import { Diagnostic } from '@codemirror/lint';
import { Exception, OutputStyle, Syntax } from 'sass';

import { ConsoleLog } from './console-utils';

export type PlaygroundState = {
  inputFormat: Syntax;
  outputFormat: OutputStyle;
  inputValue: string;
  compilerHasError: boolean;
  debugOutput: ConsoleLog[];
};

// State is persisted to the URL's hash format in the following format:
// [inputFormat, outputFormat, ...inputValue] = hash;
// inputFormat: 0=indented 1=scss
// outputFormat: 0=compressed 1=expanded
export function stateToBase64(state: PlaygroundState): string {
  const inputFormatChar = state.inputFormat === 'scss' ? 1 : 0;
  const outputFormatChar = state.outputFormat === 'expanded' ? 1 : 0;
  const persistedState = `${inputFormatChar}${outputFormatChar}${state.inputValue}`;
  return btoa(encodeURIComponent(persistedState));
}

export function base64ToState(string: string): Partial<PlaygroundState> {
  const state: Partial<PlaygroundState> = {};
  let decoded;
  try {
    // Remove hash
    decoded = decodeURIComponent(atob(string.slice(1)));
  } catch (error) {
    return {};
  }

  if (!/\d\d.*/.test(decoded)) return {};
  state.inputFormat = decoded.charAt(0) === '1' ? 'scss' : 'indented';
  state.outputFormat = decoded.charAt(1) === '1' ? 'expanded' : 'compressed';
  state.inputValue = decoded.slice(2);

  return state;
}

type ParseResultSuccess = { css: string };
type ParseResultError = { error: Exception | unknown };
export type ParseResult = ParseResultSuccess | ParseResultError;

export function errorToDiagnostic(error: Exception | unknown): Diagnostic {
  if (error instanceof Exception) {
    return {
      from: error.span.start.offset,
      to: error.span.end.offset,
      severity: 'error',
      message: error.toString(),
    };
  } else {
    let errorString = 'Unknown compilation error';
    if (typeof error === 'string') errorString = error;
    else if (typeof error?.toString() === 'string')
      errorString = error.toString();
    return {
      from: 0,
      to: 0,
      severity: 'error',
      message: errorString,
    };
  }
}