// SPDX-License-Identifier: MIT
// Copyright (c) 2020 The Pybricks Authors

import { FirmwareMetadata, FirmwareReader, HubType } from '@pybricks/firmware';
import cityHubZip from '@pybricks/firmware/build/cityhub.zip';
import moveHubZip from '@pybricks/firmware/build/movehub.zip';
import technicHubZip from '@pybricks/firmware/build/technichub.zip';
import { Ace } from 'ace-builds';
import {
    Effect,
    all,
    call,
    delay,
    getContext,
    put,
    race,
    select,
    take,
    takeEvery,
} from 'redux-saga/effects';
import { Action } from '../actions';
import {
    FlashFirmwareActionType,
    FlashFirmwareFlashAction,
    didFinish,
    didProgress,
    didStart,
} from '../actions/flash-firmware';
import {
    BootloaderChecksumRequestAction,
    BootloaderChecksumResponseAction,
    BootloaderConnectionActionType,
    BootloaderConnectionDidConnectAction,
    BootloaderConnectionDidFailToConnectAction,
    BootloaderDidRequestAction,
    BootloaderDidRequestType,
    BootloaderDisconnectRequestAction,
    BootloaderEraseRequestAction,
    BootloaderEraseResponseAction,
    BootloaderErrorResponseAction,
    BootloaderInfoRequestAction,
    BootloaderInfoResponseAction,
    BootloaderInitRequestAction,
    BootloaderInitResponseAction,
    BootloaderProgramRequestAction,
    BootloaderProgramResponseAction,
    BootloaderRebootRequestAction,
    BootloaderResponseAction,
    BootloaderResponseActionType,
    checksumRequest,
    connect,
    disconnectRequest,
    eraseRequest,
    infoRequest,
    initRequest,
    programRequest,
    rebootRequest,
} from '../actions/lwp3-bootloader';
import {
    MpyActionType,
    MpyDidCompileAction,
    MpyDidFailToCompileAction,
    compile,
} from '../actions/mpy';
import * as notification from '../actions/notification';
import { MaxProgramFlashSize } from '../protocols/lwp3-bootloader';
import { RootState } from '../reducers';
import { fmod, sumComplement32 } from '../utils/math';

const firmwareZipMap = new Map<HubType, string>([
    [HubType.CityHub, cityHubZip],
    [HubType.TechnicHub, technicHubZip],
    [HubType.MoveHub, moveHubZip],
]);

/**
 * Helper type for return value of wait() function.
 */
type WaitResponse<T extends BootloaderResponseAction> = [
    T,
    BootloaderErrorResponseAction,
    boolean,
];

function* waitForDidSend(id: number): Generator {
    const didRequest = (yield take(
        (a: Action) =>
            a.type === BootloaderDidRequestType &&
            (a as BootloaderDidRequestAction).id === id,
    )) as BootloaderDidRequestAction;
    if (didRequest.err) {
        console.error(didRequest.err);
    }
    return didRequest;
}

/**
 * Waits for a response action, an error response or timeout, whichever comes
 * first.
 * @param type The action type to wait for.
 * @param timeout The timeout in milliseconds.
 */
function waitForResponse(type: BootloaderResponseActionType, timeout = 500): Effect {
    return race([take(type), take(BootloaderResponseActionType.Error), delay(timeout)]);
}

function* firmwareIterator(data: DataView, maxSize: number): Generator<number> {
    // read each 32-bit word of the firmware
    for (let i = 0; i < data.byteLength; i += 4) {
        yield data.getUint32(i, true);
    }
    // remaining free space in flash will be 0xff after erase
    for (let i = data.byteLength; i < maxSize; i += 4) {
        yield ~0;
    }
}

/**
 * Loads Pybricks firmware from a .zip file
 * @param data The zip file raw data
 * @param program User program or `undefined` to use main.py from firmware.zip
 */
function* loadFirmware(
    data: ArrayBuffer,
    program: string | undefined,
): Generator<unknown, { firmware: Uint8Array; deviceId: HubType }> {
    const reader = (yield call(() => FirmwareReader.load(data))) as FirmwareReader;

    const firmwareBase = (yield call(() => reader.readFirmwareBase())) as Uint8Array;
    const metadata = (yield call(() => reader.readMetadata())) as FirmwareMetadata;

    // if a user program was not given, then use main.py from the frimware.zip
    if (program === undefined) {
        program = (yield call(() => reader.readMainPy())) as string;
    }

    if (metadata['mpy-abi-version'] !== 5) {
        throw Error(
            `Firmware requires mpy-cross ABI version ${metadata['mpy-abi-version']} we have v5`,
        );
    }

    yield put(compile(program, metadata['mpy-cross-options']));
    const [mpy, mpyFail] = (yield race([
        take(MpyActionType.DidCompile),
        take(MpyActionType.DidFailToCompile),
    ])) as [MpyDidCompileAction, MpyDidFailToCompileAction];

    if (mpyFail) {
        throw Error(mpyFail.err.join('\n'));
    }

    // compute offset for checksum - must be aligned to 4-byte boundary
    const checksumOffset =
        metadata['user-mpy-offset'] + 4 + mpy.data.length + fmod(-mpy.data.length, 4);

    const firmware = new Uint8Array(checksumOffset + 4);
    const firmwareView = new DataView(firmware.buffer);

    if (firmware.length > metadata['max-firmware-size']) {
        throw Error('firmware + main.mpy is too large');
    }

    firmware.set(firmwareBase);
    firmwareView.setUint32(metadata['user-mpy-offset'], mpy.data.length, true);
    firmware.set(mpy.data, metadata['user-mpy-offset'] + 4);

    if (metadata['checksum-type'] !== 'sum') {
        throw Error(`Unknown checksum type "${metadata['checksum-type']}"`);
    }

    firmwareView.setUint32(
        checksumOffset,
        sumComplement32(firmwareIterator(firmwareView, metadata['max-firmware-size'])),
        true,
    );

    return { firmware, deviceId: metadata['device-id'] };
}

/**
 * Flashes firmware to a Powered Up device.
 * @param action The action that triggered this saga.
 */
function* flashFirmware(action: FlashFirmwareFlashAction): Generator {
    let firmware: Uint8Array | undefined = undefined;
    let deviceId: HubType | undefined = undefined;

    let program: string | undefined = undefined;

    const flashCurrentProgram = (yield select(
        (s: RootState) => s.settings.flashCurrentProgram,
    )) as boolean;

    if (flashCurrentProgram) {
        const editor = (yield select(
            (s: RootState) => s.editor.current,
        )) as Ace.EditSession | null;

        // istanbul ignore if: it is a bug to dispatch this action with no current editor
        if (editor === null) {
            console.error('flashFirmware: No current editor');
            return;
        }

        program = editor.getValue();
    }

    if (action.data !== undefined) {
        ({ firmware, deviceId } = yield* loadFirmware(action.data, program));
    }

    yield put(connect());
    const connectResult = (yield take([
        BootloaderConnectionActionType.DidConnect,
        BootloaderConnectionActionType.DidFailToConnect,
    ])) as
        | BootloaderConnectionDidConnectAction
        | BootloaderConnectionDidFailToConnectAction;

    if (connectResult.type === BootloaderConnectionActionType.DidFailToConnect) {
        return;
    }

    const nextMessageId = (yield getContext('nextMessageId')) as () => number;

    const infoAction = (yield put(
        infoRequest(nextMessageId()),
    )) as BootloaderInfoRequestAction;
    const [, info] = (yield all([
        waitForDidSend(infoAction.id),
        waitForResponse(BootloaderResponseActionType.Info),
    ])) as [BootloaderDidRequestAction, WaitResponse<BootloaderInfoResponseAction>];
    if (!info[0]) {
        throw Error(`failed to get info: ${info}`);
    }

    if (deviceId !== undefined && info[0].hubType !== deviceId) {
        throw Error(`Connected to ${info[0].hubType} but firmware is for ${deviceId}`);
    }

    if (firmware === undefined) {
        const firmwarePath = firmwareZipMap.get(info[0].hubType);
        if (firmwarePath === undefined) {
            yield put(
                notification.add(
                    'error',
                    "Sorry, we don't have firmware for this hub yet.",
                ),
            );
            yield put(disconnectRequest(nextMessageId()));
            return;
        }

        const response = (yield call(() => fetch(firmwarePath))) as Response;
        if (!response.ok) {
            yield put(notification.add('error', 'Failed to fetch firmware.'));
            const disconnectAction = (yield put(
                disconnectRequest(nextMessageId()),
            )) as BootloaderDisconnectRequestAction;
            yield waitForDidSend(disconnectAction.id);
            return;
        }

        const data = (yield call(() => response.arrayBuffer())) as ArrayBuffer;
        ({ firmware, deviceId } = yield* loadFirmware(data, program));

        if (deviceId !== undefined && info[0].hubType !== deviceId) {
            throw Error(
                `Connected to ${info[0].hubType} but firmware is for ${deviceId}`,
            );
        }
    }

    yield put(didStart());

    const eraseAction = (yield put(
        eraseRequest(nextMessageId()),
    )) as BootloaderEraseRequestAction;
    const [, erase] = (yield all([
        waitForDidSend(eraseAction.id),
        waitForResponse(BootloaderResponseActionType.Erase, 5000),
    ])) as [BootloaderDidRequestAction, WaitResponse<BootloaderEraseResponseAction>];
    if (!erase[0] || erase[0].result) {
        // TODO: proper error handling
        throw Error(`Failed to erase: ${erase}`);
    }

    const initAction = (yield put(
        initRequest(nextMessageId(), firmware.length),
    )) as BootloaderInitRequestAction;
    const [, init] = (yield all([
        waitForDidSend(initAction.id),
        waitForResponse(BootloaderResponseActionType.Init),
    ])) as [BootloaderDidRequestAction, WaitResponse<BootloaderInitResponseAction>];
    if (!init[0] || init[0].result) {
        // TODO: proper error handling
        throw Error(`Failed to init: ${init}`);
    }

    let count = 0;
    const maxDataSize = MaxProgramFlashSize.get(info[0].hubType);
    if (maxDataSize === undefined) {
        // istanbul ignore next: indicates programmer error if reached
        throw Error('Missing hub type in MaxProgramFlashSize');
    }

    for (let offset = 0; ; ) {
        const payload = firmware.slice(offset, offset + maxDataSize);
        const programAction = (yield put(
            programRequest(
                nextMessageId(),
                info[0].startAddress + offset,
                payload.buffer,
            ),
        )) as BootloaderProgramRequestAction;
        yield waitForDidSend(programAction.id);

        yield put(didProgress(offset / firmware.length));

        // we don't want to request checksum if this is the last packet since
        // the bootloader will send a response to the program request already.
        offset += maxDataSize;
        if (offset >= firmware.length) {
            break;
        }

        // Request checksum every 10 packets to prevent buffer overrun on
        // the hub because of sending too much data at once. The actual
        // number of packets that can be queued in the Bluetooth chip on
        // the hub is not known and could vary by device.
        if (++count % 10 === 0) {
            const checksumAction = (yield put(
                checksumRequest(nextMessageId()),
            )) as BootloaderChecksumRequestAction;
            const [, checksum] = (yield all([
                waitForDidSend(checksumAction.id),
                waitForResponse(BootloaderResponseActionType.Checksum, 5000),
            ])) as [
                BootloaderDidRequestAction,
                WaitResponse<BootloaderChecksumResponseAction>,
            ];
            if (!checksum[0]) {
                // TODO: proper error handling
                throw Error(`Failed to get checksum: ${checksum}`);
            }
        }
    }

    const flash = (yield waitForResponse(
        BootloaderResponseActionType.Program,
        5000,
    )) as WaitResponse<BootloaderProgramResponseAction>;
    if (!flash[0]) {
        throw Error(`failed to get final response: ${flash}`);
    }
    if (flash[0].count !== firmware.length) {
        // TODO: proper error handling
        throw Error("Didn't flash all bytes");
    }

    yield put(didProgress(1));

    // this will cause the remote device to disconnect and reboot
    const rebootAction = (yield put(
        rebootRequest(nextMessageId()),
    )) as BootloaderRebootRequestAction;
    yield waitForDidSend(rebootAction.id);

    yield put(didFinish());
}

export default function* (): Generator {
    yield takeEvery(FlashFirmwareActionType.FlashFirmware, flashFirmware);
}