#include "teensy_renderer.h"

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <stdarg.h>

#include "teensy_context.h"
#include "teensy_list.h"

#define BLEND_COLOR ty_color(255, 0, 255)

struct ty_renderer r;

static
bool is_renderer_init(void)
{
    return r.screen.data != NULL && r.screen.width * r.screen.height != 0;
}

static
void image_bounds_check(struct ty_image img, struct ty_vec2i pos)
{
#ifdef TEENSY_DEBUG
    if (
        pos.x < 0 ||
        pos.x >= img.width ||
        pos.y < 0 ||
        pos.y >= img.height
    ) {
        ty_log_fatal(
            TY_ERR_RENDER_OOB,
            "OOB (%d, %d). bounds are (%d, %d)",
            pos.x, pos.y,
            img.width, img.height
        );
    }
#else 
    (void)img;
    (void)pos;
#endif
}

void ty_init_renderer(void)
{
    r.screen = ty_create_image(
        ctx.hints.scr_width,
        ctx.hints.scr_height,
        NULL
    );
}

void ty_deinit_renderer(void)
{
    assert(is_renderer_init());

    ty_free_image(r.screen);
}

struct ty_image ty_create_image(int w, int h, const struct ty_color* data)
{
    struct ty_image img;

    img.width  = w;
    img.height = h;

    size_t size = sizeof(struct ty_color) * w * h;
    img.data = ty_alloc(size);
    if (data)
        memcpy(img.data, data, size);
    else
        memset(img.data, 0, size);

    return img;
}

void ty_free_image(struct ty_image img)
{
    ty_free(img.data);
}

struct ty_color ty_img_get_pixel(struct ty_image img, struct ty_vec2i pos)
{
    image_bounds_check(img, pos);
    return img.data[pos.y * img.width + pos.x];
}

void ty_img_set_pixel(
    struct ty_image img,
    struct ty_vec2i pos,
    struct ty_color color
) {
    image_bounds_check(img, pos);
    img.data[pos.y * img.width + pos.x] = color;
}

// This function technically is not needed, but I may want unicode support in
// the future, when an abstraction like this is needed.
void ty_font_add_glyph(struct ty_font *font, uint8_t c, struct ty_image img)
{
    font->glyphs[c] = img;
}

int ty_font_width(struct ty_font *font, const char *fmt, ...)
{
    va_list args;
    va_start(args, fmt);
    int len = vsnprintf(NULL, 0, fmt, args);
    char *text = ty_talloc(sizeof(char) * (len + 1));
    va_end(args);

    va_start(args, fmt);
    vsnprintf(text, len + 1, fmt, args);
    va_end(args);

    int width = 0;
    for (uint8_t *c = (uint8_t*)text; *c != '\0'; c++)
        width += font->glyphs[*c].width;
    return width;
}

void ty_draw_clear(struct ty_color col)
{
    assert(is_renderer_init());
    for (int i = 0; i < r.screen.width * r.screen.height; i++) {
        r.screen.data[i] = col;
    }
}

void ty_draw_image(struct ty_image img, struct ty_vec2i pos)
{
    int x1 = fmin(fmax(pos.x, 0), r.screen.width);
    int y1 = fmin(fmax(pos.y, 0), r.screen.height);
    int x2 = fmin(fmax(pos.x + img.width, 0), r.screen.width);
    int y2 = fmin(fmax(pos.y + img.height, 0), r.screen.height);

    for (int dy = y1; dy < y2; dy++) {
        for (int dx = x1; dx < x2; dx++) {
            struct ty_color px = ty_img_get_pixel(
                img,
                ty_vec2i(dx - x1, dy - y1)
            );
            if (memcmp(&px, &BLEND_COLOR, sizeof(px)) == 0)
                continue;
            ty_img_set_pixel(
                r.screen,
                ty_vec2i(dx, dy),
                px
            );
        }
    }
}

void ty_draw_image_ex(
    struct ty_image img,
    struct ty_recti src,
    struct ty_recti dst
) {
    int x1 = fmin(fmax(dst.x, 0), r.screen.width);
    int y1 = fmin(fmax(dst.y, 0), r.screen.height);
    int x2 = fmin(fmax(dst.x + dst.w, 0), r.screen.width);
    int y2 = fmin(fmax(dst.y + dst.h, 0), r.screen.height);

    for (int dy = y1; dy < y2; dy++) {
        for (int dx = x1; dx < x2; dx++) {
            int img_x = ((dx - x1) * src.w) / dst.w + src.x;
            int img_y = ((dy - y1) * src.h) / dst.h + src.y;
            struct ty_color px = ty_img_get_pixel(img, ty_vec2i(img_x, img_y));
            if (memcmp(&px, &BLEND_COLOR, sizeof(px)) == 0)
                continue;

            ty_img_set_pixel(
                r.screen,
                ty_vec2i(dx, dy),
                px
            );
        }
    }
}

struct ty_vec2i clamp_point(struct ty_vec2i p, struct ty_recti rect)
{
    p.x = fmin(fmax(p.x, rect.x), rect.w);
    p.y = fmin(fmax(p.y, rect.y), rect.h);
    return p;
}

void ty_draw_image_rot(
    struct ty_image img,
    struct ty_vec2i pos,
    struct ty_vec2i offset,
    double rot
) {
    double s = sin(rot);
    double c = cos(rot);
 
    // x1 = c*x - s*y
    // y1 = s*x + c*y

    // FIXME: the corners of the rotated image get cut off.
    for (int img_y = 0; img_y < img.height; img_y++) {
        for (int img_x = 0; img_x < img.width; img_x++) {
            double pixel_x = img_x + offset.x;
            double pixel_y = img_y + offset.y;

            int dx = floor(pixel_x * c - pixel_y * s - offset.x);
            int dy = floor(pixel_x * s + pixel_y * c - offset.y);

            if (dx < 0 || dx >= img.width || dy < 0 || dy >= img.height)
                continue;

            struct ty_color px = ty_img_get_pixel(img, ty_vec2i(dx, dy));
            ty_img_set_pixel(r.screen, ty_vec2i(pos.x + img_x, pos.y + img_y), px);
        }
    }
}

void ty_draw_rect(struct ty_recti rect, struct ty_color color)
{
    int x1 = fmin(fmax(rect.x, 0), r.screen.width);
    int y1 = fmin(fmax(rect.y, 0), r.screen.height);

    int x2 = fmin(fmax(rect.x + rect.w, 0), r.screen.width);
    int y2 = fmin(fmax(rect.y + rect.h, 0), r.screen.height);

    for (int dy = y1; dy < y2; dy++) {
        for (int dx = x1; dx < x2; dx++) {
            ty_img_set_pixel(
                r.screen,
                ty_vec2i(dx, dy),
                color
            );
        }
    }
}

void ty_draw_line(
    struct ty_vec2i start,
    struct ty_vec2i end,
    struct ty_color color
) {
    int dx = end.x - start.x;
    int dy = end.y - start.y;

    if (abs(dx) > abs(dy)) {
        if (start.x > end.x) {
            int tmp = start.x;
            start.x = end.x;
            end.x   = tmp;

            tmp     = start.y;
            start.y = end.y;
            end.y   = tmp;
        }

        for (int x = start.x; x < end.x; x++) {
            int y = start.y + dy * (x - start.x) / dx;

            ty_img_set_pixel(
                r.screen,
                ty_vec2i(x, y),
                color
            );
        }
    } else {
        if (start.y > end.y) {
            int tmp = start.x;
            start.x = end.x;
            end.x   = tmp;

            tmp     = start.y;
            start.y = end.y;
            end.y   = tmp;
        }

        for (int y = start.y; y < end.y; y++) {
            int x = start.x + dx * (y - start.y) / dy;

            ty_img_set_pixel(
                r.screen,
                ty_vec2i(x, y),
                color
            );
        }
    }
}

void ty_draw_text(struct ty_font *font, struct ty_vec2i pos, const char *text)
{
    for (const uint8_t *c = (const uint8_t*)text; *c != '\0'; c++) {
        struct ty_image glyph = font->glyphs[*c];
        ty_draw_image(glyph, pos);
        pos.x += glyph.width;
    }
}

void ty_draw_text_fmt(
    struct ty_font *font,
    struct ty_vec2i pos,
    const char *fmt,
    ...
) {
    va_list args;
    va_start(args, fmt);
    int len = vsnprintf(NULL, 0, fmt, args);
    char *text = ty_talloc(sizeof(char) * (len + 1));
    va_end(args);

    va_start(args, fmt);
    vsnprintf(text, len + 1, fmt, args);
    va_end(args);

    ty_draw_text(font, pos, text);
}

void ty_draw_end(void)
{
    assert(is_renderer_init());
}