package pattern

import (
	"fmt"
	"gopkg.in/yaml.v3"
	"io/fs"
	"math"

	"gopkg.in/Knetic/govaluate.v3"
)

// DimensionID describe the ID of the dimension.
type DimensionID string

// Dimensions is a map with dimensions.
type Dimensions map[DimensionID]Dimension

// Parameters returns a govaluate.MapParameters object based on the dimensions.
func (d Dimensions) Parameters() govaluate.MapParameters {
	parameters := govaluate.MapParameters{}
	parameters["pi"] = math.Pi

	for id, dimension := range d {
		parameters[string(id)] = dimension.Value
	}

	return parameters
}

func (d Dimensions) Names(templateDir fs.FS) (map[string]string, error) {
	f, err := templateDir.Open("dimension_names.yaml")
	if err != nil {
		return nil, fmt.Errorf("open \"dimension_names.yaml\": %w", err)
	}

	namedDimensions := Dimensions{}

	err = yaml.NewDecoder(f).Decode(&namedDimensions)
	if err != nil {
		return nil, fmt.Errorf("decode yaml from \"dimension_names.yaml\": %w", err)
	}

	out := make(map[string]string)

	for id, dimension := range d {
		nd, ok := namedDimensions[id]
		if !ok {
			continue
		}

		value := math.Round(dimension.Value) / 10
		out[nd.Name] = fmt.Sprintf("%.1f mm", value)
	}

	return out, nil
}

// Dimension is a combination of a name and a value.
type Dimension struct {
	Name  string
	Value float64
}

// AddDimension adds a dimension to a pattern.
func (p *Pattern) AddDimension(id DimensionID, dimension Dimension) {
	p.dimensions[id] = dimension
}