import { createContext, type ReactNode, useCallback, useContext, useEffect, useState } from "react";
import { CalComAPIService } from "@/services/calcom";
import {
  type CalComOAuthService,
  createCalComOAuthService,
  type OAuthTokens,
} from "@/services/oauthService";
import type { UserProfile } from "@/services/types/users.types";
import { WebAuthService } from "@/services/webAuth";
import { secureStorage } from "@/utils/storage";

/**
 * Simplified user info stored in auth context
 * Contains only the essential fields needed for the app
 */
interface AuthUserInfo {
  id: number;
  email: string;
  name: string;
  username: string;
}

interface AuthContextType {
  isAuthenticated: boolean;
  accessToken: string | null;
  refreshToken: string | null;
  userInfo: AuthUserInfo | null;
  isWebSession: boolean;
  loginFromWebSession: (userInfo: UserProfile) => Promise<void>;
  loginWithOAuth: () => Promise<void>;
  logout: () => Promise<void>;
  loading: boolean;
}

const AuthContext = createContext<AuthContextType | undefined>(undefined);

const ACCESS_TOKEN_KEY = "cal_access_token";
const REFRESH_TOKEN_KEY = "cal_refresh_token";
const OAUTH_TOKENS_KEY = "cal_oauth_tokens";
const AUTH_TYPE_KEY = "cal_auth_type";

type AuthType = "oauth" | "web_session";

interface AuthProviderProps {
  children: ReactNode;
}

// Use the shared secure storage adapter
const storage = secureStorage;

const getErrorMessage = (error: unknown) =>
  error instanceof Error ? error.message : String(error);
const getErrorStack = (error: unknown) => (error instanceof Error ? error.stack : undefined);

export function AuthProvider({ children }: AuthProviderProps) {
  "use no memo";
  const [isAuthenticated, setIsAuthenticated] = useState(false);
  const [accessToken, setAccessToken] = useState<string | null>(null);
  const [refreshToken, setRefreshToken] = useState<string | null>(null);
  const [userInfo, setUserInfo] = useState<AuthUserInfo | null>(null);
  const [isWebSession, setIsWebSession] = useState(false);
  const [loading, setLoading] = useState(true);
  const [oauthService] = useState(() => {
    try {
      return createCalComOAuthService();
    } catch (error) {
      console.warn("Failed to initialize OAuth service:", error);
      return null;
    }
  });

  // Setup refresh token function for OAuth
  const setupRefreshTokenFunction = useCallback((service: CalComOAuthService) => {
    CalComAPIService.setRefreshTokenFunction(async (refreshToken: string) => {
      const newTokens = await service.refreshAccessToken(refreshToken);
      return {
        accessToken: newTokens.accessToken,
        refreshToken: newTokens.refreshToken,
      };
    });
  }, []);

  // Common post-login setup: configure API service and fetch user profile
  const setupAfterLogin = useCallback(async (token: string, refreshToken?: string) => {
    CalComAPIService.setAccessToken(token, refreshToken);

    try {
      const profile = await CalComAPIService.getUserProfile();
      // Store user info for use in the app (e.g., to display "You" in bookings)
      if (profile) {
        setUserInfo({
          email: profile.email,
          name: profile.name,
          id: profile.id,
          username: profile.username,
        });
      }
    } catch (profileError) {
      console.error("Failed to fetch user profile:", profileError);
      // Don't fail login if profile fetch fails
    }
  }, []);

  const saveOAuthTokens = useCallback(
    async (tokens: OAuthTokens) => {
      await storage.set(OAUTH_TOKENS_KEY, JSON.stringify(tokens));
      await storage.set(AUTH_TYPE_KEY, "oauth");

      if (oauthService) {
        try {
          await oauthService.syncTokensToExtension(tokens);
        } catch (error) {
          console.warn("Failed to sync tokens to extension:", error);
        }
      }
    },
    [oauthService]
  );

  const clearAuth = useCallback(async () => {
    await storage.removeAll([ACCESS_TOKEN_KEY, REFRESH_TOKEN_KEY, OAUTH_TOKENS_KEY, AUTH_TYPE_KEY]);

    if (oauthService) {
      try {
        await oauthService.clearTokensFromExtension();
      } catch (error) {
        console.warn("Failed to clear tokens from extension:", error);
      }
    }
  }, [oauthService]);

  // Reset all auth state
  const resetAuthState = useCallback(() => {
    setAccessToken(null);
    setRefreshToken(null);
    setUserInfo(null);
    setIsAuthenticated(false);
    setIsWebSession(false);
    CalComAPIService.clearAuth();
    CalComAPIService.clearUserProfile();
  }, []);

  const logout = useCallback(async () => {
    try {
      await clearAuth();
      resetAuthState();
    } catch (error) {
      const message = getErrorMessage(error);
      console.error("Failed to logout", message);
      if (__DEV__) {
        console.debug("[AuthContext] logout failed", { message, stack: getErrorStack(error) });
      }
    }
  }, [clearAuth, resetAuthState]);

  // Handle OAuth authentication
  const handleOAuthAuth = useCallback(
    async (storedTokens: OAuthTokens) => {
      if (!oauthService) return;

      // Refresh token if expired
      let tokens = storedTokens;
      let tokensWereRefreshed = false;
      if (oauthService.isTokenExpired(storedTokens) && storedTokens.refreshToken) {
        try {
          console.log("Access token expired, refreshing...");
          tokens = await oauthService.refreshAccessToken(storedTokens.refreshToken);
          await saveOAuthTokens(tokens);
          tokensWereRefreshed = true;
        } catch (refreshError) {
          console.error("Failed to refresh token:", refreshError);
          await clearAuth();
          return;
        }
      }

      // Set state
      setAccessToken(tokens.accessToken);
      setRefreshToken(tokens.refreshToken || null);
      setIsAuthenticated(true);
      setIsWebSession(false);

      // Setup API service and refresh function
      await setupAfterLogin(tokens.accessToken, tokens.refreshToken);
      if (tokens.refreshToken) {
        setupRefreshTokenFunction(oauthService);
      }

      if (!tokensWereRefreshed) {
        try {
          await oauthService.syncTokensToExtension(tokens);
        } catch (error) {
          console.warn("Failed to sync tokens to extension on init:", error);
        }
      }
    },
    [oauthService, saveOAuthTokens, clearAuth, setupAfterLogin, setupRefreshTokenFunction]
  );

  // Handle web session authentication
  const handleWebSessionAuth = useCallback(() => {
    setIsWebSession(true);
  }, []);

  const checkAuthState = useCallback(async () => {
    try {
      const authType = (await storage.get(AUTH_TYPE_KEY)) as AuthType | null;
      const storedOAuthTokens = await storage.get(OAUTH_TOKENS_KEY);
      const storedTokens = storedOAuthTokens ? JSON.parse(storedOAuthTokens) : null;

      if (authType === "oauth" && storedTokens && oauthService) {
        await handleOAuthAuth(storedTokens);
      } else if (authType === "web_session") {
        handleWebSessionAuth();
      }
      setLoading(false);
    } catch (error) {
      const message = getErrorMessage(error);
      console.error("Failed to check auth state", message);
      if (__DEV__) {
        console.debug("[AuthContext] checkAuthState failed", {
          message,
          stack: getErrorStack(error),
        });
      }
      setLoading(false);
    }
  }, [oauthService, handleOAuthAuth, handleWebSessionAuth]);

  useEffect(() => {
    checkAuthState();

    // Set up token refresh callback
    const handleTokenRefresh = async (newAccessToken: string, newRefreshToken?: string) => {
      try {
        const tokens: OAuthTokens = {
          accessToken: newAccessToken,
          refreshToken: newRefreshToken || refreshToken || undefined,
          tokenType: "Bearer",
        };

        await saveOAuthTokens(tokens);
        setAccessToken(newAccessToken);
        if (newRefreshToken) {
          setRefreshToken(newRefreshToken);
        }

        CalComAPIService.setAccessToken(
          newAccessToken,
          newRefreshToken || refreshToken || undefined
        );
      } catch (error) {
        const message = getErrorMessage(error);
        console.error("Failed to handle token refresh", message);
        if (__DEV__) {
          console.debug("[AuthContext] token refresh handler failed", {
            message,
            stack: getErrorStack(error),
          });
        }
        await logout();
      }
    };

    CalComAPIService.setTokenRefreshCallback(handleTokenRefresh);

    return () => {
      CalComAPIService.setTokenRefreshCallback(() => Promise.resolve());
    };
  }, [refreshToken, checkAuthState, logout, saveOAuthTokens]);

  const loginFromWebSession = async (sessionUserInfo: UserProfile) => {
    try {
      setUserInfo({
        id: sessionUserInfo.id,
        email: sessionUserInfo.email,
        name: sessionUserInfo.name,
        username: sessionUserInfo.username,
      });
      setIsAuthenticated(true);
      setIsWebSession(true);
      await storage.set(AUTH_TYPE_KEY, "web_session");

      // Try to get tokens from web session
      const tokens = await WebAuthService.getTokensFromWebSession();
      if (tokens.accessToken) {
        setAccessToken(tokens.accessToken);
        setRefreshToken(tokens.refreshToken || null);
        await setupAfterLogin(tokens.accessToken, tokens.refreshToken);
      }
    } catch (error) {
      const message = getErrorMessage(error);
      console.error("Failed to login from web session", message);
      if (__DEV__) {
        console.debug("[AuthContext] loginFromWebSession failed", {
          message,
          stack: getErrorStack(error),
        });
      }
      throw error;
    }
  };

  const loginWithOAuth = async (): Promise<void> => {
    if (!oauthService) {
      throw new Error("OAuth service not available. Please check your configuration.");
    }

    setLoading(true);
    try {
      const tokens = await oauthService.startAuthorizationFlow();

      // Save tokens
      await saveOAuthTokens(tokens);

      // Update state
      setAccessToken(tokens.accessToken);
      setRefreshToken(tokens.refreshToken || null);
      setIsAuthenticated(true);
      setIsWebSession(false);

      // Setup API service and refresh function
      await setupAfterLogin(tokens.accessToken, tokens.refreshToken);
      if (tokens.refreshToken) {
        setupRefreshTokenFunction(oauthService);
      }

      // Clear PKCE parameters
      oauthService.clearPKCEParams();
      setLoading(false);
    } catch (error) {
      setLoading(false);
      const message = getErrorMessage(error);
      console.error("OAuth login failed", message);
      if (__DEV__) {
        console.debug("[AuthContext] loginWithOAuth failed", {
          message,
          stack: getErrorStack(error),
        });
      }
      throw error;
    }
  };

  const value: AuthContextType = {
    isAuthenticated,
    accessToken,
    refreshToken,
    userInfo,
    isWebSession,
    loginFromWebSession,
    loginWithOAuth,
    logout,
    loading,
  };

  return <AuthContext.Provider value={value}>{children}</AuthContext.Provider>;
}

export function useAuth(): AuthContextType {
  const context = useContext(AuthContext);
  if (context === undefined) {
    throw new Error("useAuth must be used within an AuthProvider");
  }
  return context;
}