import type { InjectedMetadataKnown } from "@polkadot/extension-inject/types";
import { VARAN_WALLET_LS_KEY } from "./constants";
import { generateRequestId } from "./helpers";
import { WalletStorage } from "./types";

type WalletStoreType = {
    accounts: string[];
    injectedMetadataKnown?: InjectedMetadataKnown;
    transactions: {
        id: number;
        signedTx: string;
        status: 'signing' | 'success' | 'failed';
    }[];
}

const defaultStore: WalletStoreType = {
    accounts: [],
    injectedMetadataKnown: undefined,
    transactions: [],
}

export class WalletStore {
    private readonly store: WalletStorage;
    private readonly storeSubscribe: (cb: (ev: StorageEvent) => void) => void;
    private _store: WalletStoreType;

    constructor() {
        this.store = window.localStorage as WalletStorage;
        this._store = Object.assign(defaultStore, JSON.parse(this.store.getItem(VARAN_WALLET_LS_KEY) || '{}'));
        this.storeSubscribe = (cb): void => {
            window.addEventListener('storage', cb);
        };
        this._setupListeners();
    }

    private callbacks: {
        [K in keyof WalletStoreType]: ({
            cb: (value: WalletStoreType[K]) => void,
            id: number;
        })[];
    } = {
        accounts: [],
        injectedMetadataKnown: [],
        transactions: [],
    };

    private _setupListeners(): void {
        let currentState = this._store;
        this.storeSubscribe(ev => {
            ev.stopImmediatePropagation();
            if (ev.key !== VARAN_WALLET_LS_KEY) return;

            const data = JSON.parse(ev.newValue || '{}') as WalletStoreType;
            const keys = Object.keys(data) as (keyof WalletStoreType)[];
            for (const key of keys) {
                if (key === 'injectedMetadataKnown') continue;
                if (key === 'accounts') {
                    const currentAccounts = currentState[key];
                    const dataAccounts = data[key];
                    if (currentAccounts.length !== dataAccounts.length) {
                        currentState = data;
                        this._store = data;
                        this.dispatch(key);
                        continue;
                    }

                    let shouldDispatch = false;
                    dataAccounts.forEach(account => {
                        if (!currentAccounts.includes(account)) {
                            shouldDispatch = true;
                        }
                    });

                    if (shouldDispatch) {
                        currentState = data;
                        this._store = data;
                        this.dispatch(key);
                    }
                    continue;
                }
                if (key === 'transactions') {
                    const currentTransactions = currentState[key];
                    const dataTransactions = data[key];
                    if (currentTransactions.length !== dataTransactions.length) {
                        currentState = data;
                        this._store = data;
                        this.dispatch(key);
                        continue;
                    }

                    let shouldDispatch = false;
                    dataTransactions.forEach(transaction => {
                        const currentTransaction = currentTransactions.find(t => t.id === transaction.id);
                        if (currentTransaction && currentTransaction.status !== transaction.status) {
                            shouldDispatch = true;
                        }
                    });

                    if (shouldDispatch) {
                        currentState = data;
                        this._store = data;
                        this.dispatch(key);
                    }
                    continue;
                }
            }
        });
    }

    private dispatch<Key extends keyof WalletStoreType>(key: Key): void {
        const callbacks = this.callbacks[key];
        if (!callbacks || callbacks.length === 0) return;
        callbacks.forEach(c => c.cb(this._store[key]));
    }

    get<Key extends keyof WalletStoreType>(key: Key): WalletStoreType[Key] {
        return this._store[key] || defaultStore[key];
    }

    set<Key extends keyof WalletStoreType>(key: Key, value: WalletStoreType[Key]): void {
        this._store[key] = value;
        this.dispatch(key);
        this.store.setItem(VARAN_WALLET_LS_KEY, JSON.stringify(this._store));
    }
    
    remove<Key extends keyof WalletStoreType>(key: Key): void {
        const value = this._store[key];
        if (value) {
            this._store[key] = defaultStore[key];
        }
        this.store.setItem(VARAN_WALLET_LS_KEY, JSON.stringify(this._store));
    }

    clear(): void {
        this.store.removeItem(VARAN_WALLET_LS_KEY);
    }

    subscribe<Key extends keyof WalletStoreType>(key: Key, cb: (value: WalletStoreType[Key]) => void): number {
        if (this.callbacks[key] == undefined) {
            this.callbacks[key] = [];
        }
        const id = generateRequestId();
        this.callbacks[key].push({cb, id});
        return id;
    }

    unsubscribe<Key extends keyof WalletStoreType>(key: Key, id: number): void {
        if (this.callbacks[key] == undefined || this.callbacks[key].length === 0) return;
        const filtered = this.callbacks[key].filter(c => c.id !== id);
        this.callbacks[key] = filtered as typeof this.callbacks[Key];
    }
}