CREATE OR ALTER FUNCTION pricing.guidance_logic(
    @target       numeric(20,5),
    @last_norm    numeric(20,5),
    @list_eff     numeric(20,5),
    @last_date    date,
    @floor_pct    numeric(10,5) = 0.05,
    @cap_last_pct numeric(10,5) = 1.00,
    @cap_list_pct numeric(10,5) = 1.00
)
RETURNS @ret TABLE (
    guidance_price  numeric(20,5),
    guidance_reason nvarchar(4000)
)
AS
BEGIN
    DECLARE
        @base_price     numeric(20,5),  -- starting point (target if available, else last_norm, else list_eff)
        @after_floor    numeric(20,5),  -- after applying floor: raised if below (1 - floor_pct) * last_norm
        @after_cap_last numeric(20,5),  -- after applying last cap: lowered if above cap_last_pct * last_norm
        @final_price    numeric(20,5),  -- after applying list cap: lowered if above cap_list_pct * list_eff
        @reason         nvarchar(4000) = N'';  -- explanation text for what rules applied

    -- Early exit if nothing to work with
    IF @target IS NULL AND @last_norm IS NULL AND @list_eff IS NULL
    BEGIN
        INSERT INTO @ret VALUES (NULL, N'No target, last, or list available');
        RETURN;
    END;

    -- Pick starting base price
    SET @base_price = COALESCE(@target, @last_norm, @list_eff);

    -- Step 1: use base price unless it's more than x% below last price
    SET @after_floor = @base_price;
    IF @last_norm IS NOT NULL
        SET @after_floor = ROUND(
            CASE WHEN @base_price >= @last_norm*(1-@floor_pct)
                 THEN @base_price
                 ELSE @last_norm*(1-@floor_pct)
            END, 5);

    -- Step 2: cap vs last_norm
    SET @after_cap_last = @after_floor;
    IF @last_norm IS NOT NULL
        SET @after_cap_last = ROUND(
            CASE WHEN @after_floor <= @last_norm*@cap_last_pct
                 THEN @after_floor
                 ELSE @last_norm*@cap_last_pct
            END, 5);

    -- Step 3: cap vs list_eff
    SET @final_price = @after_cap_last;
    IF @list_eff IS NOT NULL
        SET @final_price = ROUND(
            CASE WHEN @after_cap_last <= @list_eff*@cap_list_pct
                 THEN @after_cap_last
                 ELSE @list_eff*@cap_list_pct
            END, 5);

    -- Reason text
    SET @reason = 
      CASE 
        WHEN @target IS NOT NULL THEN 'Using target price'
        WHEN @last_norm IS NOT NULL THEN 'Using last price as base'
        WHEN @list_eff IS NOT NULL THEN 'Using list price as base'
      END;

    IF @last_norm IS NOT NULL AND @floor_pct > 0 AND @after_floor > @base_price
        SET @reason += N', floored to ' + FORMAT(@floor_pct*100,'0.##') + N'% below last price';

    IF @last_norm IS NOT NULL AND @after_cap_last < @after_floor
        SET @reason += CASE WHEN @cap_last_pct = 1
                            THEN N', capped to not exceed last price'
                            ELSE N', capped to ' + FORMAT(@cap_last_pct*100,'0.##') + N'% of last price'
                       END;

    IF @list_eff IS NOT NULL AND @final_price < @after_cap_last
        SET @reason += CASE WHEN @cap_list_pct = 1
                            THEN N', capped to not exceed list price'
                            ELSE N', capped to ' + FORMAT(@cap_list_pct*100,'0.##') + N'% of list price'
                       END;

    INSERT INTO @ret VALUES (@final_price, @reason);
    RETURN;
END;