using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging.Abstractions;
using w4c_workflows.Services;
using Xunit;

namespace w4c_workflows.Tests;

/// <summary>
/// §4/S4: one async git entry point with a bounded wait, both pipes drained and
/// a short-TTL state cache. These tests cover the porcelain-v2 parser (pure),
/// the failure path, and — when git is available — a real working tree.
/// </summary>
public class GitRunnerTests
{
    private static GitRunner Runner(int stateCacheSeconds = 0)
        => new(
            new ConfigurationBuilder()
                .AddInMemoryCollection(new Dictionary<string, string?>
                {
                    ["WorkflowSource:GitStateCacheSeconds"] = stateCacheSeconds.ToString(),
                })
                .Build(),
            NullLogger<GitRunner>.Instance);

    [Fact]
    public void ParseState_clean_repo_reports_head_and_not_dirty()
    {
        var stdout = string.Join('\n',
            "# branch.oid 0123456789abcdef",
            "# branch.head main",
            "# branch.upstream origin/main",
            "# branch.ab +0 -0") + "\n";

        var state = GitRunner.ParseState(new GitResult(0, stdout, "", TimedOut: false));

        Assert.Equal("0123456789abcdef", state.HeadSha);
        Assert.False(state.Dirty);
    }

    [Theory]
    [InlineData("1 .M N... 100644 100644 100644 aaa bbb file.txt")]
    [InlineData("? new-file.txt")]
    public void ParseState_any_content_line_marks_dirty(string line)
    {
        var stdout = "# branch.oid abc123\n# branch.head main\n" + line + "\n";

        var state = GitRunner.ParseState(new GitResult(0, stdout, "", TimedOut: false));

        Assert.Equal("abc123", state.HeadSha);
        Assert.True(state.Dirty);
    }

    [Fact]
    public void ParseState_unborn_branch_has_no_head()
    {
        var state = GitRunner.ParseState(
            new GitResult(0, "# branch.oid (initial)\n# branch.head main\n", "", TimedOut: false));

        Assert.Null(state.HeadSha);
        Assert.False(state.Dirty);
    }

    [Theory]
    [InlineData(1)]
    [InlineData(128)]
    public void ParseState_failed_call_is_empty(int exitCode)
    {
        var state = GitRunner.ParseState(new GitResult(exitCode, "", "fatal: nope", TimedOut: false));
        Assert.Null(state.HeadSha);
        Assert.False(state.Dirty);
    }

    [Fact]
    public async Task RunAsync_missing_working_directory_reports_failure_instead_of_throwing()
    {
        var missing = Path.Combine(Path.GetTempPath(), "w4c-gitrunner-" + Guid.NewGuid().ToString("N"));

        var result = await Runner().RunAsync(missing, new[] { "rev-parse", "HEAD" });

        Assert.False(result.Succeeded);
        Assert.Equal(-1, result.ExitCode);
    }

    [Fact]
    public async Task GetStateAsync_reads_head_and_caches_until_invalidated()
    {
        if (!GitAvailable())
            return; // no git on PATH — parser coverage above still runs

        var dir = Directory.CreateTempSubdirectory("w4c-gitrunner-").FullName;
        try
        {
            await GitRaw(dir, "init", "-q");
            await File.WriteAllTextAsync(Path.Combine(dir, "workflow.yaml"), "name: test\n");
            await GitRaw(dir, "add", "workflow.yaml");
            await GitRaw(dir, "commit", "-q", "-m", "initial");

            // Caching enabled: the clean state is cached…
            var runner = Runner(stateCacheSeconds: 60);
            var first = await runner.GetStateAsync(dir);
            Assert.NotNull(first.HeadSha);
            Assert.False(first.Dirty);

            // …so an immediate re-read after a change still returns the cached state…
            await File.WriteAllTextAsync(Path.Combine(dir, "workflow.yaml"), "name: changed\n");
            var cached = await runner.GetStateAsync(dir);
            Assert.False(cached.Dirty);
            Assert.Equal(first.HeadSha, cached.HeadSha);

            // …until the cache is dropped, when the change is observed.
            runner.InvalidateState(dir);
            var fresh = await runner.GetStateAsync(dir);
            Assert.True(fresh.Dirty);
        }
        finally
        {
            TryDelete(dir);
        }
    }

    private static bool GitAvailable()
    {
        try
        {
            using var p = System.Diagnostics.Process.Start(new System.Diagnostics.ProcessStartInfo("git", "--version")
            {
                RedirectStandardOutput = true,
                RedirectStandardError = true,
                UseShellExecute = false,
            });
            if (p == null) return false;
            p.WaitForExit(5000);
            return p.ExitCode == 0;
        }
        catch
        {
            return false;
        }
    }

    private static async Task GitRaw(string workDir, params string[] args)
    {
        var psi = new System.Diagnostics.ProcessStartInfo("git")
        {
            WorkingDirectory = workDir,
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            UseShellExecute = false,
        };
        foreach (var a in args) psi.ArgumentList.Add(a);
        psi.Environment["GIT_AUTHOR_NAME"] = "w4c test";
        psi.Environment["GIT_AUTHOR_EMAIL"] = "test@w4c.local";
        psi.Environment["GIT_COMMITTER_NAME"] = "w4c test";
        psi.Environment["GIT_COMMITTER_EMAIL"] = "test@w4c.local";

        using var p = System.Diagnostics.Process.Start(psi)!;
        await p.WaitForExitAsync();
        Assert.Equal(0, p.ExitCode);
    }

    private static void TryDelete(string dir)
    {
        try { Directory.Delete(dir, recursive: true); }
        catch { /* best effort */ }
    }
}