using Microsoft.Graph;
using Microsoft.Graph.Models;
using Microsoft.Kiota.Abstractions;
using SharepointToolbox.Web.Core.Models;
using AppGraphClientFactory = SharepointToolbox.Web.Infrastructure.Auth.GraphClientFactory;

namespace SharepointToolbox.Web.Services;

/// <summary>
/// Delegated Graph implementation of <see cref="ISiteDiscoveryService"/>.
/// Uses the <c>/sites?search=*</c> endpoint, paging through every result.
/// Requires the delegated <c>Sites.Read.All</c> scope.
/// </summary>
public class SiteDiscoveryService : ISiteDiscoveryService
{
    private readonly AppGraphClientFactory _graphClientFactory;

    public SiteDiscoveryService(AppGraphClientFactory graphClientFactory)
    {
        _graphClientFactory = graphClientFactory;
    }

    public async Task<IReadOnlyList<SiteInfo>> SearchSitesAsync(
        TenantProfile profile,
        string? query = null,
        CancellationToken ct = default)
    {
        var graphClient = await _graphClientFactory.CreateClientAsync(profile);
        // "*" is the Graph convention for "return all sites".
        var search = string.IsNullOrWhiteSpace(query) ? "*" : query!;

        // The typed Sites.GetAsync maps its Search property to OData "$search",
        // which routes "*" through KQL and fails ("'*' is not valid at position 0").
        // The all-sites wildcard only works via the bare, non-OData "search"
        // query parameter, so build the request manually.
        var requestInfo = new RequestInformation
        {
            HttpMethod = Method.GET,
            UrlTemplate = "{+baseurl}/sites{?search,%24top}",
            PathParameters = new Dictionary<string, object>
            {
                { "baseurl", graphClient.RequestAdapter.BaseUrl ?? "https://graph.microsoft.com/v1.0" }
            },
        };
        requestInfo.QueryParameters.Add("search", search);
        requestInfo.QueryParameters.Add("%24top", 999);
        requestInfo.Headers.Add("Accept", "application/json");

        var response = await graphClient.RequestAdapter.SendAsync<SiteCollectionResponse>(
            requestInfo, SiteCollectionResponse.CreateFromDiscriminatorValue, cancellationToken: ct);

        if (response is null) return Array.Empty<SiteInfo>();

        var results = new List<SiteInfo>();
        var iter = PageIterator<Site, SiteCollectionResponse>.CreatePageIterator(
            graphClient, response,
            site =>
            {
                if (ct.IsCancellationRequested) return false;
                var url = site.WebUrl ?? string.Empty;
                if (string.IsNullOrEmpty(url)) return true;
                // Skip OneDrive personal sites — not useful for these scans.
                if (url.Contains("/personal/", StringComparison.OrdinalIgnoreCase)) return true;
                var title = site.DisplayName ?? site.Name ?? url;
                results.Add(new SiteInfo(url, title));
                return true;
            });
        await iter.IterateAsync(ct);

        return results
            .GroupBy(s => s.Url, StringComparer.OrdinalIgnoreCase)
            .Select(g => g.First())
            .OrderBy(s => s.Title, StringComparer.OrdinalIgnoreCase)
            .ToList();
    }
}