//! ----------------------------------------------------
//! Low cortisol graphics
//! ----------------------------------------------------

// --- # ---
const std = @import("std");
const gtl = @import("gtl");
const vk = @import("vulkan");
const common = @import("rhi/root.zig");
const Handle = gtl.Handle;
const Self = @This();

// --- CONFIGS ---
const PipelineConfig = common.PipelineConfig;
const BufferUsage = common.BufferUsage;

// --- HANDLES ---
const Window = @import("rhi/root.zig").Window;
const Adapter = common.Adapter;
const Device = common.Device;
const Buffer = common.Buffer;
const Surface = common.Surface;
const Swapchain = common.Swapchain;

const Shader = common.Shader;
const Pipeline = common.Pipeline;

// --- RHI ---
const VulkanRHI = @import("rhi/vulkan/vulkan.zig");

/// ----------------------------------------------------
/// ----------------------------------------------------
pub const Backend = enum { vulkan };

/// ----------------------------------------------------
/// ----------------------------------------------------
const BackendCTX = union(Backend) {
    vulkan: VulkanRHI,
};

/// ----------------------------------------------------
/// ----------------------------------------------------
pub const Config = struct {
    app_name: []const u8 = "NYXGFX",
    engine_name: []const u8 = "NYX",
    enable_validation: bool = true,

    window: Window,
    backend: Backend = .vulkan,
};

//
// FIELDS
//

ctx: BackendCTX,
config: Config,

alloc: std.mem.Allocator,
io: std.Io,

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn init(
    config: Config,
    alloc: std.mem.Allocator,
    io: std.Io,
) !Self {
    const backend_ctx: BackendCTX = switch (config.backend) {
        .vulkan => .{ .vulkan = try .init(config, alloc, io) },
    };

    return .{
        .config = config,
        .ctx = backend_ctx,
        .alloc = alloc,
        .io = io,
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn deinit(self: *Self) void {
    switch (self.ctx) {
        .vulkan => |*v| v.deinit(),
    }
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn createAdapter(self: *Self) !Handle(Adapter) {
    return try switch (self.ctx) {
        .vulkan => |*v| v.createAdapter(),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn createDevice(
    self: *Self,
    adapter: Handle(Adapter),
    surface: Handle(Surface),
) !Handle(Device) {
    return try switch (self.ctx) {
        .vulkan => |*v| v.createDevice(adapter, surface),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn destroyDevice(self: *Self, device: Handle(Device)) !void {
    try switch (self.ctx) {
        .vulkan => |*v| v.destroyDevice(device),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn createBuffer(
    self: *Self,
    value: anytype,
    usage: BufferUsage,
    adapter: Handle(Adapter),
    device: Handle(Device),
) !Buffer {
    const size = @sizeOf(@TypeOf(value));

    const handle = try switch (self.ctx) {
        .vulkan => |*v| v.createBuffer(size, usage, .exclusive, adapter, device),
    };

    var buffer: Buffer = .{
        .handle = handle,
        .device = device,
        .gfx = self,
    };
    try buffer.set(value);

    return buffer;
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn createSurface(self: *Self) !Handle(Surface) {
    return try switch (self.ctx) {
        .vulkan => |*v| v.createSurface(),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn createSwapchain(
    self: *Self,
    adapter: Handle(Adapter),
    device: Handle(Device),
    surface: Handle(Surface),
) !Handle(Swapchain) {
    return try switch (self.ctx) {
        .vulkan => |*v| v.createSwapchain(adapter, device, surface),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn createShader(
    self: *Self,
    vert_spv_path: []const u8,
    frag_spv_path: []const u8,
    device: Handle(Device),
) !Handle(Shader) {
    return try switch (self.ctx) {
        .vulkan => |*v| v.createShader(vert_spv_path, frag_spv_path, device),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn createPipeline(self: *Self, config: PipelineConfig) !Pipeline {
    return .{
        .handle = try switch (self.ctx) {
            .vulkan => |*v| v.createPipeline(config),
        },
        .device = config.device,
        .gfx = self,
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn beginFrame(
    self: *Self,
    swapchain: Handle(Swapchain),
    device: Handle(Device),
) !void {
    try switch (self.ctx) {
        .vulkan => |*v| v.beginFrame(swapchain, device),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn endFrame(
    self: *Self,
    swapchain: Handle(Swapchain),
    device: Handle(Device),
) !void {
    try switch (self.ctx) {
        .vulkan => |*v| v.endFrame(swapchain, device),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn beginRendering(
    self: *Self,
    swapchain: Handle(Swapchain),
) !void {
    try switch (self.ctx) {
        .vulkan => |*v| v.beginRendering(swapchain),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn endRendering(
    self: *Self,
    swapchain: Handle(Swapchain),
) !void {
    try switch (self.ctx) {
        .vulkan => |*v| v.endRendering(swapchain),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn draw(self: *Self, vertex_count: u32, instance_count: u32, first_vertex: u32, first_instance: u32) !void {
    try switch (self.ctx) {
        .vulkan => |*v| v.draw(vertex_count, instance_count, first_vertex, first_instance),
    };
}

/// ----------------------------------------------------
/// ----------------------------------------------------
pub fn drawIndexed(self: *Self, index_count: u32, instance_count: u32, first_index: u32, vertex_offset: i32, first_instance: u32) !void {
    switch (self.ctx) {
        .vulkan => |*v| {
            const frame = v.currentFrame();
            if (frame.cmd_buf) |cmd| {
                vk.vkCmdDrawIndexed(cmd, index_count, instance_count, first_index, vertex_offset, first_instance);
            }
        },
    }
}