import { nanoid } from 'nanoid';
import type { Context } from 'hono';
import { z } from 'zod';
import {
    authorizationRequestSchema,
    tokenRequestSchema,
    authorizationQuerySchema,
    tokenFormDataSchema,
    bearerTokenSchema,
    basicAuthSchema,
    revokeTokenRequestSchema,
    introspectTokenRequestSchema,
} from './schemas';
import type {
    OIDCProviderConfig,
    OIDCClient,
    OIDCUser,
    AuthorizationCode,
    AuthorizationRequest,
    TokenRequest,
    TokenResponse,
    OIDCError,
    DiscoveryDocument,
} from './types';
import type { StorageAdapter } from './storage/adapter';
import { TokenManager } from './auth/token-manager';
import { JWTUtils } from './utils/jwt';
import type { KeyPair } from './utils/jwt';
import { PKCEUtils } from './utils/pkce';
import { ValidationUtils } from './utils/validation';
import { PasswordAuth } from './auth';

/**
 * OIDC Provider - 简化版本，符合规范且代码简洁
 */
export class OIDCProvider {
    private readonly config: OIDCProviderConfig;
    private readonly tokenTTL: Required<NonNullable<OIDCProviderConfig['tokenTTL']>>;
    private readonly storage: StorageAdapter;
    private readonly tokenManager: TokenManager;
    private readonly jwtUtils: JWTUtils;
    private readonly findUser: (userId: string) => Promise<OIDCUser | null>;
    private readonly findClient: (clientId: string) => Promise<OIDCClient | null>;
    private passwordAuth: PasswordAuth;

    constructor(config: OIDCProviderConfig) {
        this.validateConfig(config);
        this.config = config;
        this.tokenTTL = {
            accessToken: config.tokenTTL?.accessToken || 3600,
            refreshToken: config.tokenTTL?.refreshToken || 2592000,
            authorizationCode: config.tokenTTL?.authorizationCode || 600,
            idToken: config.tokenTTL?.idToken || 3600,
        };

        this.storage = config.storage;
        this.tokenManager = new TokenManager(config.storage);
        this.findUser = config.findUser;
        this.findClient = config.findClient;

        // 创建JWT工具类，使用简化的构造函数
        this.jwtUtils = new JWTUtils(config.signingKey);

        this.passwordAuth = new PasswordAuth(config, config.authConfig.passwordValidator, config.authConfig);
    }

    private validateConfig(config: OIDCProviderConfig): void {
        const required = ['issuer', 'storage', 'findUser', 'findClient', 'authConfig'];
        for (const field of required) {
            if (!config[field as keyof OIDCProviderConfig]) {
                throw new Error(`配置项 ${field} 是必需的`);
            }
        }

        // 如果提供了signingKey且是字符串，说明使用HMAC
        // 如果没有提供signingKey，将自动生成RSA密钥
    }

    private get defaultScopes(): string[] {
        return this.config.scopes || ['openid', 'profile', 'email'];
    }

    private get supportedResponseTypes(): string[] {
        return this.config.responseTypes || ['code'];
    }

    private get supportedGrantTypes(): string[] {
        return this.config.grantTypes || ['authorization_code', 'refresh_token'];
    }

    private get supportedClaims(): string[] {
        return this.config.claims || ['sub', 'name', 'email', 'email_verified'];
    }

    private get enablePKCE(): boolean {
        return this.config.enablePKCE ?? true;
    }

    private get requirePKCE(): boolean {
        return this.config.requirePKCE ?? false;
    }

    private get rotateRefreshTokens(): boolean {
        return this.config.rotateRefreshTokens ?? true;
    }

    async findToken(token: string): Promise<{ tokenData: any; type: 'access' | 'refresh' } | null> {
        const [accessToken, refreshToken] = await Promise.all([
            this.tokenManager.getAccessToken(token),
            this.tokenManager.getRefreshToken(token)
        ]);

        const tokenData = accessToken || refreshToken;
        if (tokenData && tokenData.expires_at < new Date()) {
            // 清理过期token
            await Promise.all([
                accessToken && this.tokenManager.deleteAccessToken(token),
                refreshToken && this.tokenManager.deleteRefreshToken(token),
            ].filter(Boolean));
            return null;
        }

        if (!tokenData) return null;
        return { tokenData, type: accessToken ? 'access' : 'refresh' };
    }

    parseAuthRequest(query: Record<string, string | string[]>): AuthorizationRequest {
        const normalized = authorizationQuerySchema.parse(query);
        return authorizationRequestSchema.parse({
            response_type: normalized.response_type || '',
            client_id: normalized.client_id || '',
            redirect_uri: normalized.redirect_uri || '',
            scope: normalized.scope || 'openid',
            state: normalized.state,
            nonce: normalized.nonce,
            code_challenge: normalized.code_challenge,
            code_challenge_method: normalized.code_challenge_method as 'plain' | 'S256' | undefined,
            prompt: normalized.prompt,
            max_age: normalized.max_age ? parseInt(normalized.max_age, 10) : undefined,
            id_token_hint: normalized.id_token_hint,
            login_hint: normalized.login_hint,
            acr_values: normalized.acr_values,
        });
    }

    parseTokenRequest(body: FormData, authHeader?: string): TokenRequest {
        const formData = tokenFormDataSchema.parse(body);

        // 处理客户端认证
        if (authHeader?.startsWith('Basic ')) {
            const basicAuth = basicAuthSchema.parse(authHeader);
            formData.client_id = basicAuth.username || formData.client_id || '';
            formData.client_secret = basicAuth.password || formData.client_secret || '';
        }

        return tokenRequestSchema.parse({
            grant_type: formData.grant_type || '',
            client_id: formData.client_id || '',
            code: formData.code,
            redirect_uri: formData.redirect_uri,
            client_secret: formData.client_secret,
            refresh_token: formData.refresh_token,
            code_verifier: formData.code_verifier,
            scope: formData.scope,
        });
    }

    async validateClient(clientId: string, clientSecret?: string): Promise<OIDCClient> {
        const client = await this.findClient(clientId);
        if (!client) throw new Error('客户端不存在');

        // 机密客户端需要密钥
        if (client.client_type === 'confidential' && clientSecret !== client.client_secret) {
            throw new Error('客户端认证失败');
        }

        // 公开客户端不应该发送密钥
        if (client.client_type === 'public' && clientSecret) {
            throw new Error('公开客户端不应发送密钥');
        }

        return client;
    }

    validatePKCE(request: AuthorizationRequest, client: OIDCClient): void {
        const isPublic = client.client_type === 'public';
        const hasChallenge = !!request.code_challenge;

        if (this.requirePKCE && isPublic && !hasChallenge) {
            throw new Error('公开客户端必须使用PKCE');
        }

        if (hasChallenge && request.code_challenge) {
            const codeChallenge = request.code_challenge;
            const method = request.code_challenge_method || 'plain';

            if (!PKCEUtils.isValidCodeChallenge(codeChallenge, method)) {
                throw new Error('无效的PKCE参数');
            }
        }
    }

    getDiscoveryDocument(): DiscoveryDocument {
        const baseUrl = this.config.issuer;
        // 根据signingKey类型确定签名算法
        const signingAlgorithm = typeof this.config.signingKey === 'string' ? 'HS256' : 'RS256';

        return {
            issuer: this.config.issuer,
            authorization_endpoint: `${baseUrl}/auth`,
            token_endpoint: `${baseUrl}/token`,
            userinfo_endpoint: `${baseUrl}/userinfo`,
            jwks_uri: `${baseUrl}/.well-known/jwks.json`,
            revocation_endpoint: `${baseUrl}/revoke`,
            introspection_endpoint: `${baseUrl}/introspect`,
            end_session_endpoint: `${baseUrl}/logout`,
            response_types_supported: this.supportedResponseTypes,
            grant_types_supported: this.supportedGrantTypes,
            scopes_supported: this.defaultScopes,
            claims_supported: this.supportedClaims,
            token_endpoint_auth_methods_supported: ['client_secret_basic', 'client_secret_post', 'none'],
            id_token_signing_alg_values_supported: [signingAlgorithm],
            subject_types_supported: ['public'],
            code_challenge_methods_supported: this.enablePKCE ? ['plain', 'S256'] : undefined,
            response_modes_supported: ['query', 'fragment'],
        };
    }

    async handleAuthorizationRequest(request: AuthorizationRequest, userId?: string) {
        // 基本验证
        if (!request.client_id || !request.response_type || !request.redirect_uri) {
            throw new Error('缺少必需参数');
        }

        const client = await this.findClient(request.client_id);
        if (!client || !client.redirect_uris.includes(request.redirect_uri)) {
            throw new Error('无效的客户端或重定向URI');
        }

        // 验证请求
        const validation = ValidationUtils.validateAuthorizationRequest(
            request, client, this.defaultScopes, this.supportedResponseTypes
        );
        if (!validation.valid) {
            throw new Error(validation.errors.join(', '));
        }

        if (!userId) {
            throw new Error('需要用户认证');
        }

        this.validatePKCE(request, client);

        // 生成授权码
        if (request.response_type === 'code') {
            const code = nanoid(32);
            const authCode: AuthorizationCode = {
                code,
                client_id: request.client_id,
                user_id: userId,
                redirect_uri: request.redirect_uri,
                scope: request.scope,
                code_challenge: request.code_challenge,
                code_challenge_method: request.code_challenge_method,
                nonce: request.nonce,
                state: request.state,
                expires_at: new Date(Date.now() + this.tokenTTL.authorizationCode * 1000),
                created_at: new Date(),
            };

            await this.tokenManager.storeAuthorizationCode(authCode);
            return { code, state: request.state };
        }

        throw new Error(`不支持的响应类型: ${request.response_type}`);
    }

    async handleTokenRequest(request: TokenRequest): Promise<TokenResponse> {
        if (!request.grant_type || !request.client_id) {
            throw new Error('缺少必需参数');
        }

        const client = await this.validateClient(request.client_id, request.client_secret);

        switch (request.grant_type) {
            case 'authorization_code':
                return this.handleAuthorizationCodeGrant(request, client);
            case 'refresh_token':
                return this.handleRefreshTokenGrant(request, client);
            default:
                throw new Error(`不支持的授权类型: ${request.grant_type}`);
        }
    }

    private async handleAuthorizationCodeGrant(request: TokenRequest, client: OIDCClient): Promise<TokenResponse> {
        if (!request.code || !request.redirect_uri) {
            throw new Error('缺少授权码或重定向URI');
        }

        const authCode = await this.tokenManager.getAuthorizationCode(request.code);
        if (!authCode || authCode.expires_at < new Date()) {
            if (authCode) await this.tokenManager.deleteAuthorizationCode(request.code);
            throw new Error('授权码无效或已过期');
        }

        // 验证授权码
        if (authCode.client_id !== request.client_id || authCode.redirect_uri !== request.redirect_uri) {
            throw new Error('授权码不匹配');
        }

        // 验证PKCE
        if (authCode.code_challenge) {
            if (!request.code_verifier || !PKCEUtils.verifyCodeChallenge(
                request.code_verifier, authCode.code_challenge, authCode.code_challenge_method || 'plain'
            )) {
                throw new Error('PKCE验证失败');
            }
        }

        const user = await this.findUser(authCode.user_id);
        if (!user) throw new Error('用户不存在');

        // 删除已使用的授权码
        await this.tokenManager.deleteAuthorizationCode(request.code);

        return this.generateTokens(user, client, authCode.scope, authCode.nonce);
    }

    private async handleRefreshTokenGrant(request: TokenRequest, client: OIDCClient): Promise<TokenResponse> {
        if (!request.refresh_token) {
            throw new Error('缺少刷新token');
        }

        const refreshToken = await this.tokenManager.getRefreshToken(request.refresh_token);
        if (!refreshToken || refreshToken.expires_at < new Date()) {
            if (refreshToken) await this.tokenManager.deleteRefreshToken(request.refresh_token);
            throw new Error('刷新token无效或已过期');
        }

        if (refreshToken.client_id !== request.client_id) {
            throw new Error('刷新token客户端不匹配');
        }

        const user = await this.findUser(refreshToken.user_id);
        if (!user) throw new Error('用户不存在');

        // 验证scope
        let scope = refreshToken.scope;
        if (request.scope) {
            const requestedScopes = request.scope.split(' ');
            const originalScopes = refreshToken.scope.split(' ');
            if (!requestedScopes.every(s => originalScopes.includes(s))) {
                throw new Error('请求的scope超出原始scope');
            }
            scope = request.scope;
        }

        const tokens = await this.generateTokens(user, client, scope);

        // 旋转刷新token
        if (this.rotateRefreshTokens) {
            await this.tokenManager.deleteRefreshToken(request.refresh_token);
        } else {
            tokens.refresh_token = request.refresh_token;
        }

        return tokens;
    }

    private async generateTokens(
        user: OIDCUser,
        client: OIDCClient,
        scope: string,
        nonce?: string
    ): Promise<TokenResponse> {
        const now = new Date();
        const [accessToken, refreshTokenValue] = await Promise.all([
            this.jwtUtils.generateAccessToken({
                issuer: this.config.issuer,
                subject: user.sub,
                audience: client.client_id,
                clientId: client.client_id,
                scope,
                expiresIn: this.tokenTTL.accessToken,
            }),
            nanoid(64)
        ]);

        // 生成ID Token（如果scope包含openid）
        let idToken: string | undefined;
        if (scope.includes('openid')) {
            idToken = await this.jwtUtils.generateIDToken({
                issuer: this.config.issuer,
                subject: user.sub,
                audience: client.client_id,
                user,
                authTime: Math.floor(now.getTime() / 1000),
                nonce,
                expiresIn: this.tokenTTL.idToken,
            });
        }

        // 存储tokens
        const storeOperations = [
            this.tokenManager.storeAccessToken({
                token: accessToken,
                client_id: client.client_id,
                user_id: user.sub,
                scope,
                expires_at: new Date(now.getTime() + this.tokenTTL.accessToken * 1000),
                created_at: now,
            }),
            this.tokenManager.storeRefreshToken({
                token: refreshTokenValue,
                client_id: client.client_id,
                user_id: user.sub,
                scope,
                expires_at: new Date(now.getTime() + this.tokenTTL.refreshToken * 1000),
                created_at: now,
            })
        ];

        if (idToken) {
            storeOperations.push(this.tokenManager.storeIDToken({
                token: idToken,
                client_id: client.client_id,
                user_id: user.sub,
                nonce,
                expires_at: new Date(now.getTime() + this.tokenTTL.idToken * 1000),
                created_at: now,
            }));
        }

        await Promise.all(storeOperations);

        const response: TokenResponse = {
            access_token: accessToken,
            token_type: 'Bearer',
            expires_in: this.tokenTTL.accessToken,
            refresh_token: refreshTokenValue,
            scope,
        };

        if (idToken) response.id_token = idToken;
        return response;
    }

    async getUserInfo(accessToken: string): Promise<Partial<OIDCUser>> {
        const tokenData = await this.tokenManager.getAccessToken(accessToken);
        if (!tokenData || tokenData.expires_at < new Date()) {
            if (tokenData) await this.tokenManager.deleteAccessToken(accessToken);
            throw new Error('Token无效或已过期');
        }

        // 验证JWT
        await this.jwtUtils.verifyToken(accessToken);

        const user = await this.findUser(tokenData.user_id);
        if (!user) throw new Error('用户不存在');

        const claims = this.getClaimsForScope(tokenData.scope);
        return this.filterUserClaims(user, claims);
    }

    private getClaimsForScope(scope: string): string[] {
        const scopes = scope.split(' ');
        const claimsMap = {
            profile: ['name', 'given_name', 'family_name', 'picture'],
            email: ['email', 'email_verified'],
            phone: ['phone_number', 'phone_number_verified'],
            address: ['address'],
        };

        const claims = new Set(['sub']);
        scopes.forEach(s => {
            if (s in claimsMap) {
                claimsMap[s as keyof typeof claimsMap].forEach(c => claims.add(c));
            }
        });

        return Array.from(claims);
    }

    private filterUserClaims(user: OIDCUser, claims: string[]): Partial<OIDCUser> {
        return Object.fromEntries(
            claims
                .filter(claim => claim in user && user[claim as keyof OIDCUser] !== undefined)
                .map(claim => [claim, user[claim as keyof OIDCUser]])
        );
    }

    async revokeToken(token: string, clientId?: string): Promise<void> {
        const result = await this.findToken(token);
        if (!result) return; // Token不存在或已过期

        const { tokenData, type } = result;

        if (clientId && tokenData.client_id !== clientId) {
            throw new Error('Token不属于此客户端');
        }

        if (type === 'access') {
            await this.tokenManager.deleteAccessToken(token);
        } else {
            // 撤销刷新token时，同时撤销相关的访问token
            await Promise.all([
                this.tokenManager.deleteRefreshToken(token),
                this.tokenManager.deleteAccessTokensByUserAndClient(tokenData.user_id, tokenData.client_id)
            ]);
        }
    }

    async introspectToken(token: string, clientId?: string) {
        const result = await this.findToken(token);
        if (!result) return { active: false };

        const { tokenData, type } = result;

        if (clientId && tokenData.client_id !== clientId) {
            return { active: false };
        }

        const user = await this.findUser(tokenData.user_id);

        return {
            active: true,
            scope: tokenData.scope,
            client_id: tokenData.client_id,
            username: user?.username,
            token_type: type === 'access' ? 'Bearer' : 'refresh_token',
            exp: Math.floor(tokenData.expires_at.getTime() / 1000),
            iat: Math.floor(tokenData.created_at.getTime() / 1000),
            sub: tokenData.user_id,
            aud: tokenData.client_id,
            iss: this.config.issuer,
        };
    }

    async getJWKS() {
        return this.jwtUtils.generateJWKS();
    }

    // HTTP处理器
    private createErrorResponse(error: unknown): { error: string; error_description: string } {
        const message = error instanceof Error ? error.message : '服务器内部错误';
        console.error('OIDC Provider Error:', error);
        return {
            error: 'invalid_request',
            error_description: message
        };
    }

    async handleLogin(c: Context): Promise<Response> {
        try {
            const formData = await c.req.formData();
            const authRequest = Object.fromEntries(
                ['response_type', 'client_id', 'redirect_uri', 'scope', 'state', 'nonce', 'code_challenge', 'code_challenge_method']
                    .map(field => [field, formData.get(field)?.toString() || ''])
            );

            const authResult = await this.passwordAuth.authenticate(c);
            return authResult.success
                ? await this.passwordAuth.handleAuthenticationSuccess(c, authResult)
                : await this.passwordAuth.handleAuthenticationFailure(c, authResult, authRequest as any);
        } catch (error) {
            return c.json(this.createErrorResponse(error), 500);
        }
    }

    async handleLogout(c: Context): Promise<Response> {
        return this.passwordAuth.logout(c);
    }

    async handleAuthorization(c: Context): Promise<Response> {
        try {
            const authRequest = this.parseAuthRequest(c.req.query());
            const userId = await this.passwordAuth.getCurrentUser(c);

            if (!userId) {
                return this.passwordAuth.handleAuthenticationRequired(c, authRequest);
            }

            const result = await this.handleAuthorizationRequest(authRequest, userId);
            const params = new URLSearchParams();
            if (result.code) params.set('code', result.code);
            if (result.state) params.set('state', result.state);

            return c.redirect(`${authRequest.redirect_uri}?${params.toString()}`);
        } catch (error) {
            return c.json(this.createErrorResponse(error), 400);
        }
    }

    async handleToken(c: Context): Promise<Response> {
        try {
            const body = await c.req.formData();
            const tokenRequest = this.parseTokenRequest(body, c.req.header('Authorization'));
            const response = await this.handleTokenRequest(tokenRequest);

            c.header('Cache-Control', 'no-store');
            c.header('Pragma', 'no-cache');
            return c.json(response);
        } catch (error) {
            return c.json(this.createErrorResponse(error), 400);
        }
    }

    async handleUserInfo(c: Context): Promise<Response> {
        try {
            const authHeader = c.req.header('Authorization');
            if (!authHeader?.startsWith('Bearer ')) {
                c.header('WWW-Authenticate', 'Bearer realm="userinfo"');
                return c.json({ error: 'invalid_token', error_description: 'Bearer token required' }, 401);
            }

            const token = bearerTokenSchema.parse(authHeader);
            const user = await this.getUserInfo(token);
            return c.json(user);
        } catch (error) {
            c.header('WWW-Authenticate', 'Bearer realm="userinfo"');
            return c.json({ error: 'invalid_token', error_description: 'Invalid token' }, 401);
        }
    }

    async handleRevoke(c: Context): Promise<Response> {
        try {
            const body = await c.req.formData();
            const { token, client_id } = revokeTokenRequestSchema.parse({
                token: body.get('token')?.toString(),
                client_id: body.get('client_id')?.toString(),
            });

            if (!token) {
                return c.json({ error: 'invalid_request', error_description: 'Missing token' }, 400);
            }

            await this.revokeToken(token, client_id);
            return c.body(null, 200);
        } catch (error) {
            return c.json(this.createErrorResponse(error), 400);
        }
    }

    async handleIntrospect(c: Context): Promise<Response> {
        try {
            const body = await c.req.formData();
            const { token, client_id } = introspectTokenRequestSchema.parse({
                token: body.get('token')?.toString(),
                client_id: body.get('client_id')?.toString(),
            });

            if (!token) {
                return c.json({ error: 'invalid_request', error_description: 'Missing token' }, 400);
            }

            const result = await this.introspectToken(token, client_id);
            return c.json(result);
        } catch (error) {
            return c.json(this.createErrorResponse(error), 400);
        }
    }
}