import { useReducer, useEffect } from "react";
import { useTypedFetcher } from "remix-typedjson";
import type { action } from "./route";

export type MfaPhase = "idle" | "enabling" | "validating" | "showing-recovery" | "disabling";

export interface MfaState {
  phase: MfaPhase;
  isEnabled: boolean;
  setupData?: {
    secret: string;
    otpAuthUrl: string;
  };
  recoveryCodes?: string[];
  error?: string;
  isSubmitting: boolean;
  disableMethod: "totp" | "recovery";
}

export type MfaAction =
  | { type: "ENABLE_MFA" }
  | { type: "SETUP_DATA_RECEIVED"; setupData: { secret: string; otpAuthUrl: string } }
  | { type: "CANCEL_SETUP" }
  | { type: "VALIDATE_TOTP"; code: string }
  | { type: "VALIDATION_SUCCESS"; recoveryCodes: string[] }
  | { type: "VALIDATION_FAILED"; error: string; setupData: { secret: string; otpAuthUrl: string } }
  | { type: "RECOVERY_CODES_SAVED" }
  | { type: "OPEN_DISABLE_DIALOG" }
  | { type: "DISABLE_MFA" }
  | { type: "DISABLE_SUCCESS" }
  | { type: "DISABLE_FAILED"; error: string }
  | { type: "CANCEL_DISABLE" }
  | { type: "SET_DISABLE_METHOD"; method: "totp" | "recovery" }
  | { type: "SET_ERROR"; error: string }
  | { type: "CLEAR_ERROR" }
  | { type: "SET_SUBMITTING"; isSubmitting: boolean };

function mfaReducer(state: MfaState, action: MfaAction): MfaState {
  switch (action.type) {
    case "ENABLE_MFA":
      return {
        ...state,
        phase: "enabling",
        isSubmitting: true,
        error: undefined,
      };

    case "SETUP_DATA_RECEIVED":
      return {
        ...state,
        phase: "enabling",
        setupData: action.setupData,
        error: undefined,
        isSubmitting: false,
      };

    case "CANCEL_SETUP":
      return {
        ...state,
        phase: "idle",
        setupData: undefined,
        error: undefined,
        isSubmitting: false,
      };

    case "VALIDATE_TOTP":
      return {
        ...state,
        phase: "validating",
        isSubmitting: true,
        error: undefined,
      };

    case "VALIDATION_SUCCESS":
      return {
        ...state,
        phase: "showing-recovery",
        recoveryCodes: action.recoveryCodes,
        isSubmitting: false,
        isEnabled: true,
        error: undefined,
      };

    case "VALIDATION_FAILED":
      return {
        ...state,
        phase: "enabling",
        setupData: action.setupData,
        error: action.error,
        isSubmitting: false,
      };

    case "RECOVERY_CODES_SAVED":
      return {
        ...state,
        phase: "idle",
        setupData: undefined,
        recoveryCodes: undefined,
        isSubmitting: false,
      };

    case "OPEN_DISABLE_DIALOG":
      return {
        ...state,
        phase: "disabling",
        error: undefined,
        isSubmitting: false,
      };

    case "DISABLE_MFA":
      return {
        ...state,
        isSubmitting: true,
        error: undefined,
      };

    case "DISABLE_SUCCESS":
      return {
        ...state,
        phase: "idle",
        isEnabled: false,
        error: undefined,
        isSubmitting: false,
      };

    case "DISABLE_FAILED":
      return {
        ...state,
        error: action.error,
        isSubmitting: false,
      };

    case "CANCEL_DISABLE":
      return {
        ...state,
        phase: "idle",
        error: undefined,
        isSubmitting: false,
      };

    case "SET_DISABLE_METHOD":
      return {
        ...state,
        disableMethod: action.method,
        error: undefined,
      };

    case "SET_ERROR":
      return {
        ...state,
        error: action.error,
      };

    case "CLEAR_ERROR":
      return {
        ...state,
        error: undefined,
      };

    case "SET_SUBMITTING":
      return {
        ...state,
        isSubmitting: action.isSubmitting,
      };

    default:
      return state;
  }
}

export function useMfaSetup(initialIsEnabled: boolean) {
  const fetcher = useTypedFetcher<typeof action>();

  const [state, dispatch] = useReducer(mfaReducer, {
    phase: "idle",
    isEnabled: initialIsEnabled,
    isSubmitting: false,
    disableMethod: "totp",
  });

  // Handle fetcher responses
  useEffect(() => {
    if (fetcher.data) {
      const { data } = fetcher;

      switch (data.action) {
        case "enable-mfa":
          dispatch({
            type: "SETUP_DATA_RECEIVED",
            setupData: { secret: data.secret, otpAuthUrl: data.otpAuthUrl },
          });
          break;

        case "validate-totp":
          if (data.success) {
            dispatch({
              type: "VALIDATION_SUCCESS",
              recoveryCodes: data.recoveryCodes || [],
            });
          } else {
            dispatch({
              type: "VALIDATION_FAILED",
              error: data.error || "Invalid code",
              setupData: { secret: data.secret!, otpAuthUrl: data.otpAuthUrl! },
            });
          }
          break;

        case "disable-mfa":
          if (data.success) {
            dispatch({ type: "DISABLE_SUCCESS" });
          } else {
            dispatch({
              type: "DISABLE_FAILED",
              error: data.error || "Failed to disable MFA",
            });
          }
          break;

        case "cancel-totp":
          dispatch({ type: "CANCEL_SETUP" });
          break;
      }
    }
  }, [fetcher.data]);

  // Handle submitting state
  useEffect(() => {
    dispatch({ type: "SET_SUBMITTING", isSubmitting: fetcher.state === "submitting" });
  }, [fetcher.state]);

  const actions = {
    enableMfa: () => {
      dispatch({ type: "ENABLE_MFA" });
      fetcher.submit(
        { action: "enable-mfa" },
        { method: "POST", action: "/resources/account/mfa/setup" }
      );
    },

    cancelSetup: () => {
      dispatch({ type: "CANCEL_SETUP" });
      fetcher.submit(
        { action: "cancel-totp" },
        { method: "POST", action: "/resources/account/mfa/setup" }
      );
    },

    validateTotp: (code: string) => {
      dispatch({ type: "VALIDATE_TOTP", code });
      fetcher.submit(
        { action: "validate-totp", totpCode: code },
        { method: "POST", action: "/resources/account/mfa/setup" }
      );
    },

    saveRecoveryCodes: () => {
      dispatch({ type: "RECOVERY_CODES_SAVED" });
      fetcher.submit(
        { action: "saved-recovery-codes" },
        { method: "POST", action: "/resources/account/mfa/setup" }
      );
    },

    openDisableDialog: () => {
      dispatch({ type: "OPEN_DISABLE_DIALOG" });
    },

    disableMfa: (totpCode?: string, recoveryCode?: string) => {
      dispatch({ type: "DISABLE_MFA" });
      const formData: Record<string, string> = { action: "disable-mfa" };
      if (totpCode) formData.totpCode = totpCode;
      if (recoveryCode) formData.recoveryCode = recoveryCode;

      fetcher.submit(formData, { method: "POST", action: "/resources/account/mfa/setup" });
    },

    cancelDisable: () => {
      dispatch({ type: "CANCEL_DISABLE" });
    },

    setDisableMethod: (method: "totp" | "recovery") => {
      dispatch({ type: "SET_DISABLE_METHOD", method });
    },

    clearError: () => {
      dispatch({ type: "CLEAR_ERROR" });
    },
  };

  return {
    state,
    actions,
    // Computed properties for easier access
    isQrDialogOpen:
      (state.phase === "enabling" && !!state.setupData) ||
      (state.phase === "showing-recovery" && !!state.recoveryCodes),
    isRecoveryDialogOpen: false, // Recovery is now handled within the setup dialog
    isDisableDialogOpen: state.phase === "disabling",
  };
}