mcp-postgres 3.2.0

use crate::errors::MCPError;

const MAX_IDENTIFIER_LEN: usize = 255;

pub fn validate_identifier(name: &str, label: &str) -> Result<(), MCPError> {
    if name.is_empty() {
        return Err(MCPError::InvalidParams(format!("'{label}' must not be empty")));
    }
    if name.len() > MAX_IDENTIFIER_LEN {
        return Err(MCPError::InvalidParams(
            format!("'{label}' exceeds maximum length of {MAX_IDENTIFIER_LEN} characters (got {})", name.len())
        ));
    }
    for ch in name.chars() {
        if !ch.is_alphanumeric() && ch != '_' {
            return Err(MCPError::InvalidParams(
                format!("'{label}' contains invalid character '{ch}' — only alphanumeric and underscore allowed")
            ));
        }
    }
    if name.starts_with(|c: char| c.is_ascii_digit()) {
        return Err(MCPError::InvalidParams(
            format!("'{label}' must not start with a digit")
        ));
    }
    Ok(())
}

pub fn quote_identifier(name: &str) -> String {
    format!("\"{}\"", name)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_valid_identifier() {
        assert!(validate_identifier("users", "table").is_ok());
        assert!(validate_identifier("user_orders_2024", "table").is_ok());
    }

    #[test]
    fn test_empty_identifier() {
        let err = validate_identifier("", "table").unwrap_err();
        assert!(err.to_string().contains("must not be empty"));
    }

    #[test]
    fn test_too_long_identifier() {
        let long = "a".repeat(256);
        let err = validate_identifier(&long, "table").unwrap_err();
        assert!(err.to_string().contains("exceeds maximum length"));
    }

    #[test]
    fn test_invalid_char_identifier() {
        let err = validate_identifier("users; DROP TABLE", "table").unwrap_err();
        assert!(err.to_string().contains("invalid character"));
    }

    #[test]
    fn test_digit_start_identifier() {
        let err = validate_identifier("1users", "table").unwrap_err();
        assert!(err.to_string().contains("must not start with a digit"));
    }

    #[test]
    fn test_quote_identifier() {
        assert_eq!(quote_identifier("users"), "\"users\"");
        assert_eq!(quote_identifier("order_items"), "\"order_items\"");
    }
}