using Microsoft.AspNetCore.Hosting;

namespace w4c_workflows.Services;

/// <summary>
/// Manages per-tenant private Forgejo repositories for workflow source files.
/// Each tenant gets a repo named <c>workflows-{tenantId}</c> under the configured
/// Forgejo owner. The repo contains the tenant's workflow YAML definitions and
/// their sibling code files (shell scripts, JS, Python, etc.).
///
/// On first access the repo is created via the Forgejo admin API, cloned locally,
/// and seeded with templates from <c>WorkflowSource:SharedDir</c>. Subsequent calls
/// pull remote changes before the sync service reads the files.
///
/// The local clone lives at <c>{WorkflowSource:CopiesRoot}/{tenantId}/</c> — the
/// same directory layout the legacy <see cref="PerTenantWorkflowSource"/> used, so
/// the existing <see cref="WorkflowSyncService"/> and worker runtime need no path
/// changes when the backing store switches from plain filesystem to git.
///
/// The class is split across partial files by responsibility: this file holds
/// configuration, repo naming and the clone-directory layout;
/// <c>ForgejoWorkflowRepoService.Lifecycle.cs</c> the repo/clone/pull/push
/// lifecycle, <c>.Git.cs</c> the bounded-timeout git process calls and
/// <c>.AdminApi.cs</c> the single admin REST call.
/// </summary>
public sealed partial class ForgejoWorkflowRepoService
{
    /// <summary>
    /// Hard ceiling for any single git invocation. Without it, `git pull`/`git clone`
    /// against an unreachable remote (e.g. a stale Forgejo base URL) hangs forever,
    /// blocking the request that triggered it. See <see cref="RunGitAsync"/>.
    /// </summary>
    private static readonly TimeSpan GitOperationTimeout = TimeSpan.FromSeconds(20);

    /// <summary>Named HttpClient used for the Forgejo admin API (pooled, not per-call).</summary>
    public const string AdminClientName = "forgejo-admin";

    private readonly string _forgejoBase;
    private readonly string? _forgejoToken;
    private readonly string? _forgejoAdminToken;
    private readonly string _forgejoOwner;
    private readonly string _copiesRoot;
    private readonly HttpClient _adminHttp;
    private readonly ILogger<ForgejoWorkflowRepoService> _logger;

    public ForgejoWorkflowRepoService(IConfiguration config, IWebHostEnvironment env,
        ILogger<ForgejoWorkflowRepoService> logger, IHttpClientFactory? httpFactory = null)
    {
        _logger = logger;
        // One reused client for the service lifetime instead of `new HttpClient`
        // per admin call — the old pattern leaked sockets under load (the service
        // is a singleton, so this client is effectively shared anyway).
        _adminHttp = httpFactory?.CreateClient(AdminClientName) ?? new HttpClient();
        _adminHttp.Timeout = TimeSpan.FromSeconds(30);
        _forgejoBase = (config["Forgejo:BaseUrl"] ?? "https://forgejo.wiz4chat.com").TrimEnd('/');
        _forgejoToken = config["Forgejo:AccessToken"]?.Trim();
        _forgejoAdminToken = config["Forgejo:AdminToken"]?.Trim();
        // Prefer WorkflowRepoOwner, but treat an explicit empty string as
        // "not configured" and fall back to Forgejo:Owner. A plain `??` is not
        // enough: appsettings ships `"WorkflowRepoOwner": ""`, which is non-null
        // and would win over Forgejo:Owner, silently disabling Forgejo-backed
        // workflow mode (IsConfigured reads owner as empty).
        var workflowRepoOwner = config["Forgejo:WorkflowRepoOwner"]?.Trim();
        _forgejoOwner = !string.IsNullOrWhiteSpace(workflowRepoOwner)
            ? workflowRepoOwner
            : config["Forgejo:Owner"]?.Trim() ?? string.Empty;
        // Resolve CopiesRoot against the content root (not the process CWD) so a
        // relative value like "../source-copies" lands on the same wizard root
        // regardless of the working directory the service was launched from.
        _copiesRoot = WorkflowSourceFactory.ResolveCopiesRoot(
            config["WorkflowSource:CopiesRoot"]
            ?? throw new InvalidOperationException(
                "WorkflowSource:CopiesRoot is not configured. " +
                "Set it to a writable directory path (e.g. \"/data/workflow-tenants\")."),
            env);
        // The workflow repo name (basename). Default "workflows" → {login}/workflows,
        // so a tenant's workflows live in a repo whose name contains "workflow".
        // A per-tenant selection overrides this at runtime.
        var repoName = config["WorkflowSource:WorkflowRepoName"]?.Trim();
        WorkflowRepoName = string.IsNullOrWhiteSpace(repoName) ? "workflows" : repoName;
    }

    /// <summary>The Forgejo base URL (for building repo links).</summary>
    public string ForgejoBaseUrl => _forgejoBase;

    /// <summary>
    /// The token used for git transport (clone/pull/push) against the per-user
    /// private workflow repos. The repos are created and administered with the
    /// ADMIN token, so that is the credential that actually works against them;
    /// the plain AccessToken has no read/write grant on a user's private repo and
    /// Forgejo reports it as "Repository not found". Fall back to the access
    /// token when no admin token is configured.
    /// </summary>
    private string GitAuthToken =>
        !string.IsNullOrWhiteSpace(_forgejoAdminToken) ? _forgejoAdminToken : _forgejoToken ?? string.Empty;

    /// <summary>True when Forgejo admin provisioning is configured.</summary>
    public bool IsConfigured =>
        !string.IsNullOrWhiteSpace(_forgejoAdminToken) &&
        !string.IsNullOrWhiteSpace(_forgejoOwner);

    /// <summary>The repo full name on Forgejo (owner/repo-name).</summary>
    /// <summary>
    /// The repository name (basename) used for a tenant's workflow repo. Default
    /// is <c>workflows</c> (the repo full name <c>{login}/workflows</c>), so a
    /// tenant's workflows live in a repo whose name contains "workflow". A tenant
    /// may select a different repo (e.g. <c>wiz4apps</c>) to share the directory
    /// with the main-api Source Code explorer; the selection is persisted per
    /// tenant and overrides this default.
    /// </summary>
    public string WorkflowRepoName { get; }

    /// <summary>
    /// Consolidated repo-name resolver. Both the workflows-api engine and the
    /// webapi source-code explorer operate on a local clone whose directory name is
    /// the slug of the repo full name (<c>{owner}_{repo}</c>). Deriving full name AND
    /// slug from a single repo name is what keeps the two services pointing at the
    /// same directory.
    /// </summary>
    public static (string RepoFullName, string RepoSlug) ResolveWorkflowRepo(string login, string repoName)
    {
        var owner = Sanitize(login.ToLowerInvariant());
        var repo = Sanitize(repoName);
        return ($"{owner}/{repo}", $"{owner}_{repo}");
    }

    /// <summary>
    /// Resolves the Forgejo repo full name for a user given the configured/selected
    /// workflow repo name: <c>{login}/{repoName}</c>.
    /// </summary>
    public string RepoFullNameForLogin(string login, string? repoName = null) =>
        ResolveWorkflowRepo(login, repoName ?? WorkflowRepoName).RepoFullName;

    /// <summary>
    /// The source-copies owner-repo slug for a user's workflow repo, matching the
    /// webapi SourceCodeCopyService layout (<c>{owner}_{repo}</c>, e.g.
    /// <c>test_workflows</c>). Sharing this exact directory with the webapi
    /// source-code explorer is what keeps workflow edits visible in the source-code
    /// view without a manual fetch/pull.
    /// </summary>
    public string OwnerRepoSlug(string login, string? repoName = null) =>
        ResolveWorkflowRepo(login, repoName ?? WorkflowRepoName).RepoSlug;

    /// <summary>
    /// The absolute path to a tenant's local clone directory — shared with the
    /// webapi source-code explorer. Layout:
    /// <c>{CopiesRoot}/{tenantId}/{ownerRepo}</c> where <c>ownerRepo</c> is
    /// <see cref="OwnerRepoSlug"/> (e.g. <c>source-copies/10/test_workflows-test</c>).
    /// Both the w4c-workflows-api engine and the webapi SourceCodeController operate
    /// on this one working copy, so workflow edits and the source-code view stay
    /// consistent without a manual git pull.
    /// </summary>
    public string TenantCloneDir(string tenantId, string login, string? repoName = null)
        => Path.GetFullPath(Path.Combine(_copiesRoot, Sanitize(tenantId), OwnerRepoSlug(login, repoName)));

    private static string Sanitize(string id)
    {
        if (string.IsNullOrWhiteSpace(id))
            return "_";
        var sb = new System.Text.StringBuilder(id.Length);
        foreach (var ch in id)
            sb.Append(char.IsLetterOrDigit(ch) || ch == '-' || ch == '_' ? ch : '_');
        var result = sb.ToString();
        return result.Length > 120 ? result[..120] : result;
    }
}