package jobs

import (
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"ddc/internal/explain"
	"ddc/internal/files"
)

type MoveRequest struct {
	Paths       []string `json:"paths"`
	Destination string   `json:"destination"`
	Subfolder   string   `json:"subfolder"`
	Cleanup     bool     `json:"cleanup"`
}

func (manager *Manager) Move(id string, request MoveRequest) error {
	job, err := manager.lookup(id)
	if err != nil {
		return err
	}
	if job.currentStatus() != StatusReady {
		return ErrJobBusy
	}
	if len(request.Paths) == 0 {
		return invalid(errors.New("select at least one file or folder"))
	}

	target, err := manager.resolveTarget(request.Destination, request.Subfolder)
	if err != nil {
		return err
	}
	if target == nil {
		return invalid(errors.New("choose a destination"))
	}
	sources, err := resolveSources(job.directory, request.Paths)
	if err != nil {
		return err
	}
	destination, err := files.EnsureSubdirectory(target.destination, target.subfolder)
	if err != nil {
		return invalid(err)
	}
	if err := checkTargets(sources, destination); err != nil {
		return err
	}

	if !job.begin(StatusMoving, StatusReady) {
		return ErrJobBusy
	}
	manager.runInBackground(job, "move", func() {
		manager.moveFiles(job, sources, destination, request.Cleanup)
	})
	return nil
}

func resolveSources(root string, relativePaths []string) ([]string, error) {
	sources := make([]string, 0, len(relativePaths))
	seenNames := make(map[string]bool)

	for _, relative := range relativePaths {
		source, err := files.ResolveInside(root, relative)
		if err != nil {
			return nil, invalid(err)
		}
		name := filepath.Base(source)
		if files.IsInternal(name) {
			return nil, invalid(files.ErrUnsafePath)
		}
		if seenNames[name] {
			return nil, invalid(fmt.Errorf("more than one selected item is named %q", name))
		}
		seenNames[name] = true
		sources = append(sources, source)
	}

	for _, outer := range sources {
		for _, inner := range sources {
			if files.IsWithin(outer, inner) {
				return nil, invalid(errors.New("selection contains a folder and items inside it"))
			}
		}
	}
	return sources, nil
}

func checkTargets(sources []string, destination string) error {
	for _, source := range sources {
		name := filepath.Base(source)
		if _, err := os.Lstat(filepath.Join(destination, name)); err == nil {
			return fmt.Errorf("%w: %s", files.ErrDestinationExists, name)
		}
	}
	return nil
}

func (manager *Manager) moveFiles(job *Job, sources []string, destination string, cleanup bool) {
	job.resetProgress()
	var totalBytes int64
	for _, source := range sources {
		if size, err := files.TreeSize(source); err == nil {
			totalBytes += size
		}
	}
	job.SetTotal(totalBytes)

	movedNames := make([]string, 0, len(sources))
	defer func() { manager.recordHistory(job, destination, movedNames) }()
	started := time.Now()
	for _, source := range sources {
		if err := files.MoveInto(source, destination, manager.reservedBytes(), job.Add); err != nil {
			job.logger().Error("move failed",
				"item", filepath.Base(source),
				"destination", destination,
				"moved_before_failure", len(movedNames),
				"error", err,
			)
			job.setStatus(StatusReady, "Move failed: "+explain.Error(err))
			return
		}
		movedNames = append(movedNames, filepath.Base(source))
	}
	job.logger().Info("move finished",
		"items", len(movedNames),
		"bytes", totalBytes,
		"destination", destination,
		"duration", time.Since(started).Round(time.Second).String(),
	)

	message := fmt.Sprintf("Moved %d item(s) to %s", len(sources), destination)
	if !cleanup {
		job.setStatus(StatusReady, message)
		return
	}
	if err := os.RemoveAll(job.directory); err != nil {
		job.logger().Warn("could not remove temporary files after move", "directory", job.directory, "error", err)
		message += ", cleanup failed: " + explain.Error(err)
	}
	job.setStatus(StatusCompleted, message)
}