import { readFileSync, statSync } from 'node:fs';
import { createServer } from 'vite';

const server = await createServer({
  logLevel: 'error',
  server: { middlewareMode: true },
  appType: 'custom'
});

const minimumReadableIconFrameSize = 96;

try {
  const { battleUiIconManifest } = await server.ssrLoadModule('/src/game/data/battleUiIcons.ts');
  const { itemCatalog, equipmentSlots } = await server.ssrLoadModule('/src/game/data/battleItems.ts');
  const errors = [];

  validateBattleUiIconAtlas(errors, battleUiIconManifest);
  validateItemCatalog(errors, itemCatalog, equipmentSlots);
  validateGeneratedEquipmentIcons(errors, itemCatalog);

  if (errors.length) {
    console.error(`Visual asset data verification failed with ${errors.length} issue(s):`);
    errors.slice(0, 100).forEach((error) => console.error(`- ${error}`));
    if (errors.length > 100) {
      console.error(`- ...and ${errors.length - 100} more`);
    }
    process.exitCode = 1;
  } else {
    console.log(
      `Verified battle UI atlas ${battleUiIconManifest.columns}x${battleUiIconManifest.rows}, ` +
        `${Object.keys(battleUiIconManifest.frames).length} icon keys, and ${Object.keys(itemCatalog).length} generated equipment icons.`
    );
  }
} finally {
  await server.close();
}

function validateBattleUiIconAtlas(errors, manifest) {
  assertNonEmptyString(errors, manifest.source, 'battleUiIconManifest.source');
  assertNonEmptyString(errors, manifest.textureKey, 'battleUiIconManifest.textureKey');
  assertPositiveInteger(errors, manifest.frameWidth, 'battleUiIconManifest.frameWidth');
  assertPositiveInteger(errors, manifest.frameHeight, 'battleUiIconManifest.frameHeight');
  assertIntegerAtLeast(
    errors,
    manifest.frameWidth,
    minimumReadableIconFrameSize,
    'battleUiIconManifest.frameWidth for desktop readability'
  );
  assertIntegerAtLeast(
    errors,
    manifest.frameHeight,
    minimumReadableIconFrameSize,
    'battleUiIconManifest.frameHeight for desktop readability'
  );
  assertPositiveInteger(errors, manifest.columns, 'battleUiIconManifest.columns');
  assertPositiveInteger(errors, manifest.rows, 'battleUiIconManifest.rows');

  let dimensions;
  try {
    dimensions = readPngDimensions(manifest.source);
  } catch (error) {
    errors.push(`battle UI icon atlas cannot be read at "${manifest.source}": ${error.message}`);
    return;
  }

  const expectedWidth = manifest.columns * manifest.frameWidth;
  const expectedHeight = manifest.rows * manifest.frameHeight;
  if (dimensions.width !== expectedWidth || dimensions.height !== expectedHeight) {
    errors.push(`battle UI icon atlas is ${dimensions.width}x${dimensions.height}, expected ${expectedWidth}x${expectedHeight}`);
  }
  if (dimensions.bitDepth !== 8 || dimensions.colorType !== 6) {
    errors.push(`battle UI icon atlas must be 8-bit RGBA PNG color type 6, got bitDepth=${dimensions.bitDepth} colorType=${dimensions.colorType}`);
  }

  const frameLimit = manifest.columns * manifest.rows;
  Object.entries(manifest.frames).forEach(([key, frame]) => {
    assertNonEmptyString(errors, key, 'battle UI icon key');
    if (!Number.isInteger(frame) || frame < 0 || frame >= frameLimit) {
      errors.push(`battle UI icon "${key}" frame ${frame} is outside atlas frame range 0..${frameLimit - 1}`);
    }
  });
}

function validateItemCatalog(errors, itemCatalog, equipmentSlots) {
  const validSlots = new Set(equipmentSlots);
  const validRanks = new Set(['common', 'treasure']);

  Object.entries(itemCatalog).forEach(([id, item]) => {
    const context = `itemCatalog.${id}`;
    if (item.id !== id) {
      errors.push(`${context}: item id does not match catalog key`);
    }
    assertNonEmptyString(errors, item.name, `${context}.name`);
    assertNonEmptyString(errors, item.description, `${context}.description`);
    if (!validSlots.has(item.slot)) {
      errors.push(`${context}: unknown equipment slot "${item.slot}"`);
    }
    if (!validRanks.has(item.rank)) {
      errors.push(`${context}: unknown equipment rank "${item.rank}"`);
    }
    if (!Array.isArray(item.effects) || item.effects.length === 0) {
      errors.push(`${context}: effects must not be empty`);
    } else {
      item.effects.forEach((effect, index) => assertNonEmptyString(errors, effect, `${context}.effects[${index}]`));
    }
    ['attackBonus', 'defenseBonus', 'strategyBonus'].forEach((field) => {
      if (item[field] !== undefined && (!Number.isInteger(item[field]) || item[field] < 0)) {
        errors.push(`${context}.${field} must be a non-negative integer`);
      }
    });
  });
}

function validateGeneratedEquipmentIcons(errors, itemCatalog) {
  const bootScene = readFileSync('src/game/scenes/BootScene.ts', 'utf8');
  const generatedItemIds = new Set([...bootScene.matchAll(/createItemIcon\('item-([^']+)'/g)].map((match) => match[1]));
  const catalogItemIds = new Set(Object.keys(itemCatalog));

  Array.from(catalogItemIds)
    .sort()
    .forEach((itemId) => {
      if (!generatedItemIds.has(itemId)) {
        errors.push(`BootScene does not generate an equipment icon texture for item-${itemId}`);
      }
    });
  Array.from(generatedItemIds)
    .sort()
    .forEach((itemId) => {
      if (!catalogItemIds.has(itemId)) {
        errors.push(`BootScene generates item-${itemId}, but itemCatalog has no matching item`);
      }
    });
}

function readPngDimensions(path) {
  const stats = statSync(path);
  if (stats.size < 24) {
    throw new Error('file is too small to be a PNG');
  }

  const bytes = readFileSync(path);
  const signature = '89504e470d0a1a0a';
  if (bytes.subarray(0, 8).toString('hex') !== signature) {
    throw new Error('file does not have a PNG signature');
  }

  return {
    width: bytes.readUInt32BE(16),
    height: bytes.readUInt32BE(20),
    bitDepth: bytes[24],
    colorType: bytes[25]
  };
}

function assertPositiveInteger(errors, value, context) {
  if (!Number.isInteger(value) || value <= 0) {
    errors.push(`${context} must be a positive integer`);
  }
}

function assertIntegerAtLeast(errors, value, minimum, context) {
  if (!Number.isInteger(value) || value < minimum) {
    errors.push(`${context} must be at least ${minimum}`);
  }
}

function assertNonEmptyString(errors, value, context) {
  if (typeof value !== 'string' || value.trim().length === 0) {
    errors.push(`${context} must be a non-empty string`);
  }
}