/*
 * Copyright (C) 2026 Fluxer Contributors
 *
 * This file is part of Fluxer.
 *
 * Fluxer is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Fluxer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with Fluxer. If not, see <https://www.gnu.org/licenses/>.
 */

import type {AuthService} from '@fluxer/api/src/auth/AuthService';
import type {AuthMfaService} from '@fluxer/api/src/auth/services/AuthMfaService';
import type {SudoVerificationBody} from '@fluxer/api/src/auth/services/SudoVerificationService';
import {requireSudoMode} from '@fluxer/api/src/auth/services/SudoVerificationService';
import {createApplicationID, createGuildID, createRoleID, type UserID} from '@fluxer/api/src/BrandedTypes';
import type {GuildService} from '@fluxer/api/src/guild/services/GuildService';
import type {IGatewayService} from '@fluxer/api/src/infrastructure/IGatewayService';
import {Logger} from '@fluxer/api/src/Logger';
import type {RequestCache} from '@fluxer/api/src/middleware/RequestCacheMiddleware';
import type {ApplicationService} from '@fluxer/api/src/oauth/ApplicationService';
import {ApplicationNotOwnedError} from '@fluxer/api/src/oauth/ApplicationService';
import type {BotAuthService} from '@fluxer/api/src/oauth/BotAuthService';
import {
	mapApplicationToResponse,
	mapBotTokenResetResponse,
	mapBotUserToResponse,
} from '@fluxer/api/src/oauth/OAuth2Mappers';
import {ACCESS_TOKEN_TTL_SECONDS, type OAuth2Service} from '@fluxer/api/src/oauth/OAuth2Service';
import type {IApplicationRepository} from '@fluxer/api/src/oauth/repositories/IApplicationRepository';
import type {IOAuth2TokenRepository} from '@fluxer/api/src/oauth/repositories/IOAuth2TokenRepository';
import {parseClientCredentials} from '@fluxer/api/src/oauth/utils/ParseClientCredentials';
import type {IUserRepository} from '@fluxer/api/src/user/IUserRepository';
import {mapUserToOAuthResponse} from '@fluxer/api/src/user/UserMappers';
import {verifyPassword} from '@fluxer/api/src/utils/PasswordUtils';
import {ALL_PERMISSIONS, Permissions} from '@fluxer/constants/src/ChannelConstants';
import {JoinSourceTypes} from '@fluxer/constants/src/GuildConstants';
import {AccessDeniedError} from '@fluxer/errors/src/domains/core/AccessDeniedError';
import {InvalidPermissionsIntegerError} from '@fluxer/errors/src/domains/core/InvalidPermissionsIntegerError';
import {InvalidPermissionsNegativeError} from '@fluxer/errors/src/domains/core/InvalidPermissionsNegativeError';
import {InvalidTokenError} from '@fluxer/errors/src/domains/core/InvalidTokenError';
import {MissingPermissionsError} from '@fluxer/errors/src/domains/core/MissingPermissionsError';
import {UnknownGuildMemberError} from '@fluxer/errors/src/domains/guild/UnknownGuildMemberError';
import {BotAlreadyInGuildError} from '@fluxer/errors/src/domains/oauth/BotAlreadyInGuildError';
import {BotUserNotFoundError} from '@fluxer/errors/src/domains/oauth/BotUserNotFoundError';
import {InvalidClientError} from '@fluxer/errors/src/domains/oauth/InvalidClientError';
import {InvalidGrantError} from '@fluxer/errors/src/domains/oauth/InvalidGrantError';
import {InvalidResponseTypeForNonBotError} from '@fluxer/errors/src/domains/oauth/InvalidResponseTypeForNonBotError';
import {MissingClientSecretError} from '@fluxer/errors/src/domains/oauth/MissingClientSecretError';
import {NotABotApplicationError} from '@fluxer/errors/src/domains/oauth/NotABotApplicationError';
import {RedirectUriRequiredForNonBotError} from '@fluxer/errors/src/domains/oauth/RedirectUriRequiredForNonBotError';
import {UnknownApplicationError} from '@fluxer/errors/src/domains/oauth/UnknownApplicationError';
import type {
	ApplicationBotResponse,
	ApplicationResponse,
	AuthorizeConsentRequest,
	BotTokenResetResponse,
	IntrospectRequestForm,
	OAuth2ConsentResponse,
	OAuth2IntrospectResponse,
	OAuth2MeResponse,
	OAuth2TokenResponse,
	OAuth2UserInfoResponse,
	RevokeRequestForm,
	TokenRequest,
} from '@fluxer/schema/src/domains/oauth/OAuthSchemas';
import type {Context} from 'hono';
import type {z} from 'zod';

export class OAuth2RequestService {
	constructor(
		private readonly oauth2Service: OAuth2Service,
		private readonly applicationRepository: IApplicationRepository,
		private readonly oauth2TokenRepository: IOAuth2TokenRepository,
		private readonly userRepository: IUserRepository,
		private readonly botAuthService: BotAuthService,
		private readonly applicationService: ApplicationService,
		private readonly gatewayService: IGatewayService,
		private readonly guildService: GuildService,
		private readonly authService: AuthService,
		private readonly authMfaService: AuthMfaService,
	) {}

	async tokenExchange(params: {
		form: z.infer<typeof TokenRequest>;
		authorizationHeader?: string;
		logPrefix: string;
	}): Promise<OAuth2TokenResponse> {
		try {
			const {form, authorizationHeader, logPrefix} = params;
			const hasAuthHeader = !!authorizationHeader;
			const isAuthorizationCodeRequest = form.grant_type === 'authorization_code';
			const isRefreshRequest = form.grant_type === 'refresh_token';

			Logger.debug(
				{
					grant_type: form.grant_type,
					client_id_present: form.client_id != null,
					redirect_uri_present: isAuthorizationCodeRequest ? form.redirect_uri != null : undefined,
					code_len: isAuthorizationCodeRequest ? form.code.length : undefined,
					refresh_token_len: isRefreshRequest ? form.refresh_token.length : undefined,
					auth_header_basic: hasAuthHeader && /^Basic\s+/i.test(authorizationHeader ?? ''),
				},
				`${logPrefix} token request received`,
			);

			if (form.grant_type === 'authorization_code') {
				const response = await this.oauth2Service.tokenExchange({
					headersAuthorization: authorizationHeader,
					grantType: 'authorization_code',
					code: form.code,
					redirectUri: form.redirect_uri,
					clientId: form.client_id ? form.client_id.toString() : undefined,
					clientSecret: form.client_secret,
				});
				return this.requireTokenResponseFields(response);
			}

			const response = await this.oauth2Service.tokenExchange({
				headersAuthorization: authorizationHeader,
				grantType: 'refresh_token',
				refreshToken: form.refresh_token,
				clientId: form.client_id ? form.client_id.toString() : undefined,
				clientSecret: form.client_secret,
			});
			return this.requireTokenResponseFields(response);
		} catch (err: unknown) {
			if (err instanceof InvalidGrantError) {
				Logger.warn({error: (err as Error).message}, `${params.logPrefix} token request failed`);
			}
			throw err;
		}
	}

	async userInfo(authorizationHeader: string | undefined): Promise<OAuth2UserInfoResponse> {
		const token = this.extractBearerToken(authorizationHeader ?? '');
		if (!token) {
			throw new InvalidTokenError();
		}
		return this.oauth2Service.userInfo(token);
	}

	private requireTokenResponseFields(response: {
		access_token: string;
		token_type: string;
		expires_in: number;
		scope?: string;
		refresh_token?: string;
	}): OAuth2TokenResponse {
		if (!response.refresh_token || !response.scope) {
			throw new InvalidGrantError();
		}

		return {
			access_token: response.access_token,
			token_type: response.token_type,
			expires_in: response.expires_in,
			refresh_token: response.refresh_token,
			scope: response.scope,
		};
	}

	async revoke(params: {form: z.infer<typeof RevokeRequestForm>; authorizationHeader?: string}): Promise<void> {
		const {clientId: clientIdStr, clientSecret: secret} = parseClientCredentials(
			params.authorizationHeader,
			params.form.client_id,
			params.form.client_secret,
		);
		if (!secret) {
			throw new MissingClientSecretError();
		}
		await this.oauth2Service.revoke(params.form.token, params.form.token_type_hint ?? undefined, {
			clientId: createApplicationID(BigInt(clientIdStr)),
			clientSecret: secret,
		});
	}

	async introspect(params: {
		form: z.infer<typeof IntrospectRequestForm>;
		authorizationHeader?: string;
	}): Promise<OAuth2IntrospectResponse> {
		const {clientId: clientIdStr, clientSecret: secret} = parseClientCredentials(
			params.authorizationHeader,
			params.form.client_id,
			params.form.client_secret,
		);
		if (!secret) {
			throw new MissingClientSecretError();
		}

		const applicationId = createApplicationID(BigInt(clientIdStr));
		const application = await this.applicationRepository.getApplication(applicationId);
		if (!application) {
			throw new InvalidClientError();
		}

		if (application.clientSecretHash) {
			const valid = await verifyPassword({password: secret, passwordHash: application.clientSecretHash});
			if (!valid) {
				throw new InvalidClientError();
			}
		}

		return this.oauth2Service.introspect(params.form.token, {
			clientId: applicationId,
			clientSecret: secret,
		});
	}

	async authorizeConsent(params: {
		body: z.infer<typeof AuthorizeConsentRequest>;
		userId: UserID;
		requestCache: RequestCache;
	}): Promise<OAuth2ConsentResponse> {
		const scopeStr = params.body.scope;
		const scopeSet = new Set(scopeStr.split(/\s+/).filter(Boolean));
		const isBotOnly = scopeSet.size === 1 && scopeSet.has('bot');
		const responseType = params.body.response_type ?? (isBotOnly ? undefined : 'code');
		const guildId = params.body.guild_id ? createGuildID(params.body.guild_id) : null;
		let requestedPermissions: bigint | null = null;
		if (params.body.permissions !== undefined) {
			try {
				requestedPermissions = BigInt(params.body.permissions);
			} catch {
				throw new InvalidPermissionsIntegerError();
			}
			if (requestedPermissions < 0) {
				throw new InvalidPermissionsNegativeError();
			}
			requestedPermissions = requestedPermissions & ALL_PERMISSIONS;
		}

		if (!isBotOnly && responseType !== 'code') {
			throw new InvalidResponseTypeForNonBotError();
		}
		if (!isBotOnly && !params.body.redirect_uri) {
			throw new RedirectUriRequiredForNonBotError();
		}

		const {redirectTo} = await this.oauth2Service.authorizeAndConsent({
			clientId: params.body.client_id.toString(),
			redirectUri: params.body.redirect_uri,
			scope: params.body.scope,
			state: params.body.state ?? undefined,
			responseType: responseType as 'code' | undefined,
			userId: params.userId,
		});

		const authCode = (() => {
			try {
				const url = new URL(redirectTo);
				return url.searchParams.get('code');
			} catch {
				return null;
			}
		})();

		if (scopeSet.has('bot') && guildId) {
			try {
				const applicationId = createApplicationID(BigInt(params.body.client_id));
				const application = await this.applicationRepository.getApplication(applicationId);
				if (!application || !application.botUserId) {
					throw new NotABotApplicationError();
				}

				const botUserId = application.botUserId;
				const hasManageGuild = await this.gatewayService.checkPermission({
					guildId,
					userId: params.userId,
					permission: Permissions.MANAGE_GUILD,
				});

				if (!hasManageGuild) {
					throw new MissingPermissionsError();
				}

				try {
					await this.guildService.members.getMember({
						userId: params.userId,
						targetId: botUserId,
						guildId,
						requestCache: params.requestCache,
					});
					throw new BotAlreadyInGuildError();
				} catch (err) {
					if (!(err instanceof UnknownGuildMemberError)) {
						throw err;
					}
				}

				await this.guildService.members.addUserToGuild({
					userId: botUserId,
					guildId,
					skipGuildLimitCheck: true,
					skipBanCheck: true,
					joinSourceType: JoinSourceTypes.BOT_INVITE,
					inviterId: params.userId,
					requestCache: params.requestCache,
					initiatorId: params.userId,
				});

				if (requestedPermissions && requestedPermissions > 0n) {
					const role = await this.guildService.systemCreateRole({
						initiatorId: params.userId,
						guildId,
						data: {
							name: `${application.name}`,
							color: 0,
							permissions: requestedPermissions,
						},
					});

					await this.guildService.members.systemAddMemberRole({
						targetId: botUserId,
						guildId,
						roleId: createRoleID(BigInt(role.id)),
						initiatorId: params.userId,
						requestCache: params.requestCache,
					});
				}
			} catch (err) {
				if (authCode) {
					await this.oauth2TokenRepository.deleteAuthorizationCode(authCode);
				}
				throw err;
			}
		}

		Logger.info({redirectTo}, 'OAuth2 consent: returning redirect URL');
		return {redirect_to: redirectTo};
	}

	async getMe(authorizationHeader: string | undefined): Promise<OAuth2MeResponse> {
		const token = this.extractBearerToken(authorizationHeader ?? '');
		if (!token) {
			throw new InvalidTokenError();
		}

		try {
			const tokenData = await this.oauth2TokenRepository.getAccessToken(token);
			if (!tokenData) {
				throw new InvalidTokenError();
			}

			const application = await this.applicationRepository.getApplication(tokenData.applicationId);
			if (!application) {
				throw new InvalidTokenError();
			}

			const scopes = Array.from(tokenData.scope);
			const expiresAt = new Date(tokenData.createdAt.getTime() + ACCESS_TOKEN_TTL_SECONDS * 1000);
			const response: OAuth2MeResponse = {
				application: {
					id: application.applicationId.toString(),
					name: application.name,
					icon: null,
					description: null,
					bot_public: application.botIsPublic,
					bot_require_code_grant: application.botRequireCodeGrant,
					flags: 0,
				},
				scopes,
				expires: expiresAt.toISOString(),
			};

			if (tokenData.userId && tokenData.scope.has('identify')) {
				const user = await this.userRepository.findUnique(tokenData.userId);
				if (user) {
					response.user = mapUserToOAuthResponse(user, {includeEmail: tokenData.scope.has('email')});
				}
			}

			return response;
		} catch (err) {
			if (err instanceof InvalidTokenError) {
				throw err;
			}
			throw new InvalidTokenError();
		}
	}

	async getApplicationPublic(applicationId: bigint) {
		const application = await this.applicationRepository.getApplication(createApplicationID(applicationId));
		if (!application) {
			throw new UnknownApplicationError();
		}

		let botUser = null;
		if (application.hasBotUser() && application.getBotUserId()) {
			botUser = await this.userRepository.findUnique(application.getBotUserId()!);
		}

		const scopes: Array<string> = [];
		if (application.hasBotUser()) {
			scopes.push('bot');
		}

		return {
			id: application.applicationId.toString(),
			name: application.name,
			icon: botUser?.avatarHash ?? null,
			description: null,
			redirect_uris: Array.from(application.oauth2RedirectUris),
			scopes,
			bot_public: application.botIsPublic,
			bot: botUser ? mapBotUserToResponse(botUser) : null,
		};
	}

	async getApplicationsMe(authorizationHeader: string | undefined): Promise<{
		id: string;
		name: string;
		icon: null;
		description: null;
		bot_public: boolean;
		bot_require_code_grant: boolean;
		flags: number;
		bot?: ApplicationBotResponse;
	}> {
		const botToken = this.extractBotToken(authorizationHeader ?? '');
		if (!botToken) {
			throw new InvalidTokenError();
		}

		const botUserId = await this.botAuthService.validateBotToken(botToken);
		if (!botUserId) {
			throw new InvalidTokenError();
		}

		const [appIdStr] = botToken.split('.');
		if (!appIdStr) {
			throw new InvalidTokenError();
		}

		const application = await this.applicationRepository.getApplication(createApplicationID(BigInt(appIdStr)));
		if (!application) {
			throw new InvalidTokenError();
		}

		const response: {
			id: string;
			name: string;
			icon: null;
			description: null;
			bot_public: boolean;
			bot_require_code_grant: boolean;
			flags: number;
			bot?: ApplicationBotResponse;
		} = {
			id: application.applicationId.toString(),
			name: application.name,
			icon: null,
			description: null,
			bot_public: application.botIsPublic,
			bot_require_code_grant: application.botRequireCodeGrant,
			flags: 0,
		};

		if (application.hasBotUser() && application.getBotUserId()) {
			const botUser = await this.userRepository.findUnique(application.getBotUserId()!);
			if (botUser) {
				response.bot = mapBotUserToResponse(botUser);
			}
		}

		return response;
	}

	async resetBotToken(params: {
		ctx: Context;
		userId: UserID;
		body: SudoVerificationBody;
		applicationId: bigint;
	}): Promise<BotTokenResetResponse> {
		await requireSudoMode(params.ctx, params.ctx.get('user'), params.body, this.authService, this.authMfaService);

		try {
			const {token} = await this.applicationService.rotateBotToken(
				params.userId,
				createApplicationID(params.applicationId),
			);

			const application = await this.applicationRepository.getApplication(createApplicationID(params.applicationId));
			if (!application || !application.botUserId) {
				throw new BotUserNotFoundError();
			}

			const botUser = await this.userRepository.findUnique(application.botUserId);
			if (!botUser) {
				throw new BotUserNotFoundError();
			}

			return mapBotTokenResetResponse(botUser, token);
		} catch (err) {
			if (err instanceof ApplicationNotOwnedError) {
				throw new AccessDeniedError();
			}
			if (err instanceof InvalidClientError || err instanceof UnknownApplicationError) {
				throw new UnknownApplicationError();
			}
			throw err;
		}
	}

	async resetClientSecret(params: {
		ctx: Context;
		userId: UserID;
		body: SudoVerificationBody;
		applicationId: bigint;
	}): Promise<ApplicationResponse> {
		await requireSudoMode(params.ctx, params.ctx.get('user'), params.body, this.authService, this.authMfaService);

		try {
			const {clientSecret} = await this.applicationService.rotateClientSecret(
				params.userId,
				createApplicationID(params.applicationId),
			);
			const application = await this.applicationRepository.getApplication(createApplicationID(params.applicationId));
			if (!application) {
				throw new UnknownApplicationError();
			}

			return mapApplicationToResponse(application, {clientSecret});
		} catch (err) {
			if (err instanceof ApplicationNotOwnedError) {
				throw new AccessDeniedError();
			}
			if (err instanceof InvalidClientError || err instanceof UnknownApplicationError) {
				throw new UnknownApplicationError();
			}
			throw err;
		}
	}

	async listAuthorizations(userId: UserID) {
		const refreshTokens = await this.oauth2TokenRepository.listRefreshTokensForUser(userId);

		const appMap = new Map<
			string,
			{
				applicationId: string;
				scopes: Set<string>;
				createdAt: Date;
				application: {
					id: string;
					name: string;
					icon: string | null;
					description: null;
					bot_public: boolean;
				};
			}
		>();

		for (const token of refreshTokens) {
			const appIdStr = token.applicationId.toString();
			const existing = appMap.get(appIdStr);

			if (existing) {
				for (const scope of token.scope) {
					existing.scopes.add(scope);
				}
				if (token.createdAt < existing.createdAt) {
					existing.createdAt = token.createdAt;
				}
			} else {
				const application = await this.applicationRepository.getApplication(token.applicationId);
				if (application) {
					const nonBotScopes = new Set([...token.scope].filter((s) => s !== 'bot'));
					if (nonBotScopes.size > 0) {
						let botUser = null;
						if (application.hasBotUser() && application.getBotUserId()) {
							botUser = await this.userRepository.findUnique(application.getBotUserId()!);
						}

						appMap.set(appIdStr, {
							applicationId: appIdStr,
							scopes: nonBotScopes,
							createdAt: token.createdAt,
							application: {
								id: application.applicationId.toString(),
								name: application.name,
								icon: botUser?.avatarHash ?? null,
								description: null,
								bot_public: application.botIsPublic,
							},
						});
					}
				}
			}
		}

		return Array.from(appMap.values()).map((entry) => ({
			application: entry.application,
			scopes: Array.from(entry.scopes),
			authorized_at: entry.createdAt.toISOString(),
		}));
	}

	async deleteAuthorization(userId: UserID, applicationId: bigint): Promise<void> {
		const application = await this.applicationRepository.getApplication(createApplicationID(applicationId));
		if (!application) {
			throw new UnknownApplicationError();
		}

		await this.oauth2TokenRepository.deleteAllTokensForUserAndApplication(userId, createApplicationID(applicationId));
	}

	private extractBearerToken(authHeader: string): string | null {
		const match = /^Bearer\s+(.+)$/.exec(authHeader);
		return match ? match[1] : null;
	}

	private extractBotToken(authHeader: string): string | null {
		const match = /^Bot\s+(.+)$/i.exec(authHeader);
		return match ? match[1] : null;
	}
}