`timescale 1ns / 1ps

module collide_detection(
    input mode, 
    input [10:0] player1_tank_H,
    input [10:0] player1_tank_V,
    input [1:0] player1_tank_dir,
    input player1_tank_en,
    input [10:0] player1_bullet_H,
    input [10:0] player1_bullet_V,
    input player1_bullet_en,
    input [1:0] player1_bullet_dir,
    output reg [7:0] player1_collide,      // [bullet4, bullet3, bullet2, bullet1, tank4, tank3, tank2, tank1]

    input [10:0] player2_tank_H,
    input [10:0] player2_tank_V,
    input [1:0] player2_tank_dir,
    input player2_tank_en,
    input [10:0] player2_bullet_H,
    input [10:0] player2_bullet_V,
    input player2_bullet_en,
    input [10:0] player2_bullet_dir,
    output reg [7:0] player2_collide      // Reserved for other bullets and tanks
    );
    
    parameter TANK_WIDTH = 32;
    parameter TANK_HEIGHT = 32;
    parameter BULLET_LONGER = 10;
    parameter BULLET_SHORTER = 5;

    wire [10:0] player1_bullet_RBound, player1_bullet_DBound;
    wire [10:0] player2_bullet_RBound, player2_bullet_DBound;
    wire [10:0] player1_tank_RBound, player1_tank_DBound;
    wire [10:0] player2_tank_RBound, player2_tank_DBound;
    reg [3:0] player1_tank_collide_dir, player2_tank_collide_dir;

    assign player1_bullet_RBound = player1_bullet_H + (player1_bullet_dir == 2'b11 || 2'b10) ? BULLET_LONGER : BULLET_SHORTER;
    assign player1_bullet_DBound = player1_bullet_V + (player1_bullet_dir == 2'b00 || 2'b01) ? BULLET_LONGER : BULLET_SHORTER;

    assign player2_bullet_RBound = player2_bullet_H + (player2_bullet_dir == 2'b11 || 2'b10) ? BULLET_LONGER : BULLET_SHORTER;
    assign player2_bullet_DBound = player2_bullet_V + (player2_bullet_dir == 2'b00 || 2'b01) ? BULLET_LONGER : BULLET_SHORTER;

    assign player1_tank_RBound = player1_tank_H + TANK_WIDTH - 1;
    assign player1_tank_DBound = player1_tank_V + TANK_HEIGHT - 1;

    assign player2_tank_RBound = player2_tank_H + TANK_WIDTH - 1;
    assign player2_tank_DBound = player2_tank_V + TANK_HEIGHT - 1;

    initial begin
        player1_collide <= 0;
        player2_collide <= 0;
    end

    always @(*) begin
        if(player1_tank_en) begin
            if (player2_bullet_en) begin
                if(player1_tank_H >= player2_bullet_H && player1_tank_H <= player2_bullet_RBound &&
                    player1_tank_V >= player2_bullet_V && player1_tank_V <= player2_bullet_RBound) player1_collide[5] <= 1;
                else player1_collide[5] <= 0;
            end
          
            if(player2_tank_en && player1_tank_RBound <= player2_tank_RBound && player1_tank_RBound >= player2_tank_H &&
                ~( player1_tank_DBound < player2_tank_V || player1_tank_V > player2_tank_DBound))
                player1_tank_collide_dir[3] <= 1;
            else player1_tank_collide_dir[3] <= 0;

            if(player2_tank_en && player1_tank_H <= player2_tank_RBound && player1_tank_H >= player2_tank_H &&
                 ~( player1_tank_DBound < player2_tank_V || player1_tank_V > player2_tank_DBound) )
                player1_tank_collide_dir[2] <= 1;
            else player1_tank_collide_dir[2] <= 0;

            if(player2_tank_en && player1_tank_V <= player2_tank_DBound && player1_tank_V >= player2_tank_V 
            &&  ~(player1_tank_RBound < player2_tank_H || player1_tank_H > player2_tank_RBound) )
                player1_tank_collide_dir[0] <= 1;
            else player1_tank_collide_dir[0] <= 0;

            if(player2_tank_en && player1_tank_DBound <= player2_tank_DBound && player1_tank_DBound >= player2_tank_V 
            &&  ~(player1_tank_RBound < player2_tank_H || player1_tank_H > player2_tank_RBound) )
                player1_tank_collide_dir[1] <= 1;
            else player1_tank_collide_dir[1] <= 0;
            player1_collide[1] <= player1_tank_collide_dir[player1_tank_dir];
        end
/*
            object_collide_detection player1_2(
                .object1_H(player1_tank_H),
                .object1_V(player1_tank_V),
                .object1_dir(player1_tank_dir),
                .object1_en(player1_tank_en),
                .object1_RBound(player1_tank_RBound),
                .object1_DBound(player1_tank_DBound),
                .object2_H(player2_tank_H),
                .object2_V(player2_tank_V),
                .object2_dir(player2_tank_dir),
                .object2_en(player2_tank_en),
                .object2_RBound(player2_tank_RBound),
                .object2_DBound(player2_tank_DBound),
                .object1_collide(),
                .object2_collide());
*/
    end
    
    always @(*) begin
        if(player2_tank_en) begin
            if (player1_bullet_en) begin
                if(player2_tank_H >= player1_bullet_H && player2_tank_H <= player1_bullet_RBound &&
                    player2_tank_V >= player1_bullet_V && player2_tank_V <= player1_bullet_RBound) player2_collide[4] <= 1;
                else player2_collide[4] <= 0;
            end

           if(player1_tank_en && player2_tank_RBound <= player1_tank_RBound && player2_tank_RBound >= player1_tank_H &&
                ~( player2_tank_DBound < player1_tank_V || player2_tank_V > player1_tank_DBound))
                player2_tank_collide_dir[3] <= 1;
            else player2_tank_collide_dir[3] <= 0;

            if(player1_tank_en && player2_tank_H <= player1_tank_RBound && player2_tank_H >= player1_tank_H &&
                 ~( player2_tank_DBound < player1_tank_V || player2_tank_V > player1_tank_DBound) )
                player2_tank_collide_dir[2] <= 1;
            else player2_tank_collide_dir[2] <= 0;

            if(player1_tank_en && player2_tank_V <= player1_tank_DBound && player2_tank_V >= player1_tank_V 
            &&  ~(player2_tank_RBound < player1_tank_H || player2_tank_H > player1_tank_RBound) )
                player2_tank_collide_dir[0] <= 1;
            else player2_tank_collide_dir[0] <= 0;

            if(player1_tank_en && player2_tank_DBound <= player1_tank_DBound && player2_tank_DBound >= player1_tank_V 
            &&  ~(player2_tank_RBound < player1_tank_H || player2_tank_H > player1_tank_RBound) )
                player2_tank_collide_dir[1] <= 1;
            else player2_tank_collide_dir[1] <= 0;
            player2_collide[1] <= player2_tank_collide_dir[player2_tank_dir];
        end    
    end
    

endmodule