/**
 * 文件操作确认提示
 * 显示 diff 对比并让用户确认
 */

import * as readline from 'readline';
import * as fs from 'fs/promises';
import chalk from 'chalk';
import type { FilePermissionContext, PermissionDecision } from './types.js';
import { computeDiff, formatDiff, countChanges, formatEditDiff } from '../utils/diff.js';

/**
 * 显示文件写入的 diff 并请求确认
 */
export async function promptFileWrite(ctx: FilePermissionContext): Promise<PermissionDecision> {
  const { path: filePath, newContent } = ctx;

  if (!newContent) {
    // 没有内容，使用简单确认
    return promptSimpleConfirm(ctx);
  }

  // 读取原文件内容
  let oldContent: string | null = null;
  try {
    oldContent = await fs.readFile(filePath, 'utf-8');
  } catch {
    // 文件不存在，是新文件
  }

  // 如果内容相同，直接允许
  if (oldContent === newContent) {
    return { allow: true, remember: false };
  }

  // 计算 diff
  const diff = computeDiff(oldContent, newContent);
  const changes = countChanges(diff);

  // 显示 diff
  console.log('');
  console.log(chalk.yellow('📝 文件写入预览'));
  console.log(chalk.cyan('文件: ') + chalk.white(filePath));

  if (diff.isNew) {
    console.log(chalk.green('状态: ') + chalk.white('新文件'));
    console.log(chalk.green(`+${changes.additions} 行`));
  } else {
    console.log(chalk.green(`+${changes.additions} 行`) + ' / ' + chalk.red(`-${changes.deletions} 行`));
  }

  console.log('');
  console.log(chalk.gray('─'.repeat(60)));

  // 限制显示行数
  const diffOutput = formatDiff(diff, filePath);
  const lines = diffOutput.split('\n');
  const MAX_LINES = 50;

  if (lines.length > MAX_LINES) {
    console.log(lines.slice(0, MAX_LINES).join('\n'));
    console.log(chalk.yellow(`\n... 省略 ${lines.length - MAX_LINES} 行 ...`));
  } else {
    console.log(diffOutput);
  }

  console.log(chalk.gray('─'.repeat(60)));
  console.log('');

  // 询问用户确认
  return promptConfirm();
}

/**
 * 显示文件编辑的 diff 并请求确认
 */
export async function promptFileEdit(ctx: FilePermissionContext): Promise<PermissionDecision> {
  const { path: filePath, oldContent, newContent } = ctx;

  if (!oldContent || !newContent) {
    // 没有内容，使用简单确认
    return promptSimpleConfirm(ctx);
  }

  // 显示编辑 diff
  console.log('');
  console.log(chalk.yellow('✏️  文件编辑预览'));
  console.log(chalk.cyan('文件: ') + chalk.white(filePath));
  console.log('');
  console.log(chalk.gray('─'.repeat(60)));
  console.log(formatEditDiff(oldContent, newContent));
  console.log(chalk.gray('─'.repeat(60)));
  console.log('');

  // 询问用户确认
  return promptConfirm();
}

/**
 * 简单确认（无 diff）
 */
async function promptSimpleConfirm(ctx: FilePermissionContext): Promise<PermissionDecision> {
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });

  return new Promise((resolve) => {
    console.log('');
    console.log(chalk.yellow('⚠️  文件操作确认'));
    console.log(chalk.cyan('操作: ') + chalk.white(ctx.operation));
    console.log(chalk.cyan('文件: ') + chalk.white(ctx.path));
    console.log('');

    showConfirmOptions();

    rl.question(chalk.yellow('请选择 [y/Y/n/N]: '), (answer) => {
      rl.close();
      resolve(parseAnswer(answer));
    });
  });
}

/**
 * 通用确认提示
 */
async function promptConfirm(): Promise<PermissionDecision> {
  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
  });

  return new Promise((resolve) => {
    showConfirmOptions();

    rl.question(chalk.yellow('请选择 [y/Y/n/N]: '), (answer) => {
      rl.close();
      resolve(parseAnswer(answer));
    });
  });
}

/**
 * 显示确认选项
 */
function showConfirmOptions(): void {
  console.log(chalk.white('选择操作:'));
  console.log(chalk.green('  [y] ') + '确认执行');
  console.log(chalk.green('  [Y] ') + '确认执行，并记住此类操作（本次会话）');
  console.log(chalk.red('  [n] ') + '拒绝执行');
  console.log(chalk.red('  [N] ') + '拒绝执行，并记住此类操作（本次会话）');
  console.log('');
}

/**
 * 解析用户输入
 */
function parseAnswer(answer: string): PermissionDecision {
  const choice = answer.trim();

  switch (choice) {
    case 'y':
      return { allow: true, remember: false };
    case 'Y':
      return { allow: true, remember: true };
    case 'N':
      return { allow: false, remember: true };
    case 'n':
    default:
      return { allow: false, remember: false };
  }
}

/**
 * 根据操作类型选择合适的确认提示
 */
export async function promptFilePermission(ctx: FilePermissionContext): Promise<PermissionDecision> {
  switch (ctx.operation) {
    case 'write':
      return promptFileWrite(ctx);
    case 'edit':
      return promptFileEdit(ctx);
    default:
      return promptSimpleConfirm(ctx);
  }
}