using System.IO;
using AxCopilot.Services.Agent;
using FluentAssertions;
using Xunit;

namespace AxCopilot.Tests.Services;

public class WorkspaceContextGeneratorTests
{
    // ═══════════════════════════════════════════
    //  LoadContext
    // ═══════════════════════════════════════════

    [Fact]
    public void LoadContext_NullFolder_ReturnsNull()
    {
        WorkspaceContextGenerator.LoadContext(null).Should().BeNull();
    }

    [Fact]
    public void LoadContext_EmptyFolder_ReturnsNull()
    {
        WorkspaceContextGenerator.LoadContext("").Should().BeNull();
    }

    [Fact]
    public void LoadContext_NonExistentFile_ReturnsNull()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            // .ax-context.md가 없으면 null
            WorkspaceContextGenerator.LoadContext(tempDir).Should().BeNull();
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public void LoadContext_ExistingFile_ReturnsContent()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            var contextPath = Path.Combine(tempDir, ".ax-context.md");
            File.WriteAllText(contextPath, "# Test Context\nHello");

            var result = WorkspaceContextGenerator.LoadContext(tempDir);
            result.Should().NotBeNull();
            result.Should().Contain("Test Context");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public void LoadContext_LargeFile_Truncated()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            var contextPath = Path.Combine(tempDir, ".ax-context.md");
            // 4000자 제한 초과하는 내용 작성
            File.WriteAllText(contextPath, new string('A', 5000));

            var result = WorkspaceContextGenerator.LoadContext(tempDir);
            result.Should().NotBeNull();
            result!.Should().Contain("(truncated)");
            result!.Length.Should().BeLessOrEqualTo(4100); // 4000 + truncation message
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    // ═══════════════════════════════════════════
    //  EnsureContextAsync — 멱등성
    // ═══════════════════════════════════════════

    [Fact]
    public async Task EnsureContextAsync_NullFolder_ReturnsNull()
    {
        var result = await WorkspaceContextGenerator.EnsureContextAsync(null!);
        result.Should().BeNull();
    }

    [Fact]
    public async Task EnsureContextAsync_NonExistentFolder_ReturnsNull()
    {
        var result = await WorkspaceContextGenerator.EnsureContextAsync("/nonexistent/path/xyz");
        result.Should().BeNull();
    }

    [Fact]
    public async Task EnsureContextAsync_ExistingContextFile_ReturnsWithoutRegeneration()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            var contextPath = Path.Combine(tempDir, ".ax-context.md");
            File.WriteAllText(contextPath, "# Pre-existing context");

            var result = await WorkspaceContextGenerator.EnsureContextAsync(tempDir);
            result.Should().Contain("Pre-existing context");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    // ═══════════════════════════════════════════
    //  GenerateAsync — 실제 생성
    // ═══════════════════════════════════════════

    [Fact]
    public async Task GenerateAsync_CreatesContextFile()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            // 테스트 파일 구조 생성
            File.WriteAllText(Path.Combine(tempDir, "test.cs"), "class Test {}");
            File.WriteAllText(Path.Combine(tempDir, "helper.cs"), "class Helper {}");
            var subDir = Path.Combine(tempDir, "src");
            Directory.CreateDirectory(subDir);
            File.WriteAllText(Path.Combine(subDir, "main.cs"), "class Main {}");

            var result = await WorkspaceContextGenerator.GenerateAsync(tempDir);

            result.Should().NotBeNullOrEmpty();
            result.Should().Contain("# Workspace Context (auto-generated)");
            result.Should().Contain("## Project");
            result.Should().Contain("## Structure");
            result.Should().Contain(".cs");

            // 파일 생성 확인
            File.Exists(Path.Combine(tempDir, ".ax-context.md")).Should().BeTrue();
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task GenerateAsync_DetectsDotNetBuildSystem()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            File.WriteAllText(Path.Combine(tempDir, "MyProject.sln"), "solution content");

            var result = await WorkspaceContextGenerator.GenerateAsync(tempDir);
            result.Should().Contain(".NET");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task GenerateAsync_DetectsNodeJsBuildSystem()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            File.WriteAllText(Path.Combine(tempDir, "package.json"), """{"name": "test"}""");

            var result = await WorkspaceContextGenerator.GenerateAsync(tempDir);
            result.Should().Contain("Node.js");
            result.Should().Contain("## Key Manifests");
            result.Should().Contain("Node package");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task GenerateAsync_IncludesLanguageSnapshot()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            File.WriteAllText(Path.Combine(tempDir, "main.go"), "package main");
            File.WriteAllText(Path.Combine(tempDir, "worker.go"), "package main");
            File.WriteAllText(Path.Combine(tempDir, "helper.py"), "print('hi')");

            var result = await WorkspaceContextGenerator.GenerateAsync(tempDir);

            result.Should().Contain("## Language Snapshot");
            result.Should().Contain("Go:");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task GenerateAsync_IncludesReadmeSummary()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            File.WriteAllText(Path.Combine(tempDir, "README.md"),
                "# My Project\n\nThis is a test project for unit testing.");

            var result = await WorkspaceContextGenerator.GenerateAsync(tempDir);
            result.Should().Contain("## README Summary");
            result.Should().Contain("test project");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task GenerateAsync_DetectsContextFiles()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            File.WriteAllText(Path.Combine(tempDir, "AGENTS.md"), "Agent rules here");
            var skillsDir = Path.Combine(tempDir, ".claude", "skills", "deck");
            Directory.CreateDirectory(skillsDir);
            File.WriteAllText(Path.Combine(skillsDir, "SKILL.md"), "# skill");

            var result = await WorkspaceContextGenerator.GenerateAsync(tempDir);
            result.Should().Contain("## Existing Context Files");
            result.Should().Contain("AGENTS.md");
            result.Should().Contain("## Agent Context");
            result.Should().Contain(".claude/skills");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task GenerateAsync_SkipsHiddenDirs()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            // node_modules는 건너뛰어야 함
            var nodeModules = Path.Combine(tempDir, "node_modules");
            Directory.CreateDirectory(nodeModules);
            File.WriteAllText(Path.Combine(nodeModules, "package.json"), "{}");

            // src는 표시되어야 함
            var src = Path.Combine(tempDir, "src");
            Directory.CreateDirectory(src);
            File.WriteAllText(Path.Combine(src, "main.cs"), "class Main {}");

            var result = await WorkspaceContextGenerator.GenerateAsync(tempDir);
            result.Should().Contain("src/");
            result.Should().NotContain("node_modules/");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    // ═══════════════════════════════════════════
    //  취소 지원
    // ═══════════════════════════════════════════

    [Fact]
    public async Task EnsureContextAsync_Cancellation_Throws()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            using var cts = new CancellationTokenSource();
            cts.Cancel();

            // 이미 취소된 토큰으로 호출 — 파일이 없으므로 GenerateAsync 진입
            // OperationCanceledException 또는 정상 반환 (구현에 따라)
            // 최소한 크래시하지 않으면 OK
            try
            {
                await WorkspaceContextGenerator.EnsureContextAsync(tempDir, cts.Token);
            }
            catch (OperationCanceledException)
            {
                // 예상된 동작
            }
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }

    [Fact]
    public async Task GenerateAsync_IncludesLanguageWorkflowHints()
    {
        var tempDir = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(tempDir);
        try
        {
            File.WriteAllText(Path.Combine(tempDir, "Cargo.toml"), "[package]\nname='sample'");
            File.WriteAllText(Path.Combine(tempDir, "main.rs"), "fn main() {}");

            var result = await WorkspaceContextGenerator.GenerateAsync(tempDir);

            result.Should().Contain("## Language Workflow");
            result.Should().Contain("Rust:");
            result.Should().Contain("Cargo.toml");
            result.Should().Contain("cargo build");
        }
        finally
        {
            Directory.Delete(tempDir, recursive: true);
        }
    }
}