use arcstr::Substr;
use derive_more::Deref;
use indexmap::IndexMap;
use std::ops::Range;
use std::sync::Arc;

#[derive(Debug, Deref)]
pub struct Ident(pub Substr);

#[derive(Debug, Deref)]
pub struct Import(pub Expr);

#[derive(Debug)]
pub struct Number {
	pub text: Substr,
	pub r#type: Option<Ident>,
}

#[derive(derive_more::Debug)]
pub enum Expr {
	#[debug("uninit")]
	Uninit(Substr),
	#[debug("Ident({:?})", _0.0)]
	Ident(Ident),
	#[debug("{_0:?}")]
	Number(Number),
	String(Substr),
	#[debug("{_0:?}")]
	Binary(Box<BinaryExpr>),
	Index(Box<IndexingExpr>),
	Access(Box<AccessExpr>),
	Deref(Box<Expr>),
	Tuple(Vec<Expr>),
	List(Vec<Expr>),
	Struct(Box<StructCtor>),
	#[debug("{_0:?}")]
	Block(Arc<Block>),
	#[debug("{_0:?}")]
	Func(Arc<Function>),
	#[debug("{_0:?}")]
	Type(Box<Type>),

	#[debug("{_0:?}")]
	ConstDecl(Box<ConstDecl>),
	#[debug("{_0:?}")]
	VarDecl(Box<VarDecl>),
	#[debug("{_0:?}")]
	For(Box<For>),
	#[debug("{_0:?}")]
	While(Box<While>),
	#[debug("{_0:?}")]
	If(Box<If>),

	Call {
		func: Box<Expr>,
		args: Vec<Expr>,
	},
}

impl Expr {
	pub fn range(&self) -> Range<usize> {
		match self {
			Self::Ident(e) => e.range(),
			Self::Access(e) => e.range(),
			Self::Number(e) => e.text.range(),
			_ => todo!("{self:?}"),
		}
	}
}

#[derive(Debug)]
pub struct BinaryExpr {
	pub lhs: Expr,
	pub op: BinaryOp,
	pub rhs: Expr,
}

#[derive(Debug)]
pub struct IndexingExpr {
	pub value: Expr,
	pub index: Expr,
}

#[derive(Debug)]
pub struct AccessExpr {
	pub value: Expr,
	pub field: Ident,
}

impl AccessExpr {
	pub fn range(&self) -> Range<usize> {
		self.value.range().start..self.field.0.range().end
	}
}

#[rustfmt::skip]
#[derive(derive_more::Debug)]
pub enum BinaryOp {
	#[debug("{_0}")] Add(Substr),
	#[debug("{_0}")] Sub(Substr),
	#[debug("{_0}")] Mul(Substr),
	#[debug("{_0}")] Div(Substr),
	#[debug("{_0}")] Mod(Substr),
	#[debug("{_0}")] Eq(Substr),
	#[debug("{_0}")] Ne(Substr),
	#[debug("{_0}")] Lt(Substr),
	#[debug("{_0}")] Gt(Substr),
	#[debug("{_0}")] Le(Substr),
	#[debug("{_0}")] Ge(Substr),
	#[debug("{_0}")] Range(Substr),
	#[debug("{_0}")] Assign(Substr),
	#[debug("{_0}")] Cast(Substr),
}

#[derive(Debug)]
pub enum Type {
	Ptr { base: Expr, mutable: Option<Substr> },
	Struct(Struct),
}

#[derive(Debug)]
pub struct ConstDecl {
	pub names: NamePattern,
	pub r#type: Option<Expr>,
	pub value: Expr,
}

#[derive(Debug)]
pub struct VarDecl {
	pub names: NamePattern,
	pub r#type: Option<Expr>,
	pub value: Expr,
}

#[derive(Debug)]
pub enum NamePattern {
	Single(Ident),
	Tuple(Vec<Ident>),
	List(Vec<Ident>),
}

impl NamePattern {
	pub fn as_slice(&self) -> &[Ident] {
		match self {
			NamePattern::Single(ident) => std::slice::from_ref(ident),
			NamePattern::Tuple(idents) => idents.as_slice(),
			NamePattern::List(idents) => idents.as_slice(),
		}
	}
}

#[derive(Debug)]
pub struct Function {
	pub text: Substr,
	pub args: Vec<NameValuePair>,
	pub ret: Option<Expr>,
	pub block: Option<Arc<Block>>,
}

#[derive(Debug)]
pub struct NameValuePair {
	pub name: Ident,
	pub value: Expr,
}

#[derive(Debug)]
pub struct Struct {
	pub fields: Vec<Field>,
}

#[derive(Debug)]
pub struct Field {
	pub name: Ident,
	pub ty: Expr,
	pub public: Option<Substr>,
	pub mutable: Option<Substr>,
}

#[derive(Debug)]
pub struct StructCtor {
	pub r#type: Option<Expr>,
	pub r#values: IndexMap<Substr, NameValuePair>,
	pub(crate) range: Range<usize>,
}

impl StructCtor {
	pub fn range(&self) -> Range<usize> {
		self.range.clone()
	}
}

#[derive(Debug)]
pub struct Block(pub Vec<Expr>);

#[derive(Debug)]
pub struct For {
	pub names: NamePattern,
	pub value: Expr,
	pub block: Block,
}

#[derive(Debug)]
pub struct While {
	pub cond: Expr,
	pub block: Block,
}

#[derive(Debug)]
pub struct If {
	pub cond: Expr,
	pub block: Block,
	pub else_: Option<Box<Else>>,
}

#[derive(Debug)]
pub enum Else {
	If(If),
	Block(Block),
}

#[derive(Debug)]
pub struct CompilationUnit {
	pub imports: Vec<Import>,
	pub decls: Vec<ConstDecl>,
}