/**
 * Diff 查看器 - 调用 VSCode 内置 Diff 编辑器
 *
 * 使用 vscode.diff 命令展示原始内容 vs 变更后内容，
 * 完全不使用自定义 Webview，保持 VSCode 原生交互体验。
 */

import * as vscode from 'vscode';
import * as path from 'path';
import { EditRecord, FileChange } from '../models/types';
import { ChangeSetManager } from '../snapshot/snapshotManager';

export class DiffViewer {
  constructor(private changeSetManager: ChangeSetManager) {}

  /**
   * 打开单次编辑的 Diff（VSCode 内置 Diff 编辑器）
   */
  async showEditDiff(editRecord: EditRecord): Promise<void> {
    const beforeDoc = await vscode.workspace.openTextDocument({
      content: editRecord.beforeContent,
      language: this.getLanguageId(editRecord.filePath),
    });
    const afterDoc = await vscode.workspace.openTextDocument({
      content: editRecord.afterContent,
      language: this.getLanguageId(editRecord.filePath),
    });

    const fileName = path.basename(editRecord.filePath);
    const toolLabel = editRecord.toolName === 'Write' ? '写入' : '编辑';

    await vscode.commands.executeCommand(
      'vscode.diff',
      beforeDoc.uri,
      afterDoc.uri,
      `${fileName} — AI ${toolLabel} #${editRecord.id.slice(0, 6)} (原始 ↔ 变更后)`
    );
  }

  /**
   * 打开整个文件的聚合 Diff
   */
  async showFileDiff(fileChange: FileChange): Promise<void> {
    const beforeDoc = await vscode.workspace.openTextDocument({
      content: fileChange.originalContent,
      language: this.getLanguageId(fileChange.filePath),
    });
    const afterDoc = await vscode.workspace.openTextDocument({
      content: fileChange.latestContent,
      language: this.getLanguageId(fileChange.filePath),
    });

    const fileName = path.basename(fileChange.filePath);

    await vscode.commands.executeCommand(
      'vscode.diff',
      beforeDoc.uri,
      afterDoc.uri,
      `${fileName} — 原始 ↔ 变更后 (${fileChange.edits.length} 次编辑)`
    );
  }

  /**
   * 打开当前活动文件在编辑器中的 Diff
   */
  async showCurrentFileDiff(): Promise<void> {
    const changeSet = this.changeSetManager.getCurrentSet();
    if (!changeSet) return;

    const editor = vscode.window.activeTextEditor;
    if (!editor) return;

    const normalizedPath = path.normalize(editor.document.uri.fsPath).replace(/\\/g, '/');
    const fileChange = changeSet.changes.find(
      c => path.normalize(c.filePath).replace(/\\/g, '/') === normalizedPath && c.status === 'pending'
    );
    if (!fileChange) {
      vscode.window.showInformationMessage('AI Diff: 当前文件无待处理变更');
      return;
    }

    await this.showFileDiff(fileChange);
  }

  /**
   * 聚焦文件到编辑器（跳转到该文件并定位到第一个变更行）
   */
  async focusFileInEditor(fileChange: FileChange): Promise<void> {
    const uri = vscode.Uri.file(fileChange.filePath);
    const doc = await vscode.workspace.openTextDocument(uri);
    const editor = await vscode.window.showTextDocument(doc, { preview: false });

    // 滚动到第一个变更行
    if (fileChange.diffLines.length > 0) {
      const firstChange = fileChange.diffLines.find(
        d => d.type === 'add' || d.type === 'delete'
      );
      if (firstChange) {
        const line = (firstChange.newLineNum || firstChange.oldLineNum) - 1;
        const pos = new vscode.Position(Math.max(0, line), 0);
        editor.selection = new vscode.Selection(pos, pos);
        editor.revealRange(new vscode.Range(pos, pos), vscode.TextEditorRevealType.InCenter);
      }
    }
  }

  private getLanguageId(filePath: string): string {
    const ext = path.extname(filePath).toLowerCase();
    const map: Record<string, string> = {
      '.ts': 'typescript', '.tsx': 'typescriptreact',
      '.js': 'javascript', '.jsx': 'javascriptreact',
      '.json': 'json', '.md': 'markdown',
      '.css': 'css', '.scss': 'scss', '.less': 'less',
      '.html': 'html', '.htm': 'html',
      '.py': 'python', '.rs': 'rust', '.go': 'go',
      '.java': 'java', '.cpp': 'cpp', '.c': 'c',
      '.yaml': 'yaml', '.yml': 'yaml',
      '.xml': 'xml', '.sql': 'sql', '.sh': 'shell',
    };
    return map[ext] || 'plaintext';
  }
}