using System.Diagnostics;
using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text;
using System.Text.Json;
using ControlPlane.Core.Messages;
using ControlPlane.Core.Models;
using ControlPlane.Core.Services;
using LibGit2Sharp;
using MassTransit;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Logging;

namespace ControlPlane.Worker;

/// <summary>
/// MassTransit consumer. Triggered by BuildRequestedCommand (published by the Gitea push webhook).
/// Clones or updates the repo, runs dotnet build, and reports status back to Gitea.
/// Runs inside the SDK-based Worker container — dotnet CLI is always available.
/// </summary>
public sealed class BuildConsumer(
    BuildHistoryService  history,
    IConfiguration       config,
    IHttpClientFactory   httpFactory,
    ILogger<BuildConsumer> logger) : IConsumer<BuildRequestedCommand>
{
    private static readonly JsonSerializerOptions JsonOpts = new(JsonSerializerDefaults.Web);

    public async Task Consume(ConsumeContext<BuildRequestedCommand> context)
    {
        var cmd = context.Message;
        var ct  = context.CancellationToken;

        logger.LogInformation(
            "BuildConsumer: starting build for {Repo}@{Sha}",
            cmd.RepoName, cmd.HeadSha[..Math.Min(8, cmd.HeadSha.Length)]);

        // 1. Create a build record — CommitSha written on Complete
        var record = await history.CreateBuildAsync(BuildKind.SolutionBuild, cmd.SolutionPath);
        record.CommitSha = cmd.HeadSha;

        // 2. Signal pending to Gitea immediately so the commit shows ⏳
        await PostCommitStatusAsync(cmd.RepoName, cmd.HeadSha, "pending", "Build running…", ct);

        try
        {
            // 3. Ensure repo is cloned / up-to-date
            var workDir = await Task.Run(() => EnsureRepo(cmd.RepoName, cmd.HeadSha, record), ct);
            if (workDir is null)
            {
                await FailAsync(record, cmd, "Failed to prepare repository clone.", ct);
                return;
            }

            // 4. Run dotnet build
            var solutionPath = Path.Combine(workDir, cmd.SolutionPath
                .Replace('/', Path.DirectorySeparatorChar));

            var exitCode = await RunBuildAsync(solutionPath, record, ct);
            var status   = exitCode == 0 ? BuildStatus.Succeeded : BuildStatus.Failed;
            var summary  = exitCode == 0
                ? "✔ Build succeeded."
                : $"✖ Build failed (exit {exitCode}).";

            record.Log.Add(summary);
            logger.LogInformation("BuildConsumer: {Repo} build {Status}", cmd.RepoName, status);

            // 5. Persist final record + post status to Gitea
            await history.CompleteBuildAsync(record, status);
            await PostCommitStatusAsync(
                cmd.RepoName, cmd.HeadSha,
                exitCode == 0 ? "success" : "failure",
                summary, ct);
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "BuildConsumer: unhandled exception for {Repo}@{Sha}", cmd.RepoName, cmd.HeadSha);
            await FailAsync(record, cmd, $"Unhandled exception: {ex.Message}", ct);
        }
    }

    // ── Repository management ─────────────────────────────────────────────────

    private string? EnsureRepo(string repoName, string headSha, BuildRecord record)
    {
        var baseDir  = config["Build:WorkDir"] ?? "/opt/clarity-builds";
        var repoDir  = Path.Combine(baseDir, repoName);
        var remoteUrl = BuildRemoteUrl(repoName);

        void Log(string msg)
        {
            record.Log.Add(msg);
            logger.LogInformation("[{Repo}] {Msg}", repoName, msg);
        }

        try
        {
            if (!Repository.IsValid(repoDir))
            {
                Log($"Cloning {remoteUrl} → {repoDir}");
                Directory.CreateDirectory(repoDir);
                Repository.Clone(remoteUrl, repoDir, new CloneOptions
                {
                    FetchOptions =
                    {
                        CredentialsProvider = MakeCredentials(),
                        CertificateCheck    = (_, _, _) => true,
                    },
                });
            }
            else
            {
                Log($"Pulling latest for {repoName}");
                using var repo   = new Repository(repoDir);
                var remote = EnsureRemote(repo, repoName);
                Commands.Fetch(repo, remote.Name, remote.FetchRefSpecs.Select(r => r.Specification), new FetchOptions
                {
                    CredentialsProvider = MakeCredentials(),
                    CertificateCheck    = (_, _, _) => true,
                }, null);

                // Reset to the exact SHA we want to build
                var commit = repo.Lookup<Commit>(headSha);
                if (commit is null)
                {
                    Log($"Warning: SHA {headSha[..8]} not found after fetch — building HEAD instead.");
                }
                else
                {
                    repo.Reset(ResetMode.Hard, commit);
                    Log($"Reset to {headSha[..8]}");
                }
            }

            return repoDir;
        }
        catch (Exception ex)
        {
            Log($"✖ Git error: {ex.Message}");
            logger.LogError(ex, "Failed to prepare repo {Repo}", repoName);
            return null;
        }
    }

    private Remote EnsureRemote(Repository repo, string repoName)
    {
        var url    = BuildRemoteUrl(repoName);
        var remote = repo.Network.Remotes["origin"];
        if (remote is null)
            return repo.Network.Remotes.Add("origin", url);
        if (remote.Url != url)
            repo.Network.Remotes.Update("origin", r => r.Url = url);
        return repo.Network.Remotes["origin"]!;
    }

    private string BuildRemoteUrl(string repoName)
    {
        var baseUrl = (config["Gitea:BaseUrl"] ?? "https://opc.clarity.test").TrimEnd('/');
        var owner   = config["Gitea:Owner"] ?? "ClarityStack";
        return $"{baseUrl}/{owner}/{repoName}.git";
    }

    private LibGit2Sharp.Handlers.CredentialsHandler MakeCredentials()
    {
        var user  = config["Gitea:Owner"] ?? "git";
        var token = config["Gitea:Token"] ?? string.Empty;
        return (_, _, _) => new UsernamePasswordCredentials { Username = user, Password = token };
    }

    // ── Build execution ───────────────────────────────────────────────────────

    private async Task<int> RunBuildAsync(string solutionPath, BuildRecord record, CancellationToken ct)
    {
        var psi = new ProcessStartInfo("dotnet",
            $"build \"{solutionPath}\" -c Release --no-incremental --nologo")
        {
            RedirectStandardOutput = true,
            RedirectStandardError  = true,
            UseShellExecute        = false,
            CreateNoWindow         = true,
        };

        record.Log.Add($"▶ dotnet build {Path.GetFileName(solutionPath)} -c Release");
        record.Log.Add("──────────────────────────────────────────────────");

        using var proc = new Process { StartInfo = psi, EnableRaisingEvents = true };

        void HandleLine(string? line)
        {
            if (line is null) return;
            // Non-blocking fire-and-forget flush every 20 lines
            _ = history.AppendBuildLogAsync(record, line);
        }

        proc.OutputDataReceived += (_, e) => HandleLine(e.Data);
        proc.ErrorDataReceived  += (_, e) => HandleLine(e.Data);

        proc.Start();
        proc.BeginOutputReadLine();
        proc.BeginErrorReadLine();

        await proc.WaitForExitAsync(ct);
        return proc.ExitCode;
    }

    // ── Gitea commit status ───────────────────────────────────────────────────

    private async Task PostCommitStatusAsync(
        string repoName, string sha, string state, string description, CancellationToken ct)
    {
        try
        {
            var baseUrl = (config["Gitea:BaseUrl"] ?? "https://opc.clarity.test").TrimEnd('/');
            var owner   = config["Gitea:Owner"] ?? "ClarityStack";
            var token   = config["Gitea:Token"] ?? string.Empty;

            using var http = httpFactory.CreateClient("gitea");
            http.DefaultRequestHeaders.Authorization =
                new AuthenticationHeaderValue("token", token);

            var url  = $"{baseUrl}/api/v1/repos/{owner}/{repoName}/statuses/{sha}";
            var body = JsonSerializer.Serialize(new
            {
                state,
                description,
                context = "controlplane/build",
            }, JsonOpts);

            var resp = await http.PostAsync(
                url,
                new StringContent(body, Encoding.UTF8, "application/json"),
                ct);

            if (!resp.IsSuccessStatusCode)
            {
                var err = await resp.Content.ReadAsStringAsync(ct);
                logger.LogWarning(
                    "PostCommitStatus failed for {Repo}@{Sha}: {Status} {Err}",
                    repoName, sha[..Math.Min(8, sha.Length)], resp.StatusCode, err);
            }
        }
        catch (Exception ex)
        {
            // Never let a failed status post break the build flow
            logger.LogWarning(ex, "PostCommitStatus threw for {Repo}", repoName);
        }
    }

    // ── Helpers ───────────────────────────────────────────────────────────────

    private async Task FailAsync(
        BuildRecord record, BuildRequestedCommand cmd, string reason, CancellationToken ct)
    {
        record.Log.Add($"✖ {reason}");
        await history.CompleteBuildAsync(record, BuildStatus.Failed);
        await PostCommitStatusAsync(cmd.RepoName, cmd.HeadSha, "failure", reason, ct);
    }
}