import configureMeasurements, { allMeasures } from 'convert-units';

export const convert = configureMeasurements(allMeasures);

export const bases: {[key: number]: string[]} = {
  2: ['bin', 'binary'],
  8: ['oct', 'octal'],
  10: ['dec', 'decimal'],
  16: ['hex', 'hexadecimal']
};

export function getBaseNum(base: string): number | null {
  let result = null;
  for (const i in bases) {
    const defs = bases[i];
    if (defs.indexOf(base) === -1) {
      continue;
    }
    result = parseInt(i, 10);
  }

  if (result) {
    return result;
  }

  if (base.indexOf('b') !== 0) {
    return null;
  }

  const matcher = base.match(/b(?:ase)?-?(\d+)/);
  if (!matcher || !matcher[1] || isNaN(parseInt(matcher[1], 10))) {
    return null;
  }
  return parseInt(matcher[1], 10);
}

export function rgbToHex(r: number, g: number, b: number): string {
  // tslint:disable-next-line: no-bitwise
  return '#' + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1);
}

export function RGBToHSL(r: number, g: number, b: number): {[key: string]: number} {
  // Make r, g, and b fractions of 1
  r /= 255;
  g /= 255;
  b /= 255;

  // Find greatest and smallest channel values
  const cmin = Math.min(r, g, b);
  const cmax = Math.max(r, g, b);
  const delta = cmax - cmin;
  let h = 0;
  let s = 0;
  let l = 0;

  // Calculate hue
  // No difference
  if (delta === 0) {
    h = 0;
  } // Red is max
  else if (cmax === r) {
    h = ((g - b) / delta) % 6;
  } // Green is max
  else if (cmax === g) {
    h = (b - r) / delta + 2;
  } // Blue is max
  else {
    h = (r - g) / delta + 4;
  }

  h = Math.round(h * 60);

  // Make negative hues positive behind 360°
  if (h < 0) {
    h += 360;
  }

  // Calculate lightness
  l = (cmax + cmin) / 2;

  // Calculate saturation
  s = delta === 0 ? 0 : delta / (1 - Math.abs(2 * l - 1));

  // Multiply l and s by 100
  s = +(s * 100).toFixed(1);
  l = +(l * 100).toFixed(1);

  return { h, s, l };
}

export function hexToRgb(hex: string): {[key: string]: number} | null {
  // Expand shorthand form (e.g. "03F") to full form (e.g. "0033FF")
  const shorthandRegex = /^#?([a-f\d])([a-f\d])([a-f\d])$/i;
  hex = hex.replace(shorthandRegex, (m, r, g, b) => {
    return r + r + g + g + b + b;
  });

  const result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
  return result ? {
    r: parseInt(result[1], 16),
    g: parseInt(result[2], 16),
    b: parseInt(result[3], 16)
  } : null;
}

// Create an object to efficiently translate unit names to their abbreviations
let unitIndex: { [x: string]: string[] } = {};
let backupLowercaseUnitTable: { [x: string]: string } = {};
export function createUnitIndex(): void {
  const fullList = convert().list();
  fullList.forEach((unit) => {
    const { abbr, singular, plural } = unit;
    if (!unitIndex[abbr]) {
      unitIndex[abbr] = [
        abbr, singular.toLowerCase(), plural.toLowerCase()
      ];

      // liter <-> litres
      if (abbr === 'l') {
        unitIndex[abbr].push('liter', 'liters');
      }

      // meter -> metre
      if (singular.includes('meter')) {
        unitIndex[abbr].push(
          singular.replace('meter', 'metre').toLowerCase(),
          plural.replace('meter', 'metre').toLowerCase(),
        );
      }

      // metre -> meter
      if (singular.includes('metre')) {
        unitIndex[abbr].push(
          singular.replace('metre', 'meter').toLowerCase(),
          plural.replace('metre', 'meter').toLowerCase(),
        );
      }

      // degree(s) Celsius -> celsius
      if (singular.startsWith('degree ')) {
        unitIndex[abbr].push(
          singular.split(' ')[1].toLowerCase(),
        );
      }

      // " per " -> "/"
      const appendages: string[] = [];
      unitIndex[abbr].forEach((entry) => {
        if (entry.includes(' per ')) {
          appendages.push(entry.replace(' per ', '/'));
        }
      });
      unitIndex[abbr].push(...appendages);

      backupLowercaseUnitTable[abbr.toLowerCase()] = abbr;
    }
  });
}

// Get a unit by it's full name or abbreviation
export function getUnitAbbreviation(fullText: string): string | null {
  // Regular abbreviation
  if (unitIndex[fullText]) {
    return fullText;
  }

  // Lowercase abbreviation
  const lowerText = fullText.toLowerCase();
  if (backupLowercaseUnitTable[lowerText]) {
    return backupLowercaseUnitTable[lowerText];
  }

  // Text search
  const found = Object.keys(unitIndex).reduce((previous, current) => {
    const arrayList = unitIndex[current];
    if (arrayList.includes(lowerText)) {
      return current;
    }
    return previous;
  }, '');

  return found || null;
}

export function wipeCaches(): void {
  unitIndex = {};
  backupLowercaseUnitTable = {};
}

export function ASCIIBinaryConverter(input: string, simplified: string[]): string {
  let response = '';
  let strArr;
  let i;
  let text = input.split(' ').slice(2).join(' ');

  switch (simplified[0] ? simplified[0].toUpperCase() : null) {
  case 'ENCODE':
    strArr = text.split('');

    for (i in strArr) {
      response += ('0000000' +
          parseInt(Buffer.from(strArr[i].toString(), 'utf8').toString('hex'), 16).toString(2)).slice(-8);
    }

    response = response.substring(1);

    break;
  case 'DECODE':
    text = text.split(' ').join('');
    i = 0;

    while (8 * (i + 1) <= text.length) {
      response += Buffer.from(parseInt(text.substring(8 * i, 8), 2).toString(16), 'hex').toString('utf8');
      i++;
    }

    response = response.replace(/\n/g, '\\n').replace(/\r/g, '\\r');
  }

  return response;
}

export function ASCIIHexConverter(input: string, simplified: string[]): string {
  let response = '';
  let i;
  let text = input.split(' ').slice(2).join(' ');

  switch (simplified[0] ? simplified[0].toUpperCase() : null) {
  case 'DECODE':
    text = text.replace(/\s/g, '');

    for (i = 0; i < text.length; i += 2) {
      response += String.fromCharCode(parseInt(text.substring(i, 2), 16));
    }

    response = response.replace(/\n/g, '\\n').replace(/\r/g, '\\r');
    break;
  case 'ENCODE':
    for (i = 0; i < text.length; i++) {
      response += text.charCodeAt(i).toString(16) + ' ';
    }
    break;
  }

  return response;
}

export function base64Converter(input: string, simplified: string[]): string {
  let response = '';
  const text = input.split(' ').slice(2).join(' ');

  switch (simplified[0] ? simplified[0].toUpperCase() : null) {
  case 'DECODE':
    response = (Buffer.from(text, 'base64').toString('ascii')).replace(/\n/g, '\\n').replace(/\r/g, '\\r');
    break;
  case 'ENCODE':
    response = Buffer.from(text).toString('base64');
    break;
  }

  return response;
}

export function baseConverter(simplified: string[]): string {
  if (simplified.length < 3) {
    throw new Error('Too few arguments!');
  }

  const input = simplified[0];
  const src = simplified[1].toLowerCase();
  const dst = simplified[2].toLowerCase();

  const srcBase = getBaseNum(src);
  const dstBase = getBaseNum(dst);

  if (!srcBase || !dstBase || dstBase > 36 || dstBase < 2 || srcBase > 36 || srcBase < 2) {
    throw new Error('Invalid conversion.');
  }

  const decimal = parseInt(input, srcBase);
  return decimal.toString(dstBase);
}