// Adapted from https://raw.githubusercontent.com/babel/babel/4108524/packages/babel-code-frame/src/index.js
import * as chalk from 'chalk';

type Location = {
  column: number;
  line: number;
};

type NodeLocation = {
  end?: Location;
  start?: Location;
};

/**
 * Chalk styles for code frame token types.
 */
function getDefs(chalk) {
  return {
    gutter: chalk.grey,
    marker: chalk.red.bold,
    message: chalk.red.bold,
  };
}

/**
 * RegExp to test for newlines in terminal.
 */

const NEWLINE = /\r\n|[\n\r\u2028\u2029]/;

/**
 * Extract what lines should be marked and highlighted.
 */
function getMarkerLines(
  loc: NodeLocation,
  source: Array<string>,
  opts: { linesAbove?: number; linesBelow?: number } = {}
): { start: number; end: number; markerLines: Object } {
  const startLoc: Location = {
    column: 0,
    line: -1,
    ...loc.start,
  };
  const endLoc: Location = {
    ...startLoc,
    ...loc.end,
  };
  const { linesAbove = 2, linesBelow = 3 } = opts || {};
  const startLine = startLoc.line;
  const startColumn = startLoc.column;
  const endLine = endLoc.line;
  const endColumn = endLoc.column;

  let start = Math.max(startLine - (linesAbove + 1), 0);
  let end = Math.min(source.length, endLine + linesBelow);

  if (startLine === -1) {
    start = 0;
  }

  if (endLine === -1) {
    end = source.length;
  }

  const lineDiff = endLine - startLine;
  const markerLines = {};

  if (lineDiff) {
    for (let i = 0; i <= lineDiff; i++) {
      const lineNumber = i + startLine;

      if (!startColumn) {
        markerLines[lineNumber] = true;
      } else if (i === 0) {
        const sourceLength = source[lineNumber - 1].length;

        markerLines[lineNumber] = [startColumn, sourceLength - startColumn + 1];
      } else if (i === lineDiff) {
        markerLines[lineNumber] = [0, endColumn];
      } else {
        const sourceLength = source[lineNumber - i].length;

        markerLines[lineNumber] = [0, sourceLength];
      }
    }
  } else {
    if (startColumn === endColumn) {
      if (startColumn) {
        markerLines[startLine] = [startColumn, 0];
      } else {
        markerLines[startLine] = true;
      }
    } else {
      markerLines[startLine] = [startColumn, endColumn - startColumn];
    }
  }

  return { start, end, markerLines };
}

export function codeFrameColumns(
  rawLines: string,
  loc: NodeLocation,
  opts: {
    linesAbove?: number;
    linesBelow?: number;
    highlight?: (rawLines: string) => string;
  } = {}
): string {
  const defs = getDefs(chalk);
  const lines = rawLines.split(NEWLINE);
  const { start, end, markerLines } = getMarkerLines(loc, lines, opts);

  const numberMaxWidth = String(end).length;
  const highlightedLines = opts.highlight ? opts.highlight(rawLines) : rawLines;

  let frame = highlightedLines
    .split(NEWLINE)
    .slice(start, end)
    .map((line, index) => {
      const number = start + 1 + index;
      const paddedNumber = ` ${number}`.slice(-numberMaxWidth);
      const gutter = ` ${paddedNumber} | `;
      const hasMarker = markerLines[number];
      if (hasMarker) {
        let markerLine = '';
        if (Array.isArray(hasMarker)) {
          const markerSpacing = line
            .slice(0, Math.max(hasMarker[0] - 1, 0))
            .replace(/[^\t]/g, ' ');
          const numberOfMarkers = hasMarker[1] || 1;

          markerLine = [
            '\n ',
            defs.gutter(gutter.replace(/\d/g, ' ')),
            markerSpacing,
            defs.marker('^').repeat(numberOfMarkers),
          ].join('');
        }
        return [defs.marker('>'), defs.gutter(gutter), line, markerLine].join(
          ''
        );
      } else {
        return ` ${defs.gutter(gutter)}${line}`;
      }
    })
    .join('\n');

  return chalk.reset(frame);
}
