"""Main SecPaste client API."""

from typing import Optional, Dict
from urllib.parse import urlparse, urlunparse

from .crypto.base import CipherBackend
from .crypto.aes import AESGCMCipher
from .crypto.chacha import ChaCha20Cipher
from .providers.base import PastebinProvider
from .providers.dpaste import DPasteProvider


class SecPasteClient:
    """Main client for encrypted pastebin operations."""

    # Registry of available cipher backends
    CIPHERS: Dict[str, type] = {
        'aes-256-gcm': AESGCMCipher,
        'chacha20-poly1305': ChaCha20Cipher,
    }

    # Registry of available providers
    PROVIDERS: Dict[str, type] = {
        'dpaste': DPasteProvider,
    }

    def __init__(
        self,
        cipher: str = 'aes-256-gcm',
        provider: str = 'dpaste',
        cipher_backend: Optional[CipherBackend] = None,
        provider_backend: Optional[PastebinProvider] = None
    ):
        """
        Initialize SecPaste client.

        Args:
            cipher: Name of cipher backend to use (default: aes-256-gcm)
            provider: Name of pastebin provider (default: dpaste)
            cipher_backend: Custom cipher backend instance (overrides cipher)
            provider_backend: Custom provider instance (overrides provider)
        """
        # Initialize cipher backend
        if cipher_backend:
            self.cipher = cipher_backend
        else:
            cipher_class = self.CIPHERS.get(cipher)
            if not cipher_class:
                raise ValueError(
                    f"Unknown cipher: {cipher}. "
                    f"Available: {', '.join(self.CIPHERS.keys())}"
                )
            self.cipher = cipher_class()

        # Initialize provider backend
        if provider_backend:
            self.provider = provider_backend
        else:
            provider_class = self.PROVIDERS.get(provider)
            if not provider_class:
                raise ValueError(
                    f"Unknown provider: {provider}. "
                    f"Available: {', '.join(self.PROVIDERS.keys())}"
                )
            self.provider = provider_class()

    def paste(self, content: str, **kwargs) -> str:
        """
        Encrypt and paste content.

        Args:
            content: Plain text content to paste
            **kwargs: Provider-specific options (e.g., expiry, syntax)

        Returns:
            Complete URL with encryption key in fragment (e.g., https://paste.tld/abc#key)
        """
        # Convert to bytes
        plaintext = content.encode('utf-8')

        # Encrypt
        ciphertext, key = self.cipher.encrypt(plaintext)

        # Upload to provider
        paste_url = self.provider.paste(ciphertext, **kwargs)

        # Add cipher metadata and key to URL fragment
        cipher_name = self.cipher.get_name()
        fragment = f"{cipher_name}:{key}"
        full_url = self._add_fragment(paste_url, fragment)

        return full_url

    def fetch(self, url: str) -> str:
        """
        Fetch and decrypt content from URL.

        Args:
            url: Complete URL with encryption key in fragment

        Returns:
            Decrypted plain text content
        """
        # Parse URL to extract fragment
        parsed = urlparse(url)
        if not parsed.fragment:
            raise ValueError("URL missing encryption key in fragment (#key)")

        fragment = parsed.fragment

        # Parse fragment: cipher_name:key
        if ':' not in fragment:
            # Backwards compatibility: assume default cipher
            cipher_name = 'aes-256-gcm'
            key = fragment
        else:
            cipher_name, key = fragment.split(':', 1)

        # Get appropriate cipher backend
        cipher_class = self.CIPHERS.get(cipher_name)
        if not cipher_class:
            raise ValueError(f"Unknown cipher in URL: {cipher_name}")

        cipher = cipher_class()

        # Remove fragment from URL for fetching
        fetch_url = urlunparse((
            parsed.scheme,
            parsed.netloc,
            parsed.path,
            parsed.params,
            parsed.query,
            ''  # no fragment
        ))

        # Fetch encrypted content
        ciphertext = self.provider.fetch(fetch_url)

        # Decrypt
        plaintext = cipher.decrypt(ciphertext, key)

        return plaintext.decode('utf-8')

    @staticmethod
    def _add_fragment(url: str, fragment: str) -> str:
        """Add fragment to URL."""
        parsed = urlparse(url)
        return urlunparse((
            parsed.scheme,
            parsed.netloc,
            parsed.path,
            parsed.params,
            parsed.query,
            fragment
        ))

    @classmethod
    def register_cipher(cls, name: str, cipher_class: type):
        """Register a custom cipher backend."""
        cls.CIPHERS[name] = cipher_class

    @classmethod
    def register_provider(cls, name: str, provider_class: type):
        """Register a custom pastebin provider."""
        cls.PROVIDERS[name] = provider_class

    @classmethod
    def list_ciphers(cls) -> list:
        """List available cipher backends."""
        return list(cls.CIPHERS.keys())

    @classmethod
    def list_providers(cls) -> list:
        """List available pastebin providers."""
        return list(cls.PROVIDERS.keys())