#!/usr/bin/env -S deno run --allow-read

if (Deno.args.length !== 0) {
  console.error(
    "This script takes no argument (The source file list is hardcoded) and output the result on stdout.",
  );
  Deno.exit(1);
}

import { TextLineStream } from "jsr:@std/streams@1.1.0";

const asmFilePaths = [
  "src/consts/arch.asm",
  "src/consts/game.asm",
  "src/consts/keyboard.asm",
  "src/consts/map.asm",
  "src/consts/scene.asm",
  "src/consts/screen.asm",
  "src/consts/sprites.asm",

  "src/init.asm",
  "src/main.asm",

  "src/lib/game.asm",
  "src/lib/drawing.asm",
  "src/lib/sprite_rotation.asm",
];
const reservedSpacePath = 'src/reserved_space.asm';

const instructionLength = 4; // in bytes
const mapWidth = 15;
const spriteWidth = 5;

const mapMatchingStrings = {
  0x00_00_00: '0', // Empty
  0xFF_00_00: '1', // Wall
  0xFF_FF_00: '2', // Coin
};

const spritesMatchingStrings = {
  0x00_00_00: '0b000_000_00',
  0x00_00_FF: '0b000_000_11',
  0x00_FF_00: '0b000_111_00',
  0x77_77_77: '0b010_011_10',
  0xFF_00_00: '0b111_000_00',
  0xFF_00_FF: '0b111_000_11',
  0xFF_80_00: '0b111_100_00',
  0xFF_FF_00: '0b111_110_00',
  0xFF_FF_FF: '0b111_111_11',
};

const mapPath = 'assets/map.ppm';
const spritesPath = {
  'sprite_empty': 'assets/sprites/empty.ppm',
  'sprite_unimplemented': 'assets/sprites/placeholder.ppm',
  'sprite_wall_end': 'assets/sprites/wall_end.ppm',
  'sprite_wall_straight': 'assets/sprites/wall_straight.ppm',
  'sprite_wall_corner': 'assets/sprites/wall_corner.ppm',
  'sprite_robot': 'assets/sprites/robot.ppm',
  'sprite_ghost': 'assets/sprites/ghost.ppm',
  'sprite_coin': 'assets/sprites/coin.ppm',
};

/**
 *    START OF BUILD
 */

for (const path of asmFilePaths) {
  const file = await Deno.open(path);
  const readable = file.readable.pipeThrough(new TextDecoderStream())
    .pipeThrough(new TextLineStream());

  console.log(`
;/*******************************
;* ${path}
;*******************************/
`);

  for await (const line of readable) {
    if (!line.startsWith("include ")) {
      console.log(line);
    }
  }
}


const asmRawRepresentations = [];

const mapBytes = await getDataFromPPM(mapPath);
asmRawRepresentations.push(bytesToAsmConstU8('map', mapBytes, mapMatchingStrings, mapWidth));

for (const [label, path] of Object.entries(spritesPath)) {
  const bytes = await getDataFromPPM(path);
  asmRawRepresentations.push(bytesToAsmConstU8(label, bytes, spritesMatchingStrings, spriteWidth));
}

console.log(asmRawRepresentations.join("\n\n"));

console.log(`
;
; RESERVED RAM SPACE
;
`);

console.log(await Deno.readTextFile(reservedSpacePath))

/**
 * Return an ASM constant (U8) representation of the given data
 * 
 * If needed, the representation will be padded to ensure the following code stays aligned on the instruction's length
 * 
 * @param label The label to write before the first raw data
 * @param data An array of bytes to interprete as 24 bits values
 * @param matchingStrings An associative array with a string representation for each possible 24 bit data value
 * @param lineLength Optional: Provide a way to wrap the result in multiple lines
 * 
 * @returns The ASM representation of that raw data, pre- and post-fixed by the given label
 */
function bytesToAsmConstU8(label: string, data: Uint8Array, matchingStrings: Record<number, string>, lineLength = 0): string {
  lineLength ??= Infinity;

  const stringValues = [];
  for (let i = 0; i < data.length - 2; i += 3) {
    const pixelValue = (data[i] << 16) + (data[i+1] << 8) + (data[i+2])
    if (!Object.hasOwn(matchingStrings, pixelValue)) {
      console.error(`No matching value defined for "${pixelValue.toString(2)}" (which is ${label}'s ${i} pixel)`);
      Deno.exit(1);
    }
    
    stringValues.push(`U8 ${matchingStrings[pixelValue]}`);
  }

  const lines = [];
  if (lineLength === 0) {
    lines.push(stringValues.join("\t"));
  } else {
    for (let i = 0; i < stringValues.length; i += lineLength) {
      lines.push(stringValues.slice(i, i+lineLength).join("\t"));
    }
  }

  const paddingBytes = [];
  for (let i = 0; i < stringValues.length % instructionLength; i++) {
    paddingBytes.push('U8 0');
  }
  const paddingString = paddingBytes.length === 0 ? '' : `\n${paddingBytes.join('\t')} ; padding to preserve ${8 * instructionLength} bits alignment`
  
  return `${label}:
${lines.join("\n")}
${label}_end:${paddingString}`
}

/**
 * Return the image pixels data (excluding all other fields) from a given PPM file
 * 
 * The implementation differ from the format definition (https://netpbm.sourceforge.net/doc/ppm.html) but match the file created by GIMP.
 */
async function getDataFromPPM(path: string): Promise<Uint8Array> {
  const endOfComment = [
    0x0a,
    0x0d,
  ];
  const whitespaces = [
    0x09,
    0x0a,
    0x0b,
    0x0c,
    0x0d,
    0x20,
  ];
  const numbers = [
    0x30,
    0x31,
    0x32,
    0x33,
    0x34,
    0x35,
    0x36,
    0x37,
    0x38,
    0x39,
  ];

  const hashtag = 0x23;

  const content = await Deno.readFile(path);
  let offset = 0;

  // magic number
  while(!whitespaces.includes(content[offset])) {
    offset++;
  }

  offset++; // whitespace

  // potential comment
  if (content[offset] === hashtag) {
    while(!endOfComment.includes(content[offset])) {
      offset++;
    }

    offset++; // end of comment
  }

  // image width
  while(numbers.includes(content[offset])) {
    offset++;
  }

  offset++; // whitespace

  // image height
  while(numbers.includes(content[offset])) {
    offset++;
  }

  offset++; // whitespace

  // maximum color value
  while(numbers.includes(content[offset])) {
    offset++;
  }

  offset++; // whitespace

  return content.slice(offset, content.length);
}