using Microsoft.EntityFrameworkCore;
using PowderCoating.Application.Interfaces;
using PowderCoating.Core.Entities;
using PowderCoating.Core.Enums;
using PowderCoating.Infrastructure.Data;

namespace PowderCoating.Infrastructure.Services;

/// <summary>
/// Implements operational aggregate reports using direct DbContext access with AsNoTracking.
/// Query logic is migrated here from <c>ReportsController</c> as each report action is
/// converted during Phase 2/3 of the data-access architecture migration.
/// See <c>docs/DATA_ACCESS_ARCHITECTURE.md</c> for the full migration plan.
/// </summary>
public class OperationalReportService : IOperationalReportService
{
    private readonly ApplicationDbContext _context;

    public OperationalReportService(ApplicationDbContext context)
    {
        _context = context;
    }

    /// <inheritdoc/>
    public async Task<JobCycleTimeReport> GetJobCycleTimeAsync(int companyId, int months)
    {
        var completedCodes = new[] { "COMPLETED", "READY_FOR_PICKUP", "DELIVERED" };

        var completedJobs = await _context.Jobs
            .Include(j => j.JobStatus)
            .Where(j => !j.IsDeleted && completedCodes.Contains(j.JobStatus.StatusCode) && j.CompletedDate.HasValue)
            .AsNoTracking()
            .ToListAsync();

        var history = await _context.JobStatusHistory
            .Include(h => h.FromStatus)
            .Include(h => h.ToStatus)
            .AsNoTracking()
            .ToListAsync();

        var historyByJob = history
            .GroupBy(h => h.JobId)
            .ToDictionary(g => g.Key, g => g.OrderBy(h => h.ChangedDate).ToList());

        var statusTimings = new Dictionary<string, (string DisplayName, List<double> Days)>();

        foreach (var job in completedJobs)
        {
            if (!historyByJob.TryGetValue(job.Id, out var jobHistory) || !jobHistory.Any()) continue;

            var prevDate = job.CreatedAt;
            foreach (var entry in jobHistory)
            {
                var fc = entry.FromStatus?.StatusCode;
                var fn = entry.FromStatus?.DisplayName;
                if (fc == null) { prevDate = entry.ChangedDate; continue; }
                var d = (entry.ChangedDate - prevDate).TotalDays;
                if (d >= 0 && d <= 365)
                {
                    if (!statusTimings.ContainsKey(fc)) statusTimings[fc] = (fn ?? fc, new List<double>());
                    statusTimings[fc].Days.Add(d);
                }
                prevDate = entry.ChangedDate;
            }

            var last = jobHistory.Last();
            var tc = last.ToStatus?.StatusCode;
            var tn = last.ToStatus?.DisplayName;
            if (tc != null)
            {
                var d = (job.CompletedDate!.Value - last.ChangedDate).TotalDays;
                if (d >= 0 && d <= 365)
                {
                    if (!statusTimings.ContainsKey(tc)) statusTimings[tc] = (tn ?? tc, new List<double>());
                    statusTimings[tc].Days.Add(d);
                }
            }
        }

        var rows = statusTimings
            .Where(kv => kv.Value.Days.Any())
            .Select(kv => new JobCycleTimeRow(kv.Value.DisplayName, Math.Round(kv.Value.Days.Average(), 1), kv.Value.Days.Count))
            .ToList();

        return new JobCycleTimeReport(rows, months);
    }

    /// <inheritdoc/>
    public async Task<PowderUsageReport> GetPowderUsageAsync(int companyId, int months)
    {
        var startDate = DateTime.UtcNow.AddMonths(-months);

        var transactions = await _context.InventoryTransactions
            .Include(t => t.InventoryItem)
            .Where(t => !t.IsDeleted
                && t.TransactionType == InventoryTransactionType.JobUsage
                && t.TransactionDate >= startDate)
            .AsNoTracking()
            .ToListAsync();

        var rows = transactions
            .Where(t => t.InventoryItem != null)
            .GroupBy(t => t.InventoryItemId)
            .Select(g => new PowderUsageRow(
                ColorName: g.First().InventoryItem!.ColorName ?? g.First().InventoryItem!.Name,
                VendorName: g.First().InventoryItem!.Manufacturer ?? string.Empty,
                TotalLbs: g.Sum(t => Math.Abs(t.Quantity)),
                TotalCost: g.Sum(t => Math.Abs(t.TotalCost))))
            .OrderByDescending(r => r.TotalLbs)
            .ToList();

        return new PowderUsageReport(rows, months);
    }

    /// <inheritdoc/>
    public async Task<List<Bill>> GetActiveBillsAsync()
    {
        return await _context.Bills
            .Include(b => b.Vendor)
            .Include(b => b.Payments.Where(p => !p.IsDeleted))
            .Where(b => !b.IsDeleted && b.Status != BillStatus.Voided)
            .AsNoTracking()
            .ToListAsync();
    }

    /// <inheritdoc/>
    public async Task<List<Expense>> GetAllExpensesAsync()
    {
        return await _context.Expenses
            .Include(e => e.ExpenseAccount)
            .Where(e => !e.IsDeleted)
            .AsNoTracking()
            .ToListAsync();
    }

    /// <inheritdoc/>
    public async Task<List<JobStatusHistory>> GetAllJobStatusHistoryAsync()
    {
        return await _context.JobStatusHistory
            .Include(h => h.FromStatus)
            .Include(h => h.ToStatus)
            .AsNoTracking()
            .ToListAsync();
    }
}