//
// Lol Engine
//
// Copyright: (c) 2010-2013 Sam Hocevar <sam@hocevar.net>
//   This program is free software; you can redistribute it and/or
//   modify it under the terms of the Do What The Fuck You Want To
//   Public License, Version 2, as published by Sam Hocevar. See
//   http://www.wtfpl.net/ for more details.
//

#if defined HAVE_CONFIG_H
#   include "config.h"
#endif

#include <cstdlib>

#ifdef WIN32
#   define WIN32_LEAN_AND_MEAN
#   include <windows.h>
#endif

#include "core.h"
#include "lolgl.h"

LOLFX_RESOURCE_DECLARE(tile);
LOLFX_RESOURCE_DECLARE(line);

namespace lol
{

/*
 * The global g_scene object, initialised by Video::Init
 */

Scene *g_scene = nullptr;

/*
 * A quick and dirty Tile structure for 2D blits
 */

struct Tile
{
    TileSet *tileset;
    uint32_t prio;
    vec3 pos;
    vec2 scale;
    int id, o;
};

/*
 * Scene implementation class
 */

class SceneData
{
    friend class Scene;

private:
    static int Compare(void const *p1, void const *p2)
    {
        Tile const *t1 = (Tile const *)p1;
        Tile const *t2 = (Tile const *)p2;

        if (t1->pos.z > t2->pos.z)
            return 1;
        if (t1->pos.z < t2->pos.z)
            return -1;
        return 0;
    }

    Array<vec3, vec3, vec4> m_lines;
    Shader *m_line_shader;
    VertexDeclaration *m_line_vdecl;

    Array<Tile> m_tiles;
    Array<Light *> m_lights;

    Shader *m_tile_shader;
    VertexDeclaration *m_tile_vdecl;
    Array<VertexBuffer *> m_tile_bufs;

    Camera *m_default_cam;
    Array<Camera *> m_camera_stack;
};

/*
 * Public Scene class
 */

Scene::Scene(ivec2 size)
  : data(new SceneData())
{
    /* Create a default orthographic camera, in case the user doesn’t. */
    data->m_default_cam = new Camera();
    mat4 proj = mat4::ortho(0, size.x, 0, size.y, -1000.f, 1000.f);
    data->m_default_cam->SetProjection(proj);
    PushCamera(data->m_default_cam);

    data->m_tile_shader = 0;
    data->m_tile_vdecl = new VertexDeclaration(VertexStream<vec3>(VertexUsage::Position),
                                               VertexStream<vec2>(VertexUsage::TexCoord));

    data->m_line_shader = 0;
    data->m_line_vdecl = new VertexDeclaration(VertexStream<vec3,vec4>(VertexUsage::Position, VertexUsage::Color));
}

Scene::~Scene()
{
    PopCamera(data->m_default_cam);

    /* FIXME: this must be done while the GL context is still active.
     * Change the code architecture to make sure of that. */
    /* FIXME: also, make sure we do not add code to Reset() that will
     * reallocate stuff */
    Reset();

    delete data->m_line_vdecl;
    delete data->m_tile_vdecl;
    delete data;
}

void Scene::PushCamera(Camera *cam)
{
    Ticker::Ref(cam);
    data->m_camera_stack.Push(cam);
}

void Scene::PopCamera(Camera *cam)
{
    /* Parse from the end because that’s probably where we’ll find
     * our camera first. */
    for (int i = data->m_camera_stack.Count(); i--; )
    {
        if (data->m_camera_stack[i] == cam)
        {
            Ticker::Unref(cam);
            data->m_camera_stack.Remove(i);
            return;
        }
    }

    ASSERT(false, "trying to pop a nonexistent camera from the scene");
}

Camera *Scene::GetCamera()
{
    return data->m_camera_stack.Last();
}

void Scene::Reset()
{
    for (int i = 0; i < data->m_tile_bufs.Count(); i++)
        delete data->m_tile_bufs[i];
    data->m_tile_bufs.Empty();

    data->m_lights.Empty();
}

void Scene::AddTile(TileSet *tileset, int id, vec3 pos, int o, vec2 scale)
{
    ASSERT(id < tileset->GetTileCount());

    Tile t;
    /* FIXME: this sorting only works for a 45-degree camera */
    t.prio = -pos.y - 2 * 32 * pos.z + (o ? 0 : 32);
    t.tileset = tileset;
    t.id = id;
    t.pos = pos;
    t.o = o;
    t.scale = scale;

    data->m_tiles.Push(t);
}

void Scene::AddLine(vec3 a, vec3 b, vec4 color)
{
    data->m_lines.Push(a, b, color);
}

void Scene::AddLight(Light *l)
{
    data->m_lights.Push(l);
}

Array<Light *> const &Scene::GetLights() const
{
    return data->m_lights;
}

void Scene::Render() // XXX: rename to Blit()
{
    RenderContext rc;

    /* Early test if nothing needs to be rendered */
    if (data->m_tiles.Count())
    {
        rc.SetDepthFunc(DepthFunc::LessOrEqual);
        rc.SetBlendFunc(BlendFunc::SrcAlpha, BlendFunc::OneMinusSrcAlpha);
        rc.SetAlphaFunc(AlphaFunc::GreaterOrEqual, 0.01f);

        PushCamera(data->m_default_cam);

#if defined USE_D3D9 || defined _XBOX
#elif !defined HAVE_GLES_2X
        glEnable(GL_TEXTURE_2D);
#endif
        if (!data->m_tile_shader)
            data->m_tile_shader = Shader::Create(LOLFX_RESOURCE_NAME(tile));

#if 0
        // Randomise, then sort.
        for (int i = 0; i < data->m_tiles.Count(); i++)
        {
            Tile tmp = data->m_tiles[i];
            int j = rand<int>() % data->m_tiles.Count();
            data->m_tiles[i] = data->m_tiles[j];
            data->m_tiles[j] = tmp;
        }
#endif
        qsort(&data->m_tiles[0], data->m_tiles.Count(),
              sizeof(Tile), SceneData::Compare);

        ShaderUniform uni_mat, uni_tex, uni_texsize;
        ShaderAttrib attr_pos, attr_tex;
        attr_pos = data->m_tile_shader->GetAttribLocation("in_Position", VertexUsage::Position, 0);
        attr_tex = data->m_tile_shader->GetAttribLocation("in_TexCoord", VertexUsage::TexCoord, 0);

        data->m_tile_shader->Bind();

        uni_mat = data->m_tile_shader->GetUniformLocation("proj_matrix");
        data->m_tile_shader->SetUniform(uni_mat, GetCamera()->GetProjection());
        uni_mat = data->m_tile_shader->GetUniformLocation("view_matrix");
        data->m_tile_shader->SetUniform(uni_mat, GetCamera()->GetView());
        uni_mat = data->m_tile_shader->GetUniformLocation("model_matrix");
        data->m_tile_shader->SetUniform(uni_mat, mat4(1.f));

        uni_tex = data->m_tile_shader->GetUniformLocation("in_Texture");
        data->m_tile_shader->SetUniform(uni_tex, 0);
        uni_texsize = data->m_tile_shader->GetUniformLocation("in_TexSize");

        for (int buf = 0, i = 0, n; i < data->m_tiles.Count(); i = n, buf += 2)
        {
            /* Count how many quads will be needed */
            for (n = i + 1; n < data->m_tiles.Count(); n++)
                if (data->m_tiles[i].tileset != data->m_tiles[n].tileset)
                    break;

            /* Create a vertex array object */
            VertexBuffer *vb1 = new VertexBuffer(6 * 3 * (n - i) * sizeof(float));
            float *vertex = (float *)vb1->Lock(0, 0);
            VertexBuffer *vb2 = new VertexBuffer(6 * 2 * (n - i) * sizeof(float));
            float *texture = (float *)vb2->Lock(0, 0);

            data->m_tile_bufs.Push(vb1);
            data->m_tile_bufs.Push(vb2);

            for (int j = i; j < n; j++)
            {
                data->m_tiles[i].tileset->BlitTile(data->m_tiles[j].id,
                                data->m_tiles[j].pos, data->m_tiles[j].o,
                                data->m_tiles[j].scale,
                                vertex + 18 * (j - i), texture + 12 * (j - i));
            }

            vb1->Unlock();
            vb2->Unlock();

            /* Bind texture */
            data->m_tiles[i].tileset->Bind();
            data->m_tile_shader->SetUniform(uni_texsize,
                           (vec2)data->m_tiles[i].tileset->GetTextureSize());

            /* Bind vertex and texture coordinate buffers */
            data->m_tile_vdecl->Bind();
            data->m_tile_vdecl->SetStream(vb1, attr_pos);
            data->m_tile_vdecl->SetStream(vb2, attr_tex);

            /* Draw arrays */
            data->m_tile_vdecl->DrawElements(MeshPrimitive::Triangles, 0, (n - i) * 6);
            data->m_tile_vdecl->Unbind();
            data->m_tiles[i].tileset->Unbind();
        }

        data->m_tiles.Empty();

        data->m_tile_shader->Unbind();

#if defined USE_D3D9 || defined _XBOX
        /* TODO */
#elif !defined HAVE_GLES_2X
        glDisable(GL_TEXTURE_2D);
#endif

        PopCamera(data->m_default_cam);
    }

    if (data->m_lines.Count())
    {
        rc.SetDepthFunc(DepthFunc::LessOrEqual);
        rc.SetBlendFunc(BlendFunc::SrcAlpha, BlendFunc::OneMinusSrcAlpha);
        rc.SetAlphaFunc(AlphaFunc::GreaterOrEqual, 0.01f);

        int linecount = data->m_lines.Count();

        if (!data->m_line_shader)
            data->m_line_shader = Shader::Create(LOLFX_RESOURCE_NAME(line));

        VertexBuffer *vb = new VertexBuffer((sizeof(vec3) + sizeof(vec4)) * 2 * linecount);
        float *vertex = (float *)vb->Lock(0, 0);
        for (int i = 0; i < linecount; i++)
        {
            memcpy(vertex, &data->m_lines[i].m1, sizeof(vec3));
            vertex += 3;
            memcpy(vertex, &data->m_lines[i].m3, sizeof(vec4));
            vertex += 4;
            memcpy(vertex, &data->m_lines[i].m2, sizeof(vec3));
            vertex += 3;
            memcpy(vertex, &data->m_lines[i].m3, sizeof(vec4));
            vertex += 4;
        }
        vb->Unlock();

        data->m_line_shader->Bind();

        ShaderUniform uni_mat, uni_tex;
        ShaderAttrib attr_pos, attr_col;
        attr_pos = data->m_line_shader->GetAttribLocation("in_Position", VertexUsage::Position, 0);
        attr_col = data->m_line_shader->GetAttribLocation("in_Color", VertexUsage::Color, 0);

        data->m_line_shader->Bind();

        uni_mat = data->m_line_shader->GetUniformLocation("proj_matrix");
        data->m_line_shader->SetUniform(uni_mat, GetCamera()->GetProjection());
        uni_mat = data->m_line_shader->GetUniformLocation("view_matrix");
        data->m_line_shader->SetUniform(uni_mat, GetCamera()->GetView());

        data->m_line_vdecl->Bind();
        data->m_line_vdecl->SetStream(vb, attr_pos, attr_col);
        data->m_line_vdecl->DrawElements(MeshPrimitive::Lines, 0, 2 * linecount);
        data->m_line_vdecl->Unbind();
        data->m_line_shader->Unbind();

        data->m_lines.Empty();
        delete vb;
    }
}

} /* namespace lol */