use std::{borrow::Cow, fmt};

use paige::Frontmatter;

#[derive(Clone, Debug)]
pub struct PageFrontmatter<'r> {
	description: Option<Cow<'r, str>>,
}

impl<'r> PageFrontmatter<'r> {
	pub fn description(&self) -> Option<&Cow<'r, str>> {
		self.description.as_ref()
	}

	pub fn set_description<D: Into<Cow<'r, str>>>(&mut self, description: D) {
		self.description = Some(description.into());
	}

	pub fn has_any(&self) -> bool {
		self.description.is_some()
	}

	pub fn from_frontmatter(&mut self, fm: &'r Frontmatter<'r>) {
		self.description = fm.get("description").map(|s| Cow::Borrowed(s));
	}
}

impl<'r> Default for PageFrontmatter<'r> {
	fn default() -> Self {
		Self { description: None }
	}
}

impl<'r> fmt::Display for PageFrontmatter<'r> {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		if !self.has_any() {
			return Ok(());
		}

		macro_rules! write_field {
			($field:ident) => {
				writeln!(f, "{}={}", stringify!($field), $field)?;
			};
		}

		writeln!(f, "---")?;

		if let Some(description) = self.description.as_ref() {
			write_field!(description);
		}

		write!(f, "---")
	}
}