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.Grants;

public sealed class GrantsService(IDbContextFactory<ApplicationDbContext> contextFactory, HashService hashService) : IService
{
    public async ValueTask<Result<Contract[]>> GetContractsAsync(Pagination pagination, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<ValueTask<Result<Contract[]>>>)(async () =>
        {
            await using var context = await contextFactory.CreateDbContextAsync(cancellationToken);

            var contracts = await context.Contracts.AsNoTracking()
                .OrderByDescending(c => c.CreatedAt)
                .Skip((pagination.Page - 1) * pagination.PageSize)
                .Take(pagination.PageSize)
                .ToListAsync(cancellationToken);

            return Result.Ok(contracts.Select(c => c.Map()).ToArray());
        }));

    public async ValueTask<Result<Contract>> GetContractAsync(string contractIdHash, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<ValueTask<Result<Contract>>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(contractIdHash);

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

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

            var contract = await context.Contracts.AsNoTracking()
                .FirstOrDefaultAsync(c => c.Id == decodeResult.Value, cancellationToken);

            return contract is not null
                ? Result.Ok(contract.Map())
                : Result.Fail<Contract>(NotFoundError.New);
        }));

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

            var budgets = await context.Budgets.AsNoTracking()
                .OrderByDescending(b => b.CreatedAt)
                .Skip((pagination.Page - 1) * pagination.PageSize)
                .Take(pagination.PageSize)
                .ToListAsync(cancellationToken);

            return Result.Ok(budgets.Select(b => b.Map()).ToArray());
        }));

    public async ValueTask<Result<Budget>> GetBudgetAsync(string budgetIdHash, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<ValueTask<Result<Budget>>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(budgetIdHash);

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

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

            var budget = await context.Budgets.AsNoTracking()
                .FirstOrDefaultAsync(b => b.Id == decodeResult.Value, cancellationToken);

            return budget is not null
                ? Result.Ok(budget.Map())
                : Result.Fail<Budget>(NotFoundError.New);
        }));

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

            var awards = await context.Awards.AsNoTracking()
                .OrderByDescending(a => a.CreatedAt)
                .Skip((pagination.Page - 1) * pagination.PageSize)
                .Take(pagination.PageSize)
                .ToListAsync(cancellationToken);

            return Result.Ok(awards.Select(a => a.Map()).ToArray());
        }));

    public async ValueTask<Result<Award>> GetAwardAsync(string awardIdHash, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<ValueTask<Result<Award>>>)(async () =>
        {
            var decodeResult = hashService.DecodeLongIdHash(awardIdHash);

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

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

            var award = await context.Awards.AsNoTracking().FirstOrDefaultAsync(a => a.Id == decodeResult.Value, cancellationToken);

            return award is not null
                ? Result.Ok(award.Map())
                : Result.Fail<Award>(NotFoundError.New);
        }));

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

            var changedTotal = await context.Contracts
                .Where(c => c.Id == request.ContractId && c.Status != ContractStatus.Active)
                .ExecuteUpdateAsync(f => f
                    .SetProperty(u => u.ExternalSignatureId, request.ExternalSignatureId)
                    .SetProperty(u => u.SignedDocumentUrl, request.SignedDocumentUrl)
                    .SetProperty(u => u.CreatedBy, userId)
                    .SetProperty(u => u.Status, ContractStatus.Active), cancellationToken);

            return Result.FailIf(await context.SaveChangesAsync(cancellationToken) <= 0, UpdateError.New);
        }));

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

            var award = await context.Awards.AsNoTracking()
                .FirstOrDefaultAsync(a => a.Id == request.AwardId, cancellationToken);

            if (award == null)
                return Result.Fail(NotFoundError.New);

            var contract = new Domain.Entities.Contract
            {
                AwardId = request.AwardId,
                TotalValue = request.TotalValue,
                EffectiveAt = request.EffectiveAt,
                ExpiresAt = request.ExpiresAt,
                Status = ContractStatus.Draft,
                CreatedBy = userId,
                CreatedAt = DateTime.UtcNow
            };

            context.Contracts.Add(contract);

            return Result.FailIf(await context.SaveChangesAsync(cancellationToken) <= 0, CreateError.New);
        }));

    public async ValueTask<Result> CreateBudgetAsync(CreateBudgetRequest request, Guid userId, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<ValueTask<Result>>)(async () =>
        {
            if (request.Amount <= 0)
                return Result.Fail(ValidationError.Create("Budget amount must be greater than zero."));

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

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

            var budget = new Domain.Entities.Budget
            {
                ProjectId = request.ProjectId,
                Name = request.Name,
                Amount = request.Amount,
                CreatedBy = userId,
                CreatedAt = DateTime.UtcNow
            };

            context.Budgets.Add(budget);

            return Result.FailIf(await context.SaveChangesAsync(cancellationToken) <= 0, CreateError.New);
        }));

    public async ValueTask<Result> CreateAwardAsync(CreateAwardRequest request, Guid userId, CancellationToken cancellationToken = default) =>
        await Result.Try((Func<ValueTask<Result>>)(async () =>
        {
            if (request.Amount <= 0)
                return Result.Fail(ValidationError.Create("Approved amount must be greater than zero."));

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

            if (!await context.Organisations.AnyAsync(o => o.Id == request.OrganisationId, cancellationToken))
                return Result.Fail(NotFoundError.New);

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

            var award = new Domain.Entities.Award
            {
                OrganisationId = request.OrganisationId,
                ProgrammeId = request.ProgrammeId,
                Amount = request.Amount,
                Status = ApprovalStatus.Pending,
                CreatedBy = userId,
                CreatedAt = DateTime.UtcNow
            };

            context.Awards.Add(award);

            return Result.FailIf(await context.SaveChangesAsync(cancellationToken) <= 0, CreateError.New);
        }));
}