//! Mermaid diagram rendering via mermaid-rs-renderer.

//!

//! Converts Mermaid diagram definitions to SVG at build-time.

use mermaid_rs_renderer::RenderOptions;

use std::panic;

/// Render a Mermaid diagram to SVG.

///

/// # Arguments

/// * `code` - The Mermaid diagram definition

///

/// # Returns

/// The rendered SVG string, or an error message on failure.

///

/// # Note

/// Uses catch_unwind to handle panics in upstream dependencies gracefully.

pub fn render_diagram(code: &str) -> Result<String, String> {

let code = code.to_owned();

let result = panic::catch_unwind(move || {

let opts = RenderOptions::modern();

mermaid_rs_renderer::render_with_options(&code, opts)

});

match result {

Ok(Ok(svg)) => Ok(svg),

Ok(Err(e)) => Err(e.to_string()),

Err(_) => Err("mermaid rendering panicked (upstream bug)".to_string()),

}

}

#[cfg(test)]

mod tests {

use super::*;

#[test]

fn test_simple_flowchart() {

let result = render_diagram("flowchart LR; A-->B-->C").unwrap();

assert!(result.contains("<svg"));

assert!(result.contains("</svg>"));

}

#[test]

fn test_sequence_diagram() {

let result = render_diagram("sequenceDiagram\n Alice->>Bob: Hello").unwrap();

assert!(result.contains("<svg"));

}

#[test]

fn test_invalid_syntax_no_panic() {

// Should not panic, returns error

let result = render_diagram("invalid diagram syntax ???");

// May succeed with error node or fail gracefully

assert!(result.is_ok() || result.is_err());

}

#[test]

fn test_state_diagram() {

let result =

render_diagram("stateDiagram-v2\n [*] --> Idle\n Idle --> Processing: Start");

assert!(result.is_ok() || result.is_err());

}

}