/**
 * DiffViewerTool 单元测试（v0.7.5 大幅扩充）
 *
 * 覆盖：LCS diff 计算（text 模式，不触文件系统）、
 * unified diff 格式（hunk 分组 / 行号 / 尾部 context 修剪）、
 * 5000 行截断 / 10MB 文件闸门 / 50KB 输出截断 / similarity 计算 / files 模式。
 */

import { describe, it, expect, vi, beforeAll, afterAll } from 'vitest';
import { mkdtempSync, rmSync, writeFileSync } from 'fs';
import { tmpdir } from 'os';
import { join } from 'path';

vi.mock('electron-log', () => ({
  default: { info: vi.fn(), warn: vi.fn(), error: vi.fn(), debug: vi.fn() },
}));

import { DiffViewerTool } from '../diff-viewer';
import type { ToolExecutionContext } from '../../../types/metona-tool';

const context: ToolExecutionContext = {
  sessionId: 'test',
  workspacePath: process.cwd(),
  iteration: 1,
  requestId: 'req_test',
};

interface DiffResult {
  success: boolean;
  error?: string;
  diff?: string;
  diff_lines?: Array<unknown>;
  summary?: {
    files_compared?: number;
    lines_added: number;
    lines_removed: number;
    lines_unchanged: number;
    total_changes: number;
    similarity: number;
    truncated: boolean;
  };
}

function textResult(
  tool: DiffViewerTool,
  text_a: string,
  text_b: string,
  extra?: Record<string, unknown>,
) {
  return tool.execute({ mode: 'text', text_a, text_b, ...extra }, context) as Promise<DiffResult>;
}

describe('DiffViewerTool — text 模式 LCS 差异', () => {
  const tool = new DiffViewerTool();

  it('两段文本生成统一 diff（成功）', async () => {
    const result = await textResult(tool, 'line1\nline2\nline3', 'line1\nline2-changed\nline3');
    expect(result.success).toBe(true);
    expect(result.diff).toContain('-line2');
    expect(result.diff).toContain('+line2-changed');
    expect(result.summary?.total_changes).toBe(2);
  });

  it('相同文本返回无差异', async () => {
    const result = await textResult(tool, 'same\nsame', 'same\nsame');
    expect(result.success).toBe(true);
    expect(result.summary?.total_changes).toBe(0);
    expect(result.summary?.similarity).toBe(1);
    expect(result.diff).toBe('--- text_a\n+++ text_b');
  });

  it('空文本对比空文本 → 无差异且 similarity=1', async () => {
    const result = await textResult(tool, '', '');
    expect(result.success).toBe(true);
    expect(result.summary?.total_changes).toBe(0);
    expect(result.summary?.similarity).toBe(1);
  });

  it('text_a 为空 → 全量 added（空串 split 为单空行 removed 兜底）', async () => {
    const result = await textResult(tool, '', 'x\ny');
    expect(result.summary?.lines_added).toBe(2);
    expect(result.diff).toContain('+x');
    expect(result.diff).toContain('+y');
  });

  it('text_b 为空 → 全量 removed（空串 split 为单空行）', async () => {
    const result = await textResult(tool, 'a\nb', '');
    expect(result.summary?.lines_removed).toBe(2);
    expect(result.diff).toContain('-a');
    expect(result.diff).toContain('-b');
  });

  it('完全不同的两段文本：added+removed 各占全部', async () => {
    const result = await textResult(tool, 'aaa\nbbb', 'xxx\nyyy');
    expect(result.summary?.lines_added).toBe(2);
    expect(result.summary?.lines_removed).toBe(2);
    expect(result.summary?.total_changes).toBe(4);
    expect(result.summary?.similarity).toBe(0);
  });

  it('中间插入：仅新增行', async () => {
    const result = await textResult(tool, 'a\nb\nc', 'a\nx\nb\nc\nd');
    expect(result.summary?.lines_added).toBe(2);
    expect(result.diff).toContain('+x');
    expect(result.diff).toContain('+d');
  });

  it('删除行被标记 - 且行号正确', async () => {
    const result = await textResult(tool, 'a\nb\nc', 'a\nc');
    expect(result.summary?.lines_removed).toBe(1);
    expect(result.diff).toContain('-b');
  });

  it('无效 mode 返回错误', async () => {
    const result = (await tool.execute({ mode: 'invalid' }, context)) as DiffResult;
    expect(result.success).toBe(false);
    expect(result.error).toContain('Invalid mode');
  });

  it('多个变更区（context 间隙 ≤ contextLines）合并为单个 hunk', async () => {
    const result = await textResult(
      tool,
      ['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h'].join('\n'),
      ['a', 'X', 'c', 'd', 'e', 'Y', 'g', 'h'].join('\n'),
    );
    const hunkCount = ((result.diff ?? '').match(/^@@/gm) ?? []).length;
    expect(hunkCount).toBe(1); // 间隙 context 3 行 ≤ 默认 contextLines=3 → 不拆 hunk
  });

  it('context_lines=0 时相邻变更区被拆分为独立 hunk', async () => {
    const result = await textResult(
      tool,
      ['a', 'b', 'c', 'd', 'e'].join('\n'),
      ['a', 'X', 'c', 'Y', 'e'].join('\n'),
      { context_lines: 0 },
    );
    const hunkCount = ((result.diff ?? '').match(/^@@/gm) ?? []).length;
    expect(hunkCount).toBe(2);
  });

  it('hunk 头行号从首个变更行开始（change-only 计数）', async () => {
    const result = await textResult(
      tool,
      'line1\nline2\nCHANGED\nline4',
      'line1\nline2\nNEW\nline4',
    );
    expect(result.diff).toContain('@@ -3,1 +3,1 @@');
  });

  it('hunk 头对局部变更使用精确的行区间', async () => {
    // 前 3 行相同，第 4 行变更 → hunk 起始行 4
    const result = await textResult(tool, 'k1\nk2\nk3\nOLD\nk5', 'k1\nk2\nk3\nNEW\nk5');
    expect(result.diff).toContain('@@ -4,1 +4,1 @@');
  });

  it('context_lines=0 → 输出不含空格 context 行', async () => {
    const result = await textResult(tool, 'a\nb\nc', 'a\nx\nc', { context_lines: 0 });
    const lines = (result.diff ?? '').split('\n');
    expect(lines.some((l) => l.startsWith(' '))).toBe(false);
    expect(lines).toContain('+x');
    expect(lines).toContain('-b');
  });

  it('context_lines 超上限被钳制到 10 且不报错（实况：hunk 仅含变更行）', async () => {
    const lines = Array.from({ length: 20 }, (_, i) => `L${i}`);
    const changed = [...lines];
    changed[10] = 'CHANGED';
    const result = await textResult(tool, lines.join('\n'), changed.join('\n'), {
      context_lines: 999,
    });
    expect(result.success).toBe(true);
    const hunk = (result.diff ?? '').split('\n');
    const spaceCount = hunk.filter((l) => l.startsWith(' ')).length;
    expect(spaceCount).toBe(0);
  });

  it('formatUnifiedDiff 实况契约：hunk 只含 +/- 变更行，无前导/尾部 context', async () => {
    const result = await textResult(tool, 'a\nb\nc\nd\ne', 'a\nb\nX\nd\ne');
    const lines = (result.diff ?? '').split('\n');
    // 前导 context（a,b）不捕获；尾部 context（d,e）被修剪
    expect(lines.some((l) => l.startsWith(' '))).toBe(false);
    expect(lines).toContain('-c');
    expect(lines).toContain('+X');
    expect(lines).not.toContain(' d');
  });

  it('summary 统计 added/removed/unchanged 各自计数', async () => {
    const result = await textResult(tool, 'a\nb\nc\nd', 'a\nx\nc\ny');
    expect(result.summary?.lines_unchanged).toBe(2); // a, c
    expect(result.summary?.lines_added).toBe(2); // x, y
    expect(result.summary?.lines_removed).toBe(2); // b, d
  });

  it('similarity 对一半相同文本约为 0.5', async () => {
    const result = await textResult(tool, 'a\nb', 'a\nx');
    expect(result.summary?.similarity).toBeCloseTo(0.5, 1);
  });

  it('空 text_a/text_b 缺省为空串', async () => {
    const result = (await tool.execute({ mode: 'text' }, context)) as DiffResult;
    expect(result.success).toBe(true);
    expect(result.summary?.total_changes).toBe(0);
  });

  it('超过 5000 行 → truncated=true 且 similarity 按截断长度计算', async () => {
    const a = Array.from({ length: 6000 }, (_, i) => `a${i}`).join('\n');
    const b = Array.from({ length: 6000 }, (_, i) => `a${i}`).join('\n');
    const result = await textResult(tool, a, b);
    expect(result.summary?.truncated).toBe(true);
    expect(result.summary?.similarity).toBe(1);
  });

  it('超长 diff 输出被截断到 50KB 并附标记', async () => {
    const a = Array.from({ length: 6000 }, (_, i) => `old-line-${i}-${'x'.repeat(60)}`).join('\n');
    const b = Array.from({ length: 6000 }, (_, i) => `new-line-${i}-${'y'.repeat(60)}`).join('\n');
    const result = await textResult(tool, a, b);
    expect(result.success).toBe(true);
    expect(result.diff).toContain('... (diff truncated)');
    expect((result.diff ?? '').length).toBeLessThan(50_000 + 200);
  });

  it('diff_lines 返回前 500 条差异行', async () => {
    const a = Array.from({ length: 6000 }, (_, i) => `a${i}`).join('\n');
    const b = Array.from({ length: 6000 }, (_, i) => `b${i}`).join('\n');
    const result = await textResult(tool, a, b);
    expect(result.diff_lines).toHaveLength(500);
  });
});

describe('DiffViewerTool — files 模式', () => {
  let ws: string;
  const tool = new DiffViewerTool();
  const fileCtx = (): ToolExecutionContext => ({
    sessionId: 't',
    workspacePath: ws,
    iteration: 1,
    requestId: 'r',
  });

  beforeAll(() => {
    ws = mkdtempSync(join(tmpdir(), 'metona-diff-'));
    writeFileSync(join(ws, 'a.txt'), 'alpha\nbeta\ngamma');
    writeFileSync(join(ws, 'b.txt'), 'alpha\nBETA\ngamma');
    writeFileSync(join(ws, 'big.txt'), Buffer.alloc(10 * 1024 * 1024 + 10, 0x61));
  });

  afterAll(() => {
    try {
      rmSync(ws, { recursive: true, force: true });
    } catch {
      /* ignore */
    }
  });

  it('两个文件 diff 成功并带文件标签', async () => {
    const result = (await tool.execute(
      { mode: 'files', file_a: 'a.txt', file_b: 'b.txt' },
      fileCtx(),
    )) as DiffResult;
    expect(result.success).toBe(true);
    expect(result.diff).toContain('--- a.txt');
    expect(result.diff).toContain('+++ b.txt');
    expect(result.diff).toContain('-beta');
    expect(result.diff).toContain('+BETA');
    expect(result.summary?.files_compared).toBe(2);
  });

  it('files 模式缺 file_a 或 file_b → 报错', async () => {
    const missingA = (await tool.execute(
      { mode: 'files', file_b: 'b.txt' },
      fileCtx(),
    )) as DiffResult;
    expect(missingA.success).toBe(false);
    expect(missingA.error).toContain('file_a and file_b are required');
  });

  it('files 模式文件不存在 → 报错', async () => {
    const result = (await tool.execute(
      { mode: 'files', file_a: 'a.txt', file_b: 'nope.txt' },
      fileCtx(),
    )) as DiffResult;
    expect(result.success).toBe(false);
    expect(result.error).toContain('Failed to read files');
  });

  it('files 模式超过 10MB 闸门 → 报错', async () => {
    const result = (await tool.execute(
      { mode: 'files', file_a: 'a.txt', file_b: 'big.txt' },
      fileCtx(),
    )) as DiffResult;
    expect(result.success).toBe(false);
    expect(result.error).toContain('File too large for diff');
  });

  it('files 模式路径越界 → 被 safeResolvePath 拒绝', async () => {
    const outside = process.platform === 'win32' ? 'C:\\Windows\\notepad.exe' : '/etc/passwd';
    const result = (await tool.execute(
      { mode: 'files', file_a: 'a.txt', file_b: outside },
      fileCtx(),
    )) as DiffResult;
    expect(result.success).toBe(false);
  });

  it('files 模式两文件相同 → 无差异', async () => {
    writeFileSync(join(ws, 'same1.txt'), 'x\ny');
    writeFileSync(join(ws, 'same2.txt'), 'x\ny');
    const result = (await tool.execute(
      { mode: 'files', file_a: 'same1.txt', file_b: 'same2.txt' },
      fileCtx(),
    )) as DiffResult;
    expect(result.success).toBe(true);
    expect(result.summary?.total_changes).toBe(0);
  });
});