path: root/src/eval.ts

import { CSSUnit, Expr } from './parser'
import { Enum, constructors, match, matchString } from './utils/adt'

export interface EvalActions {
  addClass(id: string, classes: string): Promise<void>
  removeClass(id: string, classes: string): Promise<void>
  delay(num: number): Promise<void>
  jsEval(js: string): Promise<any>
  loadCssx(id: string, url: string): Promise<string>
  getVariable(name: string): Promise<string | undefined>
  updateVariable(
    id: string | undefined,
    varName: string,
    value: string,
  ): Promise<void>
  getAttribute(
    id: string | undefined,
    name: string,
  ): Promise<string | undefined>
  setAttribute(
    id: string | undefined,
    name: string,
    value: string,
  ): Promise<void>
  withEvent(fn: (e: any) => void): Promise<void>
  getFormData(): Promise<FormData | undefined>
  sendRequest(_: {
    method: string
    url: string
    data: FormData | undefined
  }): Promise<void>
  addChildren(id: string, children: Expr[]): Promise<void>
  removeElement(id: string | undefined): Promise<void>
  callMethod(
    id: string | undefined,
    method: string,
    args: (string | undefined)[],
  ): Promise<void>
  // calculate ??
}

export type EvalValue = Enum<{
  String: string
  Number: number
  Boolean: boolean
  Lazy: Expr[]
  Void: never
  VarIdentifier: string
  // Object: Record<any, any>
}>
export const EvalValue = constructors<EvalValue>()

export const evalExprAsString = async (
  expr: Expr,
  actions: EvalActions,
): Promise<string | undefined> =>
  evalValueToString(await evalExpr(expr, actions))

export const evalExpr = async (
  expr: Expr,
  actions: EvalActions,
): Promise<EvalValue> =>
  match<Promise<EvalValue>, Expr>(expr, {
    Call: async ({ name, args }) => getFunctions(name, args, actions),
    LiteralString: async s => EvalValue.String(s),
    LiteralNumber: async ({ value, unit }) =>
      EvalValue.Number(
        matchString<number, CSSUnit>(unit, {
          s: () => value * 1000,
          _: () => value,
        }),
      ),
    Identifier: async s => EvalValue.String(s),
    VarIdentifier: async s => EvalValue.VarIdentifier(s),
    _: async _ => EvalValue.Void(),
  })

const evalValueToString = (val: EvalValue): string | undefined =>
  match<string | undefined, EvalValue>(val, {
    String: s => s.replace(/(^'|")|('|"$)/g, ''),
    Boolean: b => `${b}`,
    Number: n => `${n}`,
    _: () => undefined,
  })

const evalValueToNumber = (val: EvalValue): number | undefined =>
  match<number | undefined, EvalValue>(val, {
    String: s => parseInt(s, 10),
    Boolean: b => (b ? 1 : 0),
    Number: n => n,
    _: () => undefined,
  })

const evalValueToBoolean = (val: EvalValue): boolean =>
  match<boolean, EvalValue>(val, {
    String: s => !['false', '', '0'].includes(s.replace(/(^'|")|('|"$)/g, '')),
    Boolean: b => b,
    Number: n => !!n,
    _: () => false,
  })

const getFunctions = (
  name: string,
  args: Expr[],
  actions: EvalActions,
): Promise<EvalValue> => {
  const getVariable = async () => {
    const varName = await evalExpr(args[0], actions)
    const defaultValue = args[1] && (await evalExpr(args[1], actions))

    return match<Promise<EvalValue>, EvalValue>(varName, {
      VarIdentifier: async name => {
        const value = await actions.getVariable(name)
        return value === undefined ? defaultValue : EvalValue.String(value)
      },
      _: async () => EvalValue.Void(),
    })
  }

  return matchString<Promise<EvalValue>>(name, {
    'add-class': async () => {
      const id = evalValueToString(await evalExpr(args[0], actions))
      const classes = evalValueToString(await evalExpr(args[1], actions))
      if (id && classes) {
        await actions.addClass(id, classes)
      }
      return EvalValue.Void()
    },
    'remove-class': async () => {
      const id = evalValueToString(await evalExpr(args[0], actions))
      const classes = evalValueToString(await evalExpr(args[1], actions))
      if (id && classes) {
        await actions.removeClass(id, classes)
      }
      return EvalValue.Void()
    },

    if: async () => {
      const cond = evalValueToBoolean(await evalExpr(args[0], actions))
      if (cond) {
        return evalExpr(args[1], actions)
      } else {
        return evalExpr(args[2], actions)
      }
    },
    delay: async () => {
      const num = evalValueToNumber(await evalExpr(args[0], actions))
      num !== undefined ? await actions.delay(num) : undefined
      return EvalValue.Void()
    },
    'js-eval': async () => {
      const js = evalValueToString(await evalExpr(args[0], actions))
      return js && (await actions.jsEval(js))
    },

    'load-cssx': async () => {
      const id = evalValueToString(await evalExpr(args[0], actions))
      const url = evalValueToString(await evalExpr(args[1], actions))
      if (id && url) {
        await actions.loadCssx(id, url)
      }
      return EvalValue.Void()
    },

    var: getVariable,
    'get-var': getVariable,

    update: async () => {
      const [id, name, value] =
        args.length >= 3
          ? (await evalArgs(args, 3, actions)).map(evalValueToString)
          : [
              undefined,
              ...(await evalArgs(args, 2, actions)).map(evalValueToString),
            ]
      if (name) {
        await actions.updateVariable(id ?? undefined, name, value ?? '')
      }
      return EvalValue.Void()
    },

    'set-attr': async () => {
      const [id, name, value] =
        args.length >= 3
          ? (await evalArgs(args, 3, actions)).map(evalValueToString)
          : [
              undefined,
              ...(await evalArgs(args, 2, actions)).map(evalValueToString),
            ]
      if (name) {
        actions.setAttribute(id ?? undefined, name, value ?? '')
      }
      return EvalValue.Void()
    },
    attr: async () => {
      const [id, name] =
        args.length >= 2
          ? (await evalArgs(args, 2, actions)).map(evalValueToString)
          : [undefined, evalValueToString(await evalExpr(args[0], actions))]
      if (name) {
        const val = await actions.getAttribute(id as string | undefined, name)
        return val === undefined ? EvalValue.Void() : EvalValue.String(val)
      }
      return EvalValue.Void()
    },

    'prevent-default': async () => {
      await actions.withEvent(e => e.preventDefault())
      return EvalValue.Void()
    },

    request: async () => {
      const url = evalValueToString(await evalExpr(args[0], actions))
      const method =
        (args[1] && evalValueToString(await evalExpr(args[1], actions))) ||
        'post'

      if (url) {
        const data = await actions.getFormData()
        await actions.sendRequest({ method, url, data })
      }
      return EvalValue.Void()
    },

    'add-children': async () => {
      const id = evalValueToString(await evalExpr(args[0], actions))
      if (id) await actions.addChildren(id, args.slice(1))
      return EvalValue.Void()
    },
    'remove-element': async () => {
      const selector =
        (args[0] && evalValueToString(await evalExpr(args[0], actions))) ??
        undefined
      if (selector) await actions.removeElement(selector)
      return EvalValue.Void()
    },

    'call-method': async () => {
      const [id, method, ...methodArgs] = (
        await Promise.all(args.map(a => evalExpr(a, actions)))
      ).map(evalValueToString)
      if (id && method) {
        await actions.callMethod(id, method, methodArgs)
      }
      return EvalValue.Void()
    },

    _: () => Promise.reject(new Error('not supposed to be here')),
  })
}

export const evalArgs = (
  args: Array<Expr>,
  count: number,
  actions: EvalActions,
) => Promise.all(args.slice(0, count).map(e => evalExpr(e, actions)))