package logic

import (
	"context"
	"fmt"
	"io"
	"net/http"
	"strings"
	"time"

	infmedia "spark-server/internal/infrastructure/media"
	pkgmedia "spark-server/internal/pkg/media"
)

const maxDownloadBytes = 80 << 20 // refuse absurd remote blobs before compress

// MediaCompressor downloads remote media and compresses to App-aligned specs before objectstore write.
// Square bot RSS worker should call FetchImage / FetchVideo instead of raw HTTP+Put.
type MediaCompressor struct {
	Opt    infmedia.Options
	Client *http.Client
}

// NewMediaCompressor builds a compressor; ffmpegPath may be empty (defaults to "ffmpeg").
func NewMediaCompressor(lim pkgmedia.Limits, jpegQuality, videoCRF int, ffmpegPath string) *MediaCompressor {
	return &MediaCompressor{
		Opt: infmedia.OptionsFromLimits(lim, jpegQuality, videoCRF, ffmpegPath),
		Client: &http.Client{
			Timeout: 60 * time.Second,
		},
	}
}

// FetchImage GETs url and compresses to ≤1080p JPEG/PNG.
func (c *MediaCompressor) FetchImage(ctx context.Context, url string) (*infmedia.BotAsset, error) {
	raw, err := c.download(ctx, url)
	if err != nil {
		return nil, err
	}
	return infmedia.PrepareBotImage(raw, &c.Opt)
}

// FetchAvatar GETs url and compresses to ≤200×200.
func (c *MediaCompressor) FetchAvatar(ctx context.Context, url string) (*infmedia.BotAsset, error) {
	raw, err := c.download(ctx, url)
	if err != nil {
		return nil, err
	}
	return infmedia.PrepareBotAvatar(raw, &c.Opt)
}

// FetchVideo GETs url and compresses to ≤720p (requires ffmpeg).
func (c *MediaCompressor) FetchVideo(ctx context.Context, url string) (*infmedia.BotAsset, error) {
	raw, err := c.download(ctx, url)
	if err != nil {
		return nil, err
	}
	return infmedia.PrepareBotVideo(ctx, raw, &c.Opt)
}

// CompressBytesImage compresses already-downloaded image bytes (e.g. RSS enclosure already fetched).
func (c *MediaCompressor) CompressBytesImage(src []byte) (*infmedia.BotAsset, error) {
	return infmedia.PrepareBotImage(src, &c.Opt)
}

// CompressBytesVideo compresses already-downloaded video bytes.
func (c *MediaCompressor) CompressBytesVideo(ctx context.Context, src []byte) (*infmedia.BotAsset, error) {
	return infmedia.PrepareBotVideo(ctx, src, &c.Opt)
}

func (c *MediaCompressor) download(ctx context.Context, url string) ([]byte, error) {
	url = strings.TrimSpace(url)
	if url == "" {
		return nil, fmt.Errorf("squarebot media: empty url")
	}
	client := c.Client
	if client == nil {
		client = http.DefaultClient
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}
	req.Header.Set("User-Agent", "SparkIM-SquareBot/1.0")
	res, err := client.Do(req)
	if err != nil {
		return nil, err
	}
	defer func() { _ = res.Body.Close() }()
	if res.StatusCode < 200 || res.StatusCode >= 300 {
		return nil, fmt.Errorf("squarebot media: http %d", res.StatusCode)
	}
	data, err := io.ReadAll(io.LimitReader(res.Body, maxDownloadBytes+1))
	if err != nil {
		return nil, err
	}
	if len(data) > maxDownloadBytes {
		return nil, fmt.Errorf("squarebot media: download too large")
	}
	if len(data) == 0 {
		return nil, fmt.Errorf("squarebot media: empty body")
	}
	return data, nil
}