#include <assert.h>
#include <ctype.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>


int main(int argc, char** argv)
{
	if (argc != 3)
	{
		fprintf(stderr, "Usage: %s <input image> <output header>\n", argv[0]);

		return 1;
	}

	const char* inFilename = argv[1];
	const char* outFilename = argv[2];


	int tileWidth;
	int tileHeight;
	uint8_t* tileBuffer;
	{
		FILE* inFile = fopen(inFilename, "rb");
		assert(inFile);

		#pragma pack(push,1)
		struct BmpHeader
		{
			char magic[2];
			uint32_t totalSize;
			uint32_t reserved;
			uint32_t offset;
			uint32_t headerSize;
			int32_t width;
			int32_t height;
			uint16_t planes;
			uint16_t depth;
			uint32_t compression;
			uint32_t imageSize;
			int32_t horizontalResolution;
			int32_t verticalResolution;
			uint32_t paletteColorCount;
			uint32_t importantColorcount;
		} bmpHeader;
		#pragma pack(pop)

		// Read the BMP header so we know where the image data is located
		fread(&bmpHeader, 1, sizeof(bmpHeader), inFile);
		assert(bmpHeader.magic[0] == 'B' && bmpHeader.magic[1] == 'M');
		assert(bmpHeader.depth == 8);
		assert(bmpHeader.headerSize == 40);

		// Go to location in file of image data
		fseek(inFile, bmpHeader.offset, SEEK_SET);

		// Read in the image data
		tileBuffer = malloc(bmpHeader.imageSize);
		assert(tileBuffer);
		fread(tileBuffer, 1, bmpHeader.imageSize, inFile);

		tileWidth = bmpHeader.width;
		tileHeight = bmpHeader.height;

		fclose(inFile);
	}


	printf("Input: %s\n", inFilename);
	printf("Output: %s\n", outFilename);
	printf("Width: %d\n", tileWidth);
	printf("Height: %d\n", tileHeight);

	FILE* outFile = fopen(outFilename, "w");
	assert(outFile);


	// Generate the preamble
	{
		fprintf(outFile, "// AUTOMATICALLY GENERATED. DO NOT EDIT.\n");
		fprintf(outFile, "\n");
		fprintf(outFile, "#pragma once\n");
		fprintf(outFile, "\n");
		fprintf(outFile, "#include <stdint.h>\n");
		fprintf(outFile, "\n");
		fprintf(outFile, "\n");
	}


	// Generate the font map with the calculated glyph bytes
	{
		fprintf(outFile, "static const uint8_t tile[%d][%d] =\n", tileHeight, tileWidth);
		fprintf(outFile, "{\n");
		fprintf(outFile, "	");

		int count = 0;

		for (int row = 0; row < tileHeight; ++row)
		{
			for (int col = 0; col < tileWidth; ++col)
			{
				// BMP is laid out bottom-to-top, but we want top-to-bottom (0-indexed)
				int y =  tileHeight - row - 1;

				uint8_t paletteIndex = tileBuffer[y * tileWidth + col];

				fprintf(outFile, "%d,", paletteIndex);
				++count;

				// Put a newline after sixteen values to keep it orderly
				if ((count % 16) == 0)
				{
					fprintf(outFile, "\n");
					fprintf(outFile, "	");

					count = 0;
				}
			}
		}

		fprintf(outFile, "};\n");
	}

	fclose(outFile);

	printf("\n");
	printf("DONE\n");

	return 0;
}