import { spawn } from 'node:child_process';
import { existsSync, readdirSync, statSync, writeFileSync } from 'node:fs';
import { join } from 'node:path';
import { chromium } from 'playwright';
import { desktopBrowserContextOptions, desktopBrowserViewport } from './desktop-browser-viewport.mjs';

const targetUrl = withDebugParam(process.env.MEASURE_URL ?? 'http://127.0.0.1:4173/');
const outputPath = process.env.MEASURE_OUT ?? 'dist/performance-report.json';
const baselineViewport = desktopBrowserViewport;
const legacyUiScale = 1.5;
const budgets = {
  titleReadyMs: readBudget('PERF_BUDGET_TITLE_READY_MS', 30000),
  storyReadyFromNewGameMs: readBudget('PERF_BUDGET_STORY_READY_MS', 30000),
  firstBattleReadyFromStoryMs: readBudget('PERF_BUDGET_BATTLE_READY_MS', 60000),
  firstBattlePlayableFromStoryMs: readBudget('PERF_BUDGET_BATTLE_PLAYABLE_MS', 70000),
  firstLoadEncodedKB: readBudget('PERF_BUDGET_FIRST_LOAD_KB', 10000),
  storyTransitionEncodedKB: readBudget('PERF_BUDGET_STORY_TRANSITION_KB', 130000),
  battleTransitionEncodedKB: readBudget('PERF_BUDGET_BATTLE_TRANSITION_KB', 50000),
  largestJsKB: readBudget('PERF_BUDGET_LARGEST_JS_KB', 2500)
};

async function clickLegacyUi(page, x, y, options) {
  await page.mouse.click(x * legacyUiScale, y * legacyUiScale, options);
}

async function clickBattleDeploymentStart(page) {
  const point = await page.evaluate(() => {
    const scene = window.__HEROS_GAME__?.scene.getScene('BattleScene');
    const layout = scene?.layout;
    const canvas = document.querySelector('canvas');
    const bounds = canvas?.getBoundingClientRect();
    if (!scene || !layout || !canvas || !bounds) {
      return null;
    }
    const logicalX = layout.panelX + 24 + (layout.panelWidth - 48) / 2;
    const logicalY = layout.panelY + layout.panelHeight - 76 + 17;
    return {
      x: bounds.left + logicalX * bounds.width / scene.scale.width,
      y: bounds.top + logicalY * bounds.height / scene.scale.height
    };
  });
  if (!point || !Number.isFinite(point.x) || !Number.isFinite(point.y)) {
    throw new Error(`Expected a runtime deployment start point: ${JSON.stringify(point)}`);
  }
  await page.mouse.click(point.x, point.y);
}

let serverProcess;
let browser;

try {
  serverProcess = await ensurePreviewServer(targetUrl);
  browser = await chromium.launch({ headless: true });
  const context = await browser.newContext(desktopBrowserContextOptions);
  await context.addInitScript(() => window.localStorage.clear());
  const page = await context.newPage();

  const titleStartedAt = Date.now();
  await page.goto(targetUrl, { waitUntil: 'domcontentloaded' });
  await waitForTitle(page);
  await page.waitForLoadState('networkidle', { timeout: 120000 });
  const titleMs = Date.now() - titleStartedAt;
  const titleEntries = await resourceEntries(page);

  const storyStartedAt = Date.now();
  await clickLegacyUi(page, 962, 240);
  await waitForStoryReady(page);
  await page.waitForLoadState('networkidle', { timeout: 120000 });
  const storyMs = Date.now() - storyStartedAt;
  const storyEntries = await resourceEntries(page);

  const battleStartedAt = Date.now();
  await advanceStoryUntilBattle(page, 'first-battle-zhuo-commandery');
  const battleReadyState = await waitForBattleReady(page, 'first-battle-zhuo-commandery');
  await page.waitForLoadState('networkidle', { timeout: 120000 });
  const battleMs = Date.now() - battleStartedAt;
  const battleEntries = await resourceEntries(page);

  let firstBattlePlayableMs = battleMs;
  if (battleReadyState.phase === 'deployment') {
    const playableStartedAt = Date.now();
    await clickBattleDeploymentStart(page);
    await waitForBattlePlayable(page, 'first-battle-zhuo-commandery');
    firstBattlePlayableMs += Date.now() - playableStartedAt;
  }

  const titleNames = new Set(titleEntries.map((entry) => entry.name));
  const storyNames = new Set(storyEntries.map((entry) => entry.name));
  const storyOnly = storyEntries.filter((entry) => !titleNames.has(entry.name));
  const battleOnly = battleEntries.filter((entry) => !storyNames.has(entry.name));
  const report = {
    targetUrl,
    measuredAt: new Date().toISOString(),
    viewport: { ...baselineViewport },
    deviceScaleFactor: desktopBrowserContextOptions.deviceScaleFactor,
    timingsMs: {
      titleReady: titleMs,
      storyReadyFromNewGame: storyMs,
      firstBattleReadyFromStory: battleMs,
      firstBattlePlayableFromStory: firstBattlePlayableMs
    },
    build: buildStats(),
    firstLoad: segmentStats(titleEntries),
    storyTransition: segmentStats(storyOnly),
    battleTransition: segmentStats(battleOnly)
  };
  report.budget = evaluateBudgets(report, budgets);

  writeFileSync(outputPath, `${JSON.stringify(report, null, 2)}\n`);
  console.log(`Performance report written to ${outputPath}`);
  console.log(JSON.stringify({
    timingsMs: report.timingsMs,
    firstLoad: report.firstLoad.summary,
    storyTransition: report.storyTransition.summary,
    battleTransition: report.battleTransition.summary,
    largestJs: report.build.javascript[0] ?? null,
    budget: report.budget.summary
  }, null, 2));
  if (report.budget.failures.length > 0) {
    throw new Error(`Performance budget failed: ${report.budget.failures.map((failure) => `${failure.metric}=${failure.actual} > ${failure.budget}`).join(', ')}`);
  }
} finally {
  await browser?.close();
  if (serverProcess && !serverProcess.killed) {
    serverProcess.kill();
  }
}

function withDebugParam(url) {
  const parsed = new URL(url);
  parsed.searchParams.set('debug', '1');
  parsed.searchParams.set('renderer', 'canvas');
  return parsed.toString();
}

async function waitForTitle(page) {
  await page.waitForFunction(() => document.querySelector('canvas') !== null, undefined, { timeout: 90000 });
  await page.waitForFunction(() => window.__HEROS_DEBUG__ !== undefined, undefined, { timeout: 90000 });
  await page.waitForFunction(() => {
    const activeScenes = window.__HEROS_DEBUG__?.activeScenes() ?? [];
    return activeScenes.includes('TitleScene');
  }, undefined, { timeout: 90000 });
}

async function waitForStoryReady(page) {
  await page.waitForFunction(() => {
    const activeScenes = window.__HEROS_DEBUG__?.activeScenes() ?? [];
    const story = window.__HEROS_DEBUG__?.scene('StoryScene')?.getDebugState?.();
    return activeScenes.includes('StoryScene') && story?.ready === true;
  }, undefined, { timeout: 120000 });
}

async function advanceStoryUntilBattle(page, battleId) {
  for (let i = 0; i < 48; i += 1) {
    const ready = await page.evaluate((expectedBattleId) => {
      const state = window.__HEROS_DEBUG__?.battle();
      return state?.scene === 'BattleScene' && state?.battleId === expectedBattleId;
    }, battleId);
    if (ready) {
      return;
    }

    await page.keyboard.press('Space');
    await page.waitForTimeout(220);
  }
}

async function waitForBattleReady(page, battleId) {
  return page.waitForFunction((expectedBattleId) => {
    const state = window.__HEROS_DEBUG__?.battle();
    return (
      state?.scene === 'BattleScene' &&
      state?.battleId === expectedBattleId &&
      (state?.phase === 'deployment' || state?.phase === 'idle') &&
      state?.mapBackgroundReady === true &&
      state?.resultVisible === false
    )
      ? { phase: state.phase }
      : false;
  }, battleId, { timeout: 120000 }).then((handle) => handle.jsonValue());
}

async function waitForBattlePlayable(page, battleId) {
  await page.waitForFunction((expectedBattleId) => {
    const state = window.__HEROS_DEBUG__?.battle();
    return (
      state?.scene === 'BattleScene' &&
      state?.battleId === expectedBattleId &&
      state?.phase === 'idle' &&
      state?.mapBackgroundReady === true &&
      state?.triggeredBattleEvents?.includes('opening') &&
      state?.resultVisible === false
    );
  }, battleId, { timeout: 30000 });
}

async function resourceEntries(page) {
  return page.evaluate(() =>
    performance.getEntriesByType('resource').map((entry) => ({
      name: entry.name,
      initiatorType: entry.initiatorType,
      startTime: Math.round(entry.startTime),
      duration: Math.round(entry.duration),
      transferSize: entry.transferSize || 0,
      encodedBodySize: entry.encodedBodySize || 0
    }))
  );
}

function segmentStats(entries) {
  const encodedBytes = entries.reduce((sum, entry) => sum + entry.encodedBodySize, 0);
  const transferBytes = entries.reduce((sum, entry) => sum + entry.transferSize, 0);
  const byExt = {};

  entries.forEach((entry) => {
    const ext = extensionOf(entry.name);
    byExt[ext] ??= { count: 0, encodedKB: 0, transferKB: 0 };
    byExt[ext].count += 1;
    byExt[ext].encodedKB += bytesToKb(entry.encodedBodySize);
    byExt[ext].transferKB += bytesToKb(entry.transferSize);
  });

  return {
    summary: {
      requests: entries.length,
      encodedKB: bytesToKb(encodedBytes),
      transferKB: bytesToKb(transferBytes)
    },
    byExt,
    largest: [...entries]
      .sort((left, right) => right.encodedBodySize - left.encodedBodySize)
      .slice(0, 12)
      .map((entry) => ({
        file: entry.name.split('/').pop(),
        encodedKB: bytesToKb(entry.encodedBodySize),
        startMs: entry.startTime,
        durationMs: entry.duration
      }))
  };
}

function buildStats() {
  const assetsDir = join(process.cwd(), 'dist', 'assets');
  if (!existsSync(assetsDir)) {
    return { javascript: [], sourcemaps: [] };
  }

  const assets = readdirSync(assetsDir)
    .map((file) => ({ file, sizeKB: bytesToKb(statSync(join(assetsDir, file)).size) }))
    .sort((left, right) => right.sizeKB - left.sizeKB);

  return {
    javascript: assets.filter((asset) => asset.file.endsWith('.js')),
    sourcemaps: assets.filter((asset) => asset.file.endsWith('.map'))
  };
}

function extensionOf(name) {
  const path = name.split('?')[0];
  return path.match(/\.([a-z0-9]+)$/i)?.[1]?.toLowerCase() ?? 'other';
}

function bytesToKb(bytes) {
  return Math.round((bytes / 1024) * 10) / 10;
}

function readBudget(name, fallback) {
  const value = Number(process.env[name]);
  return Number.isFinite(value) && value > 0 ? value : fallback;
}

function evaluateBudgets(report, budgetValues) {
  const largestJs = report.build.javascript[0]?.sizeKB ?? 0;
  const checks = [
    ['titleReadyMs', report.timingsMs.titleReady, budgetValues.titleReadyMs],
    ['storyReadyFromNewGameMs', report.timingsMs.storyReadyFromNewGame, budgetValues.storyReadyFromNewGameMs],
    ['firstBattleReadyFromStoryMs', report.timingsMs.firstBattleReadyFromStory, budgetValues.firstBattleReadyFromStoryMs],
    ['firstBattlePlayableFromStoryMs', report.timingsMs.firstBattlePlayableFromStory, budgetValues.firstBattlePlayableFromStoryMs],
    ['firstLoadEncodedKB', report.firstLoad.summary.encodedKB, budgetValues.firstLoadEncodedKB],
    ['storyTransitionEncodedKB', report.storyTransition.summary.encodedKB, budgetValues.storyTransitionEncodedKB],
    ['battleTransitionEncodedKB', report.battleTransition.summary.encodedKB, budgetValues.battleTransitionEncodedKB],
    ['largestJsKB', largestJs, budgetValues.largestJsKB]
  ];
  const failures = checks
    .filter(([, actual, budget]) => actual > budget)
    .map(([metric, actual, budget]) => ({ metric, actual, budget }));

  return {
    summary: {
      status: failures.length === 0 ? 'pass' : 'fail',
      checked: checks.length,
      failures: failures.length
    },
    budgets: budgetValues,
    failures
  };
}

async function ensurePreviewServer(url) {
  if (await canReach(url)) {
    return undefined;
  }

  const parsed = new URL(url);
  const isLocal = ['localhost', '127.0.0.1', '0.0.0.0'].includes(parsed.hostname);
  if (!isLocal) {
    throw new Error(`No server responded at ${url}`);
  }

  const stderr = [];
  const child = spawn(process.execPath, ['node_modules/vite/bin/vite.js', 'preview', '--host', '127.0.0.1', '--port', parsed.port || '4173'], {
    cwd: process.cwd(),
    env: process.env,
    stdio: ['ignore', 'pipe', 'pipe']
  });

  child.stderr.on('data', (chunk) => stderr.push(chunk.toString()));
  child.stdout.on('data', () => {});

  for (let i = 0; i < 120; i += 1) {
    if (await canReach(url)) {
      return child;
    }
    await delay(250);
  }

  child.kill();
  throw new Error(`Vite preview did not start at ${url}\n${stderr.join('')}`);
}

async function canReach(url) {
  try {
    const response = await fetch(url, { signal: AbortSignal.timeout(1000) });
    return response.ok;
  } catch {
    return false;
  }
}

function delay(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}