/*
 * CS5600 University of Utah
 * Charles McGarvey
 * mcgarvey@eng.utah.edu
 */

#include <cassert>
#include <cerrno>
#include <cstdio>
#include <cstring>

#include "raster.hh"


struct raster
{
    color_t*    pixels;
    int         w, h;
    int         left, right, bottom, top;
};


raster_t* raster_alloc(int width, int height, color_t fill)
{
    assert(0 < width && 0 < height && "zero-dimension raster not allowed");
    size_t size = width * height;

    raster_t* p = (raster_t*)mem_alloc(sizeof(raster_t));
    p->pixels = (color_t*)mem_alloc(sizeof(color_t) * size);
    p->w = width;
    p->h = height;
    raster_clear(p, fill);
    raster_viewport(p, 0, 0, width, height);

    return p;
}

void raster_destroy(raster_t* p)
{
    mem_free(p->pixels);
    mem_free(p);
}


color_t* raster_color(const raster_t* p, int x, int y)
{
    return p->pixels + p->w * y + x;
}

color_t raster_uv(const raster_t* p, vec_t uv)
{
    uv.x = scal_clamp(uv.x, S(0.0), S(1.0));
    uv.y = scal_clamp(uv.y, S(0.0), S(1.0));
    uv.y = S(1.0) - uv.y;
    int x = (int)((scal_t)p->w * uv.x);
    int y = (int)((scal_t)p->h * uv.y);
    if (p->w <= x) {
        x = p->w - 1;
    }
    if (p->h <= y) {
        y = p->h - 1;
    }
    return *raster_color(p, x, y);
}

int raster_width(const raster_t* p)
{
    return p->w;
}

int raster_height(const raster_t* p)
{
    return p->h;
}

void* raster_data(const raster_t* p)
{
    size_t size = p->w * p->h;
    rgba_t* data = (rgba_t*)mem_alloc(size * sizeof(rgba_t));

    for (int i = 0; i < size; ++i) {
        data[i] = rgba_from_color(p->pixels[i]);
    }
    return data;
}


void raster_clear(raster_t* p, color_t fill)
{
    size_t size = p->w * p->h;
    for (int i = 0; i < size; ++i) {
        p->pixels[i] = fill;
    }
}


void raster_viewport(raster_t* p, int x, int y, int width, int height)
{
    p->left     = x;
    p->right    = x + width;
    p->bottom   = y;
    p->top      = y + height;
}


#define _DO_OR_DIE(X) if ((X) <= 0) goto fail

int raster_export_ppm(const raster_t* p, const char* filename)
{
    FILE* file = fopen(filename, "w");
    if (file == NULL) {
fail:   fprintf(stderr, "Cannot write to %s: %s\n", filename, strerror(errno));
        return -1;
    }

    _DO_OR_DIE(fprintf(file, "P3\n%u %u\n255\n", p->w, p->h));
    for (int y = (int)p->h - 1; y >= 0; --y) {
        for (int x = 0; x < p->w; ++x) {
            rgbachan_t r, g, b;
            color_split(p->pixels[y * p->w + x], &r, &g, &b, NULL);
            _DO_OR_DIE(fprintf(file, "%hhu %hhu %hhu\n", r, g, b));
        }
    }

    fclose(file);
    return 0;
}

int raster_export_bmp(const raster_t* p, const char* filename)
{
    /*
     * This function was adapted from sample code provided with the assignment
     * instructions.
     */
    FILE* file = fopen(filename, "wb");
    if (file == NULL) {
fail:   fprintf(stderr, "Cannot write to %s: %s\n", filename, strerror(errno));
        return -1;
    }
    
    uint16_t magicNumber = 0x4D42;
    uint16_t reserved0 = 0;//0x4D41;
    uint16_t reserved1 = 0;//0x5454;
    uint32_t dataOffset = 54;
    uint32_t infoHeaderSize = 40;
    uint32_t width = p->w;
    uint32_t height = p->h;
    uint16_t colorPlanes = 1;
    uint16_t bitsPerPixel = 32;
    uint32_t compression = 0;
    uint32_t dataSize = width * height * bitsPerPixel / 8;
    uint32_t horizontalResolution = 2835;
    uint32_t verticalResolution = 2835;
    uint32_t paletteColorCount = 0;
    uint32_t importantPaletteColorCount = 0;
    uint32_t fileSize = 54 + dataSize;
    
    /*
     * Check the return values to avoid loud warnings.
     */
    _DO_OR_DIE(fwrite(&magicNumber, sizeof(magicNumber), 1, file));
    _DO_OR_DIE(fwrite(&fileSize, sizeof(fileSize), 1, file));
    _DO_OR_DIE(fwrite(&reserved0, sizeof(reserved0), 1, file));
    _DO_OR_DIE(fwrite(&reserved1, sizeof(reserved1), 1, file));
    _DO_OR_DIE(fwrite(&dataOffset, sizeof(dataOffset), 1, file));
    _DO_OR_DIE(fwrite(&infoHeaderSize, sizeof(infoHeaderSize), 1, file));
    _DO_OR_DIE(fwrite(&width, sizeof(width), 1, file));
    _DO_OR_DIE(fwrite(&height, sizeof(height), 1, file));
    _DO_OR_DIE(fwrite(&colorPlanes, sizeof(colorPlanes), 1, file));
    _DO_OR_DIE(fwrite(&bitsPerPixel, sizeof(bitsPerPixel), 1, file));
    _DO_OR_DIE(fwrite(&compression, sizeof(compression), 1, file));
    _DO_OR_DIE(fwrite(&dataSize, sizeof(dataSize), 1, file));
    _DO_OR_DIE(fwrite(&horizontalResolution, sizeof(horizontalResolution), 1, file));
    _DO_OR_DIE(fwrite(&verticalResolution, sizeof(verticalResolution), 1, file));
    _DO_OR_DIE(fwrite(&paletteColorCount, sizeof(paletteColorCount), 1, file));
    _DO_OR_DIE(fwrite(&importantPaletteColorCount, sizeof(importantPaletteColorCount), 1, file));
    
    size_t size = width * height;
    for (int i = 0; i < size; ++i)
    {
        struct {
            rgbachan_t b, g, r, a;
        } argb;
        color_split(p->pixels[i], &argb.r, &argb.g, &argb.b, &argb.a);
        _DO_OR_DIE(fwrite(&argb, sizeof(argb), 1, file));
    }
    
    fclose(file);
    return 0;
}


raster_t* raster_import(const char* filename)
{
    int         type = 0;
    const char* ext = strrchr(filename, '.');
    if (ext == NULL) {
        goto fail;
    }
    ++ext;

    if (strcmp(ext, "bmp") == 0) {
        return raster_import_bmp(filename);
    }
    if (strcmp(ext, "ppm") == 0) {
        return raster_import_ppm(filename);
    }

fail:
    fprintf(stderr, "Unknown file type: %s", filename);
    return NULL;
}

raster_t* raster_import_ppm(const char* filename)
{
    FILE* file = fopen(filename, "r");
    if (file == NULL) {
        fprintf(stderr, "Cannot read from %s: %s\n", filename, strerror(errno));
        return NULL;
    }

    int w, h;
    if (fscanf(file, "P3 %d %d 255 ", &w, &h) != 2) {
        fprintf(stderr, "Cannot read header from %s: %s\n", filename, strerror(errno));
        return NULL;
    }

    raster_t* p = raster_alloc(w, h, COLOR_WHITE);

    for (int y = h - 1; y >= 0; --y) {
        for (int x = 0; x < w; ++x) {
            uint16_t r, g, b;
            /* mingw32 does not like %hhu conversion type */
            if (fscanf(file, "%hu %hu %hu ", &r, &g, &b) != 3) {
                fprintf(stderr, "Failed reading color values from %s: %s\n", filename, strerror(errno));
                return NULL;
            }
            union {
                rgba_t rgba;
                struct {
                    rgbachan_t r, g, b, a;
                } chan;
            } u;
            u.chan.r = (rgbachan_t)r;
            u.chan.g = (rgbachan_t)g;
            u.chan.b = (rgbachan_t)b;
            u.chan.a = 255;
            p->pixels[y * w + x] = color_from_rgba(u.rgba);
        }
    }

    fclose(file);
    return p;

fail:
    raster_destroy(p);
    fclose(file);
    fprintf(stderr, "Unexpected file format in %s: %s\n", filename, strerror(errno));
    return NULL;
}

raster_t* raster_import_bmp(const char* filename)
{
    FILE* file = fopen(filename, "rb");
    if (file == NULL) {
        fprintf(stderr, "Cannot read from %s: %s\n", filename, strerror(errno));
        return NULL;
    }

    size_t size;

    uint16_t magicNumber;
    uint16_t reserved0;//0x4D41;
    uint16_t reserved1;//0x5454;
    uint32_t dataOffset;
    uint32_t infoHeaderSize;
    uint32_t width;
    uint32_t height;
    uint16_t colorPlanes;
    uint16_t bitsPerPixel;
    uint32_t compression;
    uint32_t dataSize;
    uint32_t horizontalResolution;
    uint32_t verticalResolution;
    uint32_t paletteColorCount;
    uint32_t importantPaletteColorCount;
    uint32_t fileSize;

    raster_t* p = NULL;

    _DO_OR_DIE(fread(&magicNumber, sizeof(magicNumber), 1, file));
    _DO_OR_DIE(fread(&fileSize, sizeof(fileSize), 1, file));
    _DO_OR_DIE(fread(&reserved0, sizeof(reserved0), 1, file));
    _DO_OR_DIE(fread(&reserved1, sizeof(reserved1), 1, file));
    _DO_OR_DIE(fread(&dataOffset, sizeof(dataOffset), 1, file));
    _DO_OR_DIE(fread(&infoHeaderSize, sizeof(infoHeaderSize), 1, file));
    _DO_OR_DIE(fread(&width, sizeof(width), 1, file));
    _DO_OR_DIE(fread(&height, sizeof(height), 1, file));
    _DO_OR_DIE(fread(&colorPlanes, sizeof(colorPlanes), 1, file));
    _DO_OR_DIE(fread(&bitsPerPixel, sizeof(bitsPerPixel), 1, file));
    _DO_OR_DIE(fread(&compression, sizeof(compression), 1, file));
    _DO_OR_DIE(fread(&dataSize, sizeof(dataSize), 1, file));
    _DO_OR_DIE(fread(&horizontalResolution, sizeof(horizontalResolution), 1, file));
    _DO_OR_DIE(fread(&verticalResolution, sizeof(verticalResolution), 1, file));
    _DO_OR_DIE(fread(&paletteColorCount, sizeof(paletteColorCount), 1, file));
    _DO_OR_DIE(fread(&importantPaletteColorCount, sizeof(importantPaletteColorCount), 1, file));

    if ((int)width < 0 || (int)height < 0) {
        fprintf(stderr, "Unexpected file format in %s: Try a ppm file instead\n", filename);
        fclose(file);
        return NULL;
    }
    p = raster_alloc((int)width, (int)height, COLOR_WHITE);

    size = width * height;
    for (int i = 0; i < size; ++i)
    {
        union {
            rgba_t rgba;
            struct {
                rgbachan_t r, g, b, a;
            } chan;
        } u;
        _DO_OR_DIE(fread(&u, sizeof(u), 1, file));
        rgbachan_t t = u.chan.r;
        u.chan.r = u.chan.a;
        u.chan.a = t;
        t = u.chan.g;
        u.chan.g = u.chan.b;
        u.chan.b = t;
        t = u.chan.r;
        u.chan.r = u.chan.g;
        u.chan.g = u.chan.b;
        u.chan.b = u.chan.a;
        u.chan.a = t;
        p->pixels[i] = color_from_rgba(u.rgba);
    }

    fclose(file);
    return p;

fail:
    if (p) {
        raster_destroy(p);
    }
    fclose(file);
    fprintf(stderr, "Unexpected file format in %s: %s\n", filename, strerror(errno));
    return NULL;
}

#undef _DO_OR_DIE