import { readdirSync, readFileSync, statSync } from 'node:fs';
import { join, sep } from 'node:path';
import { createServer } from 'vite';

const storyDir = join('src', 'assets', 'images', 'story');
const portraitDir = join('src', 'assets', 'images', 'portraits');
const titleImagePath = join('src', 'assets', 'images', 'taoyuan-oath-title.png');
const storyAssetsSourcePath = join('src', 'game', 'data', 'storyAssets.ts');

const expectedStorySize = { width: 1672, height: 941 };
const expectedPortraitSize = { width: 1254, height: 1254 };

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

try {
  const { storyBackgroundAssets } = await server.ssrLoadModule('/src/game/data/storyAssets.ts');
  const { portraitAssets } = await server.ssrLoadModule('/src/game/data/portraitAssets.ts');
  const errors = [];
  const storyAliasKeys = parseStoryAliasKeys(readFileSync(storyAssetsSourcePath, 'utf8'), errors);

  const storySourceKeys = validateStoryImages(errors, storyBackgroundAssets);
  validateTitleImage(errors, storyBackgroundAssets);
  validateStoryManifestKeys(errors, storyBackgroundAssets, storySourceKeys, storyAliasKeys);

  const portraitSlugs = validatePortraitImages(errors, portraitAssets);
  validatePortraitManifestKeys(errors, portraitAssets, portraitSlugs);

  if (errors.length) {
    console.error(`Story image asset 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 ${storySourceKeys.size} story backgrounds, ${portraitSlugs.size} portraits, ` +
        `${storyAliasKeys.size} story aliases, and the title artwork dimensions.`
    );
  }
} finally {
  await server.close();
}

function validateStoryImages(errors, storyBackgroundAssets) {
  const sourceKeys = new Set();
  for (const fileName of imageFiles(storyDir)) {
    const path = join(storyDir, fileName);
    validatePngFile(errors, path, expectedStorySize, 'story background');

    const key = storyKeyFromFileName(fileName);
    sourceKeys.add(key);
    if (!storyBackgroundAssets[key]) {
      errors.push(`${path}: expected storyBackgroundAssets key "${key}"`);
    }
    validateRuntimeUrl(errors, key, storyBackgroundAssets[key], path);
  }

  return sourceKeys;
}

function validateTitleImage(errors, storyBackgroundAssets) {
  validatePngFile(errors, titleImagePath, expectedStorySize, 'title artwork');
  ['story-taoyuan-oath-title', 'title-taoyuan'].forEach((key) => {
    if (!storyBackgroundAssets[key]) {
      errors.push(`${titleImagePath}: expected storyBackgroundAssets key "${key}"`);
    }
  });
  validateRuntimeUrl(errors, 'story-taoyuan-oath-title', storyBackgroundAssets['story-taoyuan-oath-title'], titleImagePath);
}

function validateStoryManifestKeys(errors, storyBackgroundAssets, sourceKeys, aliasKeys) {
  const expectedKeys = new Set([...sourceKeys, 'story-taoyuan-oath-title', ...aliasKeys]);
  Object.keys(storyBackgroundAssets)
    .sort()
    .forEach((key) => {
      if (!expectedKeys.has(key)) {
        errors.push(`storyBackgroundAssets contains unexpected key "${key}"`);
      }
    });
}

function validatePortraitImages(errors, portraitAssets) {
  const slugs = new Set();
  for (const fileName of imageFiles(portraitDir)) {
    const path = join(portraitDir, fileName);
    validatePngFile(errors, path, expectedPortraitSize, 'portrait');

    const slug = fileName.replace(/\.png$/i, '');
    slugs.add(slug);
    if (!portraitAssets[slug]) {
      errors.push(`${path}: expected portraitAssets slug "${slug}"`);
    }
    validateRuntimeUrl(errors, slug, portraitAssets[slug], path);
  }

  return slugs;
}

function validatePortraitManifestKeys(errors, portraitAssets, slugs) {
  Object.keys(portraitAssets)
    .sort()
    .forEach((slug) => {
      if (!slugs.has(slug)) {
        errors.push(`portraitAssets contains unexpected slug "${slug}"`);
      }
    });
}

function validatePngFile(errors, path, expectedSize, label) {
  let bytes;
  let stats;
  try {
    bytes = readFileSync(path);
    stats = statSync(path);
  } catch (error) {
    errors.push(`${path}: cannot read ${label}: ${error.message}`);
    return;
  }

  if (stats.size < 100 * 1024) {
    errors.push(`${path}: ${label} is suspiciously small (${stats.size} bytes)`);
  }

  const pngSignature = '89504e470d0a1a0a';
  if (bytes.subarray(0, 8).toString('hex') !== pngSignature) {
    errors.push(`${path}: ${label} does not have a PNG signature`);
    return;
  }
  if (bytes.subarray(12, 16).toString('ascii') !== 'IHDR') {
    errors.push(`${path}: ${label} is missing a PNG IHDR chunk`);
    return;
  }

  const width = bytes.readUInt32BE(16);
  const height = bytes.readUInt32BE(20);
  if (width !== expectedSize.width || height !== expectedSize.height) {
    errors.push(
      `${path}: ${label} should be ${expectedSize.width}x${expectedSize.height}, got ${width}x${height}`
    );
  }
}

function validateRuntimeUrl(errors, key, url, path) {
  assertNonEmptyString(errors, url, `${key} runtime asset URL`);
  if (typeof url !== 'string' || url.startsWith('data:')) {
    return;
  }

  const runtimePath = assetUrlToPath(url);
  if (runtimePath && runtimePath !== path) {
    errors.push(`${key}: runtime URL points at "${runtimePath}" but source file is "${path}"`);
  }
}

function imageFiles(dir) {
  return readdirSync(dir, { withFileTypes: true })
    .filter((entry) => entry.isFile())
    .map((entry) => entry.name)
    .sort()
    .filter((fileName) => /\.png$/i.test(fileName));
}

function storyKeyFromFileName(fileName) {
  const slug = fileName.replace(/\.png$/i, '').replace(/^\d+-/, '');
  return `story-${slug}`;
}

function parseStoryAliasKeys(source, errors) {
  const match = source.match(/const\s+storyAssetAliases:\s*Record<string,\s*string>\s*=\s*{([\s\S]*?)\n};/);
  if (!match) {
    errors.push(`${storyAssetsSourcePath}: cannot find storyAssetAliases`);
    return new Set();
  }

  const aliases = new Set();
  const entryPattern = /['"]([^'"]+)['"]\s*:/g;
  for (const entry of match[1].matchAll(entryPattern)) {
    aliases.add(entry[1]);
  }
  return aliases;
}

function assetUrlToPath(url) {
  const marker = 'src/assets/images/';
  const index = url.indexOf(marker);
  if (index < 0) {
    return undefined;
  }
  return url.slice(index).replaceAll('/', sep);
}

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