using StellaOps.TaskRunner.Core.Execution;
using System.Text.Json;
using System.Text.Json.Nodes;

namespace StellaOps.TaskRunner.Infrastructure.Execution;

public sealed class FilePackRunApprovalStore : IPackRunApprovalStore
{
    private readonly string rootPath;
    private readonly JsonSerializerOptions serializerOptions = new(JsonSerializerDefaults.Web)
    {
        WriteIndented = true
    };

    public FilePackRunApprovalStore(string rootPath)
    {
        ArgumentException.ThrowIfNullOrWhiteSpace(rootPath);
        this.rootPath = rootPath;
        Directory.CreateDirectory(rootPath);
    }

    public Task SaveAsync(string runId, IReadOnlyList<PackRunApprovalState> approvals, CancellationToken cancellationToken)
    {
        var path = GetFilePath(runId);
        var json = SerializeApprovals(approvals);
        File.WriteAllText(path, json);
        return Task.CompletedTask;
    }

    public Task<IReadOnlyList<PackRunApprovalState>> GetAsync(string runId, CancellationToken cancellationToken)
    {
        var path = GetFilePath(runId);
        if (!File.Exists(path))
        {
            return Task.FromResult((IReadOnlyList<PackRunApprovalState>)Array.Empty<PackRunApprovalState>());
        }

        var json = File.ReadAllText(path);
        var approvals = DeserializeApprovals(json);
        return Task.FromResult((IReadOnlyList<PackRunApprovalState>)approvals);
    }

    public async Task UpdateAsync(string runId, PackRunApprovalState approval, CancellationToken cancellationToken)
    {
        var approvals = (await GetAsync(runId, cancellationToken).ConfigureAwait(false)).ToList();
        var index = approvals.FindIndex(existing => string.Equals(existing.ApprovalId, approval.ApprovalId, StringComparison.Ordinal));
        if (index < 0)
        {
            throw new InvalidOperationException($"Approval '{approval.ApprovalId}' not found for run '{runId}'.");
        }

        approvals[index] = approval;
        await SaveAsync(runId, approvals, cancellationToken).ConfigureAwait(false);
    }

    private string GetFilePath(string runId)
    {
        var safeFile = $"{runId}.json";
        return Path.Combine(rootPath, safeFile);
    }

    private string SerializeApprovals(IReadOnlyList<PackRunApprovalState> approvals)
    {
        var array = new JsonArray();
        foreach (var approval in approvals)
        {
            var node = new JsonObject
            {
                ["approvalId"] = approval.ApprovalId,
                ["status"] = approval.Status.ToString(),
                ["requestedAt"] = approval.RequestedAt,
                ["actorId"] = approval.ActorId,
                ["completedAt"] = approval.CompletedAt,
                ["summary"] = approval.Summary,
                ["requiredGrants"] = new JsonArray(approval.RequiredGrants.Select(grant => (JsonNode)grant).ToArray()),
                ["stepIds"] = new JsonArray(approval.StepIds.Select(step => (JsonNode)step).ToArray()),
                ["messages"] = new JsonArray(approval.Messages.Select(message => (JsonNode)message).ToArray()),
                ["reasonTemplate"] = approval.ReasonTemplate
            };

            array.Add(node);
        }

        return array.ToJsonString(serializerOptions);
    }

    private static IReadOnlyList<PackRunApprovalState> DeserializeApprovals(string json)
    {
        var array = JsonNode.Parse(json)?.AsArray() ?? new JsonArray();
        var list = new List<PackRunApprovalState>(array.Count);
        foreach (var entry in array)
        {
            if (entry is not JsonObject obj)
            {
                continue;
            }

            var requiredGrants = obj["requiredGrants"]?.AsArray()?.Select(node => node!.GetValue<string>()).ToList() ?? new List<string>();
            var stepIds = obj["stepIds"]?.AsArray()?.Select(node => node!.GetValue<string>()).ToList() ?? new List<string>();
            var messages = obj["messages"]?.AsArray()?.Select(node => node!.GetValue<string>()).ToList() ?? new List<string>();
            Enum.TryParse(obj["status"]?.GetValue<string>(), ignoreCase: true, out PackRunApprovalStatus status);

            list.Add(new PackRunApprovalState(
                obj["approvalId"]?.GetValue<string>() ?? string.Empty,
                requiredGrants,
                stepIds,
                messages,
                obj["reasonTemplate"]?.GetValue<string>(),
                obj["requestedAt"]?.GetValue<DateTimeOffset>() ?? DateTimeOffset.UtcNow,
                status,
                obj["actorId"]?.GetValue<string>(),
                obj["completedAt"]?.GetValue<DateTimeOffset?>(),
                obj["summary"]?.GetValue<string>()));
        }

        return list;
    }
}