CREATE OR REPLACE FUNCTION pricequote.pick_last_price_from_hist(
    hist JSONB,
    v1ds TEXT
)
RETURNS JSONB AS $$
DECLARE
    dsq JSONB := (hist -> v1ds) -> 'dsq';
    dss JSONB := (hist -> v1ds) -> 'dss';
    mrq JSONB := hist -> 'mrq';
    mrs JSONB := hist -> 'mrs';
    result JSONB;
BEGIN
    -- Central control for age threshold
    DECLARE
        age_threshold INTERVAL := INTERVAL '1 year';
        dsq_date DATE := NULL;
        dss_date DATE := NULL;
        mrq_date DATE := NULL;
        mrs_date DATE := NULL;
        best JSONB := NULL;
        best_date DATE := NULL;
    BEGIN
        IF dsq IS NOT NULL AND (dsq->>'price') IS NOT NULL THEN
            dsq_date := (dsq->>'odate')::date;
        END IF;
        IF dss IS NOT NULL AND (dss->>'price') IS NOT NULL THEN
            dss_date := (dss->>'odate')::date;
        END IF;
        IF mrq IS NOT NULL AND (mrq->>'price') IS NOT NULL THEN
            mrq_date := (mrq->>'odate')::date;
        END IF;
        IF mrs IS NOT NULL AND (mrs->>'price') IS NOT NULL THEN
            mrs_date := (mrs->>'odate')::date;
        END IF;

        -- 1. Prefer the most recent of dss/dsq if either is within the age threshold
        IF (dsq_date IS NOT NULL AND dsq_date > (CURRENT_DATE - age_threshold))
           OR (dss_date IS NOT NULL AND dss_date > (CURRENT_DATE - age_threshold)) THEN
            IF dsq_date IS NOT NULL AND (dss_date IS NULL OR dsq_date >= dss_date) AND dsq_date > (CURRENT_DATE - age_threshold) THEN
                result := dsq || jsonb_build_object('source', 'dsq');
            ELSIF dss_date IS NOT NULL AND dss_date > (CURRENT_DATE - age_threshold) THEN
                result := dss || jsonb_build_object('source', 'dss');
            END IF;
        -- 2. If both dss/dsq are older than the threshold, use the most recent of mrs/mrq if either exists
        ELSIF (mrq_date IS NOT NULL OR mrs_date IS NOT NULL) THEN
            IF mrq_date IS NOT NULL AND (mrs_date IS NULL OR mrq_date >= mrs_date) THEN
                result := mrq || jsonb_build_object('source', 'mrq');
            ELSIF mrs_date IS NOT NULL THEN
                result := mrs || jsonb_build_object('source', 'mrs');
            END IF;
        -- 3. If all are at least as old as the threshold, pick the least oldest price available
        ELSE
            best := NULL;
            best_date := NULL;
            IF dsq_date IS NOT NULL THEN
                best := dsq || jsonb_build_object('source', 'dsq');
                best_date := dsq_date;
            END IF;
            IF dss_date IS NOT NULL AND (best_date IS NULL OR dss_date > best_date) THEN
                best := dss || jsonb_build_object('source', 'dss');
                best_date := dss_date;
            END IF;
            IF mrq_date IS NOT NULL AND (best_date IS NULL OR mrq_date > best_date) THEN
                best := mrq || jsonb_build_object('source', 'mrq');
                best_date := mrq_date;
            END IF;
            IF mrs_date IS NOT NULL AND (best_date IS NULL OR mrs_date > best_date) THEN
                best := mrs || jsonb_build_object('source', 'mrs');
                best_date := mrs_date;
            END IF;
            result := best;
        END IF;
        RETURN result;
    END;
END;
$$ LANGUAGE plpgsql IMMUTABLE;