using System.Net.Http.Headers;
using System.Net.Http.Json;
using System.Text;
using System.Text.Json;
using System.Text.Json.Serialization;
using ControlPlane.Core.Models;

namespace ControlPlane.Api.Services;

/// <summary>
/// Thin wrapper around the Gitea REST API v1.
/// Configured via Gitea__BaseUrl, Gitea__Owner, and Gitea__Token in appsettings.
/// </summary>
public class GiteaService
{
    private readonly HttpClient      _http;
    private readonly string          _defaultOwner;
    private readonly string          _defaultRepo;
    private readonly IConfiguration  _cfg;
    private readonly ILogger<GiteaService> _log;

    private static readonly JsonSerializerOptions JsonOpts = new(JsonSerializerDefaults.Web);

    public GiteaService(IHttpClientFactory factory, IConfiguration cfg, ILogger<GiteaService> log)
    {
        _log          = log;
        _cfg          = cfg;
        _defaultOwner = cfg["Gitea:Owner"] ?? "ClarityStack";
        _defaultRepo  = cfg["Gitea:Repo"]  ?? "OPC";

        var baseUrl = cfg["Gitea:BaseUrl"] ?? "https://opc.clarity.test";
        var token   = cfg["Gitea:Token"]   ?? string.Empty;

        _http = factory.CreateClient("gitea");
        _http.BaseAddress = new Uri(baseUrl.TrimEnd('/') + "/api/v1/");
        _http.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

        if (!string.IsNullOrWhiteSpace(token))
            _http.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("token", token);
    }

    // ── Repo resolution ───────────────────────────────────────────────────────

    /// Returns (owner, repo) for the given key, falling back to the defaults.
    private (string Owner, string Repo) ResolveOwnerRepo(string? repoKey = null)
    {
        if (!string.IsNullOrWhiteSpace(repoKey))
        {
            var owner = _cfg[$"Gitea:Repos:{repoKey}:Owner"];
            var repo  = _cfg[$"Gitea:Repos:{repoKey}:Repo"];
            if (!string.IsNullOrWhiteSpace(owner) && !string.IsNullOrWhiteSpace(repo))
                return (owner, repo);
        }
        return (_defaultOwner, _defaultRepo);
    }

    // ── Repos ─────────────────────────────────────────────────────────────────

    public async Task<GiteaRepo?> GetRepoAsync(string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        try
        {
            return await _http.GetFromJsonAsync<GiteaRepo>($"repos/{owner}/{repo}", JsonOpts, ct);
        }
        catch (Exception ex) { _log.LogWarning(ex, "Gitea GetRepo failed"); return null; }
    }

    // ── Branches ──────────────────────────────────────────────────────────────

    public async Task<List<GiteaBranch>> ListBranchesAsync(string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        try
        {
            return await _http.GetFromJsonAsync<List<GiteaBranch>>(
                $"repos/{owner}/{repo}/branches?limit=50", JsonOpts, ct) ?? [];
        }
        catch (Exception ex) { _log.LogWarning(ex, "Gitea ListBranches failed"); return []; }
    }

    /// Returns branches from all registered repos, tagged with repoKey.
    public async Task<List<(string RepoKey, GiteaBranch Branch)>> ListAllBranchesAsync(CancellationToken ct = default)
    {
        var result = new List<(string, GiteaBranch)>();
        var section = _cfg.GetSection("Gitea:Repos");
        var keys = section.GetChildren().Select(c => c.Key).ToList();
        if (keys.Count == 0) keys = ["default"];

        await Task.WhenAll(keys.Select(async key =>
        {
            var branches = await ListBranchesAsync(key == "default" ? null : key, ct);
            lock (result) result.AddRange(branches.Select(b => (key, b)));
        }));

        return result;
    }

    public async Task<GiteaBranch?> CreateBranchAsync(CreateBranchRequest req, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(req.RepoKey);
        // Slugify: "OPC # 0032" + title → "feature/OPC-0032-git-workflow-integration"
        var slug = SlugifyTitle(req.OpcTitle);
        var num  = req.OpcNumber.Replace("OPC # ", "OPC-").Replace(" ", "");
        var branchName = $"feature/{num}-{slug}";

        var body = JsonSerializer.Serialize(new
        {
            new_branch_name = branchName,
            old_branch_name = req.From,
        }, JsonOpts);

        var res = await _http.PostAsync(
            $"repos/{owner}/{repo}/branches",
            new StringContent(body, Encoding.UTF8, "application/json"), ct);

        if (!res.IsSuccessStatusCode)
        {
            var err = await res.Content.ReadAsStringAsync(ct);
            _log.LogWarning("Gitea CreateBranch failed {Status}: {Error}", res.StatusCode, err);
            return null;
        }

        return await res.Content.ReadFromJsonAsync<GiteaBranch>(JsonOpts, ct);
    }

    // ── Pull Requests ─────────────────────────────────────────────────────────

    public async Task<List<GiteaPullRequest>> ListPullRequestsAsync(
        string state = "open", string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        try
        {
            return await _http.GetFromJsonAsync<List<GiteaPullRequest>>(
                $"repos/{owner}/{repo}/pulls?state={state}&limit=50", JsonOpts, ct) ?? [];
        }
        catch (Exception ex) { _log.LogWarning(ex, "Gitea ListPRs failed"); return []; }
    }

    public async Task<GiteaPullRequest?> GetPullRequestAsync(long number, string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        try
        {
            return await _http.GetFromJsonAsync<GiteaPullRequest>(
                $"repos/{owner}/{repo}/pulls/{number}", JsonOpts, ct);
        }
        catch (Exception ex) { _log.LogWarning(ex, "Gitea GetPR failed"); return null; }
    }

    public async Task<GiteaPullRequest?> CreatePullRequestAsync(
        CreatePullRequestRequest req, string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        var body = JsonSerializer.Serialize(new
        {
            title = req.Title,
            head  = req.Head,
            @base = req.Base,
            body  = req.Body,
        }, JsonOpts);

        var res = await _http.PostAsync(
            $"repos/{owner}/{repo}/pulls",
            new StringContent(body, Encoding.UTF8, "application/json"), ct);

        if (!res.IsSuccessStatusCode)
        {
            var err = await res.Content.ReadAsStringAsync(ct);
            _log.LogWarning("Gitea CreatePR failed {Status}: {Error}", res.StatusCode, err);
            return null;
        }

        return await res.Content.ReadFromJsonAsync<GiteaPullRequest>(JsonOpts, ct);
    }

    // ── Tags ──────────────────────────────────────────────────────────────────

    public async Task<List<GiteaTag>> ListTagsAsync(string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        try
        {
            return await _http.GetFromJsonAsync<List<GiteaTag>>(
                $"repos/{owner}/{repo}/tags?limit=20", JsonOpts, ct) ?? [];
        }
        catch (Exception ex) { _log.LogWarning(ex, "Gitea ListTags failed"); return []; }
    }

    public async Task<GiteaTag?> CreateTagAsync(CreateTagRequest req, string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        var body = JsonSerializer.Serialize(new
        {
            tag_name = req.TagName,
            message  = req.Message,
            target   = req.CommitSha,
        }, JsonOpts);

        var res = await _http.PostAsync(
            $"repos/{owner}/{repo}/tags",
            new StringContent(body, Encoding.UTF8, "application/json"), ct);

        if (!res.IsSuccessStatusCode)
        {
            var err = await res.Content.ReadAsStringAsync(ct);
            _log.LogWarning("Gitea CreateTag failed {Status}: {Error}", res.StatusCode, err);
            return null;
        }

        return await res.Content.ReadFromJsonAsync<GiteaTag>(JsonOpts, ct);
    }

    // ── Webhooks ──────────────────────────────────────────────────────────────

    public async Task<List<GiteaWebhook>> ListWebhooksAsync(string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        try
        {
            return await _http.GetFromJsonAsync<List<GiteaWebhook>>(
                $"repos/{owner}/{repo}/hooks", JsonOpts, ct) ?? [];
        }
        catch (Exception ex) { _log.LogWarning(ex, "Gitea ListWebhooks failed"); return []; }
    }

    public async Task<GiteaWebhook?> RegisterWebhookAsync(
        CreateWebhookRequest req, string? repoKey = null, CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        var body = JsonSerializer.Serialize(new
        {
            type   = "gitea",
            active = true,
            config = new { url = req.TargetUrl, content_type = "json" },
            events = req.Events,
        }, JsonOpts);

        var res = await _http.PostAsync(
            $"repos/{owner}/{repo}/hooks",
            new StringContent(body, Encoding.UTF8, "application/json"), ct);

        if (!res.IsSuccessStatusCode)
        {
            var err = await res.Content.ReadAsStringAsync(ct);
            _log.LogWarning("Gitea RegisterWebhook failed {Status}: {Error}", res.StatusCode, err);
            return null;
        }

        return await res.Content.ReadFromJsonAsync<GiteaWebhook>(JsonOpts, ct);
    }

    // ── Commit Status ─────────────────────────────────────────────────────────

    /// <summary>
    /// Posts a commit status to Gitea (the CI "check" shown on a commit / PR).
    /// State values: "pending" | "success" | "failure" | "error".
    /// Context identifies which check — use "controlplane/build" for the build gate.
    /// </summary>
    public async Task PostCommitStatusAsync(
        string repoKey, string sha, string state, string description,
        string context = "controlplane/build", CancellationToken ct = default)
    {
        var (owner, repo) = ResolveOwnerRepo(repoKey);
        var body = JsonSerializer.Serialize(new
        {
            state,
            description,
            context,
        }, JsonOpts);

        try
        {
            var res = await _http.PostAsync(
                $"repos/{owner}/{repo}/statuses/{sha}",
                new StringContent(body, Encoding.UTF8, "application/json"), ct);

            if (!res.IsSuccessStatusCode)
            {
                var err = await res.Content.ReadAsStringAsync(ct);
                _log.LogWarning("Gitea PostCommitStatus {State} failed for {Sha}: {Err}", state, sha[..8], err);
            }
        }
        catch (Exception ex) { _log.LogWarning(ex, "Gitea PostCommitStatus threw"); }
    }

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

    private static string SlugifyTitle(string title) =>
        System.Text.RegularExpressions.Regex
            .Replace(title.ToLowerInvariant(), @"[^a-z0-9]+", "-")
            .Trim('-')[..Math.Min(40, title.Length)];
}