"""
Request Validation Utilities.

This module provides validation helpers for request parameters,
following FastAPI best practices.
"""

import uuid

from pydantic import BaseModel, Field, field_validator


class UUIDParam(BaseModel):
    """Base model for UUID path parameters with validation."""

    uuid: str = Field(..., description="UUID parameter")

    @field_validator("uuid")
    @classmethod
    def validate_uuid(cls, v: str) -> str:
        """Validate that the string is a valid UUID."""
        try:
            uuid.UUID(v)
        except ValueError:
            raise ValueError(f"Invalid UUID format: {v}")
        return v


def validate_uuid(v: str) -> str:
    """Standalone UUID validator function."""
    try:
        uuid.UUID(v)
    except ValueError:
        raise ValueError(f"Invalid UUID format: {v}")
    return v


class SessionIdParam(BaseModel):
    """Validated session ID parameter."""

    session_id: str = Field(..., min_length=36, max_length=36)

    @field_validator("session_id")
    @classmethod
    def validate_session_id(cls, v: str) -> str:
        """Validate session ID is a valid UUID."""
        try:
            uuid.UUID(v)
        except ValueError:
            raise ValueError("Invalid session_id format - must be a valid UUID")
        return v


class ProjectIdParam(BaseModel):
    """Validated project ID parameter."""

    project_id: int = Field(..., gt=0)

    @field_validator("project_id")
    @classmethod
    def validate_project_id(cls, v: int) -> int:
        """Validate project ID is positive."""
        if v <= 0:
            raise ValueError("project_id must be a positive integer")
        return v


# Re-export validation errors for consistent error handling
__all__ = [
    "UUIDParam",
    "SessionIdParam",
    "ProjectIdParam",
    "validate_uuid",
]