using System.Security.Claims;
using System.Text.Json;

namespace Campaign_Tracker.Server.Authorization;

public static class ApplicationRole
{
    public const string ClientServices = "ClientServices";
    public const string Production = "Production";
    public const string Transportation = "Transportation";
    public const string Support = "Support";
    public const string Admin = "Admin";

    private static readonly IReadOnlyDictionary<string, string> Aliases =
        new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
        {
            ["client-services"] = ClientServices,
            ["clientservices"] = ClientServices,
            ["production-lead"] = Production,
            ["production"] = Production,
            ["transportation"] = Transportation,
            ["support-analyst"] = Support,
            ["support"] = Support,
            ["operations-admin"] = Admin,
            ["admin"] = Admin,
        };

    public static string? Normalize(string role)
    {
        return Aliases.TryGetValue(role, out var normalized) ? normalized : null;
    }

    public static string[] NormalizeMany(IEnumerable<string> roles)
    {
        return roles
            .Select(Normalize)
            .OfType<string>()
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .ToArray();
    }

    public static bool HasAny(IEnumerable<string> roles, params string[] requiredRoles)
    {
        var normalizedRoles = NormalizeMany(roles);
        return normalizedRoles.Contains(Admin, StringComparer.OrdinalIgnoreCase) ||
               normalizedRoles.Intersect(requiredRoles, StringComparer.OrdinalIgnoreCase).Any();
    }

    public static IEnumerable<string> ExtractKeycloakRoles(IEnumerable<Claim> claims, string clientId)
    {
        foreach (var claim in claims)
        {
            if (claim.Type == ClaimTypes.Role || claim.Type == "roles")
            {
                yield return claim.Value;
                continue;
            }

            if (claim.Type == "realm_access")
            {
                foreach (var role in ExtractRolesFromJson(claim.Value))
                {
                    yield return role;
                }
                continue;
            }

            if (claim.Type == "resource_access")
            {
                foreach (var role in ExtractResourceRolesFromJson(claim.Value, clientId))
                {
                    yield return role;
                }
            }
        }
    }

    private static IEnumerable<string> ExtractRolesFromJson(string json)
    {
        using var document = ParseJsonOrDefault(json);
        if (document is null ||
            !document.RootElement.TryGetProperty("roles", out var roles) ||
            roles.ValueKind != JsonValueKind.Array)
        {
            yield break;
        }

        foreach (var role in roles.EnumerateArray())
        {
            if (role.ValueKind == JsonValueKind.String)
            {
                yield return role.GetString()!;
            }
        }
    }

    private static IEnumerable<string> ExtractResourceRolesFromJson(string json, string clientId)
    {
        using var document = ParseJsonOrDefault(json);
        if (document is null ||
            !document.RootElement.TryGetProperty(clientId, out var clientAccess))
        {
            yield break;
        }

        foreach (var role in ExtractRolesFromJson(clientAccess.GetRawText()))
        {
            yield return role;
        }
    }

    private static JsonDocument? ParseJsonOrDefault(string json)
    {
        try
        {
            return JsonDocument.Parse(json);
        }
        catch (JsonException)
        {
            return null;
        }
    }
}