using PostFundManagement.Application.Abstractions.Services;
using PostFundManagement.Application.Services.Shared;
using PostFundManagement.Domain;
using PostFundManagement.Domain.Abstractions;
using PostFundManagement.Domain.Errors;
using PostFundManagement.Domain.Extensions;
using PostFundManagement.Domain.Models;
using PostFundManagement.Infrastructure.Database;

namespace PostFundManagement.Application.Services.Evidence;

public sealed class EvidenceService(IDbContextFactory<ApplicationDbContext> contextFactory, HashService hashService,
    [FromKeyedServices(Constants.GeneralBucketName)] IS3Service s3Service) : IEvidenceService
{
    public async Task<Result> CreateEvidenceAsync(Guid userId, IFormCollection form, IFormFile file, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result>>)(async () =>
        {
            if (!long.TryParse(form["projectId"], out var projectId) || !long.TryParse(form["milestoneId"], out var milestoneId) ||
                !long.TryParse(form["indicatorId"], out var indicatorId) || !long.TryParse(form["activityId"], out var activityId) ||
                !Enum.TryParse<EvidenceType>(form["type"], out var type))
                return Result.Fail(CreateError.Create("Invalid or missing form data parameters."));

            await using var stream = file.OpenReadStream();

            var uploadResult = await s3Service.UploadFileAsync(file.FileName, "evidence", stream, 
                file.ContentType, cancellationToken);

            if (uploadResult.IsFailed)
                return Result.Fail(uploadResult.Errors);

            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var evidence = new Domain.Entities.Evidence
            {
                ProjectId = projectId,
                MilestoneId = milestoneId,
                IndicatorId = indicatorId,
                ActivityId = activityId,
                CreatedBy = userId,
                CreatedAt = DateTime.UtcNow,
                Version = 1,
                Type = type,
                DocumentUrl = uploadResult.Value,
                Status = ApprovalStatus.Pending
            };

            context.Evidences.Add(evidence);

            return Result.OkIf(await context.SaveChangesAsync(cancellationToken) > 0, CreateError.Create("Failed to create evidence."));
        }));

    public async Task<Result> RecordIndicatorActualAmountAsync(string indicatorIdHash, decimal amount, Guid userId, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(indicatorIdHash);

            if (decodeResult.IsFailed)
                return Result.Fail(IdDecodeError.Create()
                    .CausedBy(decodeResult.Errors));

            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var changedTotal = await context.Indicators.Where(i => i.Id == decodeResult.Value)
                .ExecuteUpdateAsync(f => f
                    .SetProperty(f => f.ActualAmount, amount)
                    .SetProperty(f => f.CreatedBy, userId), cancellationToken);

            return Result.OkIf(changedTotal > 0, UpdateError.Create("Failed to update indicator."));
        }));

    public async Task<Result<Indicator[]>> GetIndicatorsAsync(Pagination pagination, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result<Indicator[]>>>)(async () =>
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var indicators = await context.Indicators.AsNoTracking()
                .OrderByDescending(i => i.CreatedAt)
                .Skip((pagination.Page - 1) * pagination.PageSize)
                .Take(pagination.PageSize)
                .ToListAsync(cancellationToken);

            return Result.Ok(indicators?.Select(i => i.Map()).ToArray() ?? []);
        }));

    public async Task<Result<Domain.Models.Evidence[]>> GetEvidenceFilesAsync(Pagination pagination, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result<Domain.Models.Evidence[]>>>)(async () =>
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var evidence = await context.Evidences.AsNoTracking()
                .OrderByDescending(e => e.CreatedAt)
                    .Skip((pagination.Page - 1) * pagination.PageSize)
                    .Take(pagination.PageSize)
                .ToListAsync(cancellationToken);

            return Result.Ok(evidence?.Select(i => i.Map()).ToArray() ?? []);
        }));

    public async Task<Result> CreateMilestoneAsync(CreateMilestoneRequest request, Guid userId, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result>>)(async () =>
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Users.AnyAsync(u => u.Id == userId, cancellationToken))
                return Result.Fail(NotFoundError.New);

            if (!await context.Projects.AnyAsync(p => p.Id == request.ProjectId, cancellationToken))
                return Result.Fail(NotFoundError.New);

            context.Milestones.Add(new Domain.Entities.Milestone
            {
                ProjectId = request.ProjectId,
                DueAt = request.DueAt,
                Name = request.Name,
                Priority = request.Priority,
                Status = ApprovalStatus.Pending,
                CreatedBy = userId,
                CreatedAt = DateTime.UtcNow
            });

            return Result.OkIf(await context.SaveChangesAsync(cancellationToken) > 0,
                CreateError.Create("No record could be created."));
        }));

    public async Task<Result> CreateIndicatorAsync(CreateIndicatorRequest request, Guid userId, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result>>)(async () =>
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Projects.AnyAsync(p => p.Id == request.ProjectId, cancellationToken))
                return Result.Fail(NotFoundError.New);

            context.Indicators.Add(new Domain.Entities.Indicator
            {
                ProjectId = request.ProjectId,
                Name = request.Name,
                UnitOfMeasure = request.UnitOfMeasure,
                BaselineAmount = request.BaselineAmount,
                TargetAmount = request.TargetAmount,
                ActualAmount = request.BaselineAmount,
                CreatedBy = userId,
                CreatedAt = DateTime.UtcNow
            });

            return Result.OkIf(await context.SaveChangesAsync(cancellationToken) > 0, CreateError.Create("Failed to create indicator."));
        }));

    public async Task<Result<Indicator>> GetIndicatorAsync(string indicatorId, CancellationToken cancellationToken) =>
        await Result.Try((Func<Task<Result<Indicator>>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(indicatorId);

            if (decodeResult.IsFailed)
                return Result.Fail(IdDecodeError.Create()
                    .CausedBy(decodeResult.Errors));

            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var indicator = await context.Indicators.AsNoTracking().FirstOrDefaultAsync(i => i.Id == decodeResult.Value, cancellationToken);

            return Result.FailIf(indicator is null, NotFoundError.Create("Indicator not found."))
                .ToResult(indicator?.Map()!);
        }));

    public async Task<Result<Domain.Models.Evidence>> GetEvidenceAsync(string evidenceId, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result<Domain.Models.Evidence>>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(evidenceId);

            if (decodeResult.IsFailed)
                return Result.Fail<Domain.Models.Evidence>(IdDecodeError.Create()
                    .CausedBy(decodeResult.Errors));

            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var evidence = await context.Evidences.AsNoTracking().FirstOrDefaultAsync(e => e.Id == decodeResult.Value, cancellationToken);

            return Result.FailIf(evidence is null, NotFoundError.Create("Evidence not found."))
                .ToResult(evidence?.Map()!);
        }));

    public async Task<Result<Domain.Models.Evidence[]>> GetMilestoneEvidencesAsync(string milestoneIdHash, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result<Domain.Models.Evidence[]>>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(milestoneIdHash);

            if (decodeResult.IsFailed)
                return Result.Fail(IdDecodeError.Create()
                    .CausedBy(decodeResult.Errors));

            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var evidences = await context.Evidences.AsNoTracking()
                .Where(e => e.MilestoneId == decodeResult.Value)
                .OrderByDescending(o => o.CreatedAt)
                    .ThenByDescending(o => o.UpdatedAt)
                .ToListAsync(cancellationToken);

            return Result.Ok(evidences?.Select(e => e.Map()).ToArray() ?? []);
        }));

    public async Task<Result<Domain.Models.Evidence[]>> GetProjectEvidencesAsync(string projectIdHash, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result<Domain.Models.Evidence[]>>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(projectIdHash);

            if (decodeResult.IsFailed)
                return Result.Fail(IdDecodeError.Create()
                    .CausedBy(decodeResult.Errors));

            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var evidences = await context.Evidences.AsNoTracking()
                .Where(e => e.ProjectId == decodeResult.Value)
                .OrderByDescending(o => o.CreatedAt)
                    .ThenBy(o => o.UpdatedAt)
                .ToListAsync(cancellationToken);

            return Result.Ok(evidences?.Select(e => e.Map()).ToArray() ?? []);
        }));

    public async Task<Result> UpdateEvidenceAsync(UpdateEvidenceRequest request, Guid userId, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result>>)(async () =>
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            if (!await context.Evidences.AnyAsync(e => e.Id == request.EvidenceId, cancellationToken))
                return Result.Fail(NotFoundError.New);

            var changedTotal = await context.Evidences.Where(e => e.Id == request.EvidenceId)
                .ExecuteUpdateAsync(f => f
                    .SetProperty(f => f.Version, request.Version)
                    .SetProperty(f => f.Type, request.EvidenceType)
                    .SetProperty(f => f.Status, request.Status)
                    .SetProperty(f => f.UpdatedBy, userId)
                    .SetProperty(f => f.UpdatedAt, DateTime.UtcNow), cancellationToken);

            return Result.OkIf(changedTotal > 0, UpdateError.Create("Failed to update evidence."));
        }));

    public async Task<Result<string>> GetEvidenceUrlAsync(string evidenceIdHash, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<Task<Result<string>>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(evidenceIdHash);

            if (decodeResult.IsFailed)
                return Result.Fail(IdDecodeError.Create()
                    .CausedBy(decodeResult.Errors));

            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var evidence = await context.Evidences.AsNoTracking().FirstOrDefaultAsync(e => e.Id == decodeResult.Value, cancellationToken);

            if (evidence is null)
                return Result.Fail<string>(NotFoundError.New);

            if (string.IsNullOrWhiteSpace(evidence.DocumentUrl))
                return Result.Fail<string>(ValidationError.Create("Ecidence is invalid, has no saved documentUrl"));

            var secureDownloadUrlResult = await s3Service.GeneratePresignedUrlAsync(evidence.DocumentUrl, 
                TimeSpan.FromMinutes(15), null, cancellationToken);

            return Result.OkIf(secureDownloadUrlResult.IsSuccess && !string.IsNullOrWhiteSpace(secureDownloadUrlResult.Value), 
                NotFoundError.Create("Failed to generate secure file url"))
                    .ToResult(secureDownloadUrlResult.Value);
        }));
}