import { OAuthProvider, OAuthTokens, OAuthProfile, AuthorizationUrlParams, TokenExchangeParams, ProviderConfig } from "./OAuthProvider";
import { OAuthProviderBase } from "./OAuthProviderBase";

/**
 * GitHub OAuth 2.0 provider implementation
 *
 * Implements OAuth flow for GitHub:
 * - Authorization URL: https://github.com/login/oauth/authorize
 * - Token exchange: POST https://github.com/login/oauth/access_token
 * - User profile: GET https://api.github.com/user
 *
 * Default scopes: ['user:email']
 */
export class GitHubProvider extends OAuthProviderBase implements OAuthProvider {
    public readonly name = "github";

    private static readonly AUTHORIZATION_URL = "https://github.com/login/oauth/authorize";
    private static readonly TOKEN_URL = "https://github.com/login/oauth/access_token";
    private static readonly USER_PROFILE_URL = "https://api.github.com/user";
    private static readonly DEFAULT_SCOPES = ["user:email"];

    constructor(config: ProviderConfig) {
        super(config);
    }

    /**
     * Generate GitHub authorization URL
     */
    getAuthorizationUrl(params: AuthorizationUrlParams): string {
        const scopes = params.scope.length > 0 ? params.scope : GitHubProvider.DEFAULT_SCOPES;

        const queryParams = {
            client_id: this.config.clientId,
            redirect_uri: params.redirectUri,
            state: params.state,
            scope: scopes.join(" "),
        };

        return `${GitHubProvider.AUTHORIZATION_URL}?${this.buildQueryString(queryParams)}`;
    }

    /**
     * Exchange authorization code for access token
     */
    async exchangeCodeForToken(params: TokenExchangeParams): Promise<OAuthTokens> {
        const body = this.buildQueryString({
            client_id: this.config.clientId,
            client_secret: this.config.clientSecret,
            code: params.code,
            redirect_uri: params.redirectUri,
        });

        const response = await this.makeHttpRequest(GitHubProvider.TOKEN_URL, {
            method: "POST",
            headers: {
                "Content-Type": "application/x-www-form-urlencoded",
                Accept: "application/json",
            },
            body,
        });

        return {
            accessToken: response.access_token,
            refreshToken: response.refresh_token,
            scope: response.scope,
            expiresIn: response.expires_in,
        };
    }

    /**
     * Fetch user profile from GitHub
     */
    async getUserProfile(accessToken: string): Promise<OAuthProfile> {
        const response = await this.makeHttpRequest(GitHubProvider.USER_PROFILE_URL, {
            method: "GET",
            headers: {
                Authorization: `Bearer ${accessToken}`,
                Accept: "application/json",
            },
        });

        return {
            id: String(response.id),
            email: response.email,
            name: response.name,
            avatarUrl: response.avatar_url,
            raw: response,
        };
    }
}