from pydantic import BaseModel, Field
from typing import Optional


class ContentReference(BaseModel):
    """
    Reference to content location in the original trace using line numbers and character positions.
    """
    line_start: Optional[int] = Field(None, 
        description="""Starting line number where the content begins (1-based indexing from <L1>, <L2>... markers)."""
    )
    line_end: Optional[int] = Field(None, 
        description="""Ending line number where content ends (1-based indexing from <L1>, <L2>... markers)."""
    )
    
    def validate_line_range(self) -> bool:
        """Validate that line_end >= line_start"""
        return self.line_end >= self.line_start
    
    def get_line_count(self) -> int:
        """Get the number of lines this reference spans"""
        return self.line_end - self.line_start + 1
    
    def is_single_line(self) -> bool:
        """Check if this reference is within a single line"""
        return self.line_start == self.line_end
    
    def __str__(self) -> str:
        """String representation for debugging"""
        if self.is_single_line():
            return f"Line {self.line_start}"
        else:
            return f"Lines {self.line_start}-{self.line_end}"