import { readAll } from "https://deno.land/std@0.191.0/streams/read_all.ts";
import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { AsyncIterableReader } from "../src/utils.ts";
import { randomNumbers, range } from "./utils.ts";


Deno.test("AsyncIterableReader", async (t) => {

    async function* miniSource(){
        yield Promise.resolve(new Uint8Array([1, 2, 3]));
        yield Promise.resolve(new Uint8Array([4, 5, 6, 7]));
        yield Promise.resolve(new Uint8Array([8, 9]));
    }

    async function* largeSource(size: number, seed = 77):  AsyncIterable<Uint8Array>{
        
        let val = 0
        const random = randomNumbers(seed, size > 10 ? size / 4: size);
        while(val < size){
            const randomValue = random.next().value;
            const newVal = Math.min(val + randomValue, size);
            const ret = new Uint8Array(range(val, newVal));
            yield Promise.resolve(ret);
            val = newVal;
        }
    }

    await t.step('read all mini source', async () => {
        const reader = new AsyncIterableReader(miniSource());
        const expt = new Uint8Array([1, 2 ,3 ,4 ,5, 6,7,8,9])
        assertEquals(await readAll(reader), expt);
    });

    await t.step('read all large source', async () => {
        // let's run the test 1000 times to make sure implementation is ok.
        for(const i of randomNumbers(666, 100 * 1024, 1000)){
            const reader = new AsyncIterableReader(largeSource(i));
            const ret = await readAll(reader);
            assertEquals(ret.length, i);
        }
    });
    

});