------
            # Check conditions for recalculation
            # -------------------------------
            need_md5 = False

            if prev_md5 is None:
                need_md5 = True
            else:
                if prev_calc is None or prev_calc < modified:
                    need_md5 = True

            if not need_md5:
                continue

            # -------------------------------
            # Compute MD5
            # -------------------------------
            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

            # optional commit per-file:
            # conn.commit()

        conn.commit()

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

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

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


# ======================================================
# RUN EXAMPLE
# ======================================================
if __name__ == "__main__":
    # Example usage:
    run_md5_calculator(
        device_name="Z230",
        extension=".pdf",
        max_size="100MB"
    )