#include "specter/RootView.hpp"
#include "specter/TextView.hpp"
#include "specter/ViewResources.hpp"
#include "utf8proc.h"
#include "hecl/Pipeline.hpp"

#include <freetype/internal/internal.h>
#include <freetype/internal/ftobjs.h>

namespace specter
{
static logvisor::Module Log("specter::TextView");

void TextView::Resources::init(boo::IGraphicsDataFactory::Context& ctx, FontCache* fcache)
{
    m_fcache = fcache;
    m_regular = hecl::conv->convert(ctx, Shader_SpecterTextViewShader{});
    m_subpixel = hecl::conv->convert(ctx, Shader_SpecterTextViewShaderSubpixel{});
}

void TextView::_commitResources(size_t capacity)
{
    auto& res = rootView().viewRes();
    auto fontTex = m_fontAtlas.texture(res.m_factory);
    View::commitResources(res, [&](boo::IGraphicsDataFactory::Context& ctx)
    {
        buildResources(ctx, res);

        if (capacity)
        {
            m_glyphBuf = res.m_textRes.m_glyphPool.allocateBlock(res.m_factory, capacity);

            boo::ObjToken<boo::IShaderPipeline> shader;
            if (m_fontAtlas.subpixel())
                shader = res.m_textRes.m_subpixel;
            else
                shader = res.m_textRes.m_regular;

            auto vBufInfo = m_glyphBuf.getBufferInfo();
            auto uBufInfo = m_viewVertBlockBuf.getBufferInfo();
            boo::ObjToken<boo::IGraphicsBuffer> uBufs[] = {uBufInfo.first.get()};
            size_t uBufOffs[] = {size_t(uBufInfo.second)};
            size_t uBufSizes[] = {sizeof(ViewBlock)};
            boo::ObjToken<boo::ITexture> texs[] = {fontTex.get()};

            m_shaderBinding = ctx.newShaderDataBinding(shader, {}, vBufInfo.first.get(), nullptr, 1,
                                                       uBufs, nullptr, uBufOffs, uBufSizes,
                                                       1, texs, nullptr, nullptr, 0, vBufInfo.second);
        }
        return true;
    });
}

TextView::TextView(ViewResources& res,
                   View& parentView, const FontAtlas& font,
                   Alignment align, size_t capacity)
: View(res, parentView),
  m_capacity(capacity),
  m_fontAtlas(font),
  m_align(align)
{
    if (size_t(hecl::VertexBufferPool<RenderGlyph>::bucketCapacity()) < capacity)
        Log.report(logvisor::Fatal, "bucket overflow [%" PRISize "/%" PRISize "]",
                   capacity, hecl::VertexBufferPool<RenderGlyph>::bucketCapacity());

    _commitResources(0);
}

TextView::TextView(ViewResources& res, View& parentView, FontTag font, Alignment align, size_t capacity)
: TextView(res, parentView, res.m_textRes.m_fcache->lookupAtlas(font), align, capacity) {}

TextView::RenderGlyph::RenderGlyph(int& adv, const FontAtlas::Glyph& glyph, const zeus::CColor& defaultColor)
{
    m_pos[0].assign(adv + glyph.m_leftPadding, glyph.m_verticalOffset + glyph.m_height, 0.f);
    m_pos[1].assign(adv + glyph.m_leftPadding, glyph.m_verticalOffset, 0.f);
    m_pos[2].assign(adv + glyph.m_leftPadding + glyph.m_width, glyph.m_verticalOffset + glyph.m_height, 0.f);
    m_pos[3].assign(adv + glyph.m_leftPadding + glyph.m_width, glyph.m_verticalOffset, 0.f);
    m_uv[0].assign(glyph.m_uv[0], glyph.m_uv[1], glyph.m_layerFloat);
    m_uv[1].assign(glyph.m_uv[0], glyph.m_uv[3], glyph.m_layerFloat);
    m_uv[2].assign(glyph.m_uv[2], glyph.m_uv[1], glyph.m_layerFloat);
    m_uv[3].assign(glyph.m_uv[2], glyph.m_uv[3], glyph.m_layerFloat);
    m_color = defaultColor;
    adv += glyph.m_advance;
}

int TextView::DoKern(FT_Pos val, const FontAtlas& atlas)
{
    if (!val) return 0;
    val = FT_MulFix(val, atlas.FT_Xscale());

    FT_Pos  orig_x = val;

    /* we scale down kerning values for small ppem values */
    /* to avoid that rounding makes them too big.         */
    /* `25' has been determined heuristically.            */
    if (atlas.FT_XPPem() < 25)
        val = FT_MulDiv(orig_x, atlas.FT_XPPem(), 25);

    return FT_PIX_ROUND(val) >> 6;
}

void TextView::typesetGlyphs(std::string_view str, const zeus::CColor& defaultColor)
{
    UTF8Iterator it(str.begin());
    size_t charLen = str.size() ? std::min(it.countTo(str.end()), m_capacity) : 0;
    if (charLen > m_curSize)
    {
        m_curSize = charLen;
        _commitResources(charLen);
    }

    uint32_t lCh = -1;
    m_glyphs.clear();
    m_glyphs.reserve(charLen);
    m_glyphInfo.clear();
    m_glyphInfo.reserve(charLen);
    int adv = 0;

    if (charLen)
    {
        for (; it.iter() < str.end() ; ++it)
        {
            utf8proc_int32_t ch = *it;
            if (ch == -1)
            {
                Log.report(logvisor::Warning, "invalid UTF-8 char");
                break;
            }
            if (ch == '\n' || ch == '\0')
                break;

            const FontAtlas::Glyph* glyph = m_fontAtlas.lookupGlyph(ch);
            if (!glyph)
                continue;

            if (lCh != -1)
                adv += DoKern(m_fontAtlas.lookupKern(lCh, glyph->m_glyphIdx), m_fontAtlas);
            m_glyphs.emplace_back(adv, *glyph, defaultColor);
            m_glyphInfo.emplace_back(ch, glyph->m_width, glyph->m_height, adv);

            lCh = glyph->m_glyphIdx;

            if (m_glyphs.size() == m_capacity)
                break;
        }
    }

    if (m_align == Alignment::Right)
    {
        int adj = -adv;
        for (RenderGlyph& g : m_glyphs)
        {
            g.m_pos[0][0] += adj;
            g.m_pos[1][0] += adj;
            g.m_pos[2][0] += adj;
            g.m_pos[3][0] += adj;
        }
    }
    else if (m_align == Alignment::Center)
    {
        int adj = -adv / 2;
        for (RenderGlyph& g : m_glyphs)
        {
            g.m_pos[0][0] += adj;
            g.m_pos[1][0] += adj;
            g.m_pos[2][0] += adj;
            g.m_pos[3][0] += adj;
        }
    }

    m_width = adv;
    invalidateGlyphs();
    updateSize();
}

void TextView::typesetGlyphs(std::wstring_view str, const zeus::CColor& defaultColor)
{
    size_t charLen = std::min(str.size(), m_capacity);
    if (charLen > m_curSize)
    {
        m_curSize = charLen;
        _commitResources(charLen);
    }

    uint32_t lCh = -1;
    m_glyphs.clear();
    m_glyphs.reserve(charLen);
    m_glyphInfo.clear();
    m_glyphInfo.reserve(charLen);
    int adv = 0;

    for (wchar_t ch : str)
    {
        if (ch == L'\n')
            break;

        const FontAtlas::Glyph* glyph = m_fontAtlas.lookupGlyph(ch);
        if (!glyph)
            continue;

        if (lCh != -1)
            adv += DoKern(m_fontAtlas.lookupKern(lCh, glyph->m_glyphIdx), m_fontAtlas);
        m_glyphs.emplace_back(adv, *glyph, defaultColor);
        m_glyphInfo.emplace_back(ch, glyph->m_width, glyph->m_height, adv);

        lCh = glyph->m_glyphIdx;

        if (m_glyphs.size() == m_capacity)
            break;
    }

    if (m_align == Alignment::Right)
    {
        int adj = -adv;
        for (RenderGlyph& g : m_glyphs)
        {
            g.m_pos[0][0] += adj;
            g.m_pos[1][0] += adj;
            g.m_pos[2][0] += adj;
            g.m_pos[3][0] += adj;
        }
    }
    else if (m_align == Alignment::Center)
    {
        int adj = -adv / 2;
        for (RenderGlyph& g : m_glyphs)
        {
            g.m_pos[0][0] += adj;
            g.m_pos[1][0] += adj;
            g.m_pos[2][0] += adj;
            g.m_pos[3][0] += adj;
        }
    }

    m_width = adv;
    invalidateGlyphs();
    updateSize();
}

void TextView::colorGlyphs(const zeus::CColor& newColor)
{
    for (RenderGlyph& glyph : m_glyphs)
        glyph.m_color = newColor;
    invalidateGlyphs();
}

void TextView::colorGlyphsTypeOn(const zeus::CColor& newColor, float startInterval, float fadeTime)
{
}

void TextView::invalidateGlyphs()
{
    if (m_glyphBuf)
    {
        RenderGlyph* out = m_glyphBuf.access();
        size_t i = 0;
        for (RenderGlyph& glyph : m_glyphs)
            out[i++] = glyph;
    }
}

void TextView::think()
{
}

void TextView::resized(const boo::SWindowRect &root, const boo::SWindowRect& sub)
{
    View::resized(root, sub);
}

void TextView::draw(boo::IGraphicsCommandQueue* gfxQ)
{
    View::draw(gfxQ);
    if (m_glyphs.size())
    {
        gfxQ->setShaderDataBinding(m_shaderBinding);
        gfxQ->drawInstances(0, 4, m_glyphs.size());
    }
}

std::pair<int,int> TextView::queryGlyphDimensions(size_t pos) const
{
    if (pos >= m_glyphInfo.size())
        Log.report(logvisor::Fatal,
                   "TextView::queryGlyphWidth(%" PRISize ") out of bounds: %" PRISize,
                   pos, m_glyphInfo.size());

    return m_glyphInfo[pos].m_dims;
}

size_t TextView::reverseSelectGlyph(int x) const
{
    size_t ret = 0;
    size_t idx = 1;
    int minDelta = abs(x);
    for (const RenderGlyphInfo& info : m_glyphInfo)
    {
        int thisDelta = abs(info.m_adv-x);
        if (thisDelta < minDelta)
        {
            minDelta = thisDelta;
            ret = idx;
        }
        ++idx;
    }
    return ret;
}

int TextView::queryReverseAdvance(size_t idx) const
{
    if (idx > m_glyphInfo.size())
        Log.report(logvisor::Fatal,
                   "TextView::queryReverseGlyph(%" PRISize ") out of inclusive bounds: %" PRISize,
                   idx, m_glyphInfo.size());
    if (!idx) return 0;
    return m_glyphInfo[idx-1].m_adv;
}

std::pair<size_t,size_t> TextView::queryWholeWordRange(size_t idx) const
{
    if (idx > m_glyphInfo.size())
        Log.report(logvisor::Fatal,
                   "TextView::queryWholeWordRange(%" PRISize ") out of inclusive bounds: %" PRISize,
                   idx, m_glyphInfo.size());
    if (m_glyphInfo.empty())
        return {0,0};

    if (idx == m_glyphInfo.size())
        --idx;

    size_t begin = idx;
    while (begin > 0 && !m_glyphInfo[begin-1].m_space)
        --begin;

    size_t end = idx;
    while (end < m_glyphInfo.size() && !m_glyphInfo[end].m_space)
        ++end;

    return {begin, end-begin};
}

}