package main

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

	"verstak/internal/core/nodes"
)

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"`
	TrashFsPath string `json:"trashFsPath"`
	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
	}
	// Phase 1: build all DTOs and compute direct trash paths for folder-type nodes.
	nodeMap := make(map[string]*TrashNodeDTO, len(deleted))
	var allDeleted []nodes.Node
	for _, n := range deleted {
		allDeleted = append(allDeleted, n)
	}
	for _, n := range allDeleted {
		deletedAt := ""
		if n.DeletedAt != nil {
			deletedAt = n.DeletedAt.Format(time.RFC3339)
		}
		parentID := ""
		if n.ParentID != nil {
			parentID = *n.ParentID
		}
		dto := &TrashNodeDTO{
			ID:        n.ID,
			ParentID:  parentID,
			Title:     n.Title,
			Type:      n.Type,
			FsPath:    n.FsPath,
			NodePath:  a.nodes.Path(n.ID),
			DeletedAt: deletedAt,
		}
		nodeMap[n.ID] = dto
		// Try direct trash entry (for folders that were os.Rename'd).
		if p, err := a.findTrashEntryForNode(n.ID); err == nil {
			dto.TrashFsPath = p
		}
	}
	// Phase 2: propagate trash paths from parents to children that have no direct entry
	// but whose FsPath starts with the parent's FsPath.
	changed := true
	for changed {
		changed = false
		for _, n := range allDeleted {
			dto := nodeMap[n.ID]
			if dto.TrashFsPath != "" {
				continue
			}
			parentID := ""
			if n.ParentID != nil {
				parentID = *n.ParentID
			}
			if parentID == "" {
				continue
			}
			parent := nodeMap[parentID]
			if parent == nil || parent.TrashFsPath == "" {
				continue
			}
			// Child inherits parent's trash path + relative FsPath fragment.
			if n.FsPath != "" && parent.FsPath != "" && strings.HasPrefix(n.FsPath, parent.FsPath) {
				rel := strings.TrimPrefix(n.FsPath, parent.FsPath)
				rel = strings.TrimPrefix(rel, "/")
				if rel != "" {
					dto.TrashFsPath = filepath.Join(parent.TrashFsPath, rel)
					changed = true
				}
			}
		}
	}

	nodes := make([]TrashNodeDTO, 0, len(deleted))
	for _, dto := range nodeMap {
		nodes = append(nodes, *dto)
	}

	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) ReadTrashFileContent(nodeID string) (string, error) {
	if err := a.requireVault(); err != nil {
		return "", err
	}
	path, err := a.resolveTrashPath(nodeID)
	if err != nil {
		return "", err
	}
	data, err := os.ReadFile(path)
	if err != nil {
		return "", err
	}
	return string(data), nil
}

// resolveTrashPath finds the physical path of a deleted node's file in the trash.
// For directly-moved entries (folders), it looks up <nodeID>_* in trash dir.
// For nested files (moved as part of a parent folder), it walks up the ancestor
// chain until it finds a folder with a direct trash entry, then appends the
// relative filesystem path.
func (a *App) resolveTrashPath(nodeID string) (string, error) {
	// 1. Try direct lookup first (for nodes that were individually moved).
	if p, err := a.findTrashEntryForNode(nodeID); err == nil {
		return p, nil
	}
	// 2. Walk parent chain to find nearest ancestor with a direct trash entry.
	type step struct {
		ID     string
		FsPath string
		Title  string
	}
	var chain []step
	current := nodeID
	for current != "" {
		n, err := a.nodes.Get(current)
		if err != nil {
			break
		}
		chain = append(chain, step{ID: n.ID, FsPath: n.FsPath, Title: n.Title})
		if n.ParentID != nil {
			current = *n.ParentID
		} else {
			current = ""
		}
	}
	// chain[0] = the node itself, chain[len-1] = topmost ancestor.
	// Walk from closest ancestor outward to find a trash entry.
	for i := 0; i < len(chain); i++ {
		anc := chain[i]
		ancPath, err := a.findTrashEntryForNode(anc.ID)
		if err != nil {
			continue
		}
		// Build the relative path from this ancestor down to the original node.
		// The node at index 0 is the target; any step between anc and index 0
		// contributes a subdirectory name.
		// We walk from anc up to target (index 0), collecting FsPath segments.
		var relSegments []string
		for j := 0; j < i; j++ {
			child := chain[j]
			if child.FsPath != "" && anc.FsPath != "" && strings.HasPrefix(child.FsPath, anc.FsPath) {
				rel := strings.TrimPrefix(child.FsPath, anc.FsPath)
				rel = strings.TrimPrefix(rel, "/")
				if rel != "" {
					relSegments = append(relSegments, rel)
				} else if child.Title != "" {
					relSegments = append(relSegments, child.Title)
				}
			} else if child.Title != "" {
				relSegments = append(relSegments, child.Title)
			}
			anc = child
		}
		fullPath := ancPath
		if len(relSegments) > 0 {
			fullPath = filepath.Join(ancPath, filepath.Join(relSegments...))
		}
		if info, err := os.Stat(fullPath); err == nil && !info.IsDir() {
			return fullPath, nil
		}
	}
	// 3. Fallback: try node title as filename inside each ancestor's trash dir.
	for _, anc := range chain {
		ancPath, err := a.findTrashEntryForNode(anc.ID)
		if err != nil {
			continue
		}
		fi, err := os.Stat(ancPath)
		if err != nil || !fi.IsDir() {
			continue
		}
		// Try the node's title as a direct child file inside the ancestor dir.
		candidate := filepath.Join(ancPath, chain[0].Title)
		if info, err := os.Stat(candidate); err == nil && !info.IsDir() {
			return candidate, nil
		}
	}
	return "", fmt.Errorf("trash file not found for node %s", nodeID)
}

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()
}