"""
Environment configuration management for the MCP server.
"""

import ipaddress
import json
import os
from dataclasses import dataclass, field
from typing import Any
from urllib.parse import urlparse

from jose import jwt


class ConfigurationError(Exception):
    """Raised when there's an error in configuration."""

    pass


@dataclass
class EnvironmentConfig:
    """Configuration loaded from environment variables."""

    supabase_url: str
    supabase_service_key: str
    port: int  # Required - no default
    openai_api_key: str | None = None
    gemini_api_key: str | None = None
    host: str = "0.0.0.0"
    transport: str = "sse"
    token_pricing: dict[str, Any] = field(default_factory=dict)


@dataclass
class RAGStrategyConfig:
    """Configuration for RAG strategies."""

    use_contextual_embeddings: bool = False
    use_hybrid_search: bool = True
    use_agentic_rag: bool = True
    use_reranking: bool = True


def validate_openai_api_key(api_key: str) -> bool:
    """Validate OpenAI API key format, allowing test keys in test environments."""
    if not api_key:
        raise ConfigurationError("OpenAI API key cannot be empty")

    # Allow mock keys during testing if pytest is running
    if os.getenv("PYTEST_CURRENT_TEST") and api_key.startswith("test_"):
        return True

    if not api_key.startswith("sk-"):
        raise ConfigurationError("OpenAI API key must start with 'sk-'")

    return True


def validate_supabase_key(supabase_key: str) -> tuple[bool, str]:
    """Validate Supabase key type and return validation result.

    Returns:
        tuple[bool, str]: (is_valid, message)
        - (False, "ANON_KEY_DETECTED") if anon key detected
        - (True, "VALID_SERVICE_KEY") if service key detected
        - (False, "UNKNOWN_KEY_TYPE:{role}") for unknown roles
        - (True, "UNABLE_TO_VALIDATE") if JWT cannot be decoded
    """
    if not supabase_key:
        return False, "EMPTY_KEY"

    try:
        # Decode JWT without verification to check the 'role' claim
        # We don't verify the signature since we only need to check the role
        # Also skip all other validations (aud, exp, etc) since we only care about the role
        decoded = jwt.decode(
            supabase_key,
            "",
            options={
                "verify_signature": False,
                "verify_aud": False,
                "verify_exp": False,
                "verify_nbf": False,
                "verify_iat": False,
            },
        )
        role = decoded.get("role")

        if role == "anon":
            return False, "ANON_KEY_DETECTED"
        elif role == "service_role":
            return True, "VALID_SERVICE_KEY"
        else:
            return False, f"UNKNOWN_KEY_TYPE:{role}"

    except Exception:
        # If we can't decode the JWT, we'll allow it to proceed
        # This handles new key formats or non-JWT keys
        return True, "UNABLE_TO_VALIDATE"


def validate_supabase_url(url: str) -> bool:
    """Validate Supabase URL format."""
    if not url:
        raise ConfigurationError("Supabase URL cannot be empty")

    parsed = urlparse(url)
    # Allow HTTP for local development (host.docker.internal or localhost)
    if parsed.scheme not in ("http", "https"):
        raise ConfigurationError("Supabase URL must use HTTP or HTTPS")

    # Require HTTPS for production (non-local) URLs
    if parsed.scheme == "http":
        hostname = parsed.hostname or ""

        # Check for exact localhost and Docker internal hosts (security: prevent subdomain bypass)
        local_hosts = ["localhost", "127.0.0.1", "host.docker.internal"]
        if hostname in local_hosts or hostname.endswith(".localhost"):
            return True

        # Check if hostname is a private IP address
        try:
            ip = ipaddress.ip_address(hostname)
            # Allow HTTP for private IP addresses (RFC 1918)
            # Class A: 10.0.0.0/8
            # Class B: 172.16.0.0/12
            # Class C: 192.168.0.0/16
            # Also includes link-local (169.254.0.0/16) and loopback
            # Exclude unspecified address (0.0.0.0) for security
            if (ip.is_private or ip.is_loopback or ip.is_link_local) and not ip.is_unspecified:
                return True
        except ValueError:
            # hostname is not a valid IP address, could be a domain name
            pass

        # If not a local host or private IP, require HTTPS
        raise ConfigurationError(f"Supabase URL must use HTTPS for non-local environments (hostname: {hostname})")

    if not parsed.netloc:
        raise ConfigurationError("Invalid Supabase URL format")

    return True


def load_environment_config() -> EnvironmentConfig:
    """Load and validate environment configuration."""
    # OpenAI API key is optional at startup - can be set via API
    openai_api_key = os.getenv("OPENAI_API_KEY")

    # Required environment variables for database access
    supabase_url = os.getenv("SUPABASE_URL")
    if not supabase_url:
        raise ConfigurationError("SUPABASE_URL environment variable is required")

    supabase_service_key = os.getenv("SUPABASE_SERVICE_KEY")
    if not supabase_service_key:
        raise ConfigurationError("SUPABASE_SERVICE_KEY environment variable is required")

    # Validate required fields
    if openai_api_key:
        validate_openai_api_key(openai_api_key)
    validate_supabase_url(supabase_url)

    # Validate Supabase key type
    is_valid_key, key_message = validate_supabase_key(supabase_service_key)
    if not is_valid_key:
        if key_message == "ANON_KEY_DETECTED":
            raise ConfigurationError(
                "CRITICAL: You are using a Supabase ANON key instead of a SERVICE key.\n\n"
                "The ANON key is a public key with read-only permissions that cannot write to the database.\n"
                "This will cause all database operations to fail with 'permission denied' errors.\n\n"
                "To fix this:\n"
                "1. Go to your Supabase project dashboard\n"
                "2. Navigate to Settings > API keys\n"
                "3. Find the 'service_role' key (NOT the 'anon' key)\n"
                "4. Update your SUPABASE_SERVICE_KEY environment variable\n\n"
                "Key characteristics:\n"
                "- ANON key: Starts with 'eyJ...' and has role='anon' (public, read-only)\n"
                "- SERVICE key: Starts with 'eyJ...' and has role='service_role' (private, full access)\n\n"
                "Current key role detected: anon"
            )
        elif key_message.startswith("UNKNOWN_KEY_TYPE:"):
            role = key_message.split(":", 1)[1]
            raise ConfigurationError(
                f"CRITICAL: Unknown Supabase key role '{role}'.\n\n"
                f"Expected 'service_role' but found '{role}'.\n"
                f"This key type is not supported and will likely cause failures.\n\n"
                f"Please use a valid service_role key from your Supabase dashboard."
            )
        # For UNABLE_TO_VALIDATE, we continue silently

    # Optional environment variables with defaults
    host = os.getenv("HOST", "0.0.0.0")
    port_str = os.getenv("PORT")
    if not port_str:
        # This appears to be for MCP configuration based on default 8051
        port_str = os.getenv("ARCHON_MCP_PORT")
        if not port_str:
            raise ConfigurationError(
                "PORT or ARCHON_MCP_PORT environment variable is required. "
                "Please set it in your .env file or environment. "
                "Default value: 8051"
            )
    transport = os.getenv("TRANSPORT", "sse")

    # Validate and convert port
    try:
        port = int(port_str)
    except ValueError as e:
        raise ConfigurationError(f"PORT must be a valid integer, got: {port_str}") from e

    # Load Token Pricing from JSON environment variable (Phase 4.6.15)
    # This allows Charlie to adjust budget pricing without code changes.
    # Phase 4.6.15: Priority DB -> ENV
    token_pricing_json = os.getenv("TOKEN_PRICING_JSON")
    try:
        from ..utils import get_supabase_client

        db_res = (
            get_supabase_client().table("archon_settings").select("value").eq("key", "TOKEN_PRICING_JSON").execute()
        )
        if db_res.data:
            token_pricing_json = db_res.data[0]["value"]
    except Exception:
        pass
    default_pricing = {
        "gpt-4o": {"input": 2.50, "output": 10.00},
        "gpt-4o-mini": {"input": 0.15, "output": 0.60},
        "gemini-3.1-pro-preview": {"input": 1.25, "output": 5.00},
        "gemini-3.1-flash": {"input": 0.10, "output": 0.40},
        "gemini-3.1-flash-lite": {"input": 0.05, "output": 0.20},
        "text-embedding-004": {"input": 0.02, "output": 0.00},
        "ollama": {"input": 0.00, "output": 0.00},
    }

    token_pricing = default_pricing
    if token_pricing_json:
        try:
            custom_pricing = json.loads(token_pricing_json)
            # Merge custom pricing into defaults
            token_pricing.update(custom_pricing)
        except json.JSONDecodeError:
            # Fallback to defaults if JSON is malformed
            pass

    return EnvironmentConfig(
        openai_api_key=openai_api_key,
        supabase_url=supabase_url,
        supabase_service_key=supabase_service_key,
        host=host,
        port=port,
        transport=transport,
        token_pricing=token_pricing,
    )


def get_config() -> EnvironmentConfig:
    """Get environment configuration with validation."""
    return load_environment_config()


def get_rag_strategy_config() -> RAGStrategyConfig:
    """Load RAG strategy configuration from environment variables."""

    def str_to_bool(value: str | None) -> bool:
        """Convert string environment variable to boolean."""
        if value is None:
            return False
        return value.lower() in ("true", "1", "yes", "on")

    return RAGStrategyConfig(
        use_contextual_embeddings=str_to_bool(os.getenv("USE_CONTEXTUAL_EMBEDDINGS")),
        use_hybrid_search=str_to_bool(os.getenv("USE_HYBRID_SEARCH")),
        use_agentic_rag=str_to_bool(os.getenv("USE_AGENTIC_RAG")),
        use_reranking=str_to_bool(os.getenv("USE_RERANKING")),
    )