package main

import (
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

type TrashDTO struct {
	TrashPath string          `json:"trashPath"`
	Count     int             `json:"count"`
	Nodes     []TrashNodeDTO  `json:"nodes"`
	Entries   []TrashEntryDTO `json:"entries"`
}

type TrashNodeDTO struct {
	ID        string `json:"id"`
	ParentID  string `json:"parentId,omitempty"`
	Title     string `json:"title"`
	Type      string `json:"type"`
	FsPath    string `json:"fsPath"`
	NodePath  string `json:"nodePath"`
	DeletedAt string `json:"deletedAt"`
}

type TrashEntryDTO struct {
	Name       string `json:"name"`
	Path       string `json:"path"`
	IsDir      bool   `json:"isDir"`
	Size       int64  `json:"size"`
	ModifiedAt string `json:"modifiedAt"`
}

func (a *App) ListTrash() (*TrashDTO, error) {
	if err := a.requireVault(); err != nil {
		return nil, err
	}
	trashPath := filepath.Join(a.vault, ".verstak", "trash")

	deleted, err := a.nodes.ListDeleted()
	if err != nil {
		return nil, err
	}
	nodes := make([]TrashNodeDTO, 0, len(deleted))
	for _, n := range deleted {
		deletedAt := ""
		if n.DeletedAt != nil {
			deletedAt = n.DeletedAt.Format(time.RFC3339)
		}
		parentID := ""
		if n.ParentID != nil {
			parentID = *n.ParentID
		}
		nodes = append(nodes, TrashNodeDTO{
			ID:        n.ID,
			ParentID:  parentID,
			Title:     n.Title,
			Type:      n.Type,
			FsPath:    n.FsPath,
			NodePath:  a.nodes.Path(n.ID),
			DeletedAt: deletedAt,
		})
	}

	entries, err := listTrashEntries(trashPath)
	if err != nil {
		return nil, err
	}
	return &TrashDTO{TrashPath: trashPath, Count: len(nodes), Nodes: nodes, Entries: entries}, nil
}

func (a *App) TrashCount() (int, error) {
	trash, err := a.ListTrash()
	if err != nil {
		return 0, err
	}
	return trash.Count, nil
}

func (a *App) RestoreTrashNode(nodeID string) error {
	if err := a.requireVault(); err != nil {
		return err
	}
	chain, err := a.deletedAncestorChain(nodeID)
	if err != nil {
		return err
	}
	for _, n := range chain {
		if err := a.restoreTrashPath(n.ID, n.FsPath); err != nil {
			return err
		}
		if _, err := a.db.Exec(`UPDATE nodes SET deleted_at = NULL, updated_at = ? WHERE id = ?`, time.Now().UTC().Format(time.RFC3339), n.ID); err != nil {
			return err
		}
	}
	return nil
}

func (a *App) RestoreTrashNodesJSON(nodeIDsJSON string) error {
	var ids []string
	if err := json.Unmarshal([]byte(nodeIDsJSON), &ids); err != nil {
		return err
	}
	for _, id := range ids {
		if err := a.RestoreTrashNode(id); err != nil {
			return err
		}
	}
	return nil
}

func (a *App) PurgeTrashNodesJSON(nodeIDsJSON string) error {
	if err := a.requireVault(); err != nil {
		return err
	}
	var ids []string
	if err := json.Unmarshal([]byte(nodeIDsJSON), &ids); err != nil {
		return err
	}
	for _, id := range ids {
		if err := a.purgeTrashNode(id); err != nil {
			return err
		}
	}
	return nil
}

func (a *App) EmptyTrash() error {
	if err := a.requireVault(); err != nil {
		return err
	}
	trash, err := a.ListTrash()
	if err != nil {
		return err
	}
	ids := make([]string, 0, len(trash.Nodes))
	for _, n := range trash.Nodes {
		if n.ParentID == "" {
			ids = append(ids, n.ID)
		}
	}
	if len(ids) == 0 {
		for _, n := range trash.Nodes {
			ids = append(ids, n.ID)
		}
	}
	for _, id := range ids {
		if err := a.purgeTrashNode(id); err != nil {
			return err
		}
	}
	return os.RemoveAll(filepath.Join(a.vault, ".verstak", "trash"))
}

func (a *App) deletedAncestorChain(nodeID string) ([]TrashNodeDTO, error) {
	var reversed []TrashNodeDTO
	current := nodeID
	for current != "" {
		n, err := a.nodes.Get(current)
		if err != nil {
			return nil, err
		}
		if n.DeletedAt == nil {
			break
		}
		parentID := ""
		if n.ParentID != nil {
			parentID = *n.ParentID
		}
		reversed = append(reversed, TrashNodeDTO{ID: n.ID, ParentID: parentID, Title: n.Title, Type: n.Type, FsPath: n.FsPath})
		current = parentID
	}
	if len(reversed) == 0 {
		return nil, fmt.Errorf("deleted node not found")
	}
	chain := make([]TrashNodeDTO, 0, len(reversed))
	for i := len(reversed) - 1; i >= 0; i-- {
		chain = append(chain, reversed[i])
	}
	return chain, nil
}

func (a *App) restoreTrashPath(nodeID, fsPath string) error {
	if fsPath == "" {
		return nil
	}
	trashEntry, err := a.findTrashEntryForNode(nodeID)
	if err != nil {
		return nil
	}
	dst := filepath.Join(a.vault, fsPath)
	if _, err := os.Stat(dst); err == nil {
		return nil
	}
	if err := os.MkdirAll(filepath.Dir(dst), 0o750); err != nil {
		return err
	}
	return os.Rename(trashEntry, dst)
}

func (a *App) findTrashEntryForNode(nodeID string) (string, error) {
	trashPath := filepath.Join(a.vault, ".verstak", "trash")
	entries, err := os.ReadDir(trashPath)
	if err != nil {
		return "", err
	}
	prefix := nodeID + "_"
	for _, entry := range entries {
		if strings.HasPrefix(entry.Name(), prefix) {
			return filepath.Join(trashPath, entry.Name()), nil
		}
	}
	return "", fmt.Errorf("trash entry not found")
}

func (a *App) purgeTrashNode(nodeID string) error {
	ids, err := a.deletedSubtreeIDs(nodeID)
	if err != nil {
		return err
	}
	for _, id := range ids {
		if path, err := a.findTrashEntryForNode(id); err == nil {
			_ = os.RemoveAll(path)
		}
	}
	tx, err := a.db.Begin()
	if err != nil {
		return err
	}
	defer tx.Rollback()
	for i := len(ids) - 1; i >= 0; i-- {
		id := ids[i]
		_, _ = tx.Exec(`DELETE FROM node_meta WHERE node_id = ?`, id)
		_, _ = tx.Exec(`DELETE FROM notes WHERE node_id = ?`, id)
		_, _ = tx.Exec(`DELETE FROM actions WHERE node_id = ?`, id)
		_, _ = tx.Exec(`DELETE FROM links WHERE node_id = ?`, id)
		_, _ = tx.Exec(`DELETE FROM worklog_entry_events WHERE entry_id IN (SELECT id FROM worklog_entries WHERE node_id = ?)`, id)
		_, _ = tx.Exec(`DELETE FROM worklog_entries WHERE node_id = ?`, id)
		if _, err := tx.Exec(`DELETE FROM nodes WHERE id = ? AND deleted_at IS NOT NULL`, id); err != nil {
			return err
		}
	}
	return tx.Commit()
}

func (a *App) deletedSubtreeIDs(nodeID string) ([]string, error) {
	rows, err := a.db.Query(
		`WITH RECURSIVE subtree(id) AS (
			SELECT id FROM nodes WHERE id = ? AND deleted_at IS NOT NULL
			UNION ALL
			SELECT n.id FROM nodes n JOIN subtree s ON n.parent_id = s.id
			WHERE n.deleted_at IS NOT NULL
		) SELECT id FROM subtree`, nodeID)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var ids []string
	for rows.Next() {
		var id string
		if err := rows.Scan(&id); err != nil {
			return nil, err
		}
		ids = append(ids, id)
	}
	if len(ids) == 0 {
		return nil, fmt.Errorf("deleted node not found")
	}
	return ids, rows.Err()
}

func listTrashEntries(trashPath string) ([]TrashEntryDTO, error) {
	if err := os.MkdirAll(trashPath, 0o750); err != nil {
		return nil, err
	}
	dirEntries, err := os.ReadDir(trashPath)
	if err != nil {
		return nil, err
	}
	out := make([]TrashEntryDTO, 0, len(dirEntries))
	for _, entry := range dirEntries {
		info, err := entry.Info()
		if err != nil {
			continue
		}
		out = append(out, TrashEntryDTO{
			Name:       entry.Name(),
			Path:       filepath.Join(trashPath, entry.Name()),
			IsDir:      entry.IsDir(),
			Size:       info.Size(),
			ModifiedAt: info.ModTime().UTC().Format(time.RFC3339),
		})
	}
	return out, nil
}

func (a *App) OpenTrashFolder() error {
	if err := a.requireVault(); err != nil {
		return err
	}
	trashPath := filepath.Join(a.vault, ".verstak", "trash")
	if err := os.MkdirAll(trashPath, 0o750); err != nil {
		return err
	}
	return exec.Command("xdg-open", trashPath).Run()
}