/*  ========================================================
        Bitmap Font Loader Extender  

        Author : Dongkun Lee.  
        Version : 1.2.
        Date : 2023. 11. 21.  
        
        History : 2023. 11. 2. ver 1. 0.
        Description : 
            This is helper utility to load bitmap font(fnt) that have multiple atlas. 
            Just load fnt font by LadBMFontEx("filename");
            It support up to 10 atlas.
*/

#include <stdlib.h>
#include "raylib.h"
#include "string.h"
#include "stdio.h"

static Font LoadBMFontEX(const char *fileName);

static int GetLine(const char *origin, char *buffer, int maxLength);
// Load a BMFont file (AngelCode font file)
// REQUIRES: strstr(), sscanf(), strrchr(), memcpy()
Font LoadBMFontEX(const char *fileName)
{
   #define MAX_BUFFER_SIZE     256

    Font font = { 0 };

    char buffer[MAX_BUFFER_SIZE] = { 0 };
    char *searchPoint = NULL;

    int fontSize = 0;
    int glyphCount = 0;

    int imWidth = 0;
    int imHeight = 0;
    int totalPage = 1;   // page variable
    char imFileName[10][129] = { 0 };  // up to ten png file.

    int base = 0;       // Useless data
    int readBytes = 0;  // Data bytes read
    int readVars = 0;   // Variables filled by sscanf()

    char *fileText = LoadFileText(fileName);

    if (fileText == NULL) return font;

    char *fileTextPtr = fileText;

    // NOTE: We skip first line, it contains no useful information
    readBytes = GetLine(fileTextPtr, buffer, MAX_BUFFER_SIZE);
    fileTextPtr += (readBytes + 1);

    // Read line data
    readBytes = GetLine(fileTextPtr, buffer, MAX_BUFFER_SIZE);
    searchPoint = strstr(buffer, "lineHeight");
    readVars = sscanf(searchPoint, "lineHeight=%i base=%i scaleW=%i scaleH=%i pages=%i", &fontSize, &base, &imWidth, &imHeight, &totalPage);
    fileTextPtr += (readBytes + 1);
    
    if (readVars < 4) { UnloadFileText(fileText); return font; } // Some data not available, file malformed

    for (int i = 0; i < totalPage; i++)
    {
        readBytes = GetLine(fileTextPtr, buffer, MAX_BUFFER_SIZE);
        searchPoint = strstr(buffer, "file");
        readVars = sscanf(searchPoint, "file=\"%128[^\"]\"", imFileName[i]);
        fileTextPtr += (readBytes + 1);

        if (readVars < 1) { UnloadFileText(fileText); return font; } // No fileName read
    }

    readBytes = GetLine(fileTextPtr, buffer, MAX_BUFFER_SIZE);
    searchPoint = strstr(buffer, "count");
    readVars = sscanf(searchPoint, "count=%i", &glyphCount);
    fileTextPtr += (readBytes + 1);

    if (readVars < 1) { UnloadFileText(fileText); return font; } // No glyphCount read

    // Compose correct path using route of .fnt file (fileName) and imFileName
    char **imPath;
    char *lastSlash = NULL;
    imPath = malloc(sizeof(char) * 100);  // imPath Initialization

    for (int i = 0; i< totalPage; i++)
    {
        lastSlash = strrchr(fileName, '/');
        if (lastSlash == NULL) lastSlash = strrchr(fileName, '\\');

        if (lastSlash != NULL)
        {
            // NOTE: We need some extra space to avoid memory corruption on next allocations!
            imPath[i] = (char *)RL_CALLOC(TextLength(fileName) - TextLength(lastSlash) + TextLength(imFileName[i]) + 4, 1);
            memcpy(imPath[i], fileName, TextLength(fileName) - TextLength(lastSlash) + 1);
            memcpy(imPath[i] + TextLength(fileName) - TextLength(lastSlash) + 1, imFileName[i], TextLength(imFileName[i]));
        }
        else imPath[i] = imFileName[i];

    TRACELOGD("    > Image loading path: %s", imPath[i]);
    }

    // Resize and ReDraw Font Image 
    Image fullFont = LoadImage(imPath[0]);;

    Image imFont[totalPage];   // font atlas

    for (int i = 0; i < totalPage; i++)
    {
        imFont[i] =  LoadImage(imPath[i]);

        if (imFont[i].format == PIXELFORMAT_UNCOMPRESSED_GRAYSCALE)
        {
            // Convert image to GRAYSCALE + ALPHA, using the mask as the alpha channel
            Image imFontAlpha = {
                .data = RL_CALLOC(imFont[i].width*imFont[i].height, 2),
                .width = imFont[i].width,
                .height = imFont[i].height,
                .mipmaps = 1,
                .format = PIXELFORMAT_UNCOMPRESSED_GRAY_ALPHA
            };

            for (int p = 0, pi = 0; p < (imFont[i].width*imFont[i].height*2); p += 2, pi++)
            {
                ((unsigned char *)(imFontAlpha.data))[p] = 0xff;
                ((unsigned char *)(imFontAlpha.data))[p + 1] = ((unsigned char *)imFont[i].data)[pi];
            }

            UnloadImage(imFont[i]);
            imFont[i] = imFontAlpha;
        }

        if (lastSlash != NULL) RL_FREE(imPath[i]);
    } 

    fullFont =  imFont[0];

    // If multiple atlas, then merge atlas
    if (totalPage > 1)
    {
        // Resize and ReDraw Font Image 
        ImageResizeCanvas(&fullFont, imWidth, imHeight * totalPage, 0, 0, BLACK); 

        for (int index = 1; index <= totalPage; index++)
        {
            Rectangle srcRec = { 0.0f, 0.0f, (float)imWidth, (float)imHeight};
            Rectangle destRec = { 0.0f, (float)imHeight * (float)index, (float)imWidth, (float)imHeight};
            ImageDraw(&fullFont, imFont[index], srcRec, destRec, WHITE);              
        }
    }

    font.texture = LoadTextureFromImage(fullFont);



    // Fill font characters info data
    font.baseSize = fontSize;
    font.glyphCount = glyphCount;
    font.glyphPadding = 0;
    font.glyphs = (GlyphInfo *)RL_MALLOC(glyphCount*sizeof(GlyphInfo));
    font.recs = (Rectangle *)RL_MALLOC(glyphCount*sizeof(Rectangle));

    int charId, charX, charY, charWidth, charHeight, charOffsetX, charOffsetY, charAdvanceX, pageID;

    for (int i = 0; i < glyphCount; i++)
    {
        readBytes = GetLine(fileTextPtr, buffer, MAX_BUFFER_SIZE);
        readVars = sscanf(buffer, "char id=%i x=%i y=%i width=%i height=%i xoffset=%i yoffset=%i xadvance=%i page=%i",
                       &charId, &charX, &charY, &charWidth, &charHeight, &charOffsetX, &charOffsetY, &charAdvanceX, &pageID);
        fileTextPtr += (readBytes + 1);
        
        if (readVars == 9)  // Make sure all char data has been properly read
        {
            // Get character rectangle in the font atlas texture
            font.recs[i] = (Rectangle){ (float)charX, (float)charY + (float)imHeight * pageID, (float)charWidth, (float)charHeight };

            // Save data properly in sprite font
            font.glyphs[i].value = charId;
            font.glyphs[i].offsetX = charOffsetX;
            font.glyphs[i].offsetY = charOffsetY;
            font.glyphs[i].advanceX = charAdvanceX;

            // Fill character image data from imFont data
            font.glyphs[i].image = ImageFromImage(fullFont, font.recs[i]);
        }
        else TRACELOG(LOG_WARNING, "FONT: [%s] Some characters data not correctly provided", fileName);
    }

    UnloadImage(fullFont);
    UnloadFileText(fileText);

    if (font.texture.id == 0)
    {
        UnloadFont(font);
        font = GetFontDefault();
        TRACELOG(LOG_WARNING, "FONT: [%s] Failed to load texture, reverted to default font", fileName);
    }
    else TRACELOG(LOG_INFO, "FONT: [%s] Font loaded successfully (%i glyphs)", fileName, font.glyphCount);

    free(imPath);
    return font;
}

static int GetLine(const char *origin, char *buffer, int maxLength)
{
    int count = 0;
    for (; count < maxLength; count++) if (origin[count] == '\n') break;
    memcpy(buffer, origin, count);
    return count;
}