using System;
using System.Text.Json;
using System.Collections.Generic;
using StellaOps.Concelier.Bson;
using StellaOps.Concelier.Storage.Postgres.Models;
using StellaOps.Concelier.Storage.Postgres.Repositories;
using Contracts = StellaOps.Concelier.Storage.Contracts;
using MongoContracts = StellaOps.Concelier.Storage;

namespace StellaOps.Concelier.Storage.Postgres;

/// <summary>
/// Adapter that satisfies the legacy source state contract using PostgreSQL storage and provides a Postgres-native cursor contract.
/// </summary>
public sealed class PostgresSourceStateAdapter : MongoContracts.ISourceStateRepository, Contracts.ISourceStateStore
{
    private readonly ISourceRepository _sourceRepository;
    private readonly Repositories.ISourceStateRepository _stateRepository;
    private readonly TimeProvider _timeProvider;

    public PostgresSourceStateAdapter(
        ISourceRepository sourceRepository,
        Repositories.ISourceStateRepository stateRepository,
        TimeProvider? timeProvider = null)
    {
        _sourceRepository = sourceRepository ?? throw new ArgumentNullException(nameof(sourceRepository));
        _stateRepository = stateRepository ?? throw new ArgumentNullException(nameof(stateRepository));
        _timeProvider = timeProvider ?? TimeProvider.System;
    }

    public async Task<MongoContracts.SourceStateRecord?> TryGetAsync(string sourceName, CancellationToken cancellationToken)
    {
        ArgumentException.ThrowIfNullOrEmpty(sourceName);

        var source = await _sourceRepository.GetByKeyAsync(sourceName, cancellationToken).ConfigureAwait(false);
        if (source is null)
        {
            return null;
        }

        var state = await _stateRepository.GetBySourceIdAsync(source.Id, cancellationToken).ConfigureAwait(false);
        if (state is null)
        {
            return null;
        }

        var cursor = string.IsNullOrWhiteSpace(state.Cursor) ? null : BsonDocument.Parse(state.Cursor);
        var backoffUntil = TryParseBackoffUntil(state.Metadata);
        return new MongoContracts.SourceStateRecord(
            sourceName,
            Enabled: true,
            Paused: false,
            Cursor: cursor,
            LastSuccess: state.LastSuccessAt,
            LastFailure: state.LastError is null ? null : state.LastSyncAt,
            FailCount: state.ErrorCount,
            BackoffUntil: backoffUntil,
            UpdatedAt: state.UpdatedAt,
            LastFailureReason: state.LastError);
    }

    public async Task UpdateCursorAsync(string sourceName, BsonDocument cursor, DateTimeOffset completedAt, CancellationToken cancellationToken)
    {
        ArgumentException.ThrowIfNullOrEmpty(sourceName);
        ArgumentNullException.ThrowIfNull(cursor);

        var source = await EnsureSourceAsync(sourceName, cancellationToken).ConfigureAwait(false);
        var existing = await _stateRepository.GetBySourceIdAsync(source.Id, cancellationToken).ConfigureAwait(false);

        var entity = new SourceStateEntity
        {
            Id = existing?.Id ?? Guid.NewGuid(),
            SourceId = source.Id,
            Cursor = cursor.ToJson(),
            LastSyncAt = completedAt,
            LastSuccessAt = completedAt,
            LastError = null,
            SyncCount = (existing?.SyncCount ?? 0) + 1,
            ErrorCount = existing?.ErrorCount ?? 0,
            Metadata = existing?.Metadata ?? "{}",
            UpdatedAt = completedAt
        };

        _ = await _stateRepository.UpsertAsync(entity, cancellationToken).ConfigureAwait(false);
    }

    public async Task MarkFailureAsync(string sourceName, DateTimeOffset now, TimeSpan backoff, string reason, CancellationToken cancellationToken)
    {
        ArgumentException.ThrowIfNullOrEmpty(sourceName);

        var source = await EnsureSourceAsync(sourceName, cancellationToken).ConfigureAwait(false);
        var existing = await _stateRepository.GetBySourceIdAsync(source.Id, cancellationToken).ConfigureAwait(false);
        var backoffUntil = SafeAdd(now, backoff);

        var metadata = new Dictionary<string, object?>(StringComparer.Ordinal)
        {
            ["backoffUntil"] = backoffUntil.ToString("O"),
            ["reason"] = reason
        };

        var entity = new SourceStateEntity
        {
            Id = existing?.Id ?? Guid.NewGuid(),
            SourceId = source.Id,
            Cursor = existing?.Cursor,
            LastSyncAt = now,
            LastSuccessAt = existing?.LastSuccessAt,
            LastError = reason,
            SyncCount = existing?.SyncCount ?? 0,
            ErrorCount = (existing?.ErrorCount ?? 0) + 1,
            Metadata = JsonSerializer.Serialize(metadata, new JsonSerializerOptions(JsonSerializerDefaults.Web)),
            UpdatedAt = now
        };

        _ = await _stateRepository.UpsertAsync(entity, cancellationToken).ConfigureAwait(false);
    }

    public async Task UpsertAsync(MongoContracts.SourceStateRecord record, CancellationToken cancellationToken)
    {
        ArgumentNullException.ThrowIfNull(record);
        var source = await EnsureSourceAsync(record.SourceName, cancellationToken).ConfigureAwait(false);
        var entity = new SourceStateEntity
        {
            Id = Guid.NewGuid(),
            SourceId = source.Id,
            Cursor = record.Cursor?.ToJson(),
            LastSyncAt = record.UpdatedAt,
            LastSuccessAt = record.LastSuccess,
            LastError = record.LastFailureReason,
            SyncCount = record.FailCount,
            ErrorCount = record.FailCount,
            Metadata = "{}",
            UpdatedAt = record.UpdatedAt
        };

        _ = await _stateRepository.UpsertAsync(entity, cancellationToken).ConfigureAwait(false);
    }

    async Task<Contracts.SourceCursorState?> Contracts.ISourceStateStore.TryGetAsync(string sourceName, CancellationToken cancellationToken)
        => (await TryGetAsync(sourceName, cancellationToken).ConfigureAwait(false))?.ToStorageCursorState();

    Task Contracts.ISourceStateStore.UpdateCursorAsync(string sourceName, JsonDocument cursor, DateTimeOffset completedAt, CancellationToken cancellationToken)
        => UpdateCursorAsync(sourceName, cursor.ToBsonDocument(), completedAt, cancellationToken);

    Task Contracts.ISourceStateStore.MarkFailureAsync(string sourceName, DateTimeOffset now, TimeSpan backoff, string reason, CancellationToken cancellationToken)
        => MarkFailureAsync(sourceName, now, backoff, reason, cancellationToken);

    Task Contracts.ISourceStateStore.UpsertAsync(Contracts.SourceCursorState record, CancellationToken cancellationToken)
        => UpsertAsync(record.ToMongoSourceStateRecord(), cancellationToken);

    private async Task<SourceEntity> EnsureSourceAsync(string sourceName, CancellationToken cancellationToken)
    {
        var existing = await _sourceRepository.GetByKeyAsync(sourceName, cancellationToken).ConfigureAwait(false);
        if (existing is not null)
        {
            return existing;
        }

        var now = _timeProvider.GetUtcNow();
        return await _sourceRepository.UpsertAsync(new SourceEntity
        {
            Id = Guid.NewGuid(),
            Key = sourceName,
            Name = sourceName,
            SourceType = sourceName,
            Url = null,
            Priority = 0,
            Enabled = true,
            Config = "{}",
            Metadata = "{}",
            CreatedAt = now,
            UpdatedAt = now
        }, cancellationToken).ConfigureAwait(false);
    }

    private static DateTimeOffset SafeAdd(DateTimeOffset value, TimeSpan delta)
    {
        try
        {
            return value.Add(delta);
        }
        catch (ArgumentOutOfRangeException)
        {
            return delta < TimeSpan.Zero ? DateTimeOffset.MinValue : DateTimeOffset.MaxValue;
        }
    }

    private static DateTimeOffset? TryParseBackoffUntil(string? metadata)
    {
        if (string.IsNullOrWhiteSpace(metadata))
        {
            return null;
        }

        try
        {
            using var document = JsonDocument.Parse(metadata);
            if (!document.RootElement.TryGetProperty("backoffUntil", out var backoffProperty))
            {
                return null;
            }

            if (backoffProperty.ValueKind == JsonValueKind.String
                && DateTimeOffset.TryParse(backoffProperty.GetString(), out var parsed))
            {
                return parsed;
            }
        }
        catch
        {
        }

        return null;
    }
}