//! ----------------------------------------------------
//! ----------------------------------------------------

const std = @import("std");
const gtl = @import("gtl");
const Material = @import("../../common/component/material.zig");
const Mesh = @import("../../cache/resource/mesh_cache.zig").MeshID;
const Handle = gtl.Handle;
const Self = @This();

// TODO:
const Camera = struct {};

/// ----------------------------------------------------
/// ----------------------------------------------------
pub const DrawCMD = union(enum) {
    draw: struct {
        mesh: Mesh,
        material: Material,
    },

    draw_indexed: struct {
        mesh: Mesh,
        material: Material,
    },

    begin_pass: struct {
        camera: Handle(Camera),
        color: [4]f32 = .{ 0, 0, 0, 255 },
        load_op: enum {
            load,
            clear,
        } = .clear,
        store_op: enum {
            store,
            discard,
        } = .store,
    },

    end_pass,
};

//
// FIELDS
//

commands: std.ArrayList(DrawCMD),
alloc: std.mem.Allocator,

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn init(alloc: std.mem.Allocator) Self {
    return .{
        .commands = .empty,
        .alloc = alloc,
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn deinit(self: *Self) void {
    self.commands.deinit(self.alloc);
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn clear(self: *Self) void {
    self.commands.clearRetainingCapacity();
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn draw(
    self: *Self,
    cmd: DrawCMD,
) !void {
    try self.commands.append(
        self.alloc,
        cmd,
    );
}

//
// TESTING
//

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn beginPass(self: *Self) void {
    self.draw(.{ .begin_pass = .{
        .camera = undefined,
    } }) catch unreachable;
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn endPass(self: *Self) void {
    self.draw(.end_pass) catch unreachable;
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn drawTriangle(self: *Self) void {
    self.draw(.{ .draw = .{ .material = .{}, .mesh = .triangle } }) catch unreachable;
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn drawSquare(self: *Self) void {
    self.draw(.{ .draw = .{ .material = .{}, .mesh = .square } }) catch unreachable;
}