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| 1 | +import React, { |
| 2 | + createContext, FC, |
| 3 | + useCallback, |
| 4 | + useContext, |
| 5 | + useEffect, |
| 6 | + useMemo, |
| 7 | + useRef, |
| 8 | + useState, |
| 9 | +} from 'react' |
| 10 | +import Emitter from 'tiny-emitter'; |
| 11 | +const events = new Emitter.TinyEmitter(); |
| 12 | + |
| 13 | +import {IFlagsmith, IFlagsmithTrait, IFlagsmithFeature, IState} from './types' |
| 14 | + |
| 15 | +export const FlagsmithContext = createContext<IFlagsmith<string,string> | null>(null) |
| 16 | +export type FlagsmithContextType = { |
| 17 | + flagsmith: IFlagsmith // The flagsmith instance |
| 18 | + options?: Parameters<IFlagsmith['init']>[0] // Initialisation options, if you do not provide this you will have to call init manually |
| 19 | + serverState?: IState |
| 20 | + children: React.ReactElement[] | React.ReactElement; |
| 21 | +} |
| 22 | + |
| 23 | +export const FlagsmithProvider: FC<FlagsmithContextType> = ({ |
| 24 | + flagsmith, options, serverState, children, |
| 25 | +}) => { |
| 26 | + const firstRenderRef = useRef(true) |
| 27 | + if (serverState && !flagsmith.initialised) { |
| 28 | + flagsmith.setState(serverState) |
| 29 | + } |
| 30 | + if (firstRenderRef.current) { |
| 31 | + firstRenderRef.current = false |
| 32 | + if (options) { |
| 33 | + flagsmith.init({ |
| 34 | + ...options, |
| 35 | + onChange: (...args) => { |
| 36 | + if (options.onChange) { |
| 37 | + options.onChange(...args) |
| 38 | + } |
| 39 | + events.emit('event') |
| 40 | + }, |
| 41 | + }) |
| 42 | + } else { |
| 43 | + flagsmith.trigger = ()=>events.emit('event'); |
| 44 | + } |
| 45 | + } |
| 46 | + return ( |
| 47 | + <FlagsmithContext.Provider value={flagsmith}> |
| 48 | + {children} |
| 49 | + </FlagsmithContext.Provider> |
| 50 | + ) |
| 51 | +} |
| 52 | + |
| 53 | +const useConstant = function <T>(value: T): T { |
| 54 | + const ref = useRef(value) |
| 55 | + if (!ref.current) { |
| 56 | + ref.current = value |
| 57 | + } |
| 58 | + return ref.current |
| 59 | +} |
| 60 | + |
| 61 | + |
| 62 | +const flagsAsArray = (_flags: any): string[] => { |
| 63 | + if (typeof _flags === 'string') { |
| 64 | + return [_flags] |
| 65 | + } else if (typeof _flags === 'object') { |
| 66 | + // eslint-disable-next-line no-prototype-builtins |
| 67 | + if (_flags.hasOwnProperty('length')) { |
| 68 | + return _flags |
| 69 | + } |
| 70 | + } |
| 71 | + throw new Error( |
| 72 | + 'Flagsmith: please supply an array of strings or a single string of flag keys to useFlags', |
| 73 | + ) |
| 74 | +} |
| 75 | + |
| 76 | +const getRenderKey = (flagsmith: IFlagsmith, flags: string[], traits: string[] = []) => { |
| 77 | + return flags |
| 78 | + .map((k) => { |
| 79 | + return `${flagsmith.getValue(k)}${flagsmith.hasFeature(k)}` |
| 80 | + }).concat(traits.map((t) => ( |
| 81 | + `${flagsmith.getTrait(t)}` |
| 82 | + ))) |
| 83 | + .join(',') |
| 84 | +} |
| 85 | + |
| 86 | +export function useFlags<F extends string=string, T extends string=string>(_flags: readonly F[], _traits: readonly T[] = []): { |
| 87 | + [K in F]: IFlagsmithFeature |
| 88 | +} & { |
| 89 | + [K in T]: IFlagsmithTrait |
| 90 | +} { |
| 91 | + const flags = useConstant<string[]>(flagsAsArray(_flags)) |
| 92 | + const traits = useConstant<string[]>(flagsAsArray(_traits)) |
| 93 | + const flagsmith = useContext(FlagsmithContext) |
| 94 | + const [renderKey, setRenderKey] = useState<string>( |
| 95 | + getRenderKey(flagsmith as IFlagsmith, flags), |
| 96 | + ) |
| 97 | + const renderRef = useRef<string>(renderKey) |
| 98 | + const eventListener = useCallback(() => { |
| 99 | + const newRenderKey = getRenderKey(flagsmith as IFlagsmith, flags, traits) |
| 100 | + if (newRenderKey !== renderRef.current) { |
| 101 | + renderRef.current = newRenderKey |
| 102 | + setRenderKey(newRenderKey) |
| 103 | + } |
| 104 | + }, []) |
| 105 | + useEffect(() => { |
| 106 | + events.on('event', eventListener) |
| 107 | + return () => { |
| 108 | + events.off('event', eventListener) |
| 109 | + } |
| 110 | + }, []) |
| 111 | + const res = useMemo(() => { |
| 112 | + const res: any = {} |
| 113 | + flags.map((k) => { |
| 114 | + res[k] = { |
| 115 | + enabled: flagsmith!.hasFeature(k), |
| 116 | + value: flagsmith!.getValue(k), |
| 117 | + } |
| 118 | + }).concat(traits?.map((v) => { |
| 119 | + res[v] = flagsmith!.getTrait(v) |
| 120 | + })) |
| 121 | + return res |
| 122 | + }, [renderKey]) |
| 123 | + |
| 124 | + return res |
| 125 | +} |
| 126 | + |
| 127 | +export function useFlagsmith<F extends string=string, T extends string=string>() { |
| 128 | + const context = useContext(FlagsmithContext) |
| 129 | + |
| 130 | + if (!context) { |
| 131 | + throw new Error('useFlagsmith must be used with in a FlagsmithProvider') |
| 132 | + } |
| 133 | + |
| 134 | + return context as IFlagsmith<F,T> |
| 135 | +} |
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