using Extrudex.API.DTOs;
using Extrudex.API.DTOs.Filaments;
using Extrudex.Domain.Entities;
using Extrudex.Infrastructure.Data;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;

namespace Extrudex.API.Controllers;

/// <summary>
/// Controller for managing filament spools — the core inventory unit of Extrudex.
/// Exposes spool data under the user-facing "filaments" route while mapping
/// to the Spool domain entity internally.
/// </summary>
[ApiController]
[Route("api/filaments")]
public class FilamentsController : ControllerBase
{
    private readonly ExtrudexDbContext _dbContext;
    private readonly ILogger<FilamentsController> _logger;

    /// <summary>
    /// Initializes a new instance of the <see cref="FilamentsController"/> class.
    /// </summary>
    /// <param name="dbContext">The database context for data access.</param>
    /// <param name="logger">The logger for diagnostic output.</param>
    public FilamentsController(ExtrudexDbContext dbContext, ILogger<FilamentsController> logger)
    {
        _dbContext = dbContext;
        _logger = logger;
    }

    /// <summary>
    /// Gets a paginated list of filament spools with optional filtering by material,
    /// brand, and active status. Results are ordered by creation date (newest first)
    /// and include denormalized material names for display.
    /// </summary>
    /// <param name="query">Optional query parameters for pagination and filtering.</param>
    /// <returns>A paginated list of filament spools matching the filter criteria.</returns>
    /// <response code="200">Returns the paginated list of filament spools.</response>
    [HttpGet]
    [ProducesResponseType(typeof(PagedResponse<FilamentResponse>), StatusCodes.Status200OK)]
    public async Task<ActionResult<PagedResponse<FilamentResponse>>> GetFilaments(
        [FromQuery] FilamentQueryParameters query)
    {
        _logger.LogDebug(
            "Getting filaments: pageNumber={PageNumber}, pageSize={PageSize}, " +
            "materialBaseId={MaterialBaseId}, materialFinishId={MaterialFinishId}, " +
            "materialModifierId={MaterialModifierId}, brand={Brand}, isActive={IsActive}",
            query.PageNumber, query.PageSize, query.MaterialBaseId,
            query.MaterialFinishId, query.MaterialModifierId, query.Brand, query.IsActive);

        // Clamp pagination values
        var pageNumber = Math.Max(1, query.PageNumber);
        var pageSize = Math.Clamp(query.PageSize, 1, 100);

        var spoolQuery = _dbContext.Spools
            .Include(s => s.MaterialBase)
            .Include(s => s.MaterialFinish)
            .Include(s => s.MaterialModifier)
            .AsQueryable();

        // Apply filters
        if (query.MaterialBaseId.HasValue)
            spoolQuery = spoolQuery.Where(s => s.MaterialBaseId == query.MaterialBaseId.Value);

        if (query.MaterialFinishId.HasValue)
            spoolQuery = spoolQuery.Where(s => s.MaterialFinishId == query.MaterialFinishId.Value);

        if (query.MaterialModifierId.HasValue)
            spoolQuery = spoolQuery.Where(s => s.MaterialModifierId == query.MaterialModifierId.Value);

        if (!string.IsNullOrWhiteSpace(query.Brand))
            spoolQuery = spoolQuery.Where(s =>
                s.Brand.ToLower().Contains(query.Brand.ToLower()));

        if (query.IsActive.HasValue)
            spoolQuery = spoolQuery.Where(s => s.IsActive == query.IsActive.Value);

        var totalCount = await spoolQuery.CountAsync();

        var items = await spoolQuery
            .OrderByDescending(s => s.CreatedAt)
            .Skip((pageNumber - 1) * pageSize)
            .Take(pageSize)
            .Select(s => MapToFilamentResponse(s))
            .ToListAsync();

        var response = new PagedResponse<FilamentResponse>
        {
            Items = items,
            TotalCount = totalCount,
            PageNumber = pageNumber,
            PageSize = pageSize
        };

        return Ok(response);
    }

    /// <summary>
    /// Gets a specific filament spool by its unique identifier.
    /// Includes denormalized material names for display.
    /// </summary>
    /// <param name="id">The unique identifier of the filament spool.</param>
    /// <returns>The filament spool details.</returns>
    /// <response code="200">Returns the filament spool details.</response>
    /// <response code="404">If the filament spool with the given ID is not found.</response>
    [HttpGet("{id:guid}")]
    [ProducesResponseType(typeof(FilamentResponse), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status404NotFound)]
    public async Task<ActionResult<FilamentResponse>> GetFilament(Guid id)
    {
        _logger.LogDebug("Getting filament {Id}", id);

        var spool = await _dbContext.Spools
            .Include(s => s.MaterialBase)
            .Include(s => s.MaterialFinish)
            .Include(s => s.MaterialModifier)
            .FirstOrDefaultAsync(s => s.Id == id);

        if (spool is null)
        {
            _logger.LogWarning("Filament {Id} not found", id);
            return NotFound(new { error = $"Filament with ID '{id}' not found." });
        }

        return Ok(MapToFilamentResponse(spool));
    }

    /// <summary>
    /// Creates a new filament spool. Validates that all foreign keys reference
    /// existing material entities and that the SpoolSerial is unique.
    /// WeightRemainingGrams must not exceed WeightTotalGrams.
    /// </summary>
    /// <param name="request">The filament creation request with all required fields.</param>
    /// <returns>The newly created filament spool with generated ID and timestamps.</returns>
    /// <response code="201">Returns the created filament spool with location header.</response>
    /// <response code="400">If the request is invalid or foreign keys don't exist.</response>
    [HttpPost]
    [ProducesResponseType(typeof(FilamentResponse), StatusCodes.Status201Created)]
    [ProducesResponseType(StatusCodes.Status400BadRequest)]
    public async Task<ActionResult<FilamentResponse>> CreateFilament(
        [FromBody] CreateFilamentRequest request)
    {
        _logger.LogInformation("Creating filament: {Serial} - {Brand} {Color}",
            request.SpoolSerial, request.Brand, request.ColorName);

        // Validate foreign keys exist
        var materialBase = await _dbContext.MaterialBases.FindAsync(request.MaterialBaseId);
        if (materialBase is null)
            return BadRequest(new { error = $"MaterialBase with ID '{request.MaterialBaseId}' not found." });

        var materialFinish = await _dbContext.MaterialFinishes.FindAsync(request.MaterialFinishId);
        if (materialFinish is null)
            return BadRequest(new { error = $"MaterialFinish with ID '{request.MaterialFinishId}' not found." });

        if (request.MaterialModifierId.HasValue)
        {
            var modifier = await _dbContext.MaterialModifiers.FindAsync(request.MaterialModifierId.Value);
            if (modifier is null)
                return BadRequest(new { error = $"MaterialModifier with ID '{request.MaterialModifierId}' not found." });
        }

        // Validate serial uniqueness
        var serialExists = await _dbContext.Spools
            .AnyAsync(s => s.SpoolSerial == request.SpoolSerial);
        if (serialExists)
            return BadRequest(new { error = $"Filament with serial '{request.SpoolSerial}' already exists." });

        // Validate remaining weight doesn't exceed total weight
        if (request.WeightRemainingGrams > request.WeightTotalGrams)
            return BadRequest(new { error = "WeightRemainingGrams cannot exceed WeightTotalGrams." });

        var entity = new Spool
        {
            MaterialBaseId = request.MaterialBaseId,
            MaterialFinishId = request.MaterialFinishId,
            MaterialModifierId = request.MaterialModifierId,
            Brand = request.Brand,
            ColorName = request.ColorName,
            ColorHex = request.ColorHex,
            WeightTotalGrams = request.WeightTotalGrams,
            WeightRemainingGrams = request.WeightRemainingGrams,
            FilamentDiameterMm = request.FilamentDiameterMm,
            SpoolSerial = request.SpoolSerial,
            PurchasePrice = request.PurchasePrice,
            PurchaseDate = request.PurchaseDate,
            IsActive = request.IsActive
        };

        _dbContext.Spools.Add(entity);
        await _dbContext.SaveChangesAsync();

        // Reload navigation properties for the response
        await _dbContext.Entry(entity).Reference(s => s.MaterialBase).LoadAsync();
        await _dbContext.Entry(entity).Reference(s => s.MaterialFinish).LoadAsync();
        if (entity.MaterialModifierId.HasValue)
            await _dbContext.Entry(entity).Reference(s => s.MaterialModifier).LoadAsync();

        var response = MapToFilamentResponse(entity);
        return CreatedAtAction(nameof(GetFilament), new { id = entity.Id }, response);
    }

    /// <summary>
    /// Updates an existing filament spool. Validates foreign keys and serial uniqueness
    /// (excluding the current spool from the uniqueness check).
    /// WeightRemainingGrams must not exceed WeightTotalGrams.
    /// </summary>
    /// <param name="id">The unique identifier of the filament spool to update.</param>
    /// <param name="request">The filament update request with all required fields.</param>
    /// <returns>The updated filament spool with current timestamps.</returns>
    /// <response code="200">Returns the updated filament spool.</response>
    /// <response code="404">If the filament spool with the given ID is not found.</response>
    /// <response code="400">If the request is invalid or foreign keys don't exist.</response>
    [HttpPut("{id:guid}")]
    [ProducesResponseType(typeof(FilamentResponse), StatusCodes.Status200OK)]
    [ProducesResponseType(StatusCodes.Status404NotFound)]
    [ProducesResponseType(StatusCodes.Status400BadRequest)]
    public async Task<ActionResult<FilamentResponse>> UpdateFilament(
        Guid id, [FromBody] UpdateFilamentRequest request)
    {
        _logger.LogInformation("Updating filament {Id}", id);

        var entity = await _dbContext.Spools.FindAsync(id);
        if (entity is null)
        {
            _logger.LogWarning("Filament {Id} not found for update", id);
            return NotFound(new { error = $"Filament with ID '{id}' not found." });
        }

        // Validate foreign keys exist
        var materialBase = await _dbContext.MaterialBases.FindAsync(request.MaterialBaseId);
        if (materialBase is null)
            return BadRequest(new { error = $"MaterialBase with ID '{request.MaterialBaseId}' not found." });

        var materialFinish = await _dbContext.MaterialFinishes.FindAsync(request.MaterialFinishId);
        if (materialFinish is null)
            return BadRequest(new { error = $"MaterialFinish with ID '{request.MaterialFinishId}' not found." });

        if (request.MaterialModifierId.HasValue)
        {
            var modifier = await _dbContext.MaterialModifiers.FindAsync(request.MaterialModifierId.Value);
            if (modifier is null)
                return BadRequest(new { error = $"MaterialModifier with ID '{request.MaterialModifierId}' not found." });
        }

        // Check serial uniqueness (excluding current spool)
        var serialExists = await _dbContext.Spools
            .AnyAsync(s => s.SpoolSerial == request.SpoolSerial && s.Id != id);
        if (serialExists)
            return BadRequest(new { error = $"Filament with serial '{request.SpoolSerial}' already exists." });

        // Validate remaining weight doesn't exceed total weight
        if (request.WeightRemainingGrams > request.WeightTotalGrams)
            return BadRequest(new { error = "WeightRemainingGrams cannot exceed WeightTotalGrams." });

        entity.MaterialBaseId = request.MaterialBaseId;
        entity.MaterialFinishId = request.MaterialFinishId;
        entity.MaterialModifierId = request.MaterialModifierId;
        entity.Brand = request.Brand;
        entity.ColorName = request.ColorName;
        entity.ColorHex = request.ColorHex;
        entity.WeightTotalGrams = request.WeightTotalGrams;
        entity.WeightRemainingGrams = request.WeightRemainingGrams;
        entity.FilamentDiameterMm = request.FilamentDiameterMm;
        entity.SpoolSerial = request.SpoolSerial;
        entity.PurchasePrice = request.PurchasePrice;
        entity.PurchaseDate = request.PurchaseDate;
        entity.IsActive = request.IsActive;

        await _dbContext.SaveChangesAsync();

        // Reload navigation properties
        await _dbContext.Entry(entity).Reference(s => s.MaterialBase).LoadAsync();
        await _dbContext.Entry(entity).Reference(s => s.MaterialFinish).LoadAsync();
        if (entity.MaterialModifierId.HasValue)
            await _dbContext.Entry(entity).Reference(s => s.MaterialModifier).LoadAsync();

        return Ok(MapToFilamentResponse(entity));
    }

    // ── Mapping helper ─────────────────────────────────────────

    /// <summary>
    /// Maps a Spool domain entity to a FilamentResponse DTO.
    /// Denormalizes material names for display convenience.
    /// Populates the QrCodeUrl for easy frontend access to the spool's QR code.
    /// </summary>
    /// <param name="s">The spool entity to map.</param>
    /// <returns>A FilamentResponse DTO with denormalized material names and QR code URL.</returns>
    private static FilamentResponse MapToFilamentResponse(Spool s) => new()
    {
        Id = s.Id,
        MaterialBaseId = s.MaterialBaseId,
        MaterialBaseName = s.MaterialBase?.Name ?? string.Empty,
        MaterialFinishId = s.MaterialFinishId,
        MaterialFinishName = s.MaterialFinish?.Name ?? string.Empty,
        MaterialModifierId = s.MaterialModifierId,
        MaterialModifierName = s.MaterialModifier?.Name,
        Brand = s.Brand,
        ColorName = s.ColorName,
        ColorHex = s.ColorHex,
        WeightTotalGrams = s.WeightTotalGrams,
        WeightRemainingGrams = s.WeightRemainingGrams,
        FilamentDiameterMm = s.FilamentDiameterMm,
        SpoolSerial = s.SpoolSerial,
        PurchasePrice = s.PurchasePrice,
        PurchaseDate = s.PurchaseDate,
        IsActive = s.IsActive,
        CreatedAt = s.CreatedAt,
        UpdatedAt = s.UpdatedAt,
        QrCodeUrl = $"/api/qr/spool/{s.Id}"
    };
}