affine_preview 0.1.0

use merman::{MermaidConfig, render::HeadlessRenderer};
use serde_json::{Map, Value, json};

use crate::{PreviewError, Result};

#[derive(Debug, Default)]
pub struct MermaidRenderOptions {
  pub theme: Option<String>,
  pub font_family: Option<String>,
  pub font_size: Option<f64>,
}

pub fn render_mermaid_svg(source: &str, options: MermaidRenderOptions) -> Result<String> {
  let config = render_config(options);
  HeadlessRenderer::new()
    .with_site_config(config)
    .render_svg_sync(source)
    .map_err(|error| PreviewError::Mermaid(error.to_string()))?
    .ok_or_else(|| PreviewError::Mermaid("unsupported Mermaid diagram".to_string()))
}

fn render_config(options: MermaidRenderOptions) -> MermaidConfig {
  let mut config = match options.theme.as_deref() {
    Some("default") | _ => json!({ "theme": "default" }),
    Some("dark") => json!({ "theme": "dark", "darkMode": true }),
  };

  let config = config.as_object_mut().expect("preview config is an object");
  if let Some(font_family) = options.font_family.as_ref() {
    config.insert("fontFamily".to_string(), Value::String(font_family.clone()));
  }
  let variables = config
    .entry("themeVariables")
    .or_insert_with(|| Value::Object(Map::new()))
    .as_object_mut()
    .expect("theme variables are an object");

  if let Some(font_family) = options.font_family {
    variables.insert("fontFamily".to_string(), Value::String(font_family));
  }
  if let Some(font_size) = options.font_size {
    variables.insert("fontSize".to_string(), Value::String(format!("{font_size}px")));
  }

  MermaidConfig::from_value(Value::Object(config.clone()))
}

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

  #[test]
  fn renders_supported_diagram_families() {
    let diagrams = [
      ("architecture", "architecture-beta\nservice api[API]"),
      ("block", "block\n  columns 2\n  A --> B"),
      ("c4", "C4Context\nPerson(user, \"User\")"),
      ("class", "classDiagram\nAnimal <|-- Dog"),
      ("er", "erDiagram\nUSER ||--o{ ORDER : places"),
      ("flowchart", "flowchart TD\nA --> B"),
      (
        "gantt",
        "gantt\ntitle Plan\ndateFormat YYYY-MM-DD\nsection Work\nTask :2026-01-01, 1d",
      ),
      ("gitgraph", "gitGraph\ncommit id: \"start\""),
      ("info", "info"),
      ("journey", "journey\ntitle Day\nsection Work\nTask: 5: Me"),
      ("kanban", "kanban\n  Todo\n    item1"),
      ("mindmap", "mindmap\n  root((AFFiNE))\n    Preview"),
      ("packet", "packet-beta\n0-7: \"Header\""),
      ("pie", "pie\n\"A\" : 1\n\"B\" : 2"),
      (
        "quadrantchart",
        "quadrantChart\n    x-axis Low --> High\n    y-axis Low --> High\n    A: [0.3, 0.6]",
      ),
      (
        "radar",
        "radar-beta\n  axis quality[\"Quality\"], speed[\"Speed\"]\n  curve product[\"Product\"]{3, 4}\n  max 5",
      ),
      (
        "requirement",
        "requirementDiagram\nrequirement test_req {\nid: 1\ntext: Test\nrisk: low\nverifymethod: test\n}",
      ),
      ("sankey", "sankey-beta\nA,B,10\nA,C,5"),
      ("sequence", "sequenceDiagram\nAlice->>Bob: Hello"),
      ("state", "stateDiagram-v2\n[*] --> Ready"),
      ("timeline", "timeline\ntitle History\n2026 : Started"),
      ("treemap", "treemap\n  \"Root\"\n    \"Item\": 10"),
      ("venn", "venn-beta\n  set A[\"Alpha\"]:20"),
      ("xychart", "xychart-beta\nx-axis [1, 2]\ny-axis 0 --> 2\nline [1, 2]"),
      ("zenuml", "zenuml\n  Alice->Bob: Hello"),
    ];

    let supported = merman::supported_diagrams();
    assert_eq!(diagrams.len(), supported.len());
    for (family, diagram) in diagrams {
      assert!(supported.contains(&family), "missing corpus for {family}");
      let svg = render_mermaid_svg(diagram, MermaidRenderOptions::default())
        .unwrap_or_else(|error| panic!("failed to render {diagram:?}: {error}"));
      assert!(svg.starts_with("<svg"), "{diagram}");
      assert!(svg.trim_end().ends_with("</svg>"), "{diagram}");
    }
  }

  #[test]
  fn applies_theme_and_font_options() {
    let svg = render_mermaid_svg(
      "flowchart TD\nA[你好] --> B[Done]",
      MermaidRenderOptions {
        theme: Some("dark".to_string()),
        font_family: Some("IBM Plex Mono".to_string()),
        font_size: Some(18.0),
      },
    )
    .unwrap();

    assert!(svg.contains("IBM Plex Mono"));
    assert!(svg.contains("你好"));
  }
}