#include "sokol_app.h"
#include "sokol_gfx.h"
#include "sokol_time.h"
#include "sokol_audio.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <tic80.h>

#define GFX_MAX_FB_WIDTH (TIC80_FULLWIDTH)
#define GFX_MAX_FB_HEIGHT (TIC80_FULLWIDTH)

#if defined(SOKOL_GLCORE33)
static const char* gfx_vs_src =
    "#version 330\n"
    "in vec2 in_pos;\n"
    "in vec2 in_uv;\n"
    "out vec2 uv;\n"
    "void main() {\n"
    "  gl_Position = vec4(in_pos*2.0-1.0, 0.5, 1.0);\n"
    "  uv = in_uv;\n"
    "}\n";
static const char* gfx_fs_src =
    "#version 330\n"
    "uniform sampler2D tex;\n"
    "in vec2 uv;\n"
    "out vec4 frag_color;\n"
    "void main() {\n"
    "  frag_color = texture(tex, uv);\n"
    "}\n";
#elif defined(SOKOL_GLES2)
static const char* gfx_vs_src =
    "attribute vec2 in_pos;\n"
    "attribute vec2 in_uv;\n"
    "varying vec2 uv;\n"
    "void main() {\n"
    "  gl_Position = vec4(in_pos*2.0-1.0, 0.5, 1.0);\n"
    "  uv = in_uv;\n"
    "}\n";
static const char* gfx_fs_src =
    "precision mediump float;\n"
    "uniform sampler2D tex;"
    "varying vec2 uv;\n"
    "void main() {\n"
    "  gl_FragColor = texture2D(tex, uv);\n"
    "}\n";
#elif defined(SOKOL_METAL)
static const char* gfx_vs_src =
    "#include <metal_stdlib>\n"
    "using namespace metal;\n"
    "struct vs_in {\n"
    "  float2 pos [[attribute(0)]];\n"
    "  float2 uv [[attribute(1)]];\n"
    "};\n"
    "struct vs_out {\n"
    "  float4 pos [[position]];\n"
    "  float2 uv;\n"
    "};\n"
    "vertex vs_out _main(vs_in in [[stage_in]]) {\n"
    "  vs_out out;\n"
    "  out.pos = float4(in.pos*2.0-1.0, 0.5, 1.0);\n"
    "  out.uv = in.uv;\n"
    "  return out;\n"
    "}\n";
static const char* gfx_fs_src =
    "#include <metal_stdlib>\n"
    "using namespace metal;\n"
    "struct fs_in {\n"
    "  float2 uv;\n"
    "};\n"
    "fragment float4 _main(fs_in in [[stage_in]], texture2d<float> tex [[texture(0)]], sampler smp [[sampler(0)]]) {\n"
    "  return tex.sample(smp, in.uv);\n"
    "}\n";
#elif defined(SOKOL_D3D11)
static const char* gfx_vs_src =
    "struct vs_in {\n"
    "  float2 pos: POS;\n"
    "  float2 uv:  UV;\n"
    "};\n"
    "struct vs_out {\n"
    "  float2 uv: TEXCOORD0;\n"
    "  float4 pos: SV_Position;\n"
    "};\n"
    "vs_out main(vs_in inp) {\n"
    "  vs_out outp;\n"
    "  outp.pos = float4(inp.pos*2.0-1.0, 0.5, 1.0);\n"
    "  outp.uv = inp.uv;\n"
    "  return outp;\n"
    "}\n";
static const char* gfx_fs_src =
    "Texture2D<float4> tex: register(t0);\n"
    "sampler smp: register(s0);\n"
    "float4 main(float2 uv: TEXCOORD0): SV_Target0 {\n"
    "  return tex.Sample(smp, uv);\n"
    "}\n";
#endif

typedef struct {
    sg_draw_state upscale_draw_state;
    sg_pass upscale_pass;
    sg_draw_state draw_state;
    int fb_width;
    int fb_height;
    int fb_aspect_scale_x;
    int fb_aspect_scale_y;
    uint32_t rgba8_buffer[GFX_MAX_FB_WIDTH * GFX_MAX_FB_HEIGHT];
} gfx_state;

static gfx_state gfx;

void gfx_init(int w, int h, int sx, int sy) {
    gfx.fb_width = w;
    gfx.fb_height = h;
    gfx.fb_aspect_scale_x = sx;
    gfx.fb_aspect_scale_y = sy;
    sg_setup(&(sg_desc){
        .mtl_device = sapp_metal_get_device(),
        .mtl_renderpass_descriptor_cb = sapp_metal_get_renderpass_descriptor,
        .mtl_drawable_cb = sapp_metal_get_drawable,
        .d3d11_device = sapp_d3d11_get_device(),
        .d3d11_device_context = sapp_d3d11_get_device_context(),
        .d3d11_render_target_view_cb = sapp_d3d11_get_render_target_view,
        .d3d11_depth_stencil_view_cb = sapp_d3d11_get_depth_stencil_view
    });

    /* quad vertex buffers with and without flipped UVs */
    float verts[] = {
        0.0f, 0.0f, 0.0f, 0.0f,
        1.0f, 0.0f, 1.0f, 0.0f,
        0.0f, 1.0f, 0.0f, 1.0f,
        1.0f, 1.0f,  1.0f, 1.0f
    };
    float verts_flipped[] = {
        0.0f, 0.0f, 0.0f, 1.0f,
        1.0f, 0.0f, 1.0f, 1.0f,
        0.0f, 1.0f, 0.0f, 0.0f,
        1.0f, 1.0f,  1.0f, 0.0f
    };
    gfx.upscale_draw_state.vertex_buffers[0] = sg_make_buffer(&(sg_buffer_desc){
        .size = sizeof(verts),
        .content = verts,
    });
    gfx.draw_state.vertex_buffers[0] = sg_make_buffer(&(sg_buffer_desc){
        .size = sizeof(verts),
        .content = sg_query_feature(SG_FEATURE_ORIGIN_TOP_LEFT) ? verts : verts_flipped
    });

    /* a shader to render a textured quad */
    sg_shader fsq_shd = sg_make_shader(&(sg_shader_desc){
        .fs.images = {
            [0] = { .name="tex", .type=SG_IMAGETYPE_2D },
        },
        .vs.source = gfx_vs_src,
        .fs.source = gfx_fs_src,
    });

    /* 2 pipeline-state-objects, one for upscaling, one for rendering */
    sg_pipeline_desc pip_desc = {
        .layout = {
            .attrs[0] = { .name="in_pos", .sem_name="POS", .format=SG_VERTEXFORMAT_FLOAT2 },
            .attrs[1] = { .name="in_uv", .sem_name="UV", .format=SG_VERTEXFORMAT_FLOAT2 }
        },
        .shader = fsq_shd,
        .primitive_type = SG_PRIMITIVETYPE_TRIANGLE_STRIP
    };
    gfx.draw_state.pipeline = sg_make_pipeline(&pip_desc);
    pip_desc.blend.depth_format = SG_PIXELFORMAT_NONE;
    gfx.upscale_draw_state.pipeline = sg_make_pipeline(&pip_desc);

    /* a texture with the emulator's raw pixel data */
    gfx.upscale_draw_state.fs_images[0] = sg_make_image(&(sg_image_desc){
        .width = gfx.fb_width,
        .height = gfx.fb_height,
        .pixel_format = SG_PIXELFORMAT_RGBA8,
        .usage = SG_USAGE_STREAM,
        .min_filter = SG_FILTER_NEAREST,
        .mag_filter = SG_FILTER_NEAREST,
        .wrap_u = SG_WRAP_CLAMP_TO_EDGE,
        .wrap_v = SG_WRAP_CLAMP_TO_EDGE
    });
    /* a 2x upscaled render-target-texture */
    gfx.draw_state.fs_images[0] = sg_make_image(&(sg_image_desc){
        .render_target = true,
        .width = 2*gfx.fb_width,
        .height = 2*gfx.fb_height,
        .pixel_format = SG_PIXELFORMAT_RGBA8,
        .min_filter = SG_FILTER_LINEAR,
        .mag_filter = SG_FILTER_LINEAR,
        .wrap_u = SG_WRAP_CLAMP_TO_EDGE,
        .wrap_v = SG_WRAP_CLAMP_TO_EDGE
    });

    /* a render pass for the 2x upscaling */
    gfx.upscale_pass = sg_make_pass(&(sg_pass_desc){
        .color_attachments[0].image = gfx.draw_state.fs_images[0]
    });
}

static const sg_pass_action gfx_upscale_pass_action = {
    .colors[0] = { .action = SG_ACTION_DONTCARE }
};

static const sg_pass_action gfx_draw_pass_action = {
    .colors[0] = { .action = SG_ACTION_CLEAR, .val = { 0.05f, 0.05f, 0.05f, 1.0f } }
};

static void apply_viewport(void) {
    const int canvas_width = sapp_width();
    const int canvas_height = sapp_height();
    const float canvas_aspect = (float)canvas_width / (float)canvas_height;
    const float fb_aspect = (float)(gfx.fb_width*gfx.fb_aspect_scale_x) / (float)(gfx.fb_height*gfx.fb_aspect_scale_y);
    const int frame_x = 5;
    const int frame_y = 5;
    int vp_x, vp_y, vp_w, vp_h;
    if (fb_aspect < canvas_aspect) {
        vp_y = frame_y;
        vp_h = canvas_height - 2 * frame_y;
        vp_w = (int) (canvas_height * fb_aspect) - 2 * frame_x;
        vp_x = (canvas_width - vp_w) / 2;
    }
    else {
        vp_x = frame_x;
        vp_w = canvas_width - 2 * frame_x;
        vp_h = (int) (canvas_width / fb_aspect) - 2 * frame_y;
        vp_y = frame_y;
    }
    sg_apply_viewport(vp_x, vp_y, vp_w, vp_h, true);
}

void gfx_draw() {

    /* copy emulator pixel data into upscaling source texture */
    sg_update_image(gfx.upscale_draw_state.fs_images[0], &(sg_image_content){
        .subimage[0][0] = { 
            .ptr = gfx.rgba8_buffer,
            .size = gfx.fb_width*gfx.fb_height*sizeof(uint32_t)
        }
    });

    /* upscale the original framebuffer 2x with nearest filtering */
    sg_begin_pass(gfx.upscale_pass, &gfx_upscale_pass_action);
    sg_apply_draw_state(&gfx.upscale_draw_state);
    sg_draw(0, 4, 1);
    sg_end_pass();

    /* draw the final pass with linear filtering */
    sg_begin_default_pass(&gfx_draw_pass_action, sapp_width(), sapp_height());
    apply_viewport();
    sg_apply_draw_state(&gfx.draw_state);
    sg_draw(0, 4, 1);
    sg_end_pass();
    sg_commit();
}

////////////////////////////////////////////////////////////////////////////////////////////

static tic80* tic = NULL;

static void app_init(void)
{
    FILE* file = fopen("cart.tic", "rb");

    if(file)
    {
        fseek(file, 0, SEEK_END);
        int size = ftell(file);
        fseek(file, 0, SEEK_SET);

        void* cart = malloc(size);
        if(cart) fread(cart, size, 1, file);
        fclose(file);

        if(cart)
        {
            printf("%s\n", "cart loaded");
            tic = tic80_create(44100);

            if(tic)
            {
                printf("%s\n", "tic created");
                tic80_load(tic, cart, size);
            }
        }
    }

    gfx_init(TIC80_FULLWIDTH, TIC80_FULLHEIGHT, 1, 1);
}

static tic80_input tic_input;

static void app_frame(void)
{
    if(tic)
    {
        tic80_tick(tic, tic_input);
        memcpy(gfx.rgba8_buffer, tic->screen, sizeof gfx.rgba8_buffer);
    }

    gfx_draw();
}

static void app_input(const sapp_event* event)
{

}

static void app_cleanup(void)
{
    if(tic)
        tic80_delete(tic);
    
    sg_shutdown();
}

sapp_desc sokol_main(int argc, char* argv[]) {
    // args_init(argc, argv);
    return (sapp_desc) {
        .init_cb = app_init,
        .frame_cb = app_frame,
        .event_cb = app_input,
        .cleanup_cb = app_cleanup,
        .width = 3 * TIC80_FULLWIDTH,
        .height = 3 * TIC80_FULLHEIGHT,
        .window_title = "TIC-80 with Sokol renderer",
        .ios_keyboard_resizes_canvas = true
    };
}