using Extrudex.Domain.DTOs.Moonraker;
using Extrudex.Domain.Entities;
using Extrudex.Domain.Enums;
using Extrudex.Domain.Interfaces;
using Extrudex.Infrastructure.Data;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;

namespace Extrudex.Infrastructure.Services;

/// <summary>
/// Service that syncs filament usage data from Moonraker printers into the
/// Extrudex database. Queries all active Moonraker printers, fetches their
/// current filament usage metrics, persists usage entries to the UsageLog table,
/// creates FilamentUsage records for completed jobs, and updates spool remaining weights.
/// </summary>
public class FilamentUsageSyncService : IFilamentUsageSyncService
{
    private readonly ExtrudexDbContext _dbContext;
    private readonly IMoonrakerClient _moonrakerClient;
    private readonly IUsageLogService _usageLogService;
    private readonly ILogger<FilamentUsageSyncService> _logger;

    /// <summary>
    /// Creates a new FilamentUsageSyncService.
    /// </summary>
    /// <param name="dbContext">The EF Core database context for persisting updates.</param>
    /// <param name="moonrakerClient">The Moonraker HTTP client for fetching printer data.</param>
    /// <param name="usageLogService">The usage log service for persisting usage entries.</param>
    /// <param name="logger">Logger for diagnostic output.</param>
    public FilamentUsageSyncService(
        ExtrudexDbContext dbContext,
        IMoonrakerClient moonrakerClient,
        IUsageLogService usageLogService,
        ILogger<FilamentUsageSyncService> logger)
    {
        _dbContext = dbContext;
        _moonrakerClient = moonrakerClient;
        _usageLogService = usageLogService;
        _logger = logger;
    }

    /// <inheritdoc />
    public async Task<int> SyncAllAsync(CancellationToken cancellationToken = default)
    {
        _logger.LogInformation("Starting filament usage sync cycle");

        var printers = await _dbContext.Printers
            .Where(p => p.IsActive && p.ConnectionType == ConnectionType.Moonraker)
            .Include(p => p.AmsUnits)
                .ThenInclude(u => u.Slots)
                    .ThenInclude(s => s.Spool!)
                        .ThenInclude(s => s.MaterialBase)
            .Include(p => p.PrintJobs)
            .ToListAsync(cancellationToken);

        if (printers.Count == 0)
        {
            _logger.LogInformation("No active Moonraker printers found — skipping sync");
            return 0;
        }

        _logger.LogInformation("Found {PrinterCount} active Moonraker printer(s) to sync", printers.Count);

        var syncedCount = 0;

        foreach (var printer in printers)
        {
            try
            {
                await SyncPrinterAsync(printer, cancellationToken);
                syncedCount++;
            }
            catch (HttpRequestException ex)
            {
                _logger.LogError(ex,
                    "Connection error syncing filament usage from printer {PrinterName} ({Host}:{Port}) — printer may be offline",
                    printer.Name, printer.HostnameOrIp, printer.Port);

                printer.Status = PrinterStatus.Offline;
            }
            catch (Exception ex) when (ex is not OperationCanceledException)
            {
                _logger.LogError(ex,
                    "Error syncing filament usage from printer {PrinterName} ({Host}:{Port})",
                    printer.Name, printer.HostnameOrIp, printer.Port);
            }
        }

        await _dbContext.SaveChangesAsync(cancellationToken);

        _logger.LogInformation(
            "Filament usage sync cycle complete — {SyncedCount}/{TotalCount} printers synced",
            syncedCount, printers.Count);

        return syncedCount;
    }

    /// <summary>
    /// Syncs a single Moonraker printer: fetches print stats and history,
    /// persists usage data to UsageLog and FilamentUsage tables, and
    /// updates spool remaining weights.
    /// </summary>
    private async Task SyncPrinterAsync(Printer printer, CancellationToken cancellationToken)
    {
        // Step 1: Fetch current print stats for real-time filament usage
        var printStats = await _moonrakerClient.GetPrintStatsAsync(
            printer.HostnameOrIp, printer.Port, printer.ApiKey, cancellationToken);

        // Step 2: Fetch usage dictionary for backward-compatible metrics
        var usageData = await _moonrakerClient.GetFilamentUsageAsync(
            printer.HostnameOrIp, printer.Port, printer.ApiKey, cancellationToken);

        // Step 3: Update printer status based on print stats
        if (printStats != null)
        {
            printer.Status = printStats.State.ToLowerInvariant() switch
            {
                "printing" => PrinterStatus.Printing,
                "paused" => PrinterStatus.Paused,
                "complete" => PrinterStatus.Idle,
                "standby" => PrinterStatus.Idle,
                "cancelled" => PrinterStatus.Idle,
                "error" => PrinterStatus.Error,
                _ => printer.Status
            };
        }

        printer.LastSeenAt = DateTime.UtcNow;

        // Step 4: Update spool remaining weights from AMS data
        UpdateSpoolWeights(printer, usageData);

        // Step 5: If there's filament usage from print stats, persist it
        if (printStats != null && printStats.FilamentUsedMm > 0)
        {
            await PersistFilamentUsageAsync(printer, printStats, cancellationToken);
        }
        else if (usageData.TryGetValue("mm_extruded", out var mmExtruded) && mmExtruded > 0)
        {
            // Fall back to dictionary metrics if print stats aren't available
            _logger.LogInformation(
                "Printer {PrinterName} reports {MmExtruded}mm filament extruded in latest job (from usage dictionary)",
                printer.Name, mmExtruded);
        }

        _logger.LogInformation(
            "Successfully synced filament usage from printer {PrinterName}",
            printer.Name);
    }

    /// <summary>
    /// Persists filament usage data from print stats to the database.
    /// Creates a FilamentUsage record and a UsageLog entry, and deducts
    /// consumed grams from the spool's remaining weight.
    /// </summary>
    private async Task PersistFilamentUsageAsync(
        Printer printer,
        MoonrakerPrintStats printStats,
        CancellationToken cancellationToken)
    {
        // Find the default spool for this printer
        var defaultSpool = FindDefaultSpool(printer);

        if (defaultSpool == null)
        {
            _logger.LogWarning(
                "No default spool found for printer {PrinterName} — cannot persist filament usage of {MmExtruded}mm",
                printer.Name, printStats.FilamentUsedMm);
            return;
        }

        // Calculate derived grams
        var gramsDerived = CalculateGrams(
            printStats.FilamentUsedMm,
            defaultSpool.FilamentDiameterMm,
            defaultSpool.MaterialBase.DensityGperCm3);

        if (gramsDerived <= 0)
        {
            _logger.LogDebug(
                "No grams derived for printer {PrinterName} — skipping usage persistence",
                printer.Name);
            return;
        }

        // Deduct from spool remaining weight (floor at 0)
        var previousWeight = defaultSpool.WeightRemainingGrams;
        defaultSpool.WeightRemainingGrams = Math.Max(0, defaultSpool.WeightRemainingGrams - gramsDerived);

        _logger.LogInformation(
            "Deducted {Grams:F1}g from spool {SpoolSerial} (was {Previous:F1}g, now {Current:F1}g) for printer {PrinterName}",
            gramsDerived, defaultSpool.SpoolSerial, previousWeight, defaultSpool.WeightRemainingGrams, printer.Name);

        // Check if we already have a recent FilamentUsage for this printer
        // to avoid double-counting on repeated poll cycles for the same job
        var recentUsageThreshold = DateTime.UtcNow.AddMinutes(-10);
        var existingRecentUsage = await _dbContext.FilamentUsages
            .Where(fu => fu.PrinterId == printer.Id && fu.RecordedAt >= recentUsageThreshold)
            .AnyAsync(cancellationToken);

        if (existingRecentUsage)
        {
            _logger.LogDebug(
                "Recent FilamentUsage record exists for printer {PrinterName} — skipping to avoid double-counting",
                printer.Name);
            return;
        }

        // Create a FilamentUsage entity for the consumption
        var filamentUsage = new FilamentUsage
        {
            SpoolId = defaultSpool.Id,
            PrinterId = printer.Id,
            GramsUsed = gramsDerived,
            MmExtruded = printStats.FilamentUsedMm,
            RecordedAt = DateTime.UtcNow,
            Notes = $"Auto-recorded from Moonraker print stats (state: {printStats.State})"
        };

        // If there's a matching print job, link it
        var matchingJob = FindMatchingPrintJob(printer, printStats);
        if (matchingJob != null)
        {
            filamentUsage.PrintJobId = matchingJob.Id;
            filamentUsage.PrintJob = matchingJob;
        }

        _dbContext.FilamentUsages.Add(filamentUsage);

        // Also persist to UsageLog via the usage logging service
        try
        {
            await _usageLogService.RecordUsageAsync(
                spoolId: defaultSpool.Id,
                gramsUsed: gramsDerived,
                dataSource: DataSource.Moonraker,
                printerId: printer.Id,
                printJobId: matchingJob?.Id,
                mmExtruded: printStats.FilamentUsedMm,
                notes: $"Auto-recorded from Moonraker print stats (state: {printStats.State})");

            _logger.LogInformation(
                "Persisted usage log: {Grams:F1}g / {Mm:F1}mm for spool {SpoolSerial} on printer {PrinterName}",
                gramsDerived, printStats.FilamentUsedMm, defaultSpool.SpoolSerial, printer.Name);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex,
                "Failed to persist usage log for printer {PrinterName} — FilamentUsage entity was still created",
                printer.Name);
        }
    }

    /// <summary>
    /// Updates spool remaining weights based on usage data received from Moonraker.
    /// For printers with AMS units, updates the remaining weight on each slot's spool.
    /// </summary>
    private void UpdateSpoolWeights(
        Printer printer,
        Dictionary<string, decimal> usageData)
    {
        // Update AMS slot remaining weights if available
        foreach (var amsUnit in printer.AmsUnits)
        {
            foreach (var slot in amsUnit.Slots)
            {
                if (slot.Spool != null && slot.RemainingWeightG.HasValue)
                {
                    // Sync the AMS-reported remaining weight to the spool
                    slot.Spool.WeightRemainingGrams = slot.RemainingWeightG.Value;

                    _logger.LogDebug(
                        "Updated spool {SpoolSerial} remaining weight to {Weight}g from AMS data",
                        slot.Spool.SpoolSerial, slot.RemainingWeightG.Value);
                }
            }
        }

        // If usage data contains extruded mm, log it for observability
        if (usageData.TryGetValue("mm_extruded", out var mmExtruded) && mmExtruded > 0)
        {
            _logger.LogInformation(
                "Printer {PrinterName} reports {MmExtruded}mm filament extruded in latest job",
                printer.Name, mmExtruded);
        }
    }

    /// <summary>
    /// Finds the default spool for a printer. Returns the first active, non-archived spool
    /// loaded in an AMS slot, or null if no spool is available.
    /// </summary>
    private static Spool? FindDefaultSpool(Printer printer)
    {
        foreach (var amsUnit in printer.AmsUnits)
        {
            foreach (var slot in amsUnit.Slots)
            {
                if (slot.Spool != null && slot.Spool.IsActive && !slot.Spool.IsArchived)
                {
                    return slot.Spool;
                }
            }
        }

        return null;
    }

    /// <summary>
    /// Finds a PrintJob on this printer that matches the current print stats.
    /// Matches by filename and non-completed status to avoid double-linking.
    /// </summary>
    private PrintJob? FindMatchingPrintJob(Printer printer, MoonrakerPrintStats printStats)
    {
        if (string.IsNullOrEmpty(printStats.Filename))
            return null;

        return printer.PrintJobs
            .FirstOrDefault(pj => pj.PrintName == printStats.Filename
                && pj.Status != JobStatus.Completed
                && pj.Status != JobStatus.Cancelled);
    }

    /// <summary>
    /// Calculates derived grams from millimeters extruded using the standard formula:
    /// grams = mm_extruded × cross_section_area × material_density
    /// where cross_section_area = π × (diameter / 2)²
    /// </summary>
    private static decimal CalculateGrams(decimal mmExtruded, decimal diameterMm, decimal densityGperCm3)
    {
        if (mmExtruded <= 0) return 0m;

        var radiusCm = (double)diameterMm / 2.0 / 10.0; // mm to cm
        var crossSectionAreaCm2 = Math.PI * radiusCm * radiusCm;
        var mmToCm = (double)mmExtruded / 10.0;

        var grams = mmToCm * crossSectionAreaCm2 * (double)densityGperCm3;
        return (decimal)grams;
    }
}