package installer

import (
	"errors"
	"fmt"
	"math"
)

var ErrInvalidLimits = errors.New("invalid ZIP extraction limits")

const (
	DefaultMaxEntries           = 10_000
	DefaultMaxUncompressedBytes = int64(4 * 1024 * 1024 * 1024)
	DefaultMaxCompressionRatio  = 200.0
)

// Limits bounds archive metadata and decompressed output.
type Limits struct {
	MaxEntries           int
	MaxUncompressedBytes int64
	MaxCompressionRatio  float64
}

func DefaultLimits() Limits {
	return Limits{
		MaxEntries:           DefaultMaxEntries,
		MaxUncompressedBytes: DefaultMaxUncompressedBytes,
		MaxCompressionRatio:  DefaultMaxCompressionRatio,
	}
}

func (limits Limits) validate() error {
	if limits.MaxEntries <= 0 {
		return fmt.Errorf("%w: MaxEntries must be positive", ErrInvalidLimits)
	}
	if limits.MaxUncompressedBytes <= 0 {
		return fmt.Errorf("%w: MaxUncompressedBytes must be positive", ErrInvalidLimits)
	}
	if limits.MaxCompressionRatio <= 0 ||
		math.IsNaN(limits.MaxCompressionRatio) ||
		math.IsInf(limits.MaxCompressionRatio, 0) {
		return fmt.Errorf("%w: MaxCompressionRatio must be finite and positive", ErrInvalidLimits)
	}
	return nil
}