package store

import (
	"context"
	"encoding/json"
	"errors"
	"strconv"
)

// View colours only change how the web UI shows a view, so they are kept
// outside the configuration: setting one needs no changeset or deploy.
const viewColorsKey = "view_colors"

// ViewColors returns the colour of each view that has one, by view ID.
func (s *Store) ViewColors(ctx context.Context) (map[int64]string, error) {
	out := map[int64]string{}
	raw, err := s.GetMeta(ctx, viewColorsKey)
	if errors.Is(err, ErrNotFound) {
		return out, nil
	}
	if err != nil {
		return nil, err
	}
	var m map[string]string
	if err := json.Unmarshal([]byte(raw), &m); err != nil {
		return nil, err
	}
	for k, v := range m {
		if id, err := strconv.ParseInt(k, 10, 64); err == nil {
			out[id] = v
		}
	}
	return out, nil
}

// SetViewColor sets a view's colour; "" removes it. View IDs are never
// reused, so the colour of a deleted view is harmless and is left alone
// (the view may still exist in a changeset).
func (s *Store) SetViewColor(ctx context.Context, id int64, color string) error {
	m, err := s.ViewColors(ctx)
	if err != nil {
		return err
	}
	if color == "" {
		delete(m, id)
	} else {
		m[id] = color
	}
	out := map[string]string{}
	for k, v := range m {
		out[strconv.FormatInt(k, 10)] = v
	}
	b, _ := json.Marshal(out)
	return s.SetMeta(ctx, viewColorsKey, string(b))
}