package lulu

import (
	"encoding/json"
	"fmt"
	"strconv"
)

//go:generate go run github.com/yawnak/string-enumer -t Unit --text -o ./cover_gen.go .

// Unit is a unit of length measurement.
type Unit string

const (
	Points      Unit = "pt"
	Millimeters Unit = "mm"
	Inches      Unit = "inch"
)

// coverDimensionsReq is the json body of a /cover-dimensions/ request.
type coverDimensionsReq struct {
	PkgId  PkgId `json:"pod_package_id"`
	NPages uint  `json:"interior_page_count"`
	Unit   Unit  `json:"unit"`
}

type CoverDimensions struct {
	Width, Height float64
	Unit          Unit
}

func (cd *CoverDimensions) UnmarshalJSON(data []byte) error {
	s := string(data)
	var alias struct {
		Width, Height string
		Unit          Unit
	}
	if err := json.Unmarshal(data, &alias); err != nil {
		return fmt.Errorf("malformed %T: %q: %w", cd, s, err)
	}

	w, err := strconv.ParseFloat(alias.Width, 64)
	if err != nil {
		return fmt.Errorf("malformed %T.Width: %q: %w", cd, s, err)
	}
	h, err := strconv.ParseFloat(alias.Height, 64)
	if err != nil {
		return fmt.Errorf("malformed %T.Height: %q: %w", cd, s, err)
	}

	cd.Width = w
	cd.Height = h
	cd.Unit = alias.Unit
	return nil
}