#include "plutovg-private.h"

#include "sw_ft_raster.h"
#include "sw_ft_stroker.h"
#include "sw_ft_types.h"
#include "sw_ft_math.h"

#include <math.h>
#include <limits.h>

static SW_FT_Outline* sw_ft_outline_create(int points, int contours)
{
    SW_FT_Outline* ft = malloc(sizeof(SW_FT_Outline));
    ft->points = malloc((size_t)(points + contours) * sizeof(SW_FT_Vector));
    ft->tags = malloc((size_t)(points + contours) * sizeof(char));
    ft->contours = malloc((size_t)contours * sizeof(short));
    ft->contours_flag = malloc((size_t)contours * sizeof(char));
    ft->n_points = ft->n_contours = 0;
    ft->flags = 0x0;
    return ft;
}

static void sw_ft_outline_destroy(SW_FT_Outline* ft)
{
    free(ft->points);
    free(ft->tags);
    free(ft->contours);
    free(ft->contours_flag);
    free(ft);
}

#define FT_COORD(x) (SW_FT_Pos)((x) * 64)
static void sw_ft_outline_move_to(SW_FT_Outline* ft, double x, double y)
{
    ft->points[ft->n_points].x = FT_COORD(x);
    ft->points[ft->n_points].y = FT_COORD(y);
    ft->tags[ft->n_points] = SW_FT_CURVE_TAG_ON;
    if(ft->n_points)
    {
        ft->contours[ft->n_contours] = ft->n_points - 1;
        ft->n_contours++;
    }

    ft->contours_flag[ft->n_contours] = 1;
    ft->n_points++;
}

static void sw_ft_outline_line_to(SW_FT_Outline* ft, double x, double y)
{
    ft->points[ft->n_points].x = FT_COORD(x);
    ft->points[ft->n_points].y = FT_COORD(y);
    ft->tags[ft->n_points] = SW_FT_CURVE_TAG_ON;
    ft->n_points++;
}

static void sw_ft_outline_cubic_to(SW_FT_Outline* ft, double x1, double y1, double x2, double y2, double x3, double y3)
{
    ft->points[ft->n_points].x = FT_COORD(x1);
    ft->points[ft->n_points].y = FT_COORD(y1);
    ft->tags[ft->n_points] = SW_FT_CURVE_TAG_CUBIC;
    ft->n_points++;

    ft->points[ft->n_points].x = FT_COORD(x2);
    ft->points[ft->n_points].y = FT_COORD(y2);
    ft->tags[ft->n_points] = SW_FT_CURVE_TAG_CUBIC;
    ft->n_points++;

    ft->points[ft->n_points].x = FT_COORD(x3);
    ft->points[ft->n_points].y = FT_COORD(y3);
    ft->tags[ft->n_points] = SW_FT_CURVE_TAG_ON;
    ft->n_points++;
}

static void sw_ft_outline_close(SW_FT_Outline* ft)
{
    ft->contours_flag[ft->n_contours] = 0;
    int index = ft->n_contours ? ft->contours[ft->n_contours - 1] + 1 : 0;
    if(index == ft->n_points)
        return;

    ft->points[ft->n_points].x = ft->points[index].x;
    ft->points[ft->n_points].y = ft->points[index].y;
    ft->tags[ft->n_points] = SW_FT_CURVE_TAG_ON;
    ft->n_points++;
}

static void sw_ft_outline_end(SW_FT_Outline* ft)
{
    if(ft->n_points)
    {
        ft->contours[ft->n_contours] = ft->n_points - 1;
        ft->n_contours++;
    }
}

static SW_FT_Outline* sw_ft_outline_convert(const plutovg_path_t* path, const plutovg_matrix_t* matrix)
{
    SW_FT_Outline* outline = sw_ft_outline_create(path->points.size, path->contours);
    plutovg_path_element_t* elements = path->elements.data;
    plutovg_point_t* points = path->points.data;
    plutovg_point_t p[3];
    for(int i = 0;i < path->elements.size;i++)
    {
        switch(elements[i])
        {
        case plutovg_path_element_move_to:
            plutovg_matrix_map_point(matrix, &points[0], &p[0]);
            sw_ft_outline_move_to(outline, p[0].x, p[0].y);
            points += 1;
            break;
        case plutovg_path_element_line_to:
            plutovg_matrix_map_point(matrix, &points[0], &p[0]);
            sw_ft_outline_line_to(outline, p[0].x, p[0].y);
            points += 1;
            break;
        case plutovg_path_element_cubic_to:
            plutovg_matrix_map_point(matrix, &points[0], &p[0]);
            plutovg_matrix_map_point(matrix, &points[1], &p[1]);
            plutovg_matrix_map_point(matrix, &points[2], &p[2]);
            sw_ft_outline_cubic_to(outline, p[0].x, p[0].y, p[1].x, p[1].y, p[2].x, p[2].y);
            points += 3;
            break;
        case plutovg_path_element_close:
            sw_ft_outline_close(outline);
            points += 1;
            break;
        }
    }

    sw_ft_outline_end(outline);
    return outline;
}

static SW_FT_Outline* sw_ft_outline_convert_dash(const plutovg_path_t* path, const plutovg_matrix_t* matrix, const plutovg_dash_t* dash)
{
    plutovg_path_t* dashed = plutovg_dash_path(dash, path);
    SW_FT_Outline* outline = sw_ft_outline_convert(dashed, matrix);
    plutovg_path_destroy(dashed);
    return outline;
}

static void generation_callback(int count, const SW_FT_Span* spans, void* user)
{
    plutovg_rle_t* rle = user;
    plutovg_array_ensure(rle->spans, count);
    plutovg_span_t* data = rle->spans.data + rle->spans.size;
    memcpy(data, spans, (size_t)count * sizeof(plutovg_span_t));
    rle->spans.size += count;
}

static void bbox_callback(int x, int y, int w, int h, void* user)
{
    plutovg_rle_t* rle = user;
    rle->x = x;
    rle->y = y;
    rle->w = w;
    rle->h = h;
}

plutovg_rle_t* plutovg_rle_create(void)
{
    plutovg_rle_t* rle = malloc(sizeof(plutovg_rle_t));
    plutovg_array_init(rle->spans);
    rle->x = 0;
    rle->y = 0;
    rle->w = 0;
    rle->h = 0;
    return rle;
}

void plutovg_rle_destroy(plutovg_rle_t* rle)
{
    if(rle==NULL)
        return;

    free(rle->spans.data);
    free(rle);
}

#define SQRT2 1.41421356237309504880
void plutovg_rle_rasterize(plutovg_rle_t* rle, const plutovg_path_t* path, const plutovg_matrix_t* matrix, const plutovg_rect_t* clip, const plutovg_stroke_data_t* stroke, plutovg_fill_rule_t winding)
{
    SW_FT_Raster_Params params;
    params.flags = SW_FT_RASTER_FLAG_DIRECT | SW_FT_RASTER_FLAG_AA;
    params.gray_spans = generation_callback;
    params.bbox_cb = bbox_callback;
    params.user = rle;

    if(clip)
    {
        params.flags |= SW_FT_RASTER_FLAG_CLIP;
        params.clip_box.xMin = (SW_FT_Pos)clip->x;
        params.clip_box.yMin = (SW_FT_Pos)clip->y;
        params.clip_box.xMax = (SW_FT_Pos)(clip->x + clip->w);
        params.clip_box.yMax = (SW_FT_Pos)(clip->y + clip->h);
    }

    if(stroke)
    {
        SW_FT_Outline* outline = stroke->dash ? sw_ft_outline_convert_dash(path, matrix, stroke->dash) : sw_ft_outline_convert(path, matrix);
        SW_FT_Stroker_LineCap ftCap;
        SW_FT_Stroker_LineJoin ftJoin;
        SW_FT_Fixed ftWidth;
        SW_FT_Fixed ftMiterLimit;

        plutovg_point_t p1 = {0, 0};
        plutovg_point_t p2 = {SQRT2, SQRT2};
        plutovg_point_t p3;

        plutovg_matrix_map_point(matrix, &p1, &p1);
        plutovg_matrix_map_point(matrix, &p2, &p2);

        p3.x = p2.x - p1.x;
        p3.y = p2.y - p1.y;

        double scale = sqrt(p3.x*p3.x + p3.y*p3.y) / 2.0;

        ftWidth = (SW_FT_Fixed)(stroke->width * scale * 0.5 * (1 << 6));
        ftMiterLimit = (SW_FT_Fixed)(stroke->miterlimit * (1 << 16));

        switch(stroke->cap)
        {
        case plutovg_line_cap_square:
            ftCap = SW_FT_STROKER_LINECAP_SQUARE;
            break;
        case plutovg_line_cap_round:
            ftCap = SW_FT_STROKER_LINECAP_ROUND;
            break;
        default:
            ftCap = SW_FT_STROKER_LINECAP_BUTT;
            break;
        }

        switch(stroke->join)
        {
        case plutovg_line_join_bevel:
            ftJoin = SW_FT_STROKER_LINEJOIN_BEVEL;
            break;
        case plutovg_line_join_round:
            ftJoin = SW_FT_STROKER_LINEJOIN_ROUND;
            break;
        default:
            ftJoin = SW_FT_STROKER_LINEJOIN_MITER_FIXED;
            break;
        }

        SW_FT_Stroker stroker;
        SW_FT_Stroker_New(&stroker);
        SW_FT_Stroker_Set(stroker, ftWidth, ftCap, ftJoin, ftMiterLimit);
        SW_FT_Stroker_ParseOutline(stroker, outline);

        SW_FT_UInt points;
        SW_FT_UInt contours;
        SW_FT_Stroker_GetCounts(stroker, &points, &contours);

        SW_FT_Outline* strokeOutline = sw_ft_outline_create((int)points, (int)contours);
        SW_FT_Stroker_Export(stroker, strokeOutline);
        SW_FT_Stroker_Done(stroker);

        strokeOutline->flags = SW_FT_OUTLINE_NONE;
        params.source = strokeOutline;
        sw_ft_grays_raster.raster_render(NULL, &params);
        sw_ft_outline_destroy(outline);
        sw_ft_outline_destroy(strokeOutline);
    }
    else
    {
        SW_FT_Outline* outline = sw_ft_outline_convert(path, matrix);
        outline->flags = winding == plutovg_fill_rule_even_odd ? SW_FT_OUTLINE_EVEN_ODD_FILL : SW_FT_OUTLINE_NONE;
        params.source = outline;
        sw_ft_grays_raster.raster_render(NULL, &params);
        sw_ft_outline_destroy(outline);
    }
}

#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((a) > (b) ? (a) : (b))
#define DIV255(x) (((x) + ((x) >> 8) + 0x80) >> 8)
plutovg_rle_t* plutovg_rle_intersection(const plutovg_rle_t* a, const plutovg_rle_t* b)
{
    int count = MAX(a->spans.size, b->spans.size);
    plutovg_rle_t* result = malloc(sizeof(plutovg_rle_t));
    plutovg_array_init(result->spans);
    plutovg_array_ensure(result->spans, count);

    plutovg_span_t* a_spans = a->spans.data;
    plutovg_span_t* a_end = a_spans + a->spans.size;

    plutovg_span_t* b_spans = b->spans.data;
    plutovg_span_t* b_end = b_spans + b->spans.size;

    while(count && a_spans < a_end && b_spans < b_end)
    {
        if(b_spans->y > a_spans->y)
        {
            ++a_spans;
            continue;
        }

        if(a_spans->y != b_spans->y)
        {
            ++b_spans;
            continue;
        }

        int ax1 = a_spans->x;
        int ax2 = ax1 + a_spans->len;
        int bx1 = b_spans->x;
        int bx2 = bx1 + b_spans->len;

        if(bx1 < ax1 && bx2 < ax1)
        {
            ++b_spans;
            continue;
        }
        else if(ax1 < bx1 && ax2 < bx1)
        {
            ++a_spans;
            continue;
        }

        int x = MAX(ax1, bx1);
        int len = MIN(ax2, bx2) - x;
        if(len)
        {
            plutovg_span_t* span = result->spans.data + result->spans.size;
            span->x = (short)x;
            span->len = (unsigned short)len;
            span->y = a_spans->y;
            span->coverage = DIV255(a_spans->coverage * b_spans->coverage);
            ++result->spans.size;
            --count;
        }

        if(ax2 < bx2)
        {
            ++a_spans;
        }
        else
        {
            ++b_spans;
        }
    }

    if(result->spans.size==0)
    {
        result->x = 0;
        result->y = 0;
        result->w = 0;
        result->h = 0;
        return result;
    }

    plutovg_span_t* spans = result->spans.data;
    int x1 = INT_MAX;
    int y1 = spans[0].y;
    int x2 = 0;
    int y2 = spans[result->spans.size - 1].y;
    for(int i = 0;i < result->spans.size;i++)
    {
        if(spans[i].x < x1) x1 = spans[i].x;
        if(spans[i].x + spans[i].len > x2) x2 = spans[i].x + spans[i].len;
    }

    result->x = x1;
    result->y = y1;
    result->w = x2 - x1;
    result->h = y2 - y1 + 1;
    return result;
}

void plutovg_rle_clip_path(plutovg_rle_t* rle, const plutovg_rle_t* clip)
{
    if(rle==NULL || clip==NULL)
        return;

    plutovg_rle_t* result = plutovg_rle_intersection(rle, clip);
    plutovg_array_ensure(rle->spans, result->spans.size);
    memcpy(rle->spans.data, result->spans.data, (size_t)result->spans.size * sizeof(plutovg_span_t));
    rle->spans.size = result->spans.size;
    rle->x = result->x;
    rle->y = result->y;
    rle->w = result->w;
    rle->h = result->h;
    plutovg_rle_destroy(result);
}

plutovg_rle_t* plutovg_rle_clone(const plutovg_rle_t* rle)
{
    if(rle==NULL)
        return NULL;

    plutovg_rle_t* result = malloc(sizeof(plutovg_rle_t));
    plutovg_array_init(result->spans);
    plutovg_array_ensure(result->spans, rle->spans.size);

    memcpy(result->spans.data, rle->spans.data, (size_t)rle->spans.size * sizeof(plutovg_span_t));
    result->spans.size = rle->spans.size;
    result->x = rle->x;
    result->y = rle->y;
    result->w = rle->w;
    result->h = rle->h;
    return result;
}

void plutovg_rle_clear(plutovg_rle_t* rle)
{
    rle->spans.size = 0;
    rle->x = 0;
    rle->y = 0;
    rle->w = 0;
    rle->h = 0;
}