import { type Address, type Chain, createWalletClient, custom, type Hash, http, type RpcSchema as RpcSchemaGeneric, type SendTransactionParameters, type Transport, type WalletClient } from "viem";
import type { TransactionRequestEIP712 } from "viem/chains";

import { createZksyncSessionClient, type ZksyncSsoSessionClient } from "../client/index.js";
import type { Communicator } from "../communicator/index.js";
import { type CustomPaymasterHandler, getTransactionWithPaymasterData } from "../paymaster/index.js";
import { StorageItem } from "../utils/storage.js";
import type { AppMetadata, RequestArguments } from "./interface.js";
import type { AuthServerRpcSchema, ExtractParams, ExtractReturnType, Method, RPCRequestMessage, RPCResponseMessage, RpcSchema } from "./rpc.js";
import type { SessionPreferences } from "./session/index.js";
import { parseSessionConfigJSON, type SessionConfigJSON } from "./session/utils.js";

type Account = {
  address: Address;
  activeChainId: Chain["id"];
  session?: {
    sessionKey: Hash;
    sessionConfig: SessionConfigJSON;
  };
};

interface SignerInterface {
  accounts: Address[];
  chain: Chain;
  getClient(parameters?: { chainId?: number }): ZksyncSsoSessionClient | WalletClient;
  handshake(): Promise<Address[]>;
  request<TMethod extends Method>(request: RequestArguments<TMethod>): Promise<ExtractReturnType<TMethod>>;
  disconnect: () => Promise<void>;
}

type UpdateListener = {
  onAccountsUpdate: (_: Address[]) => void;
  onChainUpdate: (_: number) => void;
};

type SignerConstructorParams = {
  metadata: () => AppMetadata;
  communicator: Communicator;
  updateListener: UpdateListener;
  chains: readonly Chain[];
  transports?: Record<number, Transport>;
  session?: () => SessionPreferences | Promise<SessionPreferences>;
  paymasterHandler?: CustomPaymasterHandler;
};

type ChainsInfo = ExtractReturnType<"eth_requestAccounts", AuthServerRpcSchema>["chainsInfo"];

export class Signer implements SignerInterface {
  private readonly getMetadata: () => AppMetadata;
  private readonly communicator: Communicator;
  private readonly updateListener: UpdateListener;
  private readonly chains: readonly Chain[];
  private readonly transports: Record<number, Transport> = {};
  private readonly sessionParameters?: () => (SessionPreferences | Promise<SessionPreferences>);
  private readonly paymasterHandler?: CustomPaymasterHandler;

  private _account: StorageItem<Account | null>;
  private _chainsInfo = new StorageItem<ChainsInfo>(StorageItem.scopedStorageKey("chainsInfo"), []);
  private client: { instance: ZksyncSsoSessionClient; type: "session" } | { instance: WalletClient; type: "auth-server" } | undefined;

  constructor({ metadata, communicator, updateListener, session, chains, transports, paymasterHandler }: SignerConstructorParams) {
    if (!chains.length) throw new Error("At least one chain must be included in the config");

    this.getMetadata = metadata;
    this.communicator = communicator;
    this.updateListener = updateListener;
    this.sessionParameters = session;
    this.chains = chains;
    this.transports = transports || {};
    this.paymasterHandler = paymasterHandler;

    this._account = new StorageItem<Account | null>(StorageItem.scopedStorageKey("account"), null, {
      onChange: (newValue) => {
        if (newValue) {
          this.updateListener.onAccountsUpdate([newValue.address]);
          this.updateListener.onChainUpdate(newValue.activeChainId);
          this.createWalletClient();
        } else {
          this.updateListener.onAccountsUpdate([]);
        }
      },
    });
    try {
      if (this.account) this.createWalletClient();
    } catch (error) {
      console.error("Failed to create wallet client", error);
      console.error("Logging out to prevent crash loop");
      this.clearState();
    }
  }

  get walletClient() {
    return this.client?.instance as WalletClient | undefined;
  }

  getClient(parameters?: { chainId?: number }) {
    const chainId = parameters?.chainId || this.chain.id;
    const chain = this.chains.find((e) => e.id === chainId);
    if (!chain) throw new Error(`Chain with id ${chainId} is not supported`);

    if (!this.walletClient) throw new Error("Wallet client is not created");
    return this.walletClient;
  }

  private get account(): Account | null {
    const account = this._account.get();
    if (!account) return null;
    const chain = this.chains.find((e) => e.id === account.activeChainId);
    return {
      ...account,
      activeChainId: chain?.id || this.chains[0]!.id,
    };
  }

  private get session() { return this.account?.session; }
  private get chainsInfo() { return this._chainsInfo.get(); }
  private readonly clearState = () => {
    this._account.remove();
    this._chainsInfo.remove();
  };

  public get accounts() { return this.account ? [this.account.address] : []; }
  public get chain() {
    const chainId = this.account?.activeChainId || this.chains[0]!.id;
    return this.chains.find((e) => e.id === chainId)!;
  }

  createWalletClient() {
    const session = this.session;
    const chain = this.chain;
    const chainInfo = this.chainsInfo.find((e) => e.id === chain.id);
    if (!this.account) throw new Error("Account is not set");
    if (!chainInfo) throw new Error(`Chain info for ${chain} wasn't set during handshake`);
    if (session) {
      this.client = {
        type: "session",
        instance: createZksyncSessionClient({
          address: this.account.address,
          sessionKey: session.sessionKey,
          sessionConfig: parseSessionConfigJSON(session.sessionConfig),
          contracts: chainInfo.contracts,
          chain,
          transport: this.transports[chain.id] || http(),
          paymasterHandler: this.paymasterHandler,
        }),
      };
    } else {
      this.client = {
        type: "auth-server",
        instance: createWalletClient({
          key: "zksync-sso-auth-server-wallet",
          account: this.account.address,
          chain,
          transport: custom({
            request: this.request.bind(this),
          }),
        }),
      };
    }
  }

  async handshake(): Promise<Address[]> {
    let sessionPreferences: SessionPreferences | undefined;
    let metadata: AppMetadata = {
      name: "Unknown DApp",
      icon: null,
      configData: {},
    };
    try {
      metadata = this.getMetadata();
    } catch (error) {
      console.error("Failed to get website metadata. Proceeding with default one.", error);
    }
    if (this.sessionParameters) {
      try {
        sessionPreferences = await this.sessionParameters();
      } catch (error) {
        console.error("Failed to get session data. Proceeding connection with no session.", error);
      }
    }
    const responseMessage = await this.sendRpcRequest<"eth_requestAccounts", AuthServerRpcSchema>({
      method: "eth_requestAccounts",
      params: {
        metadata,
        sessionPreferences,
      },
    });
    const handshakeData = responseMessage.content.result!;

    this._chainsInfo.set(handshakeData.chainsInfo);
    this._account.set({
      address: handshakeData.account.address,
      activeChainId: handshakeData.account.activeChainId || this.chain.id,
      session: handshakeData.account.session,
    });
    return this.accounts;
  }

  switchChain(chainId: number): boolean {
    const chain = this.chains.find((chain) => chain.id === chainId);
    const chainInfo = this.chainsInfo.find((e) => e.id === chainId);
    if (!chainInfo) {
      console.error(`Chain ${chainId} is not supported or chain info was not set during handshake`);
      return false;
    };
    if (!chain) {
      console.error(`Chain ${chainId} is missing in the configuration`);
      return false;
    };
    if (chain.id === this.chain.id) return true;

    this._account.set({
      ...this.account!,
      activeChainId: chain.id,
    });
    return true;
  }

  async request<TMethod extends Method>(request: RequestArguments<TMethod>): Promise<ExtractReturnType<TMethod>> {
    const localResult = await this.tryLocalHandling(request);
    if (localResult !== undefined) return localResult;

    const response = await this.sendRpcRequest(request);
    return response.content.result as ExtractReturnType<TMethod>;
  }

  async disconnect() {
    this.clearState();
  }

  private async tryLocalHandling<TMethod extends Method>(request: RequestArguments<TMethod>): Promise<ExtractReturnType<TMethod> | undefined> {
    const client = this.walletClient;
    const originalClient = this.client;

    switch (request.method) {
      case "eth_estimateGas": {
        if (!client) return undefined;
        const params = request.params as ExtractParams<"eth_estimateGas">;
        const res = await client.request({ method: request.method, params: params });
        return res as ExtractReturnType<TMethod>;
      }
      case "eth_sendTransaction": {
        if (originalClient?.type !== "session") return undefined;
        const params = request.params as ExtractParams<"eth_sendTransaction">;
        const transactionRequest = params[0];
        const res = await originalClient.instance.sendTransaction(transactionRequest as unknown as SendTransactionParameters);
        return res as ExtractReturnType<TMethod>;
      }
      case "wallet_switchEthereumChain": {
        throw new Error("Chain switching is not supported yet");
        // const params = request.params as ExtractParams<"wallet_switchEthereumChain">;
        // const chainId = params[0].chainId;
        // const switched = this.switchChain(typeof chainId === "string" ? hexToNumber(chainId as Hash) : chainId);
        // return switched ? (null as ExtractReturnType<TMethod>) : undefined;
      }
      case "wallet_getCapabilities": {
        const chainInfo = this.chainsInfo.find((e) => e.id === this.chain.id);
        if (!chainInfo) throw new Error("Chain info is not set");
        return { [this.chain.id]: chainInfo.capabilities } as ExtractReturnType<TMethod>;
      }
      case "eth_accounts": {
        return this.accounts as ExtractReturnType<TMethod>;
      }
      default:
        return undefined;
    }
  }

  private async sendRpcRequest<
    TMethod extends Method<TSchema>,
    TSchema extends RpcSchemaGeneric = RpcSchema,
  >(request: RequestArguments<TMethod, TSchema>): Promise<RPCResponseMessage<ExtractReturnType<TMethod, TSchema>>> {
    // Open popup immediately to make sure popup won't be blocked by Safari
    await this.communicator.ready();

    if (request.method === "eth_sendTransaction") {
      const params = request.params![0] as TransactionRequestEIP712;
      if (params) {
        /* eslint-disable @typescript-eslint/no-unused-vars */
        const { chainId: _, ...transaction } = await getTransactionWithPaymasterData(
          this.chain.id,
          params.from,
          params,
          this.paymasterHandler,
        );
        request = {
          method: request.method,
          params: [transaction] as ExtractParams<TMethod, TSchema>,
        };
      }
    }

    const message = this.createRequestMessage<TMethod, TSchema>({
      action: request,
      chainId: this.chain.id,
    });
    const response: RPCResponseMessage<ExtractReturnType<TMethod, TSchema>>
      = await this.communicator.postRequestAndWaitForResponse(message);

    const content = response.content;
    if ("error" in content) throw content.error;

    return response;
  }

  private createRequestMessage<
    TMethod extends Method<TSchema>,
    TSchema extends RpcSchemaGeneric = RpcSchema,
  >(content: RPCRequestMessage<TMethod, TSchema>["content"]): RPCRequestMessage<TMethod, TSchema> {
    return {
      id: crypto.randomUUID(),
      content,
    };
  }
}