import * as db from "../db"
import lf from "lovefield"
import {
    SourceActionTypes,
    INIT_SOURCES,
    ADD_SOURCE,
    DELETE_SOURCE,
} from "./source"
import {
    ItemActionTypes,
    FETCH_ITEMS,
    RSSItem,
    TOGGLE_HIDDEN,
    applyItemReduction,
} from "./item"
import { ActionStatus, AppThunk, mergeSortedArrays } from "../utils"
import { PageActionTypes, SELECT_PAGE, PageType, APPLY_FILTER } from "./page"

export enum FilterType {
    None,
    ShowRead = 1 << 0,
    ShowNotStarred = 1 << 1,
    ShowHidden = 1 << 2,
    FullSearch = 1 << 3,
    CaseInsensitive = 1 << 4,
    CreatorSearch = 1 << 5,

    Default = ShowRead | ShowNotStarred,
    UnreadOnly = ShowNotStarred,
    StarredOnly = ShowRead,
    Toggles = ShowHidden | FullSearch | CaseInsensitive,
}
export class FeedFilter {
    type: FilterType
    search: string

    constructor(type: FilterType = null, search = "") {
        if (
            type === null &&
            (type = window.settings.getFilterType()) === null
        ) {
            type = FilterType.Default | FilterType.CaseInsensitive
        }
        this.type = type
        this.search = search
    }

    static toPredicates(filter: FeedFilter) {
        let type = filter.type
        const predicates = new Array<lf.Predicate>()
        if (!(type & FilterType.ShowRead))
            predicates.push(db.items.hasRead.eq(false))
        if (!(type & FilterType.ShowNotStarred))
            predicates.push(db.items.starred.eq(true))
        if (!(type & FilterType.ShowHidden))
            predicates.push(db.items.hidden.eq(false))
        if (filter.search !== "") {
            const flags = type & FilterType.CaseInsensitive ? "i" : ""
            const regex = RegExp(filter.search, flags)
            if (type & FilterType.FullSearch) {
                predicates.push(
                    lf.op.or(
                        db.items.title.match(regex),
                        db.items.snippet.match(regex)
                    )
                )
            } else {
                predicates.push(db.items.title.match(regex))
            }
        }
        return predicates
    }

    static testItem(filter: FeedFilter, item: RSSItem) {
        let type = filter.type
        let flag = true
        if (!(type & FilterType.ShowRead)) flag = flag && !item.hasRead
        if (!(type & FilterType.ShowNotStarred)) flag = flag && item.starred
        if (!(type & FilterType.ShowHidden)) flag = flag && !item.hidden
        if (filter.search !== "") {
            const flags = type & FilterType.CaseInsensitive ? "i" : ""
            const regex = RegExp(filter.search, flags)
            if (type & FilterType.FullSearch) {
                flag =
                    flag && (regex.test(item.title) || regex.test(item.snippet))
            } else if (type & FilterType.CreatorSearch) {
                flag = flag && regex.test(item.creator || "")
            } else {
                flag = flag && regex.test(item.title)
            }
        }
        return Boolean(flag)
    }
}

export const ALL = "ALL"
export const SOURCE = "SOURCE"

const LOAD_QUANTITY = 50

export class RSSFeed {
    _id: string
    loaded: boolean
    loading: boolean
    allLoaded: boolean
    sids: number[]
    iids: number[]
    filter: FeedFilter

    constructor(id: string = null, sids = [], filter = null) {
        this._id = id
        this.sids = sids
        this.iids = []
        this.loaded = false
        this.allLoaded = false
        this.filter = filter === null ? new FeedFilter() : filter
    }

    static async loadFeed(feed: RSSFeed, skip = 0): Promise<RSSItem[]> {
        const predicates = FeedFilter.toPredicates(feed.filter)
        predicates.push(db.items.source.in(feed.sids))
        return (await db.itemsDB
            .select()
            .from(db.items)
            .where(lf.op.and.apply(null, predicates))
            .orderBy(db.items.date, lf.Order.DESC)
            .skip(skip)
            .limit(LOAD_QUANTITY)
            .exec()) as RSSItem[]
    }
}

export type FeedState = {
    [_id: string]: RSSFeed
}

export const INIT_FEEDS = "INIT_FEEDS"
export const INIT_FEED = "INIT_FEED"
export const LOAD_MORE = "LOAD_MORE"
export const DISMISS_ITEMS = "DISMISS_ITEMS"

interface initFeedsAction {
    type: typeof INIT_FEEDS
    status: ActionStatus
}

interface initFeedAction {
    type: typeof INIT_FEED
    status: ActionStatus
    feed?: RSSFeed
    items?: RSSItem[]
    err?
}

interface loadMoreAction {
    type: typeof LOAD_MORE
    status: ActionStatus
    feed: RSSFeed
    items?: RSSItem[]
    err?
}

interface dismissItemsAction {
    type: typeof DISMISS_ITEMS
    fid: string
    iids: Set<number>
}

export type FeedActionTypes =
    | initFeedAction
    | initFeedsAction
    | loadMoreAction
    | dismissItemsAction

export function dismissItems(): AppThunk {
    return (dispatch, getState) => {
        const state = getState()
        let fid = state.page.feedId
        let filter = state.feeds[fid].filter
        let iids = new Set<number>()
        for (let iid of state.feeds[fid].iids) {
            let item = state.items[iid]
            if (!FeedFilter.testItem(filter, item)) {
                iids.add(iid)
            }
        }
        dispatch({
            type: DISMISS_ITEMS,
            fid: fid,
            iids: iids,
        })
    }
}

export function initFeedsRequest(): FeedActionTypes {
    return {
        type: INIT_FEEDS,
        status: ActionStatus.Request,
    }
}
export function initFeedsSuccess(): FeedActionTypes {
    return {
        type: INIT_FEEDS,
        status: ActionStatus.Success,
    }
}

export function initFeedSuccess(
    feed: RSSFeed,
    items: RSSItem[]
): FeedActionTypes {
    return {
        type: INIT_FEED,
        status: ActionStatus.Success,
        items: items,
        feed: feed,
    }
}

export function initFeedFailure(err): FeedActionTypes {
    return {
        type: INIT_FEED,
        status: ActionStatus.Failure,
        err: err,
    }
}

export function initFeeds(force = false): AppThunk<Promise<void>> {
    return (dispatch, getState) => {
        dispatch(initFeedsRequest())
        let promises = new Array<Promise<void>>()
        for (let feed of Object.values(getState().feeds)) {
            if (!feed.loaded || force) {
                let p = RSSFeed.loadFeed(feed)
                    .then(items => {
                        dispatch(initFeedSuccess(feed, items))
                    })
                    .catch(err => {
                        console.log(err)
                        dispatch(initFeedFailure(err))
                    })
                promises.push(p)
            }
        }
        return Promise.allSettled(promises).then(() => {
            dispatch(initFeedsSuccess())
        })
    }
}

export function loadMoreRequest(feed: RSSFeed): FeedActionTypes {
    return {
        type: LOAD_MORE,
        status: ActionStatus.Request,
        feed: feed,
    }
}

export function loadMoreSuccess(
    feed: RSSFeed,
    items: RSSItem[]
): FeedActionTypes {
    return {
        type: LOAD_MORE,
        status: ActionStatus.Success,
        feed: feed,
        items: items,
    }
}

export function loadMoreFailure(feed: RSSFeed, err): FeedActionTypes {
    return {
        type: LOAD_MORE,
        status: ActionStatus.Failure,
        feed: feed,
        err: err,
    }
}

export function loadMore(feed: RSSFeed): AppThunk<Promise<void>> {
    return (dispatch, getState) => {
        if (feed.loaded && !feed.loading && !feed.allLoaded) {
            dispatch(loadMoreRequest(feed))
            const state = getState()
            const skipNum = feed.iids.filter(i =>
                FeedFilter.testItem(feed.filter, state.items[i])
            ).length
            return RSSFeed.loadFeed(feed, skipNum)
                .then(items => {
                    dispatch(loadMoreSuccess(feed, items))
                })
                .catch(e => {
                    console.log(e)
                    dispatch(loadMoreFailure(feed, e))
                })
        }
        return new Promise((_, reject) => {
            reject()
        })
    }
}

export function feedReducer(
    state: FeedState = { [ALL]: new RSSFeed(ALL) },
    action:
        | SourceActionTypes
        | ItemActionTypes
        | FeedActionTypes
        | PageActionTypes
): FeedState {
    switch (action.type) {
        case INIT_SOURCES:
            switch (action.status) {
                case ActionStatus.Success:
                    return {
                        ...state,
                        [ALL]: new RSSFeed(
                            ALL,
                            Object.values(action.sources).map(s => s.sid)
                        ),
                    }
                default:
                    return state
            }
        case ADD_SOURCE:
            switch (action.status) {
                case ActionStatus.Success:
                    return {
                        ...state,
                        [ALL]: new RSSFeed(
                            ALL,
                            [...state[ALL].sids, action.source.sid],
                            state[ALL].filter
                        ),
                    }
                default:
                    return state
            }
        case DELETE_SOURCE: {
            let nextState = {}
            for (let [id, feed] of Object.entries(state)) {
                nextState[id] = new RSSFeed(
                    id,
                    feed.sids.filter(sid => sid != action.source.sid),
                    feed.filter
                )
            }
            return nextState
        }
        case APPLY_FILTER: {
            let nextState = {}
            for (let [id, feed] of Object.entries(state)) {
                nextState[id] = {
                    ...feed,
                    filter: action.filter,
                }
            }
            return nextState
        }
        case FETCH_ITEMS:
            switch (action.status) {
                case ActionStatus.Success: {
                    let nextState = { ...state }
                    for (let feed of Object.values(state)) {
                        if (feed.loaded) {
                            let items = action.items.filter(
                                i =>
                                    feed.sids.includes(i.source) &&
                                    FeedFilter.testItem(feed.filter, i)
                            )
                            if (items.length > 0) {
                                let oldItems = feed.iids.map(
                                    id => action.itemState[id]
                                )
                                let nextItems = mergeSortedArrays(
                                    oldItems,
                                    items,
                                    (a, b) =>
                                        b.date.getTime() - a.date.getTime()
                                )
                                nextState[feed._id] = {
                                    ...feed,
                                    iids: nextItems.map(i => i._id),
                                }
                            }
                        }
                    }
                    return nextState
                }
                default:
                    return state
            }
        case DISMISS_ITEMS:
            let nextState = { ...state }
            let feed = state[action.fid]
            nextState[action.fid] = {
                ...feed,
                iids: feed.iids.filter(iid => !action.iids.has(iid)),
            }
            return nextState
        case INIT_FEED:
            switch (action.status) {
                case ActionStatus.Success:
                    return {
                        ...state,
                        [action.feed._id]: {
                            ...action.feed,
                            loaded: true,
                            allLoaded: action.items.length < LOAD_QUANTITY,
                            iids: action.items.map(i => i._id),
                        },
                    }
                default:
                    return state
            }
        case LOAD_MORE:
            switch (action.status) {
                case ActionStatus.Request:
                    return {
                        ...state,
                        [action.feed._id]: {
                            ...action.feed,
                            loading: true,
                        },
                    }
                case ActionStatus.Success:
                    return {
                        ...state,
                        [action.feed._id]: {
                            ...action.feed,
                            loading: false,
                            allLoaded: action.items.length < LOAD_QUANTITY,
                            iids: [
                                ...action.feed.iids,
                                ...action.items.map(i => i._id),
                            ],
                        },
                    }
                case ActionStatus.Failure:
                    return {
                        ...state,
                        [action.feed._id]: {
                            ...action.feed,
                            loading: false,
                        },
                    }
                default:
                    return state
            }
        case TOGGLE_HIDDEN: {
            let nextItem = applyItemReduction(action.item, action.type)
            let filteredFeeds = Object.values(state).filter(
                feed =>
                    feed.loaded && !FeedFilter.testItem(feed.filter, nextItem)
            )
            if (filteredFeeds.length > 0) {
                let nextState = { ...state }
                for (let feed of filteredFeeds) {
                    nextState[feed._id] = {
                        ...feed,
                        iids: feed.iids.filter(id => id != nextItem._id),
                    }
                }
                return nextState
            } else {
                return state
            }
        }
        case SELECT_PAGE:
            switch (action.pageType) {
                case PageType.Sources:
                    return {
                        ...state,
                        [SOURCE]: new RSSFeed(
                            SOURCE,
                            action.sids,
                            action.filter
                        ),
                    }
                case PageType.AllArticles:
                    return action.init
                        ? {
                              ...state,
                              [ALL]: {
                                  ...state[ALL],
                                  loaded: false,
                                  filter: action.filter,
                              },
                          }
                        : state
                default:
                    return state
            }
        default:
            return state
    }
}
