import './style.css'
import { SourceText, SourceRegion, sourceText } from 'source-region';
import type { SourceLocation, Span } from 'source-region';


type Expr =
| { tag: "literal", value: Literal }
| { tag: "list", values: Expr[] }

namespace Expr {
  export function number(value: number): Expr {
    return { tag: "literal", value: { tag: "number", value } };
  }
  export function identifier(value: Identifier): Expr {
    return { tag: "literal", value: { tag: "identifier", value } };
  }
  export function list(values: Expr[]): Expr {
    return { tag: "list", values };
  }

  export function show(e: Expr): string {
    switch (e.tag) {
      case "literal":
        return showLiteral(e.value);
      case "list": 
        return `(${e.values.map(show).join(" ")})`;
    }
  }

  function showLiteral(e: Literal): string {
    switch (e.tag) {
      case "number":
        return `${e.value}`;
      case "identifier":
        return `${e.value}`;
    }
  }
}

type Literal =
| { tag: "number", value: number }
| { tag: "identifier", value: Identifier }

type Identifier = string


// === Examples ===

function example00() {
  const v: Expr = Expr.list([Expr.identifier("f"), Expr.number(123), Expr.number(512)]);
  console.log(v);
  console.log(Expr.show(v));
}

function example01() {
  const str = `hello, world!
foo
bar `;

  const source = sourceText(str);
  const region = source.fullRegion();

  console.log(region);
  console.log(region.lineCount);
  region.forEachLine((span, lineNo) => {
    console.log(lineNo, region.stringOf(span));
  });
}

[
  example00,
  example01,
].forEach((f, i) => {
  console.log(`====${i}===`);
  f();
})