using System;
using System.Collections.Generic;
using System.Linq;
using Jellyfin.Data.Enums;
using Jellyfin.Plugin.JRay.Models;
using Jellyfin.Plugin.JRay.Services;
using Jellyfin.Plugin.JRay.Services.Interfaces;
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;

namespace Jellyfin.Plugin.JRay.Controllers;

/// <summary>
/// Reports how much of the library has truth data (overall, by media type, and
/// by genre), and supplies the genre/series option lists the config page's
/// rule editor needs.
/// </summary>
[ApiController]
[Route("Plugins/JRay/Coverage")]
[Authorize(Roles = "Administrator")]
public class CoverageController : ControllerBase
{
    private readonly ILibraryManager _libraryManager;
    private readonly ITruthDataService _truthDataService;
    private readonly IMediaPolicyStore _policyStore;

    /// <summary>
    /// Initializes a new instance of the <see cref="CoverageController"/> class.
    /// </summary>
    /// <param name="libraryManager">The Jellyfin library manager.</param>
    /// <param name="truthDataService">The truth data service.</param>
    /// <param name="policyStore">The media policy store.</param>
    public CoverageController(ILibraryManager libraryManager, ITruthDataService truthDataService, IMediaPolicyStore policyStore)
    {
        _libraryManager = libraryManager;
        _truthDataService = truthDataService;
        _policyStore = policyStore;
    }

    /// <summary>
    /// Gets the coverage report: totals plus breakdowns by media type and by genre.
    /// </summary>
    /// <returns>The coverage report.</returns>
    [HttpGet]
    [ProducesResponseType(StatusCodes.Status200OK)]
    public ActionResult<CoverageReport> GetCoverage()
    {
        var rules = _policyStore.GetRules();

        var items = _libraryManager.GetItemList(new InternalItemsQuery
        {
            IncludeItemTypes = new[] { BaseItemKind.Movie, BaseItemKind.Episode },
            IsVirtualItem = false,
            Recursive = true,
        });

        var report = new CoverageReport();
        var byMediaType = new Dictionary<string, CoverageCounts>(StringComparer.Ordinal);
        var byGenre = new Dictionary<string, CoverageCounts>(StringComparer.OrdinalIgnoreCase);

        foreach (var item in items)
        {
            if (!TasksController.MediaFileExists(item))
            {
                continue;
            }

            var covered = _truthDataService.HasTruth(item.Id, item.Path);
            var action = PolicyResolver.Resolve(rules, item.Id, TasksController.GetSeriesId(item), item.Genres);

            Accumulate(report.Total, covered, action);
            Accumulate(GetBucket(byMediaType, MediaTypeLabel(item)), covered, action);

            foreach (var genre in item.Genres)
            {
                if (!string.IsNullOrWhiteSpace(genre))
                {
                    Accumulate(GetBucket(byGenre, genre), covered, action);
                }
            }
        }

        foreach (var kvp in byMediaType.OrderBy(k => k.Key, StringComparer.Ordinal))
        {
            report.ByMediaType.Add(new CoverageBreakdownRow { Label = kvp.Key, Counts = kvp.Value });
        }

        foreach (var kvp in byGenre.OrderBy(k => k.Key, StringComparer.OrdinalIgnoreCase))
        {
            report.ByGenre.Add(new CoverageBreakdownRow { Label = kvp.Key, Counts = kvp.Value });
        }

        return Ok(report);
    }

    /// <summary>
    /// Gets the distinct genres present on movies/episodes, for the rule editor.
    /// </summary>
    /// <returns>Genre options, sorted by name.</returns>
    [HttpGet("Genres")]
    [ProducesResponseType(StatusCodes.Status200OK)]
    public ActionResult<IEnumerable<PickerOption>> GetGenres()
    {
        var items = _libraryManager.GetItemList(new InternalItemsQuery
        {
            IncludeItemTypes = new[] { BaseItemKind.Movie, BaseItemKind.Episode },
            IsVirtualItem = false,
            Recursive = true,
        });

        var genres = items
            .SelectMany(item => item.Genres)
            .Where(g => !string.IsNullOrWhiteSpace(g))
            .Distinct(StringComparer.OrdinalIgnoreCase)
            .OrderBy(g => g, StringComparer.OrdinalIgnoreCase)
            .Select(g => new PickerOption { Value = g, Label = g });

        return Ok(genres);
    }

    /// <summary>
    /// Gets the series in the library, for the rule editor's series picker.
    /// </summary>
    /// <returns>Series options (id + title), sorted by title.</returns>
    [HttpGet("Series")]
    [ProducesResponseType(StatusCodes.Status200OK)]
    public ActionResult<IEnumerable<PickerOption>> GetSeries()
    {
        var series = _libraryManager.GetItemList(new InternalItemsQuery
        {
            IncludeItemTypes = new[] { BaseItemKind.Series },
            IsVirtualItem = false,
            Recursive = true,
        });

        var options = series
            .OrderBy(s => s.Name, StringComparer.OrdinalIgnoreCase)
            .Select(s => new PickerOption { Value = s.Id.ToString("D"), Label = s.Name });

        return Ok(options);
    }

    /// <summary>
    /// Searches movies/episodes by name, for the rule editor's item picker.
    /// </summary>
    /// <param name="search">A name fragment to match (case-insensitive). Required.</param>
    /// <param name="limit">The maximum number of results (default 25, max 100).</param>
    /// <returns>Matching item options (id + name), sorted by name.</returns>
    [HttpGet("Items")]
    [ProducesResponseType(StatusCodes.Status200OK)]
    public ActionResult<IEnumerable<PickerOption>> SearchItems([FromQuery] string? search, [FromQuery] int limit = 25)
    {
        if (string.IsNullOrWhiteSpace(search))
        {
            return Ok(Array.Empty<PickerOption>());
        }

        var items = _libraryManager.GetItemList(new InternalItemsQuery
        {
            IncludeItemTypes = new[] { BaseItemKind.Movie, BaseItemKind.Episode },
            IsVirtualItem = false,
            Recursive = true,
            SearchTerm = search,
            Limit = Math.Clamp(limit, 1, 100),
        });

        var options = items
            .OrderBy(i => i.Name, StringComparer.OrdinalIgnoreCase)
            .Select(i => new PickerOption { Value = i.Id.ToString("D"), Label = ItemLabel(i) });

        return Ok(options);
    }

    private static string ItemLabel(BaseItem item)
    {
        // Give episodes a series-qualified label so identically-named episodes
        // (e.g. "Pilot") are distinguishable in the picker.
        if (item is Episode episode && !string.IsNullOrEmpty(episode.SeriesName))
        {
            return episode.SeriesName + " — " + item.Name;
        }

        return item.Name;
    }

    private static void Accumulate(CoverageCounts counts, bool covered, PolicyAction? action)
    {
        counts.Total++;

        if (action == PolicyAction.Ignore)
        {
            counts.Ignored++;
            return;
        }

        if (covered)
        {
            counts.Covered++;
            return;
        }

        counts.Pending++;
        if (action == PolicyAction.Prioritise)
        {
            counts.Prioritised++;
        }
    }

    private static CoverageCounts GetBucket(Dictionary<string, CoverageCounts> buckets, string key)
    {
        if (!buckets.TryGetValue(key, out var counts))
        {
            counts = new CoverageCounts();
            buckets[key] = counts;
        }

        return counts;
    }

    private static string MediaTypeLabel(BaseItem item)
    {
        return item.GetBaseItemKind() == BaseItemKind.Episode ? "TV" : "Film";
    }
}