using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using Jellyfin.Plugin.JRay.Configuration;
using Jellyfin.Plugin.JRay.Models;
using Jellyfin.Plugin.JRay.Services;
using Jellyfin.Plugin.JRay.Services.Interfaces;
using MediaBrowser.Common.Api;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Entities.TV;
using MediaBrowser.Controller.Library;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Plugin.JRay.Controllers;

/// <summary>
/// Fetches actor-timeline manifests from the configured public servers.
/// </summary>
// TRACES: JR-025, JR-031 | PR-006
[ApiController]
[Authorize(Policy = Policies.RequiresElevation)]
[Route("Plugins/JRay")]
[Produces("application/json")]
public class ManifestController : ControllerBase
{
    private readonly ILibraryManager _libraryManager;
    private readonly IManifestExchangeClient _exchange;
    private readonly IManagedTruthStore _truthStore;
    private readonly ManifestAligner _aligner;
    private readonly ILogger<ManifestController> _logger;

    /// <summary>
    /// Initializes a new instance of the <see cref="ManifestController"/> class.
    /// </summary>
    /// <param name="libraryManager">Library manager.</param>
    /// <param name="exchange">Manifest exchange client.</param>
    /// <param name="truthStore">Managed truth store.</param>
    /// <param name="aligner">Aligns a fetched manifest to the local file.</param>
    /// <param name="logger">Logger.</param>
    public ManifestController(
        ILibraryManager libraryManager,
        IManifestExchangeClient exchange,
        IManagedTruthStore truthStore,
        ManifestAligner aligner,
        ILogger<ManifestController> logger)
    {
        _libraryManager = libraryManager;
        _exchange = exchange;
        _truthStore = truthStore;
        _aligner = aligner;
        _logger = logger;
    }

    /// <summary>
    /// Resolves an item across the configured servers and stores the first
    /// acceptable manifest.
    /// </summary>
    /// <param name="itemId">The library item id.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>What was fetched, and from where.</returns>
    /// <response code="200">A manifest was stored.</response>
    /// <response code="404">The item does not exist, or no server had a manifest for it.</response>
    /// <response code="409">Manifest sharing is disabled in the plugin configuration.</response>
    [HttpPost("Items/{itemId}/Fetch")]
    [ProducesResponseType(StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status404NotFound)]
    [ProducesResponseType(StatusCodes.Status409Conflict)]
    public async Task<ActionResult<ManifestFetchResult>> FetchItem(
        [FromRoute] Guid itemId,
        CancellationToken cancellationToken)
    {
        var config = Plugin.Instance?.Configuration;
        if (config is null || !config.EnableManifestSharing)
        {
            // Off by default and opt-in: this is a network egress feature, so it
            // never runs merely because an endpoint was called.
            return Conflict(new { error = "manifest sharing is disabled" });
        }

        var item = _libraryManager.GetItemById(itemId);
        if (item is null)
        {
            return NotFound();
        }

        var query = BuildQuery(item);
        if (query is null)
        {
            return NotFound(new { error = "item has no TMDB or IMDB id to look up" });
        }

        var servers = config.Servers.ToList();
        var outcome = item is Episode
            ? await _exchange.FetchEpisodeAsync(servers, config.MinimumMatchTier, query, cancellationToken)
                .ConfigureAwait(false)
            : await _exchange.FetchMovieAsync(servers, config.MinimumMatchTier, query, cancellationToken)
                .ConfigureAwait(false);

        if (outcome?.Manifest is null)
        {
            return NotFound(new { error = "no configured server had an acceptable manifest" });
        }

        // Align before storing. The server has never seen this file, so where a
        // local audio alignment is possible it supersedes the offset the server
        // sent — and it needs no round trip, so no signature leaves the
        // instance (JR-047).
        var alignment = await _aligner.AlignAsync(
                item.Path ?? string.Empty,
                item.RunTimeTicks is { } ticks ? TimeSpan.FromTicks(ticks).TotalSeconds : 0.0,
                outcome.Manifest,
                outcome.Tier,
                outcome.OffsetSec,
                config.ComputeAudioSignatures,
                cancellationToken)
            .ConfigureAwait(false);

        var caveat = ManifestConverter.DescribeCaveat(alignment.Tier, alignment.OffsetSec, alignment);

        // The offset is applied here, once, so the stored truth is always in the
        // local file's own timebase and no reader needs offset awareness.
        var truth = ManifestConverter.ToTruthFile(outcome.Manifest, alignment.OffsetSec, item.Path ?? string.Empty);
        var provenance = new TruthProvenance
        {
            Source = TruthSource.Fetched,
            ServerUrl = outcome.ServerUrl,
            MatchTier = alignment.Tier,
            OffsetSec = alignment.OffsetSec,
            Alignment = alignment,
            Caveat = caveat,
            RecordedAt = DateTime.UtcNow,
        };

        await _truthStore.SaveAsync(itemId, truth, provenance, cancellationToken).ConfigureAwait(false);

        _logger.LogInformation(
            "Stored manifest for {ItemId} from {Server} at tier {Tier} (offset {Offset}s, aligned by {Source})",
            itemId,
            outcome.ServerUrl,
            alignment.Tier,
            alignment.OffsetSec,
            alignment.Source);

        return Ok(new ManifestFetchResult
        {
            ServerUrl = outcome.ServerUrl,
            Match = alignment.Tier.ToString().ToLowerInvariant(),
            OffsetSec = alignment.OffsetSec,
            ActorCount = truth.Actors.Count,
            Caveat = caveat,
        });
    }

    /// <summary>
    /// Per-server reachability and last error, for the configuration page.
    /// </summary>
    /// <returns>One entry per configured server, in configured order.</returns>
    /// <response code="200">Status for each configured server.</response>
    [HttpGet("Servers/Status")]
    [ProducesResponseType(StatusCodes.Status200OK)]
    public ActionResult<IReadOnlyList<ServerStatus>> GetServerStatus()
    {
        var config = Plugin.Instance?.Configuration;
        if (config is null)
        {
            return Ok(Array.Empty<ServerStatus>());
        }

        return Ok(_exchange.GetStatus(config.Servers.ToList()));
    }

    /// <summary>
    /// Reads a provider id from an item, or null when it is absent.
    /// </summary>
    private static string? ProviderId(BaseItem? item, string provider) =>
        item?.ProviderIds is { } ids && ids.TryGetValue(provider, out var value)
            && !string.IsNullOrWhiteSpace(value)
                ? value
                : null;

    /// <summary>
    /// Builds the lookup query from an item's provider ids and measured runtime.
    /// </summary>
    private static TitleQuery? BuildQuery(BaseItem item)
    {
        var runtimeSec = item.RunTimeTicks.HasValue
            ? TimeSpan.FromTicks(item.RunTimeTicks.Value).TotalSeconds
            : (double?)null;

        if (item is Episode episode)
        {
            var series = episode.Series;
            var seriesTmdb = ProviderId(series, "Tmdb");
            if (string.IsNullOrEmpty(seriesTmdb))
            {
                return null;
            }

            return new TitleQuery
            {
                SeriesTmdbId = seriesTmdb,
                Season = episode.ParentIndexNumber,
                Episode = episode.IndexNumber,
                RuntimeSec = runtimeSec,
            };
        }

        var tmdb = ProviderId(item, "Tmdb");
        var imdb = ProviderId(item, "Imdb");
        if (string.IsNullOrEmpty(tmdb) && string.IsNullOrEmpty(imdb))
        {
            return null;
        }

        return new TitleQuery { TmdbId = tmdb, ImdbId = imdb, RuntimeSec = runtimeSec };
    }
}