using System;
using System.Linq;
using Jellyfin.Plugin.SRFPlay.Api.Models;
using Jellyfin.Plugin.SRFPlay.Configuration;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Plugin.SRFPlay.Services;

/// <summary>
/// Service for resolving stream URLs from media composition resources.
/// </summary>
public class StreamUrlResolver
{
    private readonly ILogger<StreamUrlResolver> _logger;

    /// <summary>
    /// Initializes a new instance of the <see cref="StreamUrlResolver"/> class.
    /// </summary>
    /// <param name="logger">The logger instance.</param>
    public StreamUrlResolver(ILogger<StreamUrlResolver> logger)
    {
        _logger = logger;
    }

    /// <summary>
    /// Gets the best stream URL from a chapter based on quality preference.
    /// </summary>
    /// <param name="chapter">The chapter containing resources.</param>
    /// <param name="qualityPreference">The quality preference.</param>
    /// <returns>The stream URL, or null if no suitable stream found.</returns>
    public string? GetStreamUrl(Chapter chapter, QualityPreference qualityPreference)
    {
        if (chapter?.ResourceList == null || chapter.ResourceList.Count == 0)
        {
            _logger.LogWarning("No resources found for chapter: {ChapterId}", chapter?.Id);
            return null;
        }

        _logger.LogInformation(
            "Processing chapter {ChapterId} with {ResourceCount} resources",
            chapter.Id,
            chapter.ResourceList.Count);

        // Filter out DRM-protected content
        var nonDrmResources = chapter.ResourceList
            .Where(r => r.DrmList == null || r.DrmList.ToString() == "[]")
            .ToList();

        _logger.LogInformation(
            "Chapter {ChapterId}: Total resources={Total}, Non-DRM resources={NonDrm}",
            chapter.Id,
            chapter.ResourceList.Count,
            nonDrmResources.Count);

        if (nonDrmResources.Count == 0)
        {
            _logger.LogWarning("All resources for chapter {ChapterId} require DRM", chapter.Id);
            // Log what DRM types are present
            foreach (var resource in chapter.ResourceList)
            {
                _logger.LogDebug(
                    "DRM resource: Protocol={Protocol}, Streaming={Streaming}, DRM={Drm}",
                    resource.Protocol,
                    resource.Streaming,
                    resource.DrmList);
            }

            return null;
        }

        // Prefer HLS protocol
        var hlsResources = nonDrmResources
            .Where(r => string.Equals(r.Protocol, "HLS", StringComparison.OrdinalIgnoreCase) ||
                       string.Equals(r.Streaming, "HLS", StringComparison.OrdinalIgnoreCase) ||
                       r.Url.Contains(".m3u8", StringComparison.OrdinalIgnoreCase))
            .ToList();

        _logger.LogInformation(
            "Chapter {ChapterId}: HLS resources found={HlsCount}",
            chapter.Id,
            hlsResources.Count);

        if (hlsResources.Count == 0)
        {
            _logger.LogWarning("No HLS resources found for chapter: {ChapterId}", chapter.Id);
            // Log available protocols
            foreach (var resource in nonDrmResources)
            {
                _logger.LogDebug(
                    "Non-HLS resource: Protocol={Protocol}, Streaming={Streaming}, URL={Url}",
                    resource.Protocol,
                    resource.Streaming,
                    resource.Url);
            }

            // Fallback to any available non-DRM resource
            var fallbackResource = nonDrmResources.FirstOrDefault();
            if (fallbackResource != null)
            {
                _logger.LogInformation(
                    "Using fallback resource for chapter {ChapterId}: {Url}",
                    chapter.Id,
                    fallbackResource.Url);
            }

            return fallbackResource?.Url;
        }

        // Select based on quality preference
        Resource? selectedResource = qualityPreference switch
        {
            QualityPreference.HD => SelectHDResource(hlsResources) ?? SelectBestAvailableResource(hlsResources),
            QualityPreference.SD => SelectSDResource(hlsResources) ?? SelectBestAvailableResource(hlsResources),
            QualityPreference.Auto => SelectBestAvailableResource(hlsResources),
            _ => SelectBestAvailableResource(hlsResources)
        };

        if (selectedResource != null)
        {
            _logger.LogDebug(
                "Selected stream for chapter {ChapterId}: Quality={Quality}, Protocol={Protocol}, URL={Url}",
                chapter.Id,
                selectedResource.Quality,
                selectedResource.Protocol,
                selectedResource.Url);
            return selectedResource.Url;
        }

        _logger.LogWarning("Could not select appropriate stream for chapter: {ChapterId}", chapter.Id);
        return null;
    }

    /// <summary>
    /// Checks if a chapter has non-DRM playable content.
    /// </summary>
    /// <param name="chapter">The chapter to check.</param>
    /// <returns>True if playable content is available.</returns>
    public bool HasPlayableContent(Chapter chapter)
    {
        if (chapter?.ResourceList == null || chapter.ResourceList.Count == 0)
        {
            return false;
        }

        return chapter.ResourceList.Any(r => r.DrmList == null || r.DrmList.ToString() == "[]");
    }

    /// <summary>
    /// Checks if content is expired based on ValidTo date.
    /// </summary>
    /// <param name="chapter">The chapter to check.</param>
    /// <returns>True if the content is expired.</returns>
    public bool IsContentExpired(Chapter chapter)
    {
        if (chapter?.ValidTo == null)
        {
            return false;
        }

        return DateTime.UtcNow > chapter.ValidTo.Value.ToUniversalTime();
    }

    private Resource? SelectHDResource(System.Collections.Generic.List<Resource> resources)
    {
        return resources.FirstOrDefault(r =>
            string.Equals(r.Quality, "HD", StringComparison.OrdinalIgnoreCase) ||
            string.Equals(r.Quality, "1080", StringComparison.OrdinalIgnoreCase) ||
            string.Equals(r.Quality, "720", StringComparison.OrdinalIgnoreCase));
    }

    private Resource? SelectSDResource(System.Collections.Generic.List<Resource> resources)
    {
        return resources.FirstOrDefault(r =>
            string.Equals(r.Quality, "SD", StringComparison.OrdinalIgnoreCase) ||
            string.Equals(r.Quality, "480", StringComparison.OrdinalIgnoreCase) ||
            string.Equals(r.Quality, "360", StringComparison.OrdinalIgnoreCase));
    }

    private Resource? SelectBestAvailableResource(System.Collections.Generic.List<Resource> resources)
    {
        // Try HD first
        var hdResource = SelectHDResource(resources);
        if (hdResource != null)
        {
            return hdResource;
        }

        // Fall back to SD
        var sdResource = SelectSDResource(resources);
        if (sdResource != null)
        {
            return sdResource;
        }

        // Return first available
        return resources.FirstOrDefault();
    }
}