using System.Collections.Generic;
using System.Security.Claims;
using System.Threading;
using System.Threading.Tasks;
using GermanApp.Application.DTOs;
using GermanApp.Application.Services;
using GermanApp.Domain.Interfaces;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;

namespace GermanApp.Presentation.Controllers;

/// <summary>
/// API controller for story operations.
/// This is part of the Presentation layer.
/// </summary>
[ApiController]
[Route("api/[controller]")]
[Authorize] // All story endpoints require authentication
public class StoryController : ControllerBase
{
    private readonly StoryService _storyService;
    private readonly StoryGenerationService _generationService;
    private readonly StoryUnlockService _unlockService;
    private readonly ILevelRepository _levelRepository;
    private readonly ILessonRepository _lessonRepository;
    private readonly ILogger<StoryController> _logger;

    /// <summary>
    /// Creates a new StoryController.
    /// </summary>
    /// <param name="storyService">Service for story operations</param>
    /// <param name="generationService">Service for story generation</param>
    /// <param name="unlockService">Service for story unlocking</param>
    /// <param name="levelRepository">Repository for levels</param>
    /// <param name="lessonRepository">Repository for lessons</param>
    /// <param name="logger">Logger for controller operations</param>
    public StoryController(
        StoryService storyService,
        StoryGenerationService generationService,
        StoryUnlockService unlockService,
        ILevelRepository levelRepository,
        ILessonRepository lessonRepository,
        ILogger<StoryController> logger)
    {
        _storyService = storyService;
        _generationService = generationService;
        _unlockService = unlockService;
        _levelRepository = levelRepository;
        _lessonRepository = lessonRepository;
        _logger = logger;
    }

    /// <summary>
    /// Gets all levels that have stories.
    /// </summary>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>List of levels with story segments</returns>
    [HttpGet("levels")]
    public async Task<ActionResult<IReadOnlyList<LevelWithStoriesDto>>> GetLevelsWithStoriesAsync(
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Getting levels with stories");

        var levels = await _levelRepository.GetAllOrderedAsync(cancellationToken);
        
        var result = new List<LevelWithStoriesDto>();
        foreach (var level in levels)
        {
            var segments = await _storyService.GetByLevelAsync(level.Id, false, cancellationToken);
            var hasStories = segments.Count > 0;
            
            result.Add(new LevelWithStoriesDto(
                level.Id,
                level.Name,
                level.Code,
                level.Order,
                hasStories,
                segments.Count));
        }

        return Ok(result);
    }

    /// <summary>
    /// Gets all story segments for a specific level.
    /// </summary>
    /// <param name="levelId">The level ID</param>
    /// <param name="includeInactive">Whether to include inactive segments</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>List of story segments for the level</returns>
    [HttpGet("levels/{levelId}/segments")]
    public async Task<ActionResult<IReadOnlyList<StorySegmentDto>>> GetSegmentsByLevelAsync(
        int levelId,
        [FromQuery] bool includeInactive = false,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Getting story segments for level {LevelId}", levelId);

        var segments = await _storyService.GetByLevelAsync(levelId, includeInactive, cancellationToken);
        
        if (!segments.Any())
        {
            _logger.LogInformation("No story segments found for level {LevelId}", levelId);
            return Ok(new List<StorySegmentDto>()); // Return empty list instead of NotFound
        }

        return Ok(segments);
    }

    /// <summary>
    /// Gets a specific story segment by ID.
    /// </summary>
    /// <param name="id">The segment ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>The story segment</returns>
    [HttpGet("segments/{id}")]
    public async Task<ActionResult<StorySegmentDto>> GetSegmentByIdAsync(
        int id,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Getting story segment by ID: {Id}", id);

        var segment = await _storyService.GetByIdAsync(id, cancellationToken);
        
        if (segment == null)
        {
            _logger.LogWarning("Story segment not found: {Id}", id);
            return NotFound();
        }

        return Ok(segment);
    }

    /// <summary>
    /// Creates a new story segment (Admin only).
    /// </summary>
    /// <param name="dto">The DTO containing segment data</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>The created story segment</returns>
    [HttpPost("segments")]
    [Authorize(Roles = "Admin")]
    public async Task<ActionResult<StorySegmentDto>> CreateSegmentAsync(
        [FromBody] CreateStorySegmentDto dto,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Creating story segment");

        try
        {
            var created = await _storyService.CreateAsync(dto, cancellationToken);
            return CreatedAtAction(nameof(GetSegmentByIdAsync), new { id = created.Id }, created);
        }
        catch (InvalidOperationException ex)
        {
            _logger.LogError(ex, "Failed to create story segment");
            return Conflict(ex.Message);
        }
    }

    /// <summary>
    /// Updates an existing story segment (Admin only).
    /// </summary>
    /// <param name="id">The segment ID</param>
    /// <param name="dto">The DTO containing updated data</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>The updated story segment</returns>
    [HttpPut("segments/{id}")]
    [Authorize(Roles = "Admin")]
    public async Task<ActionResult<StorySegmentDto>> UpdateSegmentAsync(
        int id,
        [FromBody] UpdateStorySegmentDto dto,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Updating story segment {Id}", id);

        var updated = await _storyService.UpdateAsync(id, dto, cancellationToken);
        
        if (updated == null)
        {
            _logger.LogWarning("Story segment not found for update: {Id}", id);
            return NotFound();
        }

        return Ok(updated);
    }

    /// <summary>
    /// Deletes a story segment (Admin only).
    /// </summary>
    /// <param name="id">The segment ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>No content if successful</returns>
    [HttpDelete("segments/{id}")]
    [Authorize(Roles = "Admin")]
    public async Task<IActionResult> DeleteSegmentAsync(
        int id,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Deleting story segment {Id}", id);

        var deleted = await _storyService.DeleteAsync(id, cancellationToken);
        
        if (!deleted)
        {
            _logger.LogWarning("Story segment not found for deletion: {Id}", id);
            return NotFound();
        }

        return NoContent();
    }

    /// <summary>
    /// Generates a story for a level using AI.
    /// </summary>
    /// <param name="levelId">The level ID</param>
    /// <param name="request">The generation request</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>The generated story with segments</returns>
    [HttpPost("levels/{levelId}/generate")]
    [Authorize(Roles = "Admin")]
    public async Task<ActionResult<StoryGenerationResponseDto>> GenerateStoryAsync(
        int levelId,
        [FromBody] StoryGenerationRequestDto request,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Generating story for level {LevelId} with theme '{Theme}'",
            levelId, request.Theme);

        try
        {
            // Get all lessons for the level
            var lessons = await _lessonRepository.GetByLevelAsync(levelId, cancellationToken);
            
            if (!lessons.Any())
            {
                _logger.LogWarning("No lessons found for level {LevelId}", levelId);
                return BadRequest("No lessons found for this level");
            }

            var response = await _generationService.GenerateStoryAsync(
                levelId,
                request.Theme,
                lessons,
                request.SegmentCount,
                request.CustomPrompt,
                cancellationToken);

            return Ok(response);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to generate story for level {LevelId}", levelId);
            return StatusCode(500, ex.Message);
        }
    }

    /// <summary>
    /// Generates audio for a specific story segment.
    /// </summary>
    /// <param name="segmentId">The segment ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>The updated segment with audio URL</returns>
    [HttpPost("segments/{segmentId}/audio")]
    [Authorize(Roles = "Admin")]
    public async Task<ActionResult<StorySegmentDto>> GenerateSegmentAudioAsync(
        int segmentId,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Generating audio for story segment {SegmentId}", segmentId);

        try
        {
            var result = await _generationService.GenerateAudioAsync(segmentId, cancellationToken);
            
            if (result == null)
            {
                _logger.LogWarning("Segment not found or audio generation failed: {SegmentId}", segmentId);
                return NotFound();
            }

            return Ok(result);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to generate audio for segment {SegmentId}", segmentId);
            return StatusCode(500, ex.Message);
        }
    }

    /// <summary>
    /// Gets the user's progress through a story for a level.
    /// </summary>
    /// <param name="levelId">The level ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>The user's story progress</returns>
    [HttpGet("levels/{levelId}/progress")]
    public async Task<ActionResult<StoryProgressDto>> GetUserProgressAsync(
        int levelId,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Getting story progress for user in level {LevelId}", levelId);

        var userId = GetUserId();
        
        var progress = await _unlockService.GetUserProgressAsync(userId, levelId, cancellationToken);
        
        return Ok(progress);
    }

    /// <summary>
    /// Marks a story segment as completed (read/listened to).
    /// </summary>
    /// <param name="segmentId">The segment ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>No content if successful</returns>
    [HttpPost("segments/{segmentId}/complete")]
    public async Task<IActionResult> MarkSegmentAsCompletedAsync(
        int segmentId,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Marking segment {SegmentId} as completed", segmentId);

        var userId = GetUserId();
        
        var success = await _unlockService.MarkSegmentAsCompletedAsync(
            userId, segmentId, cancellationToken);
        
        if (!success)
        {
            _logger.LogWarning("Failed to mark segment {SegmentId} as completed for user {UserId}",
                segmentId, userId);
            return NotFound();
        }

        return NoContent();
    }

    /// <summary>
    /// Gets the next story segment for a user to read.
    /// </summary>
    /// <param name="levelId">The level ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>The next segment to read</returns>
    [HttpGet("levels/{levelId}/next")]
    public async Task<ActionResult<StorySegmentDto?>> GetNextSegmentAsync(
        int levelId,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Getting next story segment for user in level {LevelId}", levelId);

        var userId = GetUserId();
        
        // Get user's progress
        var progress = await _unlockService.GetUserProgressAsync(userId, levelId, cancellationToken);
        
        // Find the first unlocked but not completed segment
        foreach (var segmentProgress in progress.Segments.OrderBy(s => s.Order))
        {
            if (segmentProgress.IsUnlocked && !segmentProgress.IsCompleted)
            {
                var segment = await _storyService.GetByIdAsync(segmentProgress.SegmentId, cancellationToken);
                if (segment != null)
                {
                    return Ok(segment);
                }
            }
        }

        // If no segment is unlocked, check if we can unlock one
        // This would typically be triggered by lesson completion, but we can check here too
        return Ok(null); // No segment available
    }

    /// <summary>
    /// Checks if a specific segment is unlocked for the current user.
    /// </summary>
    /// <param name="segmentId">The segment ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>True if unlocked</returns>
    [HttpGet("segments/{segmentId}/unlocked")]
    public async Task<ActionResult<bool>> IsSegmentUnlockedAsync(
        int segmentId,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Checking if segment {SegmentId} is unlocked", segmentId);

        var userId = GetUserId();
        
        var isUnlocked = await _unlockService.IsSegmentUnlockedAsync(userId, segmentId, cancellationToken);
        
        return Ok(isUnlocked);
    }

    /// <summary>
    /// Gets the audio file for a story segment.
    /// </summary>
    /// <param name="segmentId">The segment ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>The audio file</returns>
    [HttpGet("segments/{segmentId}/audio")]
    public async Task<IActionResult> GetSegmentAudioAsync(
        int segmentId,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Getting audio for segment {SegmentId}", segmentId);

        var segment = await _storyService.GetByIdAsync(segmentId, cancellationToken);
        
        if (segment == null || string.IsNullOrEmpty(segment.AudioUrl))
        {
            _logger.LogWarning("Segment not found or no audio: {SegmentId}", segmentId);
            return NotFound();
        }

        // Static files are served from wwwroot, and audio files are stored at wwwroot/audio/story/
        // The segment.AudioUrl is already in the format "/audio/story/levelN-segmentM.wav"
        // The static file middleware will serve it automatically
        return Ok(new { AudioUrl = segment.AudioUrl });
    }

    /// <summary>
    /// Gets all lessons in a level with their associated story segments.
    /// </summary>
    /// <param name="levelId">The level ID</param>
    /// <param name="cancellationToken">Cancellation token</param>
    /// <returns>List of lessons with story segment status</returns>
    [HttpGet("levels/{levelId}/lessons-with-stories")]
    public async Task<ActionResult<IReadOnlyList<LessonWithStoryStatusDto>>> GetLessonsWithStoryStatusAsync(
        int levelId,
        CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Getting lessons with story status for level {LevelId}", levelId);

        var lessons = await _lessonRepository.GetByLevelAsync(levelId, cancellationToken);
        var segments = await _storyService.GetByLevelAsync(levelId, false, cancellationToken);
        
        var result = new List<LessonWithStoryStatusDto>();
        foreach (var lesson in lessons)
        {
            var lessonSegments = segments.Where(s => s.LessonId == lesson.Id).ToList();
            
            result.Add(new LessonWithStoryStatusDto(
                lesson.Id,
                lesson.Title,
                lesson.Order,
                lesson.Topic,
                lessonSegments.Count > 0,
                lessonSegments.Count));
        }

        return Ok(result);
    }

    /// <summary>
    /// Gets the current user's ID from the JWT claims.
    /// </summary>
    /// <returns>The user ID</returns>
    private int GetUserId()
    {
        // Note: JWT "sub" claim is mapped by ASP.NET Core JWT middleware to ClaimTypes.NameIdentifier
        var userIdClaim = User.FindFirst(ClaimTypes.NameIdentifier) ?? User.FindFirst("sub");
        
        if (userIdClaim == null || !int.TryParse(userIdClaim.Value, out var userId))
        {
            throw new UnauthorizedAccessException("User ID not found in token");
        }
        
        return userId;
    }
}

/// <summary>
/// DTO for level with story information.
/// </summary>
public record LevelWithStoriesDto(
    int Id,
    string Name,
    string Code,
    int Order,
    bool HasStories,
    int StorySegmentCount);

/// <summary>
/// DTO for lesson with story segment status.
/// </summary>
public record LessonWithStoryStatusDto(
    int Id,
    string Title,
    int Order,
    string Topic,
    bool HasStorySegment,
    int StorySegmentCount);