package settings

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

// LoadActionWidgets reads and parses node-action-widgets.json from dir.
func LoadActionWidgets(dir string) (ActionWidgetStore, error) {
	path := filepath.Join(dir, NodeActionWidgetsFileName)
	payload, err := os.ReadFile(path)
	if err != nil {
		return ActionWidgetStore{}, err
	}

	var store ActionWidgetStore
	if err := json.Unmarshal(payload, &store); err != nil {
		return ActionWidgetStore{}, fmt.Errorf("parse action widgets: %w", err)
	}
	if store.Widgets == nil {
		store.Widgets = []ActionWidgetSnapshot{}
	}
	return store, nil
}

// LoadActionWidgetsOrEmpty returns an empty store when the file is missing.
func LoadActionWidgetsOrEmpty(dir string) (ActionWidgetStore, error) {
	store, err := LoadActionWidgets(dir)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return ActionWidgetStore{Widgets: []ActionWidgetSnapshot{}}, nil
		}
		return ActionWidgetStore{}, err
	}
	return store, nil
}

// SaveActionWidgets writes node-action-widgets.json to dir with mode 0640.
func SaveActionWidgets(dir string, store ActionWidgetStore) error {
	if err := ensureConfigDir(dir); err != nil {
		return err
	}
	if store.Widgets == nil {
		store.Widgets = []ActionWidgetSnapshot{}
	}

	payload, err := json.MarshalIndent(store, "", "  ")
	if err != nil {
		return fmt.Errorf("encode action widgets: %w", err)
	}
	payload = append(payload, '\n')

	path := filepath.Join(dir, NodeActionWidgetsFileName)
	return os.WriteFile(path, payload, 0o640)
}

// WidgetsForNode returns snapshots belonging to nodeID.
func WidgetsForNode(store ActionWidgetStore, nodeID string) []ActionWidgetSnapshot {
	out := make([]ActionWidgetSnapshot, 0)
	for _, widget := range store.Widgets {
		if widget.NodeID == nodeID {
			out = append(out, widget)
		}
	}
	return out
}

// UpsertActionWidgetSnapshot replaces or appends a snapshot keyed by node_id + item_id.
func UpsertActionWidgetSnapshot(dir string, snapshot ActionWidgetSnapshot) error {
	if strings.TrimSpace(snapshot.NodeID) == "" {
		return fmt.Errorf("node id is required")
	}
	if strings.TrimSpace(snapshot.ItemID) == "" {
		return fmt.Errorf("item id is required")
	}
	if snapshot.UpdatedAt.IsZero() {
		snapshot.UpdatedAt = time.Now().UTC()
	}

	store, err := LoadActionWidgetsOrEmpty(dir)
	if err != nil {
		return err
	}

	found := false
	for index := range store.Widgets {
		if store.Widgets[index].NodeID == snapshot.NodeID &&
			store.Widgets[index].ItemID == snapshot.ItemID {
			store.Widgets[index] = snapshot
			found = true
			break
		}
	}
	if !found {
		store.Widgets = append(store.Widgets, snapshot)
	}
	return SaveActionWidgets(dir, store)
}

// DeleteActionWidgetsForItem removes the snapshot for a node action item, if any.
func DeleteActionWidgetsForItem(dir string, nodeID string, itemID string) error {
	store, err := LoadActionWidgetsOrEmpty(dir)
	if err != nil {
		return err
	}
	filtered := make([]ActionWidgetSnapshot, 0, len(store.Widgets))
	changed := false
	for _, widget := range store.Widgets {
		if widget.NodeID == nodeID && widget.ItemID == itemID {
			changed = true
			continue
		}
		filtered = append(filtered, widget)
	}
	if !changed {
		return nil
	}
	store.Widgets = filtered
	return SaveActionWidgets(dir, store)
}