/**
 * Read commands — extract data from pages without side effects
 *
 * text, html, links, forms, accessibility, js, eval, css, attrs,
 * console, network, cookies, storage, perf
 */

import type { BrowserManager } from './browser-manager';
import { consoleBuffer, networkBuffer } from './buffers';
import * as fs from 'fs';

export async function handleReadCommand(
  command: string,
  args: string[],
  bm: BrowserManager
): Promise<string> {
  const page = bm.getPage();

  switch (command) {
    case 'text': {
      return await page.evaluate(() => {
        const body = document.body;
        if (!body) return '';
        const clone = body.cloneNode(true) as HTMLElement;
        clone.querySelectorAll('script, style, noscript, svg').forEach(el => el.remove());
        return clone.innerText
          .split('\n')
          .map(line => line.trim())
          .filter(line => line.length > 0)
          .join('\n');
      });
    }

    case 'html': {
      const selector = args[0];
      if (selector) {
        return await page.innerHTML(selector);
      }
      return await page.content();
    }

    case 'links': {
      const links = await page.evaluate(() =>
        [...document.querySelectorAll('a[href]')].map(a => ({
          text: a.textContent?.trim().slice(0, 120) || '',
          href: (a as HTMLAnchorElement).href,
        })).filter(l => l.text && l.href)
      );
      return links.map(l => `${l.text} → ${l.href}`).join('\n');
    }

    case 'forms': {
      const forms = await page.evaluate(() => {
        return [...document.querySelectorAll('form')].map((form, i) => {
          const fields = [...form.querySelectorAll('input, select, textarea')].map(el => {
            const input = el as HTMLInputElement;
            return {
              tag: el.tagName.toLowerCase(),
              type: input.type || undefined,
              name: input.name || undefined,
              id: input.id || undefined,
              placeholder: input.placeholder || undefined,
              required: input.required || undefined,
              value: input.value || undefined,
              options: el.tagName === 'SELECT'
                ? [...(el as HTMLSelectElement).options].map(o => ({ value: o.value, text: o.text }))
                : undefined,
            };
          });
          return {
            index: i,
            action: form.action || undefined,
            method: form.method || 'get',
            id: form.id || undefined,
            fields,
          };
        });
      });
      return JSON.stringify(forms, null, 2);
    }

    case 'accessibility': {
      const snapshot = await page.locator("body").ariaSnapshot();
      return snapshot;
    }

    case 'js': {
      const expr = args[0];
      if (!expr) throw new Error('Usage: browse js <expression>');
      const result = await page.evaluate(expr);
      return typeof result === 'object' ? JSON.stringify(result, null, 2) : String(result ?? '');
    }

    case 'eval': {
      const filePath = args[0];
      if (!filePath) throw new Error('Usage: browse eval <js-file>');
      if (!fs.existsSync(filePath)) throw new Error(`File not found: ${filePath}`);
      const code = fs.readFileSync(filePath, 'utf-8');
      const result = await page.evaluate(code);
      return typeof result === 'object' ? JSON.stringify(result, null, 2) : String(result ?? '');
    }

    case 'css': {
      const [selector, property] = args;
      if (!selector || !property) throw new Error('Usage: browse css <selector> <property>');
      const value = await page.evaluate(
        ([sel, prop]) => {
          const el = document.querySelector(sel);
          if (!el) return `Element not found: ${sel}`;
          return getComputedStyle(el).getPropertyValue(prop);
        },
        [selector, property]
      );
      return value;
    }

    case 'attrs': {
      const selector = args[0];
      if (!selector) throw new Error('Usage: browse attrs <selector>');
      const attrs = await page.evaluate((sel) => {
        const el = document.querySelector(sel);
        if (!el) return `Element not found: ${sel}`;
        const result: Record<string, string> = {};
        for (const attr of el.attributes) {
          result[attr.name] = attr.value;
        }
        return result;
      }, selector);
      return typeof attrs === 'string' ? attrs : JSON.stringify(attrs, null, 2);
    }

    case 'console': {
      if (args[0] === '--clear') {
        consoleBuffer.length = 0;
        return 'Console buffer cleared.';
      }
      if (consoleBuffer.length === 0) return '(no console messages)';
      return consoleBuffer.map(e =>
        `[${new Date(e.timestamp).toISOString()}] [${e.level}] ${e.text}`
      ).join('\n');
    }

    case 'network': {
      if (args[0] === '--clear') {
        networkBuffer.length = 0;
        return 'Network buffer cleared.';
      }
      if (networkBuffer.length === 0) return '(no network requests)';
      return networkBuffer.map(e =>
        `${e.method} ${e.url} → ${e.status || 'pending'} (${e.duration || '?'}ms, ${e.size || '?'}B)`
      ).join('\n');
    }

    case 'cookies': {
      const cookies = await page.context().cookies();
      return JSON.stringify(cookies, null, 2);
    }

    case 'storage': {
      if (args[0] === 'set' && args[1]) {
        const key = args[1];
        const value = args[2] || '';
        await page.evaluate(([k, v]) => localStorage.setItem(k, v), [key, value]);
        return `Set localStorage["${key}"] = "${value}"`;
      }
      const storage = await page.evaluate(() => ({
        localStorage: { ...localStorage },
        sessionStorage: { ...sessionStorage },
      }));
      return JSON.stringify(storage, null, 2);
    }

    case 'perf': {
      const timings = await page.evaluate(() => {
        const nav = performance.getEntriesByType('navigation')[0] as PerformanceNavigationTiming;
        if (!nav) return 'No navigation timing data available.';
        return {
          dns: Math.round(nav.domainLookupEnd - nav.domainLookupStart),
          tcp: Math.round(nav.connectEnd - nav.connectStart),
          ssl: Math.round(nav.secureConnectionStart > 0 ? nav.connectEnd - nav.secureConnectionStart : 0),
          ttfb: Math.round(nav.responseStart - nav.requestStart),
          download: Math.round(nav.responseEnd - nav.responseStart),
          domParse: Math.round(nav.domInteractive - nav.responseEnd),
          domReady: Math.round(nav.domContentLoadedEventEnd - nav.startTime),
          load: Math.round(nav.loadEventEnd - nav.startTime),
          total: Math.round(nav.loadEventEnd - nav.startTime),
        };
      });
      if (typeof timings === 'string') return timings;
      return Object.entries(timings)
        .map(([k, v]) => `${k.padEnd(12)} ${v}ms`)
        .join('\n');
    }

    default:
      throw new Error(`Unknown read command: ${command}`);
  }
}