using Fitness_core_BE.Models;
using Fitness_core_BE.Interfaces;
using Fitness_core_BE.DTOs.Workout;
using Microsoft.EntityFrameworkCore;

namespace Fitness_core_BE.Repos
{
    public class WorkoutRepository : IWorkoutRepository
    {
        // Client-authored (non-template) workout plans + all CustomerWorkout assignment rows.
        private readonly TenantDbContext _dbContext;
        // Admin-authored templates (WorkoutCategories, and WorkoutPlans/Items/Exercises where IsTemplate=true).
        private readonly CentralDbContext _central;

        public WorkoutRepository(TenantDbContext dbContext, CentralDbContext central)
        {
            _dbContext = dbContext;
            _central = central;
        }

        // Workout Category operations -- global lookup, admin-owned, always central.
        public async Task<List<WorkoutCategoryDto>> GetWorkoutCategoryListAsync(CancellationToken ct = default)
        {
            return await _central.WorkoutCategories
                .AsNoTracking()
                .Where(wc => wc.IsActive)
                .OrderBy(wc => wc.WorkoutCategoryName)
                .Select(wc => new WorkoutCategoryDto
                {
                    WorkoutCategoryId = wc.WorkoutCategoryId,
                    Name = wc.WorkoutCategoryName,
                    Description = wc.Description,
                    IsActive = wc.IsActive,
                    CreateDate = wc.CreateDate
                })
                .ToListAsync(ct);
        }

        // Categories are central; the plan row is tenant-side with no enforceable cross-DB
        // FK, so the id has to be checked here rather than left to the database.
        public Task<bool> WorkoutCategoryExistsAsync(Guid workoutCategoryId, CancellationToken ct = default)
        {
            return _central.WorkoutCategories
                .AsNoTracking()
                .AnyAsync(wc => wc.WorkoutCategoryId == workoutCategoryId && wc.IsActive, ct);
        }

        public async Task<WorkoutCategory> CreateWorkoutCategoryAsync(WorkoutCategory workoutCategory, CancellationToken ct = default)
        {
            await _central.WorkoutCategories.AddAsync(workoutCategory, ct);
            return workoutCategory;
        }

        // Workout Plan operations
        public async Task<List<WorkoutPlanDto>> GetWorkoutPlanListAsync(string userType, Guid clientId, CancellationToken ct = default)
        {
            // A customer browsing sees admin-authored templates (central); the coach/owner
            // dashboard only manages this gym's own custom plans (tenant) -- disjoint sets
            // post-split, never merged in one query.
            if (userType == "Customer")
            {
                return await _central.WorkoutPlans
                    .AsNoTracking()
                    .Include(wp => wp.WorkoutCategory)
                    .Where(wp => wp.IsActive && wp.IsTemplate)
                    .OrderByDescending(wp => wp.CreateDate)
                    .Select(wp => new WorkoutPlanDto
                    {
                        WorkoutPlanId = wp.WorkoutPlanId,
                        Name = wp.WorkoutPlanName,
                        Description = wp.Description,
                        IsTemplate = wp.IsTemplate,
                        WorkoutCategoryId = wp.FKWorkoutCategoryId,
                        WorkoutCategoryName = wp.WorkoutCategory != null ? wp.WorkoutCategory.WorkoutCategoryName : "",
                        ClientId = wp.FKClientId,
                        ClientName = null,
                        IsActive = wp.IsActive,
                        CreateDate = wp.CreateDate,
                        AssignedCustomers = new List<CustomerWorkoutDto>()
                    })
                    .ToListAsync(ct);
            }

            // Categories live centrally, so the tenant query can't join them -- resolve the
            // names in a second round-trip and stitch them on below.
            var categoryNames = await _central.WorkoutCategories
                .AsNoTracking()
                .ToDictionaryAsync(wc => wc.WorkoutCategoryId, wc => wc.WorkoutCategoryName, ct);

            var tenantPlans = await _dbContext.WorkoutPlans
                .AsNoTracking()
                .Include(wp => wp.CustomerWorkouts.Where(cw => cw.IsActive))
                    .ThenInclude(cw => cw.TenantCustomerLink)
                .Where(wp => wp.IsActive && !wp.IsTemplate && wp.FKClientId == clientId)
                .OrderByDescending(wp => wp.CreateDate)
                .Select(wp => new WorkoutPlanDto
                {
                    WorkoutPlanId = wp.WorkoutPlanId,
                    Name = wp.WorkoutPlanName,
                    Description = wp.Description,
                    IsTemplate = wp.IsTemplate,
                    WorkoutCategoryId = wp.FKWorkoutCategoryId,
                    WorkoutCategoryName = "",
                    ClientId = wp.FKClientId,
                    ClientName = null,
                    IsActive = wp.IsActive,
                    CreateDate = wp.CreateDate,
                    AssignedCustomers = wp.CustomerWorkouts
                        .Where(cw => cw.IsActive)
                        .Select(cw => new CustomerWorkoutDto
                        {
                            CustomerWorkoutId = cw.CustomerWorkoutId,
                            CustomerId = cw.FKCustomerId,
                            CustomerName = cw.TenantCustomerLink != null ? cw.TenantCustomerLink.DisplayName : null,
                            WorkoutPlanId = cw.FKWorkoutPlanId,
                            IsActive = cw.IsActive,
                            IsFollowing = cw.IsFollowing,
                            AssignedDate = cw.AssignedDate,
                            CompletedDate = cw.CompletedDate,
                            Notes = cw.Notes
                        }).ToList()
                })
                .ToListAsync(ct);

            foreach (var plan in tenantPlans)
            {
                plan.WorkoutCategoryName =
                    categoryNames.TryGetValue(plan.WorkoutCategoryId, out var name) ? name : "";
            }

            return tenantPlans;
        }

        public async Task<WorkoutPlanDetailDto?> GetWorkoutPlanByIdAsync(Guid id, CancellationToken ct = default)
        {
            // The id could belong to either bucket (an admin template or a client-owned
            // plan) -- try central first, fall back to tenant.
            var centralPlan = await _central.WorkoutPlans
                .AsNoTracking()
                .Include(wp => wp.WorkoutCategory)
                .Include(wp => wp.WorkoutItems)
                    .ThenInclude(wi => wi.WorkoutExercises)
                .FirstOrDefaultAsync(wp => wp.WorkoutPlanId == id && wp.IsActive, ct);
            if (centralPlan != null)
                return MapDetail(centralPlan, Array.Empty<CustomerWorkout>());

            var tenantPlan = await _dbContext.WorkoutPlans
                .AsNoTracking()
                .Include(wp => wp.CustomerWorkouts.Where(cw => cw.IsActive))
                    .ThenInclude(cw => cw.TenantCustomerLink)
                .Include(wp => wp.WorkoutItems)
                    .ThenInclude(wi => wi.WorkoutExercises)
                .FirstOrDefaultAsync(wp => wp.WorkoutPlanId == id && wp.IsActive, ct);
            if (tenantPlan == null)
                return null;

            var detail = MapDetail(tenantPlan, tenantPlan.CustomerWorkouts.Where(cw => cw.IsActive).ToList());
            // Category is central-only, so it can't be Include()d from the tenant context.
            detail.WorkoutCategoryName = await _central.WorkoutCategories
                .AsNoTracking()
                .Where(wc => wc.WorkoutCategoryId == tenantPlan.FKWorkoutCategoryId)
                .Select(wc => wc.WorkoutCategoryName)
                .FirstOrDefaultAsync(ct) ?? "";
            return detail;
        }

        private static WorkoutPlanDetailDto MapDetail(WorkoutPlan workoutPlan, IReadOnlyCollection<CustomerWorkout> assigned)
        {
            return new WorkoutPlanDetailDto
            {
                WorkoutPlanId = workoutPlan.WorkoutPlanId,
                Name = workoutPlan.WorkoutPlanName,
                Description = workoutPlan.Description,
                IsTemplate = workoutPlan.IsTemplate,
                WorkoutCategoryId = workoutPlan.FKWorkoutCategoryId,
                WorkoutCategoryName = workoutPlan.WorkoutCategory != null ? workoutPlan.WorkoutCategory.WorkoutCategoryName : "",
                ClientId = workoutPlan.FKClientId,
                ClientName = null,
                IsActive = workoutPlan.IsActive,
                CreateDate = workoutPlan.CreateDate,
                WorkoutItems = workoutPlan.WorkoutItems
                    .Where(wi => wi.IsActive)
                    .Select(MapWorkoutItem)
                    .ToList(),
                AssignedCustomers = assigned
                    .Select(cw => new CustomerWorkoutDto
                    {
                        CustomerWorkoutId = cw.CustomerWorkoutId,
                        CustomerId = cw.FKCustomerId,
                        CustomerName = cw.TenantCustomerLink?.DisplayName,
                        WorkoutPlanId = cw.FKWorkoutPlanId,
                        IsActive = cw.IsActive,
                        IsFollowing = cw.IsFollowing,
                        AssignedDate = cw.AssignedDate,
                        CompletedDate = cw.CompletedDate,
                        Notes = cw.Notes
                    }).ToList()
            };
        }

        // Shared WorkoutItem -> WorkoutItemDto mapping (including structured exercises) for the
        // client/coach-facing read paths, which operate on already-materialized entity graphs
        // rather than server-translated queries.
        private static WorkoutItemDto MapWorkoutItem(WorkoutItem wi)
        {
            var exerciseDtos = wi.WorkoutExercises
                .Where(we => we.IsActive)
                .OrderBy(we => we.SortOrder)
                .Select(we => new WorkoutExerciseDto
                {
                    WorkoutExerciseId = we.WorkoutExerciseId,
                    Name = we.Name,
                    MuscleGroup = we.MuscleGroup,
                    Sets = we.Sets,
                    Reps = we.Reps,
                    Description = we.Description,
                    BreathIn = we.BreathIn,
                    BreathOut = we.BreathOut,
                    VideoUrl = we.VideoUrl,
                    SortOrder = we.SortOrder,
                    IsCompleted = false
                })
                .ToList();

            return new WorkoutItemDto
            {
                WorkoutItemId = wi.WorkoutItemId,
                ExerciseDay = wi.ExerciseDay,
                Description = wi.Description,
                Exercises = wi.Exercises,
                HowToDo = wi.HowToDo,
                DoURL = wi.DoURL,
                Duration = wi.Duration,
                WormUp = wi.WormUp,
                Cooldown = wi.Cooldown,
                WorkoutPlanId = wi.FKWorkoutPlanId,
                IsActive = wi.IsActive,
                CreateDate = wi.CreateDate,
                UpdatedAt = wi.UpdatedAt,
                WorkoutExercises = exerciseDtos,
                TotalExercises = exerciseDtos.Count,
                CompletedExercises = 0,
                IsCompleted = false
            };
        }

        public async Task<List<WorkoutPlanDetailDto>> GetWorkoutPlansByCustomerIdAsync(Guid customerId, CancellationToken ct = default)
        {
            // CustomerWorkout (tenant) records which plans this customer follows at this gym;
            // each followed plan is resolved from whichever bucket it actually lives in.
            var follows = await _dbContext.CustomerWorkouts
                .AsNoTracking()
                .Where(cw => cw.FKCustomerId == customerId && cw.IsActive)
                .OrderByDescending(cw => cw.AssignedDate)
                .Select(cw => cw.FKWorkoutPlanId)
                .Distinct()
                .ToListAsync(ct);

            var result = new List<WorkoutPlanDetailDto>();
            foreach (var workoutPlanId in follows)
            {
                var detail = await GetWorkoutPlanByIdAsync(workoutPlanId, ct);
                if (detail != null && detail.IsActive)
                    result.Add(detail);
            }
            return result;
        }

        public async Task<WorkoutPlan?> GetWorkoutPlanEntityByIdAsync(Guid id, CancellationToken ct = default)
        {
            return await _dbContext.WorkoutPlans
                .FirstOrDefaultAsync(wp => wp.WorkoutPlanId == id && wp.IsActive, ct);
        }

        public async Task<WorkoutPlan> CreateWorkoutPlanAsync(WorkoutPlan workoutPlan, CancellationToken ct = default)
        {
            await _dbContext.WorkoutPlans.AddAsync(workoutPlan, ct);
            return workoutPlan;
        }

        public async Task<WorkoutPlan> UpdateWorkoutPlanAsync(WorkoutPlan workoutPlan, CancellationToken ct = default)
        {
            _dbContext.WorkoutPlans.Update(workoutPlan);
            return workoutPlan;
        }

        public async Task<bool> DeleteWorkoutPlanAsync(Guid id, CancellationToken ct = default)
        {
            var workoutPlan = await _dbContext.WorkoutPlans.FindAsync(new object[] { id }, ct);

            if (workoutPlan == null)
            {
                return false;
            }

            workoutPlan.IsActive = false;
            _dbContext.WorkoutPlans.Update(workoutPlan);

            return true;
        }

        public async Task<WorkoutItem?> GetWorkoutItemByIdAsync(Guid id, CancellationToken ct = default)
        {
            return await _dbContext.WorkoutItems
                .FirstOrDefaultAsync(wi => wi.WorkoutItemId == id && wi.IsActive, ct);
        }

        // Workout Item operations
        public async Task<List<WorkoutItemDto>> GetWorkoutItemsByWorkoutPlanIdAsync(Guid workoutPlanId, CancellationToken ct = default)
        {
            var items = await _dbContext.WorkoutItems
                .AsNoTracking()
                .Include(wi => wi.WorkoutExercises)
                .Where(wi => wi.FKWorkoutPlanId == workoutPlanId && wi.IsActive)
                .OrderBy(wi => wi.CreateDate)
                .ToListAsync(ct);

            return items.Select(MapWorkoutItem).ToList();
        }

        public async Task<WorkoutItem> CreateWorkoutItemAsync(WorkoutItem workoutItem, CancellationToken ct = default)
        {
            await _dbContext.WorkoutItems.AddAsync(workoutItem, ct);
            return workoutItem;
        }

        public async Task<WorkoutItem> UpdateWorkoutItemAsync(WorkoutItem workoutItem, CancellationToken ct = default)
        {
            _dbContext.WorkoutItems.Update(workoutItem);
            return workoutItem;
        }

        public async Task DeleteWorkoutItemAsync(Guid id, CancellationToken ct = default)
        {
            var workoutItem = await _dbContext.WorkoutItems.FindAsync(new object[] { id }, ct);
            if (workoutItem != null)
            {
                // Soft delete by setting IsActive to false
                workoutItem.IsActive = false;
                _dbContext.WorkoutItems.Update(workoutItem);
            }
        }

        // Customer Workout Assignment operations
        // Assigning a plan puts the customer on it the same way self-follow does: only one
        // plan can be "followed" at a time, and an assigned plan must show up under the
        // customer's Followed tab immediately.
        public async Task<CustomerWorkout> AssignWorkoutToCustomerAsync(CustomerWorkout customerWorkout, CancellationToken ct = default)
        {
            var currentFollow = await _dbContext.CustomerWorkouts
                .FirstOrDefaultAsync(cw => cw.FKCustomerId == customerWorkout.FKCustomerId && cw.IsFollowing, ct);

            if (currentFollow != null && currentFollow.FKWorkoutPlanId != customerWorkout.FKWorkoutPlanId)
            {
                currentFollow.IsFollowing = false;
                _dbContext.CustomerWorkouts.Update(currentFollow);
            }

            var existing = await _dbContext.CustomerWorkouts
                .FirstOrDefaultAsync(cw => cw.FKCustomerId == customerWorkout.FKCustomerId && cw.FKWorkoutPlanId == customerWorkout.FKWorkoutPlanId, ct);

            if (existing != null)
            {
                existing.IsFollowing = true;
                existing.IsActive = true;
                existing.AssignedDate = customerWorkout.AssignedDate;
                existing.Notes = customerWorkout.Notes;
                _dbContext.CustomerWorkouts.Update(existing);
                return existing;
            }

            customerWorkout.IsFollowing = true;
            await _dbContext.CustomerWorkouts.AddAsync(customerWorkout, ct);
            return customerWorkout;
        }

        public async Task<bool> UnassignWorkoutFromCustomerAsync(Guid customerWorkoutId, CancellationToken ct = default)
        {
            var customerWorkout = await _dbContext.CustomerWorkouts.FindAsync(new object[] { customerWorkoutId }, ct);

            if (customerWorkout == null)
            {
                return false;
            }

            // Soft delete by setting IsActive to false
            customerWorkout.IsActive = false;
            _dbContext.CustomerWorkouts.Update(customerWorkout);

            return true;
        }

        // A followed plan id may name a central template or a tenant plan, so names are
        // resolved from both buckets rather than through a (now un-enforced) navigation.
        private async Task<Dictionary<Guid, string>> ResolvePlanNamesAsync(
            IReadOnlyCollection<Guid> planIds, CancellationToken ct)
        {
            if (planIds.Count == 0)
                return new Dictionary<Guid, string>();

            var names = await _dbContext.WorkoutPlans
                .AsNoTracking()
                .Where(wp => planIds.Contains(wp.WorkoutPlanId))
                .ToDictionaryAsync(wp => wp.WorkoutPlanId, wp => wp.WorkoutPlanName, ct);

            var missing = planIds.Where(id => !names.ContainsKey(id)).ToList();
            if (missing.Count > 0)
            {
                var centralNames = await _central.WorkoutPlans
                    .AsNoTracking()
                    .Where(wp => missing.Contains(wp.WorkoutPlanId))
                    .ToDictionaryAsync(wp => wp.WorkoutPlanId, wp => wp.WorkoutPlanName, ct);
                foreach (var pair in centralNames)
                    names[pair.Key] = pair.Value;
            }

            return names;
        }

        private async Task<List<CustomerWorkoutDto>> BuildCustomerWorkoutDtosAsync(
            IQueryable<CustomerWorkout> query, CancellationToken ct)
        {
            var rows = await query
                .AsNoTracking()
                .Include(cw => cw.TenantCustomerLink)
                .OrderByDescending(cw => cw.AssignedDate)
                .Select(cw => new CustomerWorkoutDto
                {
                    CustomerWorkoutId = cw.CustomerWorkoutId,
                    CustomerId = cw.FKCustomerId,
                    CustomerName = cw.TenantCustomerLink != null ? cw.TenantCustomerLink.DisplayName : null,
                    WorkoutPlanId = cw.FKWorkoutPlanId,
                    WorkoutPlanName = null,
                    IsActive = cw.IsActive,
                    IsFollowing = cw.IsFollowing,
                    AssignedDate = cw.AssignedDate,
                    CompletedDate = cw.CompletedDate,
                    Notes = cw.Notes
                })
                .ToListAsync(ct);

            var names = await ResolvePlanNamesAsync(
                rows.Select(r => r.WorkoutPlanId).Distinct().ToList(), ct);

            foreach (var row in rows)
                row.WorkoutPlanName = names.TryGetValue(row.WorkoutPlanId, out var name) ? name : null;

            return rows;
        }

        public Task<List<CustomerWorkoutDto>> GetCustomerWorkoutsByPlanIdAsync(Guid workoutPlanId, CancellationToken ct = default)
            => BuildCustomerWorkoutDtosAsync(
                _dbContext.CustomerWorkouts.Where(cw => cw.FKWorkoutPlanId == workoutPlanId && cw.IsActive), ct);

        public Task<List<CustomerWorkoutDto>> GetCustomerWorkoutsByCustomerIdAsync(Guid customerId, CancellationToken ct = default)
            => BuildCustomerWorkoutDtosAsync(
                _dbContext.CustomerWorkouts.Where(cw => cw.FKCustomerId == customerId && cw.IsActive), ct);
    }
}