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/// Handlers to manipulate uploaded files
module MyWebLog.Handlers.Upload
open System
open System.IO
open Microsoft.Net.Http.Headers
/// Helper functions for this module
[<AutoOpen>]
module private Helpers =
open Microsoft.AspNetCore.StaticFiles
/// A MIME type mapper instance to use when serving files from the database
let mimeMap = FileExtensionContentTypeProvider()
/// A cache control header that instructs the browser to cache the result for no more than 30 days
let cacheForThirtyDays =
let hdr = CacheControlHeaderValue()
hdr.MaxAge <- Some (TimeSpan.FromDays 30) |> Option.toNullable
hdr
/// Shorthand for the directory separator
let slash = Path.DirectorySeparatorChar
/// The base directory where uploads are stored, relative to the executable
let uploadDir = Path.Combine("wwwroot", "upload")
// ~~ SERVING UPLOADS ~~
open System.Globalization
open Giraffe
open Microsoft.AspNetCore.Http
open NodaTime
/// Determine if the file has been modified since the date/time specified by the If-Modified-Since header
let checkModified since (ctx: HttpContext) : HttpHandler option =
match ctx.Request.Headers.IfModifiedSince with
| it when it.Count < 1 -> None
| it when since > Instant.FromDateTimeUtc(DateTime.Parse(it[0], null, DateTimeStyles.AdjustToUniversal)) -> None
| _ -> Some (setStatusCode 304)
open Microsoft.AspNetCore.Http.Headers
/// Derive a MIME type based on the extension of the file
let deriveMimeType path =
match mimeMap.TryGetContentType path with true, typ -> typ | false, _ -> "application/octet-stream"
/// Send a file, caching the response for 30 days
let sendFile updatedOn path (data : byte[]) : HttpHandler = fun next ctx ->
let headers = ResponseHeaders ctx.Response.Headers
headers.ContentType <- (deriveMimeType >> MediaTypeHeaderValue) path
headers.CacheControl <- cacheForThirtyDays
let stream = new MemoryStream(data)
streamData true stream None (Some (DateTimeOffset updatedOn)) next ctx
open MyWebLog
// GET /upload/{web-log-slug}/{**path}
let serve (urlParts: string seq) : HttpHandler = fun next ctx -> task {
let webLog = ctx.WebLog
let parts = (urlParts |> Seq.skip 1 |> Seq.head).Split '/'
let slug = Array.head parts
if slug = webLog.Slug then
// Static file middleware will not work in subdirectories; check for an actual file first
let fileName = Path.Combine("wwwroot", (Seq.head urlParts)[1..])
if File.Exists fileName then
return! streamFile true fileName None None next ctx
else
let path = String.Join('/', Array.skip 1 parts)
match! ctx.Data.Upload.FindByPath path webLog.Id with
| Some upload ->
match checkModified upload.UpdatedOn ctx with
| Some threeOhFour -> return! threeOhFour next ctx
| None -> return! sendFile (upload.UpdatedOn.ToDateTimeUtc()) path upload.Data next ctx
| None -> return! Error.notFound next ctx
else
return! Error.notFound next ctx
}
// ~~ ADMINISTRATION ~~
open System.Text.RegularExpressions
open MyWebLog.ViewModels
/// Turn a string into a lowercase URL-safe slug
let makeSlug it = (Regex """\s+""").Replace((Regex "[^A-z0-9 -]").Replace(it, ""), "-").ToLowerInvariant()
// GET /admin/uploads
let list : HttpHandler = requireAccess Author >=> fun next ctx -> task {
let webLog = ctx.WebLog
let! dbUploads = ctx.Data.Upload.FindByWebLog webLog.Id
let diskUploads =
let path = Path.Combine(uploadDir, webLog.Slug)
try
Directory.EnumerateFiles(path, "*", SearchOption.AllDirectories)
|> Seq.map (fun file ->
let name = Path.GetFileName file
let create =
match File.GetCreationTime(Path.Combine(path, file)) with
| dt when dt > DateTime.UnixEpoch -> Some dt
| _ -> None
{ DisplayUpload.Id = ""
Name = name
Path = file.Replace($"{path}{slash}", "").Replace(name, "").Replace(slash, '/')
UpdatedOn = create
Source = string Disk })
with
| :? DirectoryNotFoundException -> [] // This is fine
| ex ->
warn "Upload" ctx $"Encountered {ex.GetType().Name} listing uploads for {path}:\n{ex.Message}"
[]
return!
dbUploads
|> Seq.ofList
|> Seq.map (DisplayUpload.FromUpload webLog Database)
|> Seq.append diskUploads
|> Seq.sortByDescending (fun file -> file.UpdatedOn, file.Path)
|> Views.WebLog.uploadList
|> adminPage "Uploaded Files" next ctx
}
// GET /admin/upload/new
let showNew : HttpHandler = requireAccess Author >=> fun next ctx ->
adminPage "Upload a File" next ctx Views.WebLog.uploadNew
// POST /admin/upload/save
let save : HttpHandler = requireAccess Author >=> fun next ctx -> task {
if ctx.Request.HasFormContentType && ctx.Request.Form.Files.Count > 0 then
let upload = Seq.head ctx.Request.Form.Files
let fileName = String.Concat (makeSlug (Path.GetFileNameWithoutExtension upload.FileName),
Path.GetExtension(upload.FileName).ToLowerInvariant())
let now = Noda.now ()
let localNow = ctx.WebLog.LocalTime now
let year = localNow.ToString "yyyy"
let month = localNow.ToString "MM"
let! form = ctx.BindFormAsync<UploadFileModel>()
match UploadDestination.Parse form.Destination with
| Database ->
use stream = new MemoryStream()
do! upload.CopyToAsync stream
let file =
{ Id = UploadId.Create()
WebLogId = ctx.WebLog.Id
Path = Permalink $"{year}/{month}/{fileName}"
UpdatedOn = now
Data = stream.ToArray() }
do! ctx.Data.Upload.Add file
| Disk ->
let fullPath = Path.Combine(uploadDir, ctx.WebLog.Slug, year, month)
let _ = Directory.CreateDirectory fullPath
use stream = new FileStream(Path.Combine(fullPath, fileName), FileMode.Create)
do! upload.CopyToAsync stream
do! addMessage ctx { UserMessage.Success with Message = $"File uploaded to {form.Destination} successfully" }
return! redirectToGet "admin/uploads" next ctx
else
return! RequestErrors.BAD_REQUEST "Bad request; no file present" next ctx
}
// DELETE /admin/upload/{id}
let deleteFromDb upId : HttpHandler = fun next ctx -> task {
match! ctx.Data.Upload.Delete (UploadId upId) ctx.WebLog.Id with
| Ok fileName ->
do! addMessage ctx { UserMessage.Success with Message = $"{fileName} deleted successfully" }
return! list next ctx
| Error _ -> return! Error.notFound next ctx
}
/// Remove a directory tree if it is empty
let removeEmptyDirectories (webLog: WebLog) (filePath: string) =
let mutable path = Path.GetDirectoryName filePath
let mutable finished = false
while (not finished) && path > "" do
let fullPath = Path.Combine(uploadDir, webLog.Slug, path)
if Directory.EnumerateFileSystemEntries fullPath |> Seq.isEmpty then
Directory.Delete fullPath
path <- String.Join(slash, path.Split slash |> Array.rev |> Array.skip 1 |> Array.rev)
else finished <- true
// DELETE /admin/upload/disk/{**path}
let deleteFromDisk urlParts : HttpHandler = fun next ctx -> task {
let filePath = urlParts |> Seq.skip 1 |> Seq.head
let path = Path.Combine(uploadDir, ctx.WebLog.Slug, filePath)
if File.Exists path then
File.Delete path
removeEmptyDirectories ctx.WebLog filePath
do! addMessage ctx { UserMessage.Success with Message = $"{filePath} deleted successfully" }
return! list next ctx
else return! Error.notFound next ctx
}