using Microsoft.EntityFrameworkCore;
using Mizuki.Database;
using Mizuki.Database.Models;
using Mizuki.Helpers;

namespace Mizuki.Services;

/// <summary>
/// The service managing uploads.
/// </summary>
public class UploadService(
    MizukiDbContext dbContext,
    DriveService driveService)
{
    /// <summary>
    /// Creates a new upload record for a given user.
    /// </summary>
    /// <param name="user">The user.</param>
    /// <param name="file">The form file.</param>
    /// <returns>The created upload.</returns>
    public async Task<Upload?> CreateUpload(
        User user,
        IFormFile file)
    {
        var upload = new Upload
        {
            Id = Guid.NewGuid(),

            Filename = Tid.NewTid().ToString(),
            OriginalFilename = file.FileName,
            SizeInBytes = file.Length,
            
            TimeOfUpload = DateTimeOffset.UtcNow,
            
            Author = user,
            AuthorId = user.Id
        };

        await dbContext.Uploads.AddAsync(upload);
        await dbContext.SaveChangesAsync();

        driveService.SaveFileByFilename(upload.Filename, file.OpenReadStream());
        return upload;
    }

    /// <summary>
    /// Deletes an upload.
    /// </summary>
    /// <param name="user">The user.</param>
    /// <param name="filename">The name of the file that the user wishes to delete.</param>
    public async Task DeleteUpload(
        User user,
        string filename)
    {
        var upload = await dbContext.Uploads
            .Where(u => u.AuthorId == user.Id && u.Filename == filename)
            .FirstOrDefaultAsync();

        if (upload is null)
            return;

        dbContext.Uploads.Remove(upload);
        await dbContext.SaveChangesAsync();
        
        driveService.DeleteFileByFilename(filename);
    }

    /// <summary>
    /// Gets all the uploads for a user.
    /// </summary>
    /// <param name="user">The user.</param>
    /// <returns>Their uploads.</returns>
    public async Task<IEnumerable<Upload>> GetAllUploadsForUser(
        User user)
    {
        return await dbContext.Uploads
            .OrderByDescending(u => u.TimeOfUpload)
            .Where(u => u.AuthorId == user.Id)
            .ToListAsync();
    }

    /// <summary>
    /// Gets an upload by its filename.
    /// </summary>
    /// <param name="filename">The filename.</param>
    /// <returns>The upload, if it exists.</returns>
    public async Task<Upload?> GetByFilename(string filename)
    {
        return await dbContext.Uploads
            .FirstOrDefaultAsync(u => u.Filename == filename);
    }
}