#!/usr/bin/env python3
"""
Validate WhatsApp Cloud API configuration.

Checks environment variables and tests API connectivity.

Usage:
    python validate_config.py
    python validate_config.py --env-file /path/to/.env
"""

import argparse
import os
import sys

try:
    import httpx
except ImportError:
    print("Error: httpx not installed. Run: pip install httpx")
    sys.exit(1)

try:
    from dotenv import load_dotenv
except ImportError:
    print("Warning: python-dotenv not installed. Using system environment only.")
    load_dotenv = None

GRAPH_API = "https://graph.facebook.com/v21.0"

REQUIRED_VARS = [
    ("WHATSAPP_TOKEN", "Access token for WhatsApp Cloud API"),
    ("PHONE_NUMBER_ID", "Phone Number ID from API Setup"),
    ("WABA_ID", "WhatsApp Business Account ID"),
    ("APP_SECRET", "App Secret from App Settings > Basic"),
    ("VERIFY_TOKEN", "Custom token for webhook verification"),
]


def check_env_vars() -> tuple[bool, list[str]]:
    """Check if all required environment variables are set."""
    missing = []
    for var_name, description in REQUIRED_VARS:
        value = os.environ.get(var_name)
        if not value or value.startswith("your_"):
            missing.append(f"  {var_name} - {description}")

    return len(missing) == 0, missing


def _mask_secret(value: str) -> str:
    """Return a masked version of a secret for safe logging."""
    if not value or len(value) < 8:
        return "***masked***"
    return f"{value[:6]}...masked"


def test_api_connection() -> tuple[bool, str]:
    """Test connection to WhatsApp Cloud API."""
    token = os.environ.get("WHATSAPP_TOKEN", "")
    phone_id = os.environ.get("PHONE_NUMBER_ID", "")

    try:
        response = httpx.get(
            f"{GRAPH_API}/{phone_id}",
            params={"fields": "verified_name,code_verification_status,display_phone_number,quality_rating"},
            headers={"Authorization": f"Bearer {token}"},
            timeout=10.0,
        )

        if response.status_code == 200:
            data = response.json()
            return True, (
                f"Phone: {data.get('display_phone_number', 'N/A')}\n"
                f"  Name: {data.get('verified_name', 'N/A')}\n"
                f"  Status: {data.get('code_verification_status', 'N/A')}\n"
                f"  Quality: {data.get('quality_rating', 'N/A')}"
            )
        else:
            error = response.json().get("error", {})
            return False, f"API Error {error.get('code', '?')}: {error.get('message', 'Unknown')}"

    except httpx.ConnectError:
        return False, "Connection failed. Check your internet connection."
    except httpx.TimeoutException:
        return False, "Request timed out after 10 seconds."
    except Exception as e:
        # Mask token in error output to prevent credential leakage
        safe_err = str(e).replace(token, _mask_secret(token)) if token else str(e)
        return False, f"Unexpected error: {safe_err}"


def test_waba_access() -> tuple[bool, str]:
    """Test access to WhatsApp Business Account."""
    token = os.environ.get("WHATSAPP_TOKEN", "")
    waba_id = os.environ.get("WABA_ID", "")

    try:
        response = httpx.get(
            f"{GRAPH_API}/{waba_id}/phone_numbers",
            headers={"Authorization": f"Bearer {token}"},
            timeout=10.0,
        )

        if response.status_code == 200:
            data = response.json()
            count = len(data.get("data", []))
            return True, f"WABA accessible. {count} phone number(s) found."
        else:
            error = response.json().get("error", {})
            return False, f"API Error {error.get('code', '?')}: {error.get('message', 'Unknown')}"

    except Exception as e:
        # Mask token in error output to prevent credential leakage
        safe_err = str(e).replace(token, _mask_secret(token)) if token else str(e)
        return False, f"Error: {safe_err}"


def main():
    parser = argparse.ArgumentParser(description="Validate WhatsApp Cloud API configuration")
    parser.add_argument("--env-file", default=".env", help="Path to .env file (default: .env)")
    args = parser.parse_args()

    # Load environment
    if load_dotenv and os.path.exists(args.env_file):
        load_dotenv(args.env_file)
        print(f"Loaded: {args.env_file}")
    elif not os.path.exists(args.env_file):
        print(f"Warning: {args.env_file} not found. Using system environment.")

    print()
    print("=" * 50)
    print("WhatsApp Cloud API - Configuration Validator")
    print("=" * 50)
    print()

    all_ok = True

    # Check 1: Environment variables
    print("[1/3] Checking environment variables...")
    env_ok, missing = check_env_vars()
    if env_ok:
        print("  OK - All required variables are set")
    else:
        print("  FAIL - Missing variables:")
        for m in missing:
            print(f"    {m}")
        all_ok = False

    print()

    if not env_ok:
        print("Cannot test API without required variables. Fix the above and retry.")
        sys.exit(1)

    # Check 2: API connection
    print("[2/3] Testing API connection (Phone Number)...")
    api_ok, api_msg = test_api_connection()
    if api_ok:
        print(f"  OK - Connected successfully")
        print(f"  {api_msg}")
    else:
        print(f"  FAIL - {api_msg}")
        all_ok = False

    print()

    # Check 3: WABA access
    print("[3/3] Testing WABA access...")
    waba_ok, waba_msg = test_waba_access()
    if waba_ok:
        print(f"  OK - {waba_msg}")
    else:
        print(f"  FAIL - {waba_msg}")
        all_ok = False

    print()
    print("=" * 50)
    if all_ok:
        print("All checks passed! Your configuration is valid.")
        print("You can start sending messages.")
    else:
        print("Some checks failed. Please fix the issues above.")
        print("Need help? Read: references/setup-guide.md")
    print("=" * 50)

    sys.exit(0 if all_ok else 1)


if __name__ == "__main__":
    main()