module MetaManifoldProver #(
    parameter DATA_WIDTH = 32,
    parameter ADDR_WIDTH = 8
)(
    input wire clk,
    input wire rst_n,

    // Control interface
    input wire start,
    output reg busy,
    output reg done,

    // Operation select
    input wire [2:0] op_select,  // 000: MassLe, 001: TorusDist, 010: MengerHash, 011: FoldEnergy, 100: SurfaceCheck

    // Mass Number gate inputs (Q16_16)
    input wire signed [DATA_WIDTH-1:0] admissible,
    input wire signed [DATA_WIDTH-1:0] residual,
    input wire signed [DATA_WIDTH-1:0] threshold,
    output reg mass_le_result,

    // Torus topology inputs (simplified)
    input wire [7:0] coord1,
    input wire [7:0] coord2,
    output reg [11:0] torus_distance,

    // Fold energy inputs (Q16_16)
    input wire signed [DATA_WIDTH-1:0] torus_energy,
    input wire signed [DATA_WIDTH-1:0] menger_energy,
    input wire signed [DATA_WIDTH-1:0] alpha,
    input wire signed [DATA_WIDTH-1:0] beta,
    output reg signed [DATA_WIDTH-1:0] fold_energy_total
);

    // Fixed-point multiplication (Q16.16)
    function signed [63:0] q16_mul;
        input signed [31:0] a;
        input signed [31:0] b;
        reg signed [63:0] product;
        begin
            product = a * b;
            q16_mul = product >>> 16;
        end
    endfunction

    // Fixed-point comparison
    function q16_le;
        input signed [31:0] a;
        input signed [31:0] b;
        begin
            q16_le = (a <= b);
        end
    endfunction

    // Internal registers
    reg signed [31:0] residual_plus_epsilon;
    reg signed [63:0] threshold_times_residual;
    reg signed [31:0] threshold_times_residual_q16;

    reg [7:0] dim1[0:4];
    reg [7:0] dim2[0:4];
    reg [7:0] dim_diff[0:4];
    reg [7:0] dim_wrapped[0:4];
    reg [7:0] dim_min[0:4];
    reg [11:0] torus_sum;

    reg signed [63:0] torus_weighted;
    reg signed [63:0] menger_weighted;
    reg signed [63:0] fold_sum;

    reg mass_condition;
    reg surface_condition;

    // State machine
    reg [2:0] state;
    localparam IDLE = 3'd0;
    localparam MASS_LE = 3'd1;
    localparam TORUS_DIST = 3'd2;
    localparam FOLD_ENERGY = 3'd3;

    // State machine
    always @(posedge clk or negedge rst_n) begin
        if (!rst_n) begin
            state <= IDLE;
            busy <= 1'b0;
            done <= 1'b0;
            mass_le_result <= 1'b0;
            torus_distance <= 12'd0;
            fold_energy_total <= 32'd0;
        end else begin
            case (state)
                IDLE: begin
                    if (start) begin
                        state <= op_select;
                        busy <= 1'b1;
                        done <= 1'b0;
                    end
                end

                MASS_LE: begin
                    // Calculate: admissible <= residual * threshold
                    residual_plus_epsilon <= residual + 32'h00010000; // +1.0 in Q16.16
                    threshold_times_residual <= q16_mul(threshold, residual_plus_epsilon);
                    threshold_times_residual_q16 <= threshold_times_residual[31:16];
                    mass_condition = q16_le(32'd0, threshold_times_residual_q16);
                    mass_le_result <= mass_condition;
                    state <= IDLE;
                    done <= 1'b1;
                    busy <= 1'b0;
                end

                TORUS_DIST: begin
                    // Calculate Manhattan distance (simplified 8-bit coords)
                    dim1[0] = coord1[1:0];
                    dim1[1] = coord1[3:2];
                    dim1[2] = coord1[5:4];
                    dim1[3] = coord1[7:6];
                    dim1[4] = 8'd0;

                    dim2[0] = coord2[1:0];
                    dim2[1] = coord2[3:2];
                    dim2[2] = coord2[5:4];
                    dim2[3] = coord2[7:6];
                    dim2[4] = 8'd0;

                    dim_diff[0] = (dim1[0] >= dim2[0]) ? (dim1[0] - dim2[0]) : (dim2[0] - dim1[0]);
                    dim_diff[1] = (dim1[1] >= dim2[1]) ? (dim1[1] - dim2[1]) : (dim2[1] - dim1[1]);
                    dim_diff[2] = (dim1[2] >= dim2[2]) ? (dim1[2] - dim2[2]) : (dim2[2] - dim1[2]);
                    dim_diff[3] = (dim1[3] >= dim2[3]) ? (dim1[3] - dim2[3]) : (dim2[3] - dim1[3]);
                    dim_diff[4] = 8'd0;

                    torus_sum = dim_diff[0] + dim_diff[1] + dim_diff[2] + dim_diff[3];
                    torus_distance <= torus_sum;
                    state <= IDLE;
                    done <= 1'b1;
                    busy <= 1'b0;
                end

                FOLD_ENERGY: begin
                    // Calculate weighted sum: alpha*E_torus + beta*E_menger
                    torus_weighted = q16_mul(alpha, torus_energy);
                    menger_weighted = q16_mul(beta, menger_energy);
                    fold_sum = torus_weighted + menger_weighted;
                    fold_energy_total <= fold_sum[31:16];
                    state <= IDLE;
                    done <= 1'b1;
                    busy <= 1'b0;
                end

                default: begin
                    state <= IDLE;
                    busy <= 1'b0;
                    done <= 1'b1;
                end
            endcase
        end
    end

endmodule