const std = @import("std");
const tokens = @import("tokens.zig");
const Token = tokens.Token;

pub const NodeList = std.ArrayList(*Node);
pub const StmtList = std.ArrayList(*Stmt);
pub const ExprList = std.ArrayList(*Expr);
pub const ParamList = std.ArrayList(ParamDecl);
pub const ConstList = std.ArrayList(SingleConst);

pub const NodeType = enum {
    Root,
    FnDecl,
    ConstDecl,
    Block,
    Expr,
    Stmt,
};

pub const ParamDecl = struct {
    name: Token,
    typ: Token,
};

pub const FnDecl = struct {
    func_name: Token,
    params: ParamList,
    return_type: Token,
    body: StmtList,
};

pub const SingleConst = struct {
    name: Token,
    expr: *Expr,
};

pub const BinaryExpr = struct {
    left: *Expr,
    op: Token,
    right: *Expr,
};

pub const UnaryExpr = struct {
    op: Token,
    right: *Expr,
};

// looks like a BinaryExpr, but is not a BinaryExpr
pub const LogicalExpr = struct {
    left: *Expr,
    op: Token,
    right: *Expr,
};

pub const LiteralExpr = union(enum) {
    Bool: bool,
    Integer: []const u8,
    Float: []const u8,
    String: []const u8,
};

pub const AssignExpr = struct {
    name: Token,
    value: *Expr,
};

pub const ExprType = enum {
    Assign,

    // vardecls as expressions is a hack
    VarDecl,

    Binary,
    Unary,
    Logical,
    Literal,
    Variable,
    Call,
    Grouping,
};

pub const VarDecl = struct {
    assign: AssignExpr,
    mutable: bool = false,
};

pub const CallExpr = struct {
    callee: *Expr,
    paren: Token,
    arguments: ExprList,
};

pub const Expr = union(ExprType) {
    Assign: AssignExpr,
    VarDecl: VarDecl,

    Binary: BinaryExpr,
    Unary: UnaryExpr,
    Logical: LogicalExpr,
    Literal: LiteralExpr,

    Variable: Token,
    Grouping: *Expr,
    Call: CallExpr,
};

pub const Block = std.ArrayList(*Stmt);

pub const IfStmt = struct {
    condition: *Expr,
    then_branch: Block,
    else_branch: ?Block,
};

pub const LoopStmt = struct {
    condition: ?*Expr,
    then_branch: Block,
};

pub const Stmt = union(enum) {
    Expr: *Expr,
    Println: *Expr,

    If: IfStmt,
    Loop: LoopStmt,

    Return: ReturnStmt,

    pub const ReturnStmt = struct {
        keyword: Token,
        value: *Expr,
    };

    pub fn mkPrintln(allocator: *std.mem.Allocator, expr: *Expr) !*Stmt {
        var stmt = try allocator.create(Stmt);
        stmt.* = Stmt{ .Println = expr };
        return stmt;
    }

    pub fn mkIfStmt(
        allocator: *std.mem.Allocator,
        condition: *Expr,
        then: Block,
        else_branch: ?Block,
    ) !*Stmt {
        var stmt = try allocator.create(Stmt);
        stmt.* = Stmt{
            .If = IfStmt{
                .condition = condition,
                .then_branch = then,
                .else_branch = else_branch,
            },
        };

        return stmt;
    }

    pub fn mkLoop(
        allocator: *std.mem.Allocator,
        condition: ?*Expr,
        then: Block,
    ) !*Stmt {
        var stmt = try allocator.create(Stmt);
        stmt.* = Stmt{
            .Loop = LoopStmt{
                .condition = condition,
                .then_branch = then,
            },
        };

        return stmt;
    }

    pub fn mkReturn(allocator: *std.mem.Allocator, tok: Token, value: *Expr) !*Stmt {
        var stmt = try allocator.create(Stmt);
        stmt.* = Stmt{
            .Return = ReturnStmt{
                .keyword = tok,
                .value = value,
            },
        };

        return stmt;
    }
};

pub const Node = union(NodeType) {
    Root: NodeList,
    FnDecl: FnDecl,
    ConstDecl: ConstList,

    Block: StmtList,

    Expr: *Expr,
    Stmt: *Stmt,
};

pub fn mkRoot(allocator: *std.mem.Allocator) !*Node {
    var node = try allocator.create(Node);
    node.* = Node{ .Root = NodeList.init(allocator) };
    return node;
}