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          _owner;
    private readonly string          _repo;
    private readonly ILogger<GiteaService> _log;

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

    public GiteaService(IHttpClientFactory factory, IConfiguration cfg, ILogger<GiteaService> log)
    {
        _log   = log;
        _owner = cfg["Gitea:Owner"] ?? "Clarity";
        _repo  = cfg["Gitea:Repo"]  ?? "Clarity";

        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);
    }

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

    public async Task<GiteaRepo?> GetRepoAsync(CancellationToken ct = default)
    {
        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(CancellationToken ct = default)
    {
        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 []; }
    }

    public async Task<GiteaBranch?> CreateBranchAsync(CreateBranchRequest req, CancellationToken ct = default)
    {
        // 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", CancellationToken ct = default)
    {
        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, CancellationToken ct = default)
    {
        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, CancellationToken ct = default)
    {
        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(CancellationToken ct = default)
    {
        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, CancellationToken ct = default)
    {
        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(CancellationToken ct = default)
    {
        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, CancellationToken ct = default)
    {
        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);
    }

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

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