import { FeatureFlagCallback, useFeatureFlag } from './useFeatureFlag';
import { Environment, getInsightsEnvironment } from '../types/Environment';
import { useCallback, useMemo } from 'react';
import { InsightsType } from '../utils';

type EnvironmentFlagSignature = {
    <T>(
        currentEnvironment: Environment,
        targetEnvironments: Environment | ReadonlyArray<Environment>,
        ifTrue: FeatureFlagCallback<T>,
        ifFalse?: FeatureFlagCallback<T>
    ): T | undefined;
    <T>(
        currentEnvironment: Environment,
        targetEnvironments: Environment | ReadonlyArray<Environment>,
        ifTrue: FeatureFlagCallback<T> | undefined,
        ifFalse: FeatureFlagCallback<T>
    ): T | undefined;
};

export const useEnvironmentFlag: EnvironmentFlagSignature = <T>(
    currentEnvironment: Environment,
    targetEnvironments: Environment | ReadonlyArray<Environment>,
    ifTrue: FeatureFlagCallback<T> | undefined,
    ifFalse: FeatureFlagCallback<T> | undefined
) => {
    const resolver = useCallback(() => targetEnvironments.includes(currentEnvironment), [ currentEnvironment, targetEnvironments ]);

    // Both elements can't be undefined because we are guarded by EnvironmentFlagSignature.
    // But we have to typecast because current declaration has both as possible undefined.
    return useFeatureFlag(resolver, ifTrue, ifFalse as any);
};

type InsightsEnvironmentFlagSignature = {
    <T>(
        insights: InsightsType,
        targetEnvironments: Environment | ReadonlyArray<Environment>,
        ifTrue: FeatureFlagCallback<T>,
        ifFalse?: FeatureFlagCallback<T>
    ): T | undefined;
    <T>(
        insights: InsightsType,
        targetEnvironments: Environment | ReadonlyArray<Environment>,
        ifTrue: FeatureFlagCallback<T> | undefined,
        ifFalse: FeatureFlagCallback<T>
    ): T | undefined;
};

export const useInsightsEnvironmentFlag: InsightsEnvironmentFlagSignature = <T>(
    insights: InsightsType,
    targetEnvironments: Environment | ReadonlyArray<Environment>,
    ifTrue: FeatureFlagCallback<T> | undefined,
    ifFalse: FeatureFlagCallback<T> | undefined
) => {
    const current = useMemo(() => getInsightsEnvironment(insights), [ insights ]);

    // Same as above
    return useEnvironmentFlag(current, targetEnvironments, ifTrue, ifFalse as any);
};