import { assert, AssertionError } from "chai"
import { AsyncFunc, Context, Func, Test, TestFunction } from "mocha"

type XFailFunction = {
    it: TestFunction
    unless: (condition: boolean | (() => boolean)) => { it: TestFunction }
}

const wrap = (
    fn: Func | AsyncFunc,
    condition: boolean | (() => boolean),
): Func => {
    return function Wrapped(this: Context): PromiseLike<any> {
        if (typeof condition === "function") {
            if (!condition()) {
                return Promise.resolve()
            }
        } else if (condition === false) {
            return Promise.resolve()
        }

        return new Promise<void>((ok, fail) => {
            if (fn.length > 1) {
                fn.call(context, (err: any) => (err ? fail(err) : ok()))
            } else {
                ok(fn.call(context))
            }
        }).then(
            (e: any) => assert.fail("Expected this test to fail"),
            (e: any) => {
                if (!(e instanceof AssertionError)) {
                    throw e
                }
            },
        )
    }
}

function unless(condition: boolean | (() => boolean)): { it: TestFunction } {
    const xfailIt: TestFunction = (
        fnOrTitle: Func | AsyncFunc | string,
        fn?: Func | AsyncFunc,
    ): Test => {
        if (typeof fnOrTitle === "string") {
            return it(fnOrTitle, wrap(fn!, condition))
        } else {
            return it(wrap(fnOrTitle, condition))
        }
    }

    xfailIt.only = (
        fnOrTitle: Func | AsyncFunc | string,
        fn?: Func | AsyncFunc,
    ): Test => {
        if (typeof fnOrTitle === "string") {
            return it.skip(fnOrTitle, wrap(fn!, condition))
        } else {
            return it.skip(wrap(fnOrTitle, condition))
        }
    }

    xfailIt.skip = (
        fnOrTitle: Func | AsyncFunc | string,
        fn?: Func | AsyncFunc,
    ): Test => {
        if (typeof fnOrTitle === "string") {
            return it.skip(fnOrTitle, wrap(fn!, condition))
        } else {
            return it.skip(wrap(fnOrTitle, condition))
        }
    }

    xfailIt.retries = (n: number): void => {
        it.retries(n)
    }

    return { it: xfailIt }
}

const xfail: XFailFunction = {
    ...unless(true),
    unless,
}

export { xfail }