Add resumable downloads, download paths, queue controls and history

internal/jobs/download.go

@@ -0,0 +1,122 @@
+package jobs
+
+import (
+	"context"
+	"errors"
+	"path/filepath"
+
+	"ddc/internal/extract"
+	"ddc/internal/fetch"
+)
+
+func (manager *Manager) Pause(id string) error {
+	job, err := manager.lookup(id)
+	if err != nil {
+		return err
+	}
+	if !job.pause() {
+		return ErrJobBusy
+	}
+	return nil
+}
+
+func (manager *Manager) Resume(id string) error {
+	job, err := manager.lookup(id)
+	if err != nil {
+		return err
+	}
+	if !job.begin(StatusQueued, StatusPaused, StatusFailed) {
+		return ErrJobBusy
+	}
+	job.saveRecord()
+	manager.launchDownload(job)
+	return nil
+}
+
+func (manager *Manager) Reorder(id, direction string) error {
+	if direction != queueFirst && direction != queueUp && direction != queueDown {
+		return invalid(errors.New("direction must be first, up or down"))
+	}
+	job, err := manager.lookup(id)
+	if err != nil {
+		return err
+	}
+	if job.currentStatus() != StatusQueued || !manager.slots.reorder(id, direction) {
+		return ErrJobBusy
+	}
+	return nil
+}
+
+func (manager *Manager) launchDownload(job *Job) {
+	runContext, cancelRun := job.startRun()
+	manager.slots.enqueue(job.id)
+	go func() {
+		defer job.workers.Done()
+		defer cancelRun(nil)
+		manager.download(job, runContext)
+	}()
+}
+
+func (manager *Manager) download(job *Job, runContext context.Context) {
+	if !manager.slots.acquire(runContext, job.id, manager.concurrencyLimit) {
+		manager.handleDownloadError(job, runContext, context.Cause(runContext))
+		return
+	}
+	defer manager.slots.release()
+
+	job.setStatus(StatusDownloading, "")
+	filePath, err := manager.downloader.Download(runContext, manager.fetchRequest(job))
+	if err != nil {
+		manager.handleDownloadError(job, runContext, err)
+		return
+	}
+	job.markDownloaded(filepath.Base(filePath))
+
+	if job.autoExtract && extract.IsArchive(filePath) {
+		job.setStatus(StatusExtracting, "")
+		destination, err := manager.extractArchive(job, filePath)
+		if err != nil {
+			manager.finishWithError(job, StatusReady, "Extraction failed: ", err)
+			job.saveRecord()
+			return
+		}
+		job.SetFileName(filepath.Base(destination))
+	}
+
+	job.setStatus(StatusReady, "")
+	job.saveRecord()
+	manager.moveToTarget(job)
+}
+
+func (manager *Manager) fetchRequest(job *Job) fetch.Request {
+	current := manager.preferences.Get()
+	return fetch.Request{
+		URL:           job.sourceURL,
+		Directory:     job.directory,
+		FileName:      job.requestedName,
+		ReservedBytes: current.MinFreeBytes(),
+		Connections:   current.ConnectionsPerDownload,
+		State:         job.currentDownloadState(),
+		Progress:      job,
+		Checkpoint: func(state fetch.State) {
+			job.setDownloadState(&state)
+			job.saveRecord()
+		},
+	}
+}
+
+func (manager *Manager) handleDownloadError(job *Job, runContext context.Context, err error) {
+	switch {
+	case errors.Is(context.Cause(runContext), errPaused):
+		job.setStatus(StatusPaused, "")
+	case job.jobContext.Err() != nil:
+		job.setStatus(StatusCancelled, "")
+		return
+	default:
+		if errors.Is(err, fetch.ErrSourceChanged) || errors.Is(err, fetch.ErrResumeUnsupported) {
+			job.setDownloadState(nil)
+		}
+		job.setStatus(StatusFailed, err.Error())
+	}
+	job.saveRecord()
+}