import {
  codegenExpression,
  constants,
  functions
} from 'vega-expression';

import {
  isTuple
} from 'vega-dataflow';

import {
  selectionIdTest,
  selectionResolve,
  selectionTest,
  selectionTuples,
  selectionVisitor
} from 'vega-selections';

import {
  cumulativeLogNormal,
  cumulativeNormal,
  cumulativeUniform,
  densityLogNormal,
  densityNormal,
  densityUniform,
  quantileLogNormal,
  quantileNormal,
  quantileUniform,
  random,
  sampleLogNormal,
  sampleNormal,
  sampleUniform
} from 'vega-statistics';

import {
  dayofyear,
  timeOffset,
  timeSequence,
  timeUnitSpecifier,
  utcOffset,
  utcSequence,
  utcdayofyear,
  utcweek,
  week
} from 'vega-time';

import {
  clampRange,
  extend,
  extent,
  flush,
  inrange,
  isArray,
  isBoolean,
  isDate,
  isNumber,
  isObject,
  isRegExp,
  isString,
  lerp,
  pad,
  panLinear,
  panLog,
  panPow,
  panSymlog,
  peek,
  quarter,
  span,
  stringValue,
  toBoolean,
  toDate,
  toNumber,
  toString,
  truncate,
  utcquarter,
  zoomLinear,
  zoomLog,
  zoomPow,
  zoomSymlog
} from 'vega-util';

import {
  range as sequence
} from 'd3-array';

import {
  hcl,
  hsl,
  lab,
  rgb
} from 'd3-color';

import {
  contrast,
  luminance
} from './functions/luminance';

import {
  data,
  indata,
  setdata
} from './functions/data';

import encode from './functions/encode';

import {
  dayAbbrevFormat,
  dayFormat,
  format,
  monthAbbrevFormat,
  monthFormat,
  timeFormat,
  timeParse,
  utcFormat,
  utcParse
} from './functions/format';

import {
  geoArea,
  geoBounds,
  geoCentroid,
  geoScale
} from './functions/geo';

import inScope from './functions/inscope';

import intersect from './functions/intersect';

import {
  debug,
  info,
  warn
} from './functions/log';

import merge from './functions/merge';

import modify from './functions/modify';

import {
  pinchAngle,
  pinchDistance
} from './functions/pinch';

import pluck from './functions/pluck';

import {
  indexof,
  join,
  lastindexof,
  replace,
  reverse,
  slice
} from './functions/sequence';

import {
  intersectLasso,
  lassoAppend,
  lassoPath
} from './functions/lasso';

import {
  bandspace,
  bandwidth,
  copy,
  domain,
  invert,
  range,
  scale
} from './functions/scale';

import scaleGradient from './functions/scale-gradient';

import {
  geoShape,
  pathShape
} from './functions/shape';

import {
  treeAncestors,
  treePath
} from './functions/tree';

import {
  containerSize,
  screen,
  windowSize
} from './functions/window';

import {
  SignalPrefix
} from './constants';

import {
  internalScaleFunctions
} from './scales';

import {
  dataVisitor,
  indataVisitor,
  scaleVisitor
} from './visitors';

// Expression function context object
export const functionContext = {
  random() { return random(); }, // override default
  cumulativeNormal,
  cumulativeLogNormal,
  cumulativeUniform,
  densityNormal,
  densityLogNormal,
  densityUniform,
  quantileNormal,
  quantileLogNormal,
  quantileUniform,
  sampleNormal,
  sampleLogNormal,
  sampleUniform,
  isArray,
  isBoolean,
  isDate,
  isDefined(_) { return _ !== undefined; },
  isNumber,
  isObject,
  isRegExp,
  isString,
  isTuple,
  isValid(_) { return _ != null && _ === _; },
  toBoolean,
  toDate(_) { return toDate(_); }, // suppress extra arguments
  toNumber,
  toString,
  indexof,
  join,
  lastindexof,
  replace,
  reverse,
  slice,
  flush,
  lerp,
  merge,
  pad,
  peek,
  pluck,
  span,
  inrange,
  truncate,
  rgb,
  lab,
  hcl,
  hsl,
  luminance,
  contrast,
  sequence,
  format,
  utcFormat,
  utcParse,
  utcOffset,
  utcSequence,
  timeFormat,
  timeParse,
  timeOffset,
  timeSequence,
  timeUnitSpecifier,
  monthFormat,
  monthAbbrevFormat,
  dayFormat,
  dayAbbrevFormat,
  quarter,
  utcquarter,
  week,
  utcweek,
  dayofyear,
  utcdayofyear,
  warn,
  info,
  debug,
  extent(_) { return extent(_); }, // suppress extra arguments
  inScope,
  intersect,
  clampRange,
  pinchDistance,
  pinchAngle,
  screen,
  containerSize,
  windowSize,
  bandspace,
  setdata,
  pathShape,
  panLinear,
  panLog,
  panPow,
  panSymlog,
  zoomLinear,
  zoomLog,
  zoomPow,
  zoomSymlog,
  encode,
  modify,
  lassoAppend,
  lassoPath,
  intersectLasso
};

const eventFunctions = ['view', 'item', 'group', 'xy', 'x', 'y'], // event functions
      eventPrefix = 'event.vega.', // event function prefix
      thisPrefix = 'this.', // function context prefix
      astVisitors = {}; // AST visitors for dependency analysis

// export code generator parameters
export const codegenParams = {
  forbidden:  ['_'],
  allowed:    ['datum', 'event', 'item'],
  fieldvar:   'datum',
  globalvar:  id => `_[${stringValue(SignalPrefix + id)}]`,
  functions:  buildFunctions,
  constants:  constants,
  visitors:   astVisitors
};

// export code generator
export const codeGenerator = codegenExpression(codegenParams);

// Build expression function registry
function buildFunctions(codegen) {
  const fn = functions(codegen);
  eventFunctions.forEach(name => fn[name] = eventPrefix + name);
  for (const name in functionContext) { fn[name] = thisPrefix + name; }
  extend(fn, internalScaleFunctions(codegen, functionContext, astVisitors));
  return fn;
}

// Register an expression function
export function expressionFunction(name, fn, visitor) {
  if (arguments.length === 1) {
    return functionContext[name];
  }

  // register with the functionContext
  functionContext[name] = fn;

  // if there is an astVisitor register that, too
  if (visitor) astVisitors[name] = visitor;

  // if the code generator has already been initialized,
  // we need to also register the function with it
  if (codeGenerator) codeGenerator.functions[name] = thisPrefix + name;
  return this;
}

// register expression functions with ast visitors
expressionFunction('bandwidth', bandwidth, scaleVisitor);
expressionFunction('copy', copy, scaleVisitor);
expressionFunction('domain', domain, scaleVisitor);
expressionFunction('range', range, scaleVisitor);
expressionFunction('invert', invert, scaleVisitor);
expressionFunction('scale', scale, scaleVisitor);
expressionFunction('gradient', scaleGradient, scaleVisitor);
expressionFunction('geoArea', geoArea, scaleVisitor);
expressionFunction('geoBounds', geoBounds, scaleVisitor);
expressionFunction('geoCentroid', geoCentroid, scaleVisitor);
expressionFunction('geoShape', geoShape, scaleVisitor);
expressionFunction('geoScale', geoScale, scaleVisitor);
expressionFunction('indata', indata, indataVisitor);
expressionFunction('data', data, dataVisitor);
expressionFunction('treePath', treePath, dataVisitor);
expressionFunction('treeAncestors', treeAncestors, dataVisitor);

// register Vega-Lite selection functions
expressionFunction('vlSelectionTest', selectionTest, selectionVisitor);
expressionFunction('vlSelectionIdTest', selectionIdTest, selectionVisitor);
expressionFunction('vlSelectionResolve', selectionResolve, selectionVisitor);
expressionFunction('vlSelectionTuples', selectionTuples);