package rrdbinary

import (
	"encoding/binary"
	"encoding/json"
	"math"
)

type Architecture struct {
	ByteOrder binary.ByteOrder
	// C `double`
	DoubleWidth int // always 8 -- we assume IEEE 754 doubles
	DoubleAlign int
	// C `long` or `unsigned long`
	LongWidth int
	LongAlign int
	// C `union { unsigned long; double; }`
	UnivalWidth int // max(DoubleWidth, LongWidth)
	UnivalAlign int // max(DoubleAlign, LongAlign)
	// C `time_t`
	TimeWidth int
	TimeAlign int
}

type String string  // \0-terminated
type Double float64 // 8 bytes
type ULong uint64   // 4 or 8 bytes
type Long int64     // 4 or 8 bytes
type Unival uint64  // 8 bytes
type Time int64     // 4 or 8 bytes, only has second-precision
type EOF struct{}   // 0 bytes

func (u Unival) AsUint64() uint64   { return uint64(u) }
func (u Unival) AsFloat64() float64 { return math.Float64frombits(uint64(u)) }

// MarshalJSON is for my own debugging.
func (f Double) MarshalJSON() ([]byte, error) {
	raw := float64(f)
	if math.IsNaN(raw) {
		return json.Marshal("NaN")
	}
	return json.Marshal(raw)
}

// Statically assert that each of the above types implements the
// 'unmarshaler' interface.
var _ unmarshaler = func() *String { return nil }()
var _ unmarshaler = func() *Double { return nil }()
var _ unmarshaler = func() *ULong { return nil }()
var _ unmarshaler = func() *Long { return nil }()
var _ unmarshaler = func() *Unival { return nil }()
var _ unmarshaler = func() *Time { return nil }()
var _ unmarshaler = func() *EOF { return nil }()