package config

import (
	"fmt"
	"os"
	"strconv"
)

// v1.0.6: single source of truth for upload-size limits. Previously the same
// values were duplicated in track/service.go, handlers/upload.go,
// handlers/education_handler.go, apps/web/.../upload-modal/constants.ts, and
// apps/web/.../CloudUploadModal.tsx — a drift waiting to happen. The frontend
// now consumes these via GET /api/v1/upload/limits and the backend reads them
// from env with sane defaults.

const (
	// DefaultAudioMaxMB is the default upper bound for uploaded audio tracks.
	DefaultAudioMaxMB = 100
	// DefaultImageMaxMB is the default upper bound for cover art / avatars.
	DefaultImageMaxMB = 10
	// DefaultVideoMaxMB is the default upper bound for education videos.
	DefaultVideoMaxMB = 500
)

// UploadLimitMB represents a single category's limit and its environment
// variable override. The bytes form is the authoritative value used for
// validation; the human form is what we send back to the UI.
type UploadLimitMB struct {
	Category     string
	EnvVar       string
	DefaultMB    int
	AllowedMIMEs []string
}

// AudioLimit, ImageLimit, VideoLimit expose the category definitions used by
// both the upload handler and the track service. Values are resolved lazily
// from the environment (no global state) so config changes take effect on
// the next request without a rebuild.
var (
	AudioLimit = UploadLimitMB{
		Category:  "audio",
		EnvVar:    "MAX_UPLOAD_AUDIO_MB",
		DefaultMB: DefaultAudioMaxMB,
		AllowedMIMEs: []string{
			"audio/mpeg",
			"audio/mp3",
			"audio/wav",
			"audio/flac",
			"audio/aac",
			"audio/ogg",
			"audio/m4a",
		},
	}
	ImageLimit = UploadLimitMB{
		Category:     "image",
		EnvVar:       "MAX_UPLOAD_IMAGE_MB",
		DefaultMB:    DefaultImageMaxMB,
		AllowedMIMEs: []string{"image/jpeg", "image/png", "image/gif", "image/webp"},
	}
	VideoLimit = UploadLimitMB{
		Category:     "video",
		EnvVar:       "MAX_UPLOAD_VIDEO_MB",
		DefaultMB:    DefaultVideoMaxMB,
		AllowedMIMEs: []string{"video/mp4", "video/webm", "video/ogg", "video/avi"},
	}
)

// Bytes returns the category's current byte limit, honoring the env override.
// Invalid or negative env values fall back to the compile-time default.
func (l UploadLimitMB) Bytes() int64 {
	return int64(l.MB()) * 1024 * 1024
}

// MB returns the category's current megabyte limit, honoring the env override.
func (l UploadLimitMB) MB() int {
	if raw := os.Getenv(l.EnvVar); raw != "" {
		if v, err := strconv.Atoi(raw); err == nil && v > 0 {
			return v
		}
	}
	return l.DefaultMB
}

// HumanReadable renders the limit in "%dMB" form for UI consumption.
func (l UploadLimitMB) HumanReadable() string {
	return fmt.Sprintf("%dMB", l.MB())
}