current_streak_all_years.sql

-- takes a 2d array of checkins sorted by year desc.
-- it is assumed that the first elem in the array is the
-- checkins for the same year in the as_of. it will continue to
-- call current_streak for the year data until it finds a break in the streak
CREATE OR REPLACE FUNCTION current_streak_all_years(arr integer[][], as_of date) RETURNS INTEGER AS
$$
DECLARE
    total_streak integer := 0;
    year_streak integer;
    dt date;
    start_year integer := EXTRACT(year from as_of);
BEGIN
    FOR i IN array_lower(arr, 1)..array_upper(arr, 1) LOOP
        IF i = array_lower(arr, 1) THEN
            dt := as_of;
        ELSE
            dt := last_day_year(start_year - i + 1);
        END IF;
        year_streak := current_streak_single_year(ARRAY(SELECT unnest(arr[i:i])), dt);
        IF year_streak = 0 THEN
            IF total_streak > 0 THEN
                RETURN total_streak;
            ELSE
                RETURN year_streak;
            END IF;
        ELSIF year_streak < extract(doy from dt) THEN
            RETURN total_streak + year_streak;
        ELSE
            total_streak := total_streak + year_streak;
        END IF;
    END LOOP;
    RETURN total_streak;
END;
$$ LANGUAGE 'plpgsql';