use std::num::NonZeroU64;
use std::ops::Range;
use std::sync::Arc;

use orchid_api_derive::{Coding, Hierarchy};
use orchid_api_traits::Request;

use crate::error::OrcError;
use crate::interner::{TStr, TStrv};
use crate::location::Location;
use crate::proto::HostExtReq;
use crate::system::SysId;
use crate::{Atom, Expr};

/// A token tree from a lexer recursion request. Its lifetime is the lex call,
/// the lexer can include it in its output or discard it by implication.
///
/// Similar to [crate::expr::ExprTicket] in that it represents a token tree the
/// lifetime of which is managed by the interpreter, and as such should probably
/// not be exposed to libraries directly but rather wrapped in a
/// lifetime-controlled abstraction.
#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Coding)]
pub struct TreeTicket(pub NonZeroU64);

#[derive(Clone, Debug, Coding)]
pub struct TokenTree {
  pub token: Token,
  pub range: Range<u32>,
}

#[derive(Clone, Debug, Coding)]
pub enum Token {
  /// Lambda function head, from the opening \ until the beginning of the body.
  Lambda(Vec<TokenTree>),
  /// A name segment or an operator.
  Name(TStr),
  /// ::
  NS,
  /// Line break.
  BR,
  /// ( Round parens ), [ Square brackets ] or { Curly braces }
  S(Paren, Vec<TokenTree>),
  /// A new atom
  Atom(Atom),
  /// Anchor to insert a subtree
  Slot(TreeTicket),
  /// A static compile-time error returned by failing lexers if
  /// the rest of the source is likely still meaningful
  Bottom(Vec<OrcError>),
  /// A comment
  Comment(Arc<String>),
}

#[derive(Clone, Debug, Hash, PartialEq, Eq, Coding)]
pub enum Paren {
  Round,
  Square,
  Curly,
}

#[derive(Copy, Clone, Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Coding)]
pub struct TreeId(pub NonZeroU64);

#[derive(Clone, Debug, Coding)]
pub struct Item {
  pub location: Location,
  pub comments: Vec<(Arc<String>, Location)>,
  pub kind: ItemKind,
}

#[derive(Clone, Debug, Coding)]
pub enum ItemKind {
  Member(Member),
  Raw(Vec<TokenTree>),
  Export(TStr),
  Import(CompName),
}

#[derive(Clone, Debug, Coding)]
pub struct Member {
  pub name: TStr,
  pub exported: bool,
  pub kind: MemberKind,
}

#[derive(Clone, Debug, Coding)]
pub enum MemberKind {
  Const(Expr),
  Module(Module),
  Lazy(TreeId),
}

#[derive(Clone, Debug, Coding)]
pub struct Module {
  pub imports: Vec<TStrv>,
  pub items: Vec<Item>,
}

#[derive(Clone, Debug, Coding)]
pub struct CompName {
  pub path: Vec<TStr>,
  pub name: Option<TStr>,
  pub location: Location,
}

#[derive(Clone, Copy, Debug, Coding, Hierarchy)]
#[extends(HostExtReq)]
pub struct GetMember(pub SysId, pub TreeId);
impl Request for GetMember {
  type Response = MemberKind;
}