using System.Net.Http.Json;
using System.Text.Json;

namespace Hokm.Server.Payments;

/// <summary>
/// Config for store in-app billing verification. Fill these from the Cafe Bazaar
/// (pardakht) and Myket developer panels. Bound from the "Iab" config section /
/// <c>Iab__*</c> env vars.
/// </summary>
public sealed class IabOptions
{
    /// <summary>Android package name registered in the store panels.</summary>
    public string PackageName { get; set; } = "com.bargevasat.app";

    // ── Cafe Bazaar (pardakht dev API, OAuth refresh-token flow) ──
    public string BazaarClientId { get; set; } = "";
    public string BazaarClientSecret { get; set; } = "";
    public string BazaarRefreshToken { get; set; } = "";

    /// <summary>
    /// Cafe Bazaar in-app billing RSA public key (panel: «دریافت کلید RSA برای
    /// قراردادن در برنامه»). Used to verify a purchase payload's signature locally
    /// (Poolakey in-app library flow). NOT used by the current deep-link flow,
    /// which verifies server-to-server via the pardakht API above — kept here so
    /// the key has a home if/when the native Poolakey plugin is added.
    /// </summary>
    public string BazaarRsaPublicKey { get; set; } = "";

    // ── Myket (developer validation API) ──
    public string MyketAccessToken { get; set; } = "";

    /// <summary>
    /// DEV ONLY. When true, purchases are credited WITHOUT remote verification
    /// (use for local testing before you have store credentials). NEVER enable in
    /// production — it lets a forged token mint coins.
    /// </summary>
    public bool AllowUnverified { get; set; } = false;
}

/// <summary>
/// Verifies a store purchase token (Cafe Bazaar / Myket) server-to-server before
/// coins are credited. Endpoints are config-driven; confirm the exact URLs against
/// your store panel — the request/response shapes mirror Google Play's IAB API.
/// </summary>
public sealed class IabService
{
    private static readonly HttpClient Http = new();
    private readonly IabOptions _opts;
    private readonly ILogger<IabService> _log;

    public IabService(IabOptions opts, ILogger<IabService> log)
    {
        _opts = opts;
        _log = log;
    }

    public async Task<bool> Verify(string store, string productId, string token)
    {
        if (string.IsNullOrWhiteSpace(token)) return _opts.AllowUnverified;
        store = (store ?? "").Trim().ToLowerInvariant();
        try
        {
            return store switch
            {
                "bazaar" or "cafebazaar" => await VerifyBazaar(productId, token),
                "myket" => await VerifyMyket(productId, token),
                _ => _opts.AllowUnverified,
            };
        }
        catch (Exception ex)
        {
            _log.LogWarning(ex, "IAB verify failed for store {Store} product {Product}", store, productId);
            return _opts.AllowUnverified;
        }
    }

    /// <summary>
    /// Cafe Bazaar: exchange the refresh token for an access token, then validate
    /// the in-app purchase. See https://pardakht.cafebazaar.ir/devapi/v2/.
    /// </summary>
    private async Task<bool> VerifyBazaar(string productId, string token)
    {
        if (string.IsNullOrWhiteSpace(_opts.BazaarRefreshToken)) return _opts.AllowUnverified;

        // 1) refresh_token → access_token
        var form = new FormUrlEncodedContent(new Dictionary<string, string>
        {
            ["grant_type"] = "refresh_token",
            ["client_id"] = _opts.BazaarClientId,
            ["client_secret"] = _opts.BazaarClientSecret,
            ["refresh_token"] = _opts.BazaarRefreshToken,
        });
        var tokenResp = await Http.PostAsync("https://pardakht.cafebazaar.ir/devapi/v2/auth/token/", form);
        if (!tokenResp.IsSuccessStatusCode) return false;
        using var tokenDoc = JsonDocument.Parse(await tokenResp.Content.ReadAsStringAsync());
        if (!tokenDoc.RootElement.TryGetProperty("access_token", out var at)) return false;
        var access = at.GetString();

        // 2) validate the purchase
        var url = $"https://pardakht.cafebazaar.ir/devapi/v2/api/validate/{_opts.PackageName}/inapp/{Uri.EscapeDataString(productId)}/purchases/{Uri.EscapeDataString(token)}/?access_token={access}";
        var vResp = await Http.GetAsync(url);
        if (!vResp.IsSuccessStatusCode) return false;
        using var vDoc = JsonDocument.Parse(await vResp.Content.ReadAsStringAsync());
        // purchaseState: 0 = purchased (1 = refunded/cancelled). Absent ⇒ a 200 body
        // is itself proof of a valid purchase.
        if (vDoc.RootElement.TryGetProperty("purchaseState", out var ps) && ps.ValueKind == JsonValueKind.Number)
            return ps.GetInt32() == 0;
        return true;
    }

    /// <summary>
    /// Myket: validate via the developer API. POST the purchase token in the body
    /// (`{ "tokenId": ... }`) to the partners/verify endpoint with an X-Access-Token
    /// header. The access token comes from the Myket developer panel → in-app
    /// products. See https://myket.ir/kb/pages/server-to-server-payment-validation-api/
    /// </summary>
    private async Task<bool> VerifyMyket(string productId, string token)
    {
        if (string.IsNullOrWhiteSpace(_opts.MyketAccessToken)) return _opts.AllowUnverified;

        var url = $"https://developer.myket.ir/api/partners/applications/{_opts.PackageName}/purchases/products/{Uri.EscapeDataString(productId)}/verify";
        using var req = new HttpRequestMessage(HttpMethod.Post, url);
        req.Headers.Add("X-Access-Token", _opts.MyketAccessToken);
        req.Content = new StringContent(
            JsonSerializer.Serialize(new { tokenId = token }),
            System.Text.Encoding.UTF8,
            "application/json");
        var resp = await Http.SendAsync(req);
        if (!resp.IsSuccessStatusCode) return false;
        using var doc = JsonDocument.Parse(await resp.Content.ReadAsStringAsync());
        // purchaseState: 0 = successful purchase, 1 = failed.
        if (doc.RootElement.TryGetProperty("purchaseState", out var ps) && ps.ValueKind == JsonValueKind.Number)
            return ps.GetInt32() == 0;
        return true;
    }
}