package media

import "fmt"

// Kind classifies media for policy checks.
type Kind string

const (
	KindImage  Kind = "image"
	KindVideo  Kind = "video"
	KindAvatar Kind = "avatar"
)

// Violation describes an oversize resource (dimensions and/or bytes).
type Violation struct {
	Kind     Kind
	Reason   string
	Width    int
	Height   int
	MaxEdge  int
	Size     int64
	MaxSize  int64
	Duration int // ms; video only
}

func (v *Violation) Error() string {
	if v == nil {
		return ""
	}
	return fmt.Sprintf("media %s oversize: %s", v.Kind, v.Reason)
}

// Policy controls user-path detection (bots always compress via infrastructure/media).
type Policy struct {
	Enabled    bool // master switch for user checks
	UserReject bool // when true, publish/upload returns ErrMediaOversized; else log-only
	Limits     Limits
}

// CheckImageMeta validates declared image width/height/size against Limits.
// Zero width/height skips dimension check (client omitted); size 0 skips byte check.
func (p Policy) CheckImageMeta(w, h int, size int64) *Violation {
	return p.check(KindImage, w, h, size, 0)
}

// CheckVideoMeta validates declared video metadata.
func (p Policy) CheckVideoMeta(w, h int, size int64, durationMS int) *Violation {
	return p.check(KindVideo, w, h, size, durationMS)
}

// CheckAvatarMeta validates avatar dimensions/size (≤200×200 by default).
func (p Policy) CheckAvatarMeta(w, h int, size int64) *Violation {
	return p.check(KindAvatar, w, h, size, 0)
}

func (p Policy) check(kind Kind, w, h int, size int64, durationMS int) *Violation {
	if !p.Enabled {
		return nil
	}
	lim := p.Limits.Normalize()
	maxEdge, maxSize := lim.ImageMaxEdge, lim.ImageMaxBytes
	switch kind {
	case KindVideo:
		maxEdge, maxSize = lim.VideoMaxEdge, lim.VideoMaxBytes
	case KindAvatar:
		maxEdge, maxSize = lim.AvatarMaxEdge, lim.AvatarMaxBytes
	}
	if w > 0 && h > 0 && NeedsResize(w, h, maxEdge) {
		return &Violation{
			Kind: kind, Reason: "edge_exceeded",
			Width: w, Height: h, MaxEdge: maxEdge,
			Size: size, MaxSize: maxSize, Duration: durationMS,
		}
	}
	if size > 0 && maxSize > 0 && size > maxSize {
		return &Violation{
			Kind: kind, Reason: "size_exceeded",
			Width: w, Height: h, MaxEdge: maxEdge,
			Size: size, MaxSize: maxSize, Duration: durationMS,
		}
	}
	return nil
}