// Package jsonv coerces values out of BYD's loosely typed JSON.
//
// The same field arrives as a JSON number in one response and a quoted string
// in the next, and absent fields arrive as null rather than being omitted, so
// every read goes through here rather than through a type assertion.
package jsonv

import (
	"fmt"
	"math"
	"strconv"
	"strings"
)

// Str renders a value as a string, mapping nil to "" rather than "<nil>".
func Str(v any) string {
	switch t := v.(type) {
	case nil:
		return ""
	case string:
		return t
	case float64:
		// JSON has no integers, so ids and codes arrive as float64. Exponent
		// notation would corrupt them ("1.23456789e+09" as a user id), so
		// integral values are rendered as integers.
		if t == math.Trunc(t) && math.Abs(t) < 1e15 {
			return strconv.FormatInt(int64(t), 10)
		}
		return strconv.FormatFloat(t, 'g', -1, 64)
	case bool:
		return strconv.FormatBool(t)
	default:
		return fmt.Sprint(v)
	}
}

// Num coerces a value to a float. It reports false for anything that is not a
// number, a bool, or a string holding a number.
func Num(v any) (float64, bool) {
	switch t := v.(type) {
	case float64:
		return t, true
	case bool:
		if t {
			return 1, true
		}
		return 0, true
	case string:
		f, err := strconv.ParseFloat(strings.TrimSpace(t), 64)
		return f, err == nil
	default:
		return 0, false
	}
}