use std::collections::HashMap;

use serde::{Deserialize, Deserializer, de};
use smartstring::{LazyCompact, SmartString};
use thiserror::Error;

use crate::{Label, objectpath::PathParseError as ObjectPathError};

mod parser;
pub use parser::GroupSegment;

#[derive(Debug, Error, PartialEq)]
pub enum GroupPatternParseError {
	/// A `{` or `}` appeared in an invalid position, or a `{` was never closed.
	#[error("syntax error at index {position}")]
	Syntax { position: usize },

	/// The contents of a `{...}` block could not be parsed as an object path.
	#[error("invalid object path {path:?}: {source}")]
	InvalidObjectPath {
		start: usize,
		end: usize,
		path: SmartString<LazyCompact>,
		source: ObjectPathError,
	},
}

#[derive(Debug, Clone, Default)]
pub struct GroupPattern {
	pub pattern: HashMap<Label, Vec<GroupSegment>>,
}

impl<'de> Deserialize<'de> for GroupPattern {
	fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
		let raw = HashMap::<String, String>::deserialize(deserializer)?;
		let mut parts = HashMap::with_capacity(raw.len());
		for (key, value) in raw {
			let label = Label::try_from(key.as_str()).map_err(de::Error::custom)?;
			let segments = parser::Parser::new()
				.parse(&value)
				.map_err(de::Error::custom)?
				.into_iter()
				.map(|(_, seg)| seg)
				.collect();
			parts.insert(label, segments);
		}
		Ok(GroupPattern { pattern: parts })
	}
}