package com.github.jreddit.oauth;

import org.apache.oltu.oauth2.client.response.OAuthJSONAccessTokenResponse;

import com.github.jreddit.oauth.param.RedditScope;
import com.github.jreddit.oauth.param.RedditTokenCompleteScope;

/**
 * OAuth2 token wrapper for reddit.<br>
 * <br>
 * This class wraps the information received from reddit following
 * the request for a token.<br>
 * A token has three dimensions:
 * <ul>
 * <li><b>scope:</b> what can it be used for?
 * <li><b>expiration:</b> how long can it be used?
 * <li><b>refreshable:</b> can its duration be prolonged?
 * </ul>
 * 
 * @author Simon Kassing
 *
 */
public class RedditToken {

    /** Token type parameter. */
    public static final String PARAM_TOKEN_TYPE = "token_type";
    
    /** Access token. */
    private String accessToken;
    
    /** Refresh token. */
    private String refreshToken;
    
    /** Manager of the scopes that this token applies to. */
    private RedditTokenCompleteScope scopes;
    
    /** Token type. Only value possible (15-06-2015): bearer */
    private String tokenType;
    
    /** Time at which the token expires (seconds since UNIX epoch). */
    private long expiration;
    
    /** How long the token was valid starting from its creation (in seconds). */
    private long expirationSpan;
    
    /**
     * @param token JSON response after an OAuth2 token request
     */
    protected RedditToken(OAuthJSONAccessTokenResponse token) {
        this.accessToken = token.getAccessToken();
        this.refreshToken = token.getRefreshToken();
        this.expiration = currentTimeSeconds() + token.getExpiresIn();
        this.expirationSpan = token.getExpiresIn();
        this.scopes = new RedditTokenCompleteScope(token.getScope());
        this.tokenType = token.getParam(PARAM_TOKEN_TYPE);
    }
    
    /**
     * Reddit token constructor with specific user-provided parameters.
     * 
     * @param accessToken Access token
     * @param tokenType Type of token (commonly "bearer")
     * @param expiresIn Expires in (seconds)
     * @param scope Scope
     */
    protected RedditToken(String accessToken, String tokenType, long expiresIn, String scope) {
        this.accessToken = accessToken;
        this.refreshToken = null;
        this.expiration = currentTimeSeconds() + expiresIn;
        this.expirationSpan = expiresIn;
        this.scopes = new RedditTokenCompleteScope(scope);
        this.tokenType = tokenType;
    }
    
    /**
     * Refresh this reddit token with data received from the new token.
     * 
     * @param token Token received from a refresh request to reddit
     */
    public void refresh(OAuthJSONAccessTokenResponse token) {
        this.accessToken = token.getAccessToken();
        this.expiration = currentTimeSeconds() + token.getExpiresIn();
        this.expirationSpan = token.getExpiresIn();
        this.scopes = new RedditTokenCompleteScope(token.getScope());
        this.tokenType = token.getParam(PARAM_TOKEN_TYPE);
    }

    /**
     * Retrieve the access token.
     * 
     * @return Access token (e.g. "jsdkjfskaj9f8-dnafk")
     */
    public String getAccessToken() {
        return accessToken;
    }
    
    /**
     * Retrieve the refresh token.
     * 
     * @return Refresh token (e.g. "nvkJu9kjdada2-d98afj")
     */
    public String getRefreshToken() {
        return refreshToken;
    }

    /**
     * Retrieve whether the token is expired.
     * 
     * @return Is the token expired?
     */
    public boolean isExpired() {
        return expiration < currentTimeSeconds();
    }
    
    /**
     * Check whether this token possess this particular authorization scope.
     * If it does not support the scope, it means that the token does
     * not have approval from the user to perform the actions belonging to 
     * that scope.
     * 
     * @param scope Reddit scope
     * 
     * @return Does this token support this scope?
     */
    public boolean hasScope(RedditScope scope) {
        return this.scopes.has(scope);
    }
    
    /**
     * Retrieve the expiration.
     * 
     * @return Expiration time (seconds since UNIX epoch)
     */
    public long getExpiration() {
        return expiration;
    }    
    /**
     * Retrieve the token type.
     * 
     * @return Token type (e.g. "bearer")
     */
    public String getTokenType() {
        return tokenType;
    }
    
    /**
     * Check whether the token can be refreshed.
     * This means that a refresh token exists.
     * 
     * @return Can the token be refreshed?
     */
    public boolean isRefreshable() {
        return this.getRefreshToken() != null;
    }
    
    /**
     * Check whether this token will expire within the given time frame (given in seconds).
     * 
     * @param seconds Amount of seconds
     * 
     * @return Will the token expire within the given time frame?
     */
    public boolean willExpireIn(long seconds) {
        return currentTimeSeconds() + seconds > expiration;
    }
    
    /**
     * Retrieve the original expiration span of the token starting from its creation.
     * 
     * @return Expiration span (in seconds)
     */
    public long getExpirationSpan() {
        return expirationSpan;
    }
    
    /**
     * Retrieve the current time in seconds.
     * 
     * Uses <i>System.currentTimeMillis()</i>.
     * 
     * @return Current time in seconds.
     */
    private static long currentTimeSeconds() {
        return System.currentTimeMillis() / (long) 1000;
    }
    
}