#![allow(clippy::upper_case_acronyms)]
#![allow(clippy::enum_variant_names)]

use std::{
    convert::{AsRef, From},
    fmt,
    rc::Rc,
};

mod operators;
mod visitor;
mod visualize;

pub use operators::{BinOp, PrefixOp};
pub use visitor::*;

use crate::{
    derivative::Derivative,
    identifier::{define_id_kind, Id},
    parsing::Location,
};

define_id_kind!(ASTItem);

pub type ItemId = Id<ASTItem>;

#[derive(Derivative, Debug)]
#[derivative(PartialEq)]
pub struct AST {
    #[derivative(PartialEq = "ignore")]
    pub id: ItemId,
    pub statements: Block,
}

impl fmt::Display for AST {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", visualize::render_ast(self))
    }
}

#[derive(Derivative, Debug, Clone)]
#[derivative(PartialEq)]
pub struct Statement {
    #[derivative(PartialEq = "ignore")]
    pub id: ItemId,
    #[derivative(PartialEq = "ignore")]
    pub location: Location,
    pub kind: StatementKind,
}

#[derive(Debug, PartialEq, Clone)]
pub enum StatementKind {
    Expression(Expression),
    Declaration(Declaration),
    Import(ImportSpecifier),
    Flow(FlowControl),
}

#[derive(Debug, Clone, PartialEq)]
pub enum FlowControl {
    Continue,
    Break,
    Return(Option<Expression>),
}

#[derive(Debug, Clone, PartialEq, Default)]
pub struct Block {
    pub statements: Vec<Statement>,
}

impl From<Vec<Statement>> for Block {
    fn from(statements: Vec<Statement>) -> Self {
        Self { statements }
    }
}

impl From<Statement> for Block {
    fn from(statement: Statement) -> Self {
        Self { statements: vec![statement] }
    }
}

impl AsRef<[Statement]> for Block {
    fn as_ref(&self) -> &[Statement] {
        self.statements.as_ref()
    }
}

pub type ParamName = Rc<String>;

#[derive(Debug, Derivative, Clone)]
#[derivative(PartialEq)]
pub struct QualifiedName {
    #[derivative(PartialEq = "ignore")]
    pub id: ItemId,
    pub components: Vec<Rc<String>>,
}

impl fmt::Display for QualifiedName {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match &self.components[..] {
            [] => write!(f, "[<empty>]"),
            [name] => write!(f, "{}", name),
            [name, rest @ ..] => {
                write!(f, "{}", name)?;
                for c in rest {
                    write!(f, "::{}", c)?;
                }
                Ok(())
            }
        }
    }
}

#[derive(Debug, PartialEq, Clone)]
pub struct FormalParam {
    pub name: ParamName,
    pub default: Option<Expression>,
    pub anno: Option<TypeIdentifier>,
}

#[derive(Debug, PartialEq, Clone)]
pub enum Declaration {
    FuncSig(Signature),
    FuncDecl(Signature, Block),
    TypeDecl { name: TypeSingletonName, body: TypeBody, mutable: bool },
    //TODO TypeAlias `original` needs to be a more complex type definition
    TypeAlias { alias: Rc<String>, original: Rc<String> },
    Binding { name: Rc<String>, constant: bool, type_anno: Option<TypeIdentifier>, expr: Expression },
    Impl { type_name: TypeIdentifier, interface_name: Option<TypeSingletonName>, block: Vec<Declaration> },
    Interface { name: Rc<String>, signatures: Vec<Signature> },
    //TODO need to limit the types of statements that can be annotated
    Annotation { name: Rc<String>, arguments: Vec<Expression>, inner: Box<Statement> },
    Module { name: Rc<String>, items: Block },
}

#[derive(Debug, PartialEq, Clone)]
pub struct Signature {
    pub name: Rc<String>,
    pub operator: bool,
    pub params: Vec<FormalParam>,
    pub type_anno: Option<TypeIdentifier>,
}

//TODO I can probably get rid of TypeBody
#[derive(Debug, PartialEq, Clone)]
pub enum TypeBody {
    Variants(Vec<Variant>),
    ImmediateRecord(ItemId, Vec<(Rc<String>, TypeIdentifier)>),
}

#[derive(Debug, Derivative, Clone)]
#[derivative(PartialEq)]
pub struct Variant {
    #[derivative(PartialEq = "ignore")]
    pub id: ItemId,
    pub name: Rc<String>,
    pub kind: VariantKind,
}

#[derive(Debug, PartialEq, Clone)]
pub enum VariantKind {
    UnitStruct,
    TupleStruct(Vec<TypeIdentifier>),
    Record(Vec<(Rc<String>, TypeIdentifier)>),
}

#[derive(Debug, Derivative, Clone)]
#[derivative(PartialEq)]
pub struct Expression {
    #[derivative(PartialEq = "ignore")]
    pub id: ItemId,
    pub kind: ExpressionKind,
    //TODO this should only allow singletons, not tuples
    pub type_anno: Option<TypeIdentifier>,
}

impl Expression {
    pub fn new(id: ItemId, kind: ExpressionKind) -> Expression {
        Expression { id, kind, type_anno: None }
    }
}

#[derive(Debug, PartialEq, Clone)]
pub enum TypeIdentifier {
    Tuple(Vec<TypeIdentifier>),
    Singleton(TypeSingletonName),
}

#[derive(Debug, PartialEq, Clone)]
pub struct TypeSingletonName {
    pub name: Rc<String>,
    pub params: Vec<TypeIdentifier>,
}

#[derive(Debug, PartialEq, Clone)]
pub enum ExpressionKind {
    NatLiteral(u64),
    FloatLiteral(f64),
    //TODO StringLiteral variant needs to support prefixes
    StringLiteral(Rc<String>),
    BoolLiteral(bool),
    BinExp(BinOp, Box<Expression>, Box<Expression>),
    PrefixExp(PrefixOp, Box<Expression>),
    TupleLiteral(Vec<Expression>),
    Value(QualifiedName),
    NamedStruct { name: QualifiedName, fields: Vec<(Rc<String>, Expression)> },
    Call { f: Box<Expression>, arguments: Vec<InvocationArgument> },
    Index { indexee: Box<Expression>, indexers: Vec<Expression> },
    IfExpression { discriminator: Option<Box<Expression>>, body: Box<IfExpressionBody> },
    WhileExpression { condition: Option<Box<Expression>>, body: Block },
    ForExpression { enumerators: Vec<Enumerator>, body: Box<ForBody> },
    Lambda { params: Vec<FormalParam>, type_anno: Option<TypeIdentifier>, body: Block },
    Access { name: Rc<String>, expr: Box<Expression> },
    ListLiteral(Vec<Expression>),
}

#[derive(Debug, PartialEq, Clone)]
pub enum InvocationArgument {
    Positional(Expression),
    Keyword { name: Rc<String>, expr: Expression },
    Ignored,
}

#[derive(Debug, PartialEq, Clone)]
pub enum IfExpressionBody {
    SimpleConditional { then_case: Block, else_case: Option<Block> },
    SimplePatternMatch { pattern: Pattern, then_case: Block, else_case: Option<Block> },
    CondList(Vec<ConditionArm>),
}

#[derive(Debug, PartialEq, Clone)]
pub struct ConditionArm {
    pub condition: Condition,
    pub guard: Option<Expression>,
    pub body: Block,
}

#[derive(Debug, PartialEq, Clone)]
pub enum Condition {
    Pattern(Pattern),
    TruncatedOp(BinOp, Expression),
    //Expression(Expression), //I'm pretty sure I don't actually want this
    Else,
}

#[derive(Debug, PartialEq, Clone)]
pub enum Pattern {
    Ignored,
    TuplePattern(Vec<Pattern>),
    Literal(PatternLiteral),
    TupleStruct(QualifiedName, Vec<Pattern>),
    Record(QualifiedName, Vec<(Rc<String>, Pattern)>),
    VarOrName(QualifiedName),
}

#[derive(Debug, PartialEq, Clone)]
pub enum PatternLiteral {
    NumPattern { neg: bool, num: ExpressionKind },
    StringPattern(Rc<String>),
    BoolPattern(bool),
}

#[derive(Debug, PartialEq, Clone)]
pub struct Enumerator {
    pub id: Rc<String>, //TODO rename this field
    pub generator: Expression,
}

#[derive(Debug, PartialEq, Clone)]
pub enum ForBody {
    MonadicReturn(Expression),
    StatementBlock(Block),
}

#[derive(Debug, Derivative, Clone)]
#[derivative(PartialEq)]
pub struct ImportSpecifier {
    #[derivative(PartialEq = "ignore")]
    pub id: ItemId,
    pub path_components: Vec<Rc<String>>,
    pub imported_names: ImportedNames,
}

#[derive(Debug, PartialEq, Clone)]
pub enum ImportedNames {
    All,
    LastOfPath,
    List(Vec<Rc<String>>),
}

#[derive(Debug, PartialEq, Clone)]
pub struct ModuleSpecifier {
    pub name: Rc<String>,
    pub contents: Block,
}