using Microsoft.Extensions.Options;
using StellaOps.Concelier.Core.Linksets;
using StellaOps.Scanner.WebService.Options;
using System.Collections.Immutable;
using System.Net.Http.Json;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace StellaOps.Scanner.WebService.Services;

internal sealed class ConcelierHttpLinksetQueryService : IAdvisoryLinksetQueryService
{
    private readonly HttpClient _client;
    private readonly ConcelierLinksetOptions _options;

    private static readonly JsonSerializerOptions SerializerOptions = new(JsonSerializerDefaults.Web)
    {
        DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
        PropertyNameCaseInsensitive = true
    };

    public ConcelierHttpLinksetQueryService(HttpClient client, IOptions<ConcelierLinksetOptions> options)
    {
        _client = client ?? throw new ArgumentNullException(nameof(client));
        _options = options?.Value ?? throw new ArgumentNullException(nameof(options));
    }

    public async Task<AdvisoryLinksetQueryResult> QueryAsync(AdvisoryLinksetQueryOptions options, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(options);
        cancellationToken.ThrowIfCancellationRequested();

        if (options.AdvisoryIds is null)
        {
            return new AdvisoryLinksetQueryResult(ImmutableArray<AdvisoryLinkset>.Empty, null, false);
        }

        var results = ImmutableArray.CreateBuilder<AdvisoryLinkset>();
        foreach (var advisoryId in options.AdvisoryIds)
        {
            if (string.IsNullOrWhiteSpace(advisoryId))
            {
                continue;
            }

            var path = $"/v1/lnm/linksets/{Uri.EscapeDataString(advisoryId)}?tenant={Uri.EscapeDataString(options.Tenant)}&includeConflicts=true&includeObservations=false&includeTimeline=false";
            try
            {
                using var response = await _client.GetAsync(path, cancellationToken).ConfigureAwait(false);
                if (!response.IsSuccessStatusCode)
                {
                    continue;
                }

                var payload = await response.Content.ReadFromJsonAsync<LinksetDetailResponse>(SerializerOptions, cancellationToken).ConfigureAwait(false);
                if (payload?.Linksets is null || payload.Linksets.Length == 0)
                {
                    continue;
                }

                foreach (var linkset in payload.Linksets)
                {
                    results.Add(Map(linkset));
                }
            }
            catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
            {
                throw;
            }
            catch
            {
                // swallow and continue; caller will see partial results
            }
        }

        var linksets = results.ToImmutable();
        return new AdvisoryLinksetQueryResult(linksets, null, false);
    }

    private static AdvisoryLinkset Map(LinksetDto dto)
    {
        var normalized = dto.Normalized is null
            ? null
            : new AdvisoryLinksetNormalized(
                dto.Normalized.Purls,
                dto.Normalized.Cpes,
                dto.Normalized.Versions,
                dto.Normalized.Ranges,
                dto.Normalized.Severities);

        var conflicts = dto.Conflicts is null
            ? null
            : dto.Conflicts.Select(c => new AdvisoryLinksetConflict(c.Field, c.Reason ?? string.Empty, c.Values, c.SourceIds)).ToList();

        return new AdvisoryLinkset(
            TenantId: dto.Tenant ?? string.Empty,
            Source: dto.Source ?? string.Empty,
            AdvisoryId: dto.AdvisoryId ?? string.Empty,
            ObservationIds: dto.ObservationIds?.ToImmutableArray() ?? ImmutableArray<string>.Empty,
            Normalized: normalized,
            Provenance: null,
            Confidence: dto.Confidence,
            Conflicts: conflicts,
            CreatedAt: dto.CreatedAt ?? DateTimeOffset.MinValue,
            BuiltByJobId: dto.BuiltByJobId);
    }

    private sealed record LinksetDetailResponse([property: JsonPropertyName("linksets")] LinksetDto[] Linksets);

    private sealed record LinksetDto
    {
        [JsonPropertyName("advisoryId")]
        public string? AdvisoryId { get; init; }

        [JsonPropertyName("source")]
        public string? Source { get; init; }

        [JsonPropertyName("tenant")]
        public string? Tenant { get; init; }

        [JsonPropertyName("confidence")]
        public double? Confidence { get; init; }

        [JsonPropertyName("createdAt")]
        public DateTimeOffset? CreatedAt { get; init; }

        [JsonPropertyName("builtByJobId")]
        public string? BuiltByJobId { get; init; }

        [JsonPropertyName("observationIds")]
        public string[]? ObservationIds { get; init; }

        [JsonPropertyName("normalized")]
        public LinksetNormalizedDto? Normalized { get; init; }

        [JsonPropertyName("conflicts")]
        public LinksetConflictDto[]? Conflicts { get; init; }
    }

    private sealed record LinksetNormalizedDto
    {
        [JsonPropertyName("purls")]
        public IReadOnlyList<string>? Purls { get; init; }

        [JsonPropertyName("cpes")]
        public IReadOnlyList<string>? Cpes { get; init; }

        [JsonPropertyName("versions")]
        public IReadOnlyList<string>? Versions { get; init; }

        [JsonPropertyName("ranges")]
        public IReadOnlyList<Dictionary<string, object?>>? Ranges { get; init; }

        [JsonPropertyName("severities")]
        public IReadOnlyList<Dictionary<string, object?>>? Severities { get; init; }
    }

    private sealed record LinksetConflictDto
    {
        [JsonPropertyName("field")]
        public string Field { get; init; } = string.Empty;

        [JsonPropertyName("reason")]
        public string? Reason { get; init; }

        [JsonPropertyName("values")]
        public IReadOnlyList<string>? Values { get; init; }

        [JsonPropertyName("sourceIds")]
        public IReadOnlyList<string>? SourceIds { get; init; }
    }
}