/**
 * Expr-lang token types and AST definitions
 */

export enum TokenKind {
  Identifier = 'Identifier',
  Number = 'Number',
  String = 'String',
  Operator = 'Operator',
  Bracket = 'Bracket',
  EOF = 'EOF',
}

export interface Token {
  kind: TokenKind;
  value: string;
  start: number;
  end: number;
  line: number;
  column: number;
}

export interface ParseError {
  message: string;
  startLine: number;
  startColumn: number;
  endLine: number;
  endColumn: number;
}

export const EOF_TOKEN: Token = {
  kind: TokenKind.EOF,
  value: '',
  start: 0,
  end: 0,
  line: 0,
  column: 0,
};

// Operator precedence (higher = binds tighter)
export const OPERATOR_PRECEDENCE: Record<string, number> = {
  '??': 1,
  '||': 2,
  or: 2,
  '&&': 3,
  and: 3,
  '==': 4,
  '!=': 4,
  '<': 5,
  '>': 5,
  '<=': 5,
  '>=': 5,
  in: 5,
  matches: 5,
  contains: 5,
  startsWith: 5,
  endsWith: 5,
  '+': 6,
  '-': 6,
  '*': 7,
  '/': 7,
  '%': 7,
  '^': 8,
  '**': 8,
};

// Unary operators
export const UNARY_OPERATORS = new Set(['!', 'not', '-']);

// Right-associative operators
export const RIGHT_ASSOCIATIVE = new Set(['**', '^']);

// Comparison operators (for chained comparisons)
export const COMPARISON_OPERATORS = new Set(['<', '>', '<=', '>=', '==', '!=']);

// Keywords
export const KEYWORDS = new Set(['let', 'true', 'false', 'nil', 'in', 'not', 'and', 'or', 'if', 'else']);