"""Environment-based configuration using Pydantic Settings.

All settings are configurable via environment variables or .env file.
"""

from __future__ import annotations

from pydantic import BaseModel, Field


class APIConfig(BaseModel):
    """API server configuration."""
    host: str = Field(default="0.0.0.0", description="Server bind host")
    port: int = Field(default=8000, description="Server bind port")
    workers: int = Field(default=1, description="Number of worker processes")
    cors_origins: list[str] = Field(default=["*"], description="CORS allowed origins")
    api_key: str | None = Field(default=None, description="API key for authentication")
    rate_limit: int = Field(default=120, description="Rate limit (requests per window)")
    rate_window: float = Field(default=60.0, description="Rate limit window in seconds")


class DatabaseConfig(BaseModel):
    """Database configuration."""
    url: str = Field(default="sqlite:///fusionagi.db", description="Database URL")
    pool_size: int = Field(default=5, description="Connection pool size")
    max_overflow: int = Field(default=10, description="Max overflow connections")
    echo: bool = Field(default=False, description="Echo SQL statements")


class CacheConfig(BaseModel):
    """Cache configuration."""
    enabled: bool = Field(default=True, description="Enable response caching")
    max_size: int = Field(default=1000, description="Max cached entries")
    ttl_seconds: float = Field(default=300.0, description="Cache TTL in seconds")
    backend: str = Field(default="memory", description="Cache backend (memory or redis)")
    redis_url: str | None = Field(default=None, description="Redis URL if backend is redis")


class LoggingConfig(BaseModel):
    """Logging configuration."""
    level: str = Field(default="INFO", description="Log level")
    format: str = Field(default="json", description="Log format (json or text)")
    correlation_id_header: str = Field(default="X-Request-ID", description="Request ID header")


class GovernanceConfig(BaseModel):
    """Governance configuration."""
    mode: str = Field(default="advisory", description="Governance mode (advisory or enforcing)")
    max_file_size: int | None = Field(default=None, description="Max file size in bytes (None=unlimited)")
    allow_private_urls: bool = Field(default=True, description="Allow private/internal URLs")


class FusionAGIConfig(BaseModel):
    """Root configuration for FusionAGI."""
    api: APIConfig = Field(default_factory=APIConfig)
    database: DatabaseConfig = Field(default_factory=DatabaseConfig)
    cache: CacheConfig = Field(default_factory=CacheConfig)
    logging: LoggingConfig = Field(default_factory=LoggingConfig)
    governance: GovernanceConfig = Field(default_factory=GovernanceConfig)
    tenant_isolation: bool = Field(default=True, description="Enable tenant isolation")
    max_concurrent_tasks: int = Field(default=5, description="Max background tasks")


def load_config() -> FusionAGIConfig:
    """Load configuration from environment variables.

    Environment variables are mapped using the pattern:
    FUSIONAGI_<SECTION>_<KEY> (e.g., FUSIONAGI_API_PORT=9000)
    """
    import os
    config = FusionAGIConfig()

    env_map = {
        "FUSIONAGI_API_HOST": ("api", "host"),
        "FUSIONAGI_API_PORT": ("api", "port"),
        "FUSIONAGI_API_WORKERS": ("api", "workers"),
        "FUSIONAGI_API_KEY": ("api", "api_key"),
        "FUSIONAGI_RATE_LIMIT": ("api", "rate_limit"),
        "FUSIONAGI_RATE_WINDOW": ("api", "rate_window"),
        "FUSIONAGI_DB_URL": ("database", "url"),
        "FUSIONAGI_DB_POOL_SIZE": ("database", "pool_size"),
        "FUSIONAGI_CACHE_ENABLED": ("cache", "enabled"),
        "FUSIONAGI_CACHE_TTL": ("cache", "ttl_seconds"),
        "FUSIONAGI_CACHE_BACKEND": ("cache", "backend"),
        "FUSIONAGI_REDIS_URL": ("cache", "redis_url"),
        "FUSIONAGI_LOG_LEVEL": ("logging", "level"),
        "FUSIONAGI_LOG_FORMAT": ("logging", "format"),
        "FUSIONAGI_GOVERNANCE_MODE": ("governance", "mode"),
    }

    for env_var, (section, key) in env_map.items():
        value = os.environ.get(env_var)
        if value is not None:
            section_obj = getattr(config, section)
            field_info = type(section_obj).model_fields.get(key)
            if field_info and field_info.annotation:
                annotation = field_info.annotation
                if annotation is int:
                    value = int(value)  # type: ignore[assignment]
                elif annotation is float:
                    value = float(value)  # type: ignore[assignment]
                elif annotation is bool:
                    value = value.lower() in ("true", "1", "yes")  # type: ignore[assignment]
            setattr(section_obj, key, value)

    return config