/**
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

import type { CompareKeys } from 'pretty-format'
import { getColors } from '../colors'
import type { DiffOptions, DiffOptionsNormalized } from './types'

export const noColor = (string: string): string => string

const DIFF_CONTEXT_DEFAULT = 5

function getDefaultOptions(): DiffOptionsNormalized {
  const c = getColors()

  return {
    aAnnotation: 'Expected',
    aColor: c.green,
    aIndicator: '-',
    bAnnotation: 'Received',
    bColor: c.red,
    bIndicator: '+',
    changeColor: c.inverse,
    changeLineTrailingSpaceColor: noColor,
    commonColor: c.dim,
    commonIndicator: ' ',
    commonLineTrailingSpaceColor: noColor,
    compareKeys: undefined,
    contextLines: DIFF_CONTEXT_DEFAULT,
    emptyFirstOrLastLinePlaceholder: '',
    expand: true,
    includeChangeCounts: false,
    omitAnnotationLines: false,
    patchColor: c.yellow,
  }
}

function getCompareKeys(compareKeys?: CompareKeys): CompareKeys {
  return (compareKeys && typeof compareKeys === 'function')
    ? compareKeys
    : undefined
}

function getContextLines(contextLines?: number): number {
  return (typeof contextLines === 'number'
  && Number.isSafeInteger(contextLines)
  && contextLines >= 0)
    ? contextLines
    : DIFF_CONTEXT_DEFAULT
}

// Pure function returns options with all properties.
export function normalizeDiffOptions(options: DiffOptions = {}): DiffOptionsNormalized {
  return {
    ...getDefaultOptions(),
    ...options,
    compareKeys: getCompareKeys(options.compareKeys),
    contextLines: getContextLines(options.contextLines),
  }
}